WO2005062422A1

WO2005062422A1 - Multi-band, broadband, fully-planar antennas

Info

Publication number: WO2005062422A1
Application number: PCT/AU2004/001810
Authority: WO
Inventors: Karunanayake Pathirannahalage Asoka Priyathama Esselle; Yuehe Ge
Original assignee: Macquarie University
Priority date: 2003-12-23
Filing date: 2004-12-23
Publication date: 2005-07-07

Abstract

Antennas (200) and methods of manufacturing and using such antennas are disclosed. In one aspect, an antenna (200) comprises first and second bent metal strips (230, 232) for radiating energy, a feedline (220) coupled to the first and second strips (230, 232), and a truncated groundplane (212) adjacent to the feedline (220). The groundplane (212) is truncated at or near a point where the feedline (220) is coupled to the first metal strip or the second metal strip. The first metal strip (230) bends around the second metal strip (232), leaving a separation (d) of at least 0.025 guided wavelengths at a mid-frequency of a low band between the metal strips (230, 232) for a substantial portion of the length of the first metal strip (230). The metal strips (230, 232) is laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band. The feedline (220) and at least one of the first and second metal strips (230, 232) are co-planar.

Description

MULTI-BAND, BROADBAND, FULLY-PLANAR ANTENNAS

FIELD OF THE INVENTION The present invention relates generally to antennas for use with radio frequency (RF) transceivers and in particular to compact broadband, multi-band antennas for wireless communications.

BACKGROUND Wireless communications is rapidly expanding area of technology. Cellular telephones, portable computers, handheld computers, and numerous other wireless communications devices are used by ever-increasing numbers of people and have become ubiquitous. A corresponding trend is that such equipment is becoming more compact and often lighter. With reduced equipment sizes has grown a need for more compact antennas for use in cellular communications and other wireless technologies, such as Personal Communications Services (PCS), Bluetooth, IEEE 802.11 Wireless Local Area Networks (WLAN, also called Wi-Fi or "wireless Ethernet") family (e.g., 802.1 la, 802.1 lb, 802.1 lg, 802.1 lj), HIPERLAN Wireless Local Area Networks family, Global Positioning System (GPS) and other emerging standards such as WiMax and UWB. Further, there has been a trend to internalize the antennas within the equipment to the extent possible, rather than have the antennas be separate, protruding elements of the equipment. Along with these developments has been the emergence of multi-band or broadband communications networks imposing additional requirements on the antenna design. For example, cellular phones in Global System for Mobile Communication (GSM) were initially single band (900 MHz), then dual-band (900 MHz, 1800 MHz), and now are tri-band (900 MHz, 1800 MHz, 1900 MHz) communications devices. For operation in different countries over different communication standards, some cellular phones need to cover even more frequency bands, for example 900 MHz (GSM), 1800 MHz (DCS), 1900 MHz (PCS) and 2050 MHz (UMTS). Similarly, for global universal operation using multiple standards, wireless transceivers in wireless local area networks (LAN) must operate over multiple bands, for example 2.4-2.5 GHz (802.1 lb and 802.1 lg), 4.9-5.1 GHz (802.11J in Japan), 5.15-5.35 GHz (802.1 la U-NII lower and middle bands in USA), and 5.725-5.825 GHz (802.1 la U-NII upper band in USA etc.). Antennas that have been proposed for some of these applications include printed, monopole antennas with a truncated ground plane. However, such an antenna has only a single-band and is quite long, which militates against use in compact applications requiring multiband or broadband communications. Also, printed F and double-T antennas have been proposed with a truncated ground plane, but these antennas are still quite large and may not be broadband enough to cover all frequency bands. Patch radiators with a narrow slot, or slit, of uniform width have been proposed for 0.9 GHz and 2 GHz mobile phone bands. In this frequency range, the slot width is 0.5mm or 0.003 guided wavelengths at the mid-frequency of the low band and the antenna area is 360 square millimeters or about 0.014 square guided wavelengths at the same frequency. However, the antenna return loss is less than 10 dB at some frequencies in the low band. See Wong, Lee and Chiou, "A Low-Profile Planar Monopole Antenna for Multiband Operation of Mobile Handsets", IEEE Transactions on Antennas and Propagation, Vol. 51, No. 1, January 2003, pp. 121 - 125. A chip antenna involves a piece of dielectric of specific shape, a metal pattern on/in the dielectric chip and a connection between the metal pattern on or in the chip and a feed line on a substrate. However, such an antenna cannot be made entirely using standard printed circuit fabrication technology. Further, chip antennas cannot be printed or etched directly on the circuit board or substrate that contains other components of the transceiver. Instead, the chip antennas need to be fabricated separately and be mounted on to the circuit board using surface mount technology or other means. The "chip" or the dielectric volume is fabricated to the required shape by cutting or other ways. One or more metal connectors are required on side edge surfaces of the "chip" to connect the metal pattern on or in the chip to the feedline on the circuit board. Lee, G Y, Chen W S, and Wong K L, "A Dual-Frequency Triangular Chip Antenna for WLAN Operation", Microwave and Optical Technology Letters, Vol. 38, No. 3, 5 August 2003, pp. 244-247, propose a triangular chip antenna with a spiral slit of uniform width in a triangular patch. The chip of 1.6 mm height is mounted on a substrate of 0.8 mm thickness; therefore, the total height of the antenna is 2.4mm. A metal strip is formed on one side edge surface of the chip to connect the metal pattern on the chip to a feedline on the substrate. European Patent Application Publication No. EP 1414109 A2 entitled "Dual band single feed dipole antenna and method of making the same" published on 28 April 2004 in the name of Centurion Wireless Technologies, Inc. (Shanmuganthan Suganthan and Nladimir Stoiljkovic) and a conference paper by N. Stoiljkovic, S. Suganthan, and M. Benhaddou, "A Novel Dual-Band Centre-Fed Printed Dipole Antenna", IEEE Antenna and Propagation Society International Symposium, Vol. 2, 22-27, June 2003, pp. 938-941 describe an antenna that has printable radiating elements and a coaxial feedline. The conference paper describes a dual-band WLAN antenna that works at 2.4-2.5 GHz and 5.15-5.35 GHz. The dimensions of the antenna are 50 mm by 20 mm. Using the mid-frequency of the lower band as 2.45 GHz, the guided wavelength at this frequency is 58.4 mm. Thus, the area of the antenna is 0.29 square guided wavelengths at the mid-frequency of the lower operating band. This antenna is large in the size and is not optimized for electromagnetic mutual coupling between the printed elements to reduce size. This antenna has a large area in terms of square-guided wavelengths at the lowest operating frequency, as indicated in the conference paper.

SUMMARY In accordance with an aspect of the invention, there is provided an antenna, comprising: a first bent metal strip for radiating energy; a second bent metal strip for radiating energy connected to the first metal strip, the first metal strip bending around the second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the metal strips for a substantial portion of the length of the first metal strip, the metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band; a feedline coupled to at least one of the first and second bent metal strips, the feedline and at least one of the first and second metal strips being co-planar; and at least one truncated groundplane adjacent to the feedline, the at least one groundplane being truncated at or near a point where the feedline is coupled to the first metal strip or the second metal strip. The feedline, the first metal strip and the second metal strip may be co-planar. The truncated ground plane may be co-planar with the first metal strip, the second metal strip, and the feedline. The antenna may further comprise insulation material joining the truncated ground plane, the first metal strip, the second metal strip, and the feedline together. The antenna may further comprise at least one more truncated groundplane adjacent to the feedline, the groundplanes being truncated at or near a point where the feedline is coupled to the first metal strip, the second metal strip, or both. The antenna may further comprise a dielectric substrate, wherein the first metal strip, the second metal strip, and the feedline are foraied on planar surfaces of the dielectric substrate. The truncated ground plane may be disposed on the same planar surface of the dielectric substrate relative to the feedline. Alternatively, the truncated ground plane may be disposed on an opposite planar surface of the dielectric substrate relative to the feedline. The truncated ground plane may have an edge substantially parallel to an edge of the dielectric substrate. The truncated ground plane may have an edge substantially diagonal relative to two edges of the dielectric substrate. The dielectric substrate may be a multi-layer microwave substrate. At least two truncated groundplanes may be on different dielectric layer surfaces. The antenna may further comprise a plated via formed through the substrate coupling the first and second metal strips, the first and second metal strips being formed on opposite planar surfaces of the dielectric substrate. The truncated ground plane may be co-planar with the feedline. The antenna may be manufactured using standard microstrip circuit fabrication methods. The total resonance length of each metal strip is about one-quarter, free-space wavelength long at a mid-frequency of a predetermined frequency range. The total resonance length of each metal strip may be about one half guided wavelengths long at a mid-frequency of a predetermined frequency range. The total resonance length of each metal strip may be about 0.35 guided wavelengths to about 0.55 guided wavelengths long at a mid-frequency of a predetermined frequency range. The metal strips have an overall layout of: a G-shape; an arcuate shape; a substantially circular shape; a G-shape with oppositely projecting stubs forming terminal ends of the metal strips; and a substantially triangular shape. The metal strips may have stubs extending orthogonally from the respective terminal portion of the metal strips. At least one of the first and second metal strips may comprise a tapered section of metal matching the width of the at least one metal strip to the width of the feedline. The antenna may further comprise: a third bent metal strip for radiating energy coupled to at least one of the first and second metal strips; and a fourth metal strip for radiating energy coupled to one of the first, second and third metal strips, the third and fourth metal strips being separated from each other for substantial portions of their lengths, a portion of at least one of the third and fourth metal strips partially surrounding a portion of at least the other one of the third and fourth metal strip, the first, second, third and fourth metal strips and the feedline being co-planar. The antenna may be a multi-band and broadband, fully planar antenna. The antenna may further comprise a reflector coupled to the antenna. In accordance with a further aspect of the invention, there is provided multi- band antenna system comprising: at least two antennas, each comprising: a first bent metal strip for radiating energy; a second bent metal strip for radiating energy connected to the first metal strip, the first metal strip bending around the second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the metal strips for a substantial portion of the length of the first metal strip, the metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band; a feedline coupled to at least one of the first and second bent metal strips, the feedline and at least one of the first and second metal strips being co-planar; and at least one truncated groundplane adjacent to the feedline, the at least one groundplane being truncated at or near a point where the feedline is coupled to the first metal strip or the second metal strip. hi accordance with another aspect of the invention, there is provided wireless electronic apparatus. The apparatus comprises: a housing; an RF circuit disposed within the housing; at least one antenna coupled to the RF circuit and disposed within the housing, the antenna comprising: a first bent metal strip for radiating energy; a second bent metal strip for radiating energy connected to the first metal strip, the first metal strip bending around the second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the metal strips for a substantial portion of the length of the first metal strip, the metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid- frequency of the low band; a feedline coupled to at least one of the first and second bent metal strips, the feedline and at least one of the first and second metal strips being co-planar; and at least one truncated groundplane adjacent to the feedline, the at least one groundplane being truncated at or near a point where the feedline is coupled to the first metal strip or the second metal strip. The apparatus may be: a cellular telephone; a wireless LAN card; a PC wireless LAN card; a PCMCIA wireless LAN card; a Cardbus wireless LAN card; a Wi-Fi wireless LAN card; a WiMax wireless communication card; a multi-standard wireless communication card; a computer; a printer; a wireless mouse; a computer peripheral; a PDA; an electronic organizer; an electronic memory device; an electronic or optical storage device; a wireless LAN access point; a cellular telephone base-station; a wireless game controller; a wireless security device; a home appliance with wireless interface; a wireless headset; a wireless communication PCI card; a USB-connected device with wireless interface; a wireless network integration (NIC) card; a SDIO card with wireless interface; a camera with a wireless interface; a video camera with a wireless interface; a multi-purpose device with a wireless interface; or an electronic device with a wireless interface. In accordance with yet another aspect of the invention, there is provided antenna, comprising: a plurality of radiating elements, each radiating element comprising a first bent metal strip for radiating energy, and a second bent metal strip for radiating energy connected to the first metal strip, the first metal strip bending around the second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band for the radiating element between the metal strips for a substantial portion of the length of the first metal strip, the metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band for the radiating element; at least one feedline coupled to the radiating elements, at least one of the radiating elements and the at least one feedline being co-planar; and at least one truncated groundplane adjacent to the feedline, the groundplane being truncated at or near a point where the feedline is coupled to at least one of the first and second metal strips. The truncated ground plane may be co-planar with the feedline. The antenna may further comprise insulation material joining the truncated ground plane, the radiating elements and the feedline together. The antenna may further comprise a dielectric substrate, the radiating elements and the feedline being formed on at least one planar surface of the dielectric substrate. The truncated ground plane may be disposed on the same planar surface of the dielectric substrate as the feedline. Alternatively, the truncated ground plane may be disposed on an opposite planar surface of the dielectric substrate relative to the feedline. The truncated ground plane is co-planar with the feedline. The antenna may further comprise at least one plated via through the substrate coupling at least two of the radiating elements formed on opposite planar surfaces of the dielectric substrate. The antenna may be manufactured using standard microstrip circuit fabrication methods. The total resonance length of each metal strip may be about one-quarter, free- space wavelength long at a mid-frequency of a predetermined frequency range for the radiating element. The total resonance length of each metal strip may be about one half guided wavelengths long at a mid-frequency of a predetermined frequency range for the radiating element. The total resonance length of each metal strip may be about 0.35 guided wavelengths to about 0.55 guided wavelengths long at a mid-frequency of a predetermined frequency range for the radiating element. The antenna may further comprise three radiating elements and two dielectric substrates, one of the radiating elements disposed on a top surface of a first dielectric substrate, another of the radiating elements disposed on a bottom surface of a second dielectric substrate, and the remaining radiating element disposed on at least one of a bottom surface of the first dielectric substrate and a top surface of the second dielectric substrate. The antenna may further comprise at least one plated via through the substrates coupling the three radiating elements. The plurality of radiating elements may be arranged substantially linearly in at least one dimension. Each radiating element may be disposed in a corner of a dielectric substrate in at least one dimension. The radiating element may be triangularly shaped in overall form. The truncated groundplane may have diagonal edges demarcating the corners without the groundplane beneath the radiating elements, the corners being triangular in form. The antenna may further comprise a plurality of dielectric substrates, the radiating elements disposed on at least two surfaces of the plurality of substrates. The radiating elements may have at least two sizes. The radiating elements may have different configurations. The radiating elements may be each disposed along a line. The radiating elements may each be disposed along a curve. The radiating elements may each be disposed on a planar surface. The radiating elements may each be disposed on a curved surface. The radiating elements may be uniformly spaced. The radiating elements may be non-uniformly spaced. The antenna may further comprise a reflector coupled to the antenna. In accordance with a further aspect of the invention, there is provided a wireless electronic apparatus. The apparatus comprises: a housing; an RF circuit disposed within the housing; an antenna coupled to the RF circuit and disposed within the housing, the antenna comprising: a plurality of radiating elements, each radiating element comprising a first bent metal strip for radiating energy, and a second bent metal strip for radiating energy connected to the first metal strip, the first metal strip bending around the second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band for the radiating element between the metal strips for a substantial portion of the length of the first metal strip, the metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band for the radiating element; at least one feedline coupled to the radiating elements, at least one of the radiating elements and the at least one feedline being co- planar; and at least one truncated groundplane adjacent to the feedline, the groundplane being truncated at or near a point where the feedline is coupled to at least one of the first and second metal strips. The apparatus may be: a cellular telephone; a wireless LAN card; a PC wireless LAN card; a PCMCIA wireless LAN card; a computer; a printer; a wireless mouse; a computer peripheral; a PDA; an electronic organizer; an electronic memory device; an electronic or optical storage device; a wireless LAN access point; a cellular telephone base-station; a wireless game controller; a wireless security device; a wireless home appliance; a wireless headset; a wireless PCI card; a wireless USB-connected device; a wireless network integration (NIC) card; a camera with a wireless interface; a video camera with a wireless interface; a multi-purpose device with a wireless interface; or an electronic device with a wireless interface. hi accordance with still a further aspect of the invention, there is provided an multi-band antenna system, comprising: two or more antennas each comprising: a plurality of radiating elements, each radiating element comprising a first bent metal strip for radiating energy, and a second bent metal strip for radiating energy connected to the first metal strip, the first metal strip bending around the second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band for the radiating element between the metal strips for a substantial portion of the length of the first metal strip, the metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band for the radiating element; at least one feedline coupled to the radiating elements, at least one of the radiating elements and the at least one feedline being co- planar; and at least one truncated groundplane adjacent to the feedline, the groundplane being truncated at or near a point where the feedline is coupled to at least one of the first and second metal strips. hi accordance with another aspect of the invention, there is provided an antenna, comprising: a feedline; and a metal sheet coupled to the feedline, the metal sheet having a first bent metal slot for radiating energy formed therein and a second bent metal slot for radiating energy foπned therein and coupled to the first radiating slot, the first slot bending around the second slot, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the slots for a substantial portion of the length of the first slot, the slots being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band. The antenna may further comprise a reflector coupled to the antenna, hi accordance with still another aspect of the invention, there is provided a wireless electronic apparatus. The apparatus comprises: a housing; an RF circuit disposed within the housing; an antenna coupled to the RF circuit and disposed within the housing, the antenna comprising: a feedline; and a metal sheet coupled to the feedline, the metal sheet having a first bent metal slot for radiating energy formed therein and a second bent metal slot for radiating energy formed therein and coupled to the first radiating slot, the first slot bending around the second slot, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the slots for a substantial portion of the length of the first slot, the slots being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band.

The apparatus may be: a cellular telephone; a wireless LAN card; a PC wireless LAN card; a PCMCIA wireless LAN card; a computer; a printer; a wireless mouse; a computer peripheral; a PDA; an electronic organizer; an electronic memory device; an electronic or optical storage device; a wireless LAN access point; a cellular telephone base-station; a wireless game controller; a wireless security device; a wireless home appliance; a wireless headset; a wireless PCI card; a wireless USB-connected device; a wireless network integration (NIC) card; a camera with a wireless interface; a video camera with a wireless interface; a multi-purpose device with a wireless interface; or an electronic device with a wireless interface. hi accordance with a further aspect of the invention, there is provided a multi- band antenna system comprising: two or more antennas each comprising: a feedline; and a metal sheet coupled to the feedline, the metal sheet having a first bent metal slot for radiating energy formed therein and a second bent metal slot for radiating energy formed therein and coupled to the first radiating slot, the first slot bending around the second slot, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the slots for a substantial portion of the length of the first slot, the slots being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band In accordance with another aspect of the invention, there is provided a method of manufacturing an antenna. The method comprises the steps of: forming a first bent metal strip for radiating energy; forming a second bent metal strip for radiating energy connected to the first metal strip, the first metal strip bending around the second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the metal strips for a substantial portion of the length of the first metal strip, the metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band; forming a feedline coupled to the first and second strips, the feedline and at least one of the first and second metal strips being co-planar; and fonning at least one truncated groundplane adjacent to the feedline, the groundplanes being truncated at or near a point where the feedline is coupled to the first metal strip or the second metal strip. The method may further comprise the step of providing a planar, dielectric substrate, wherein the first metal strip, the second metal strip, and the feedline are formed on at least one surface of the dielectric substrate. All metal components may be on the two surfaces of the dielectric substrate. The total resonance length of each metal strip may be about one-quarter, free- space wavelength long at a mid-frequency of a predetermined frequency range. The total resonance length of each metal strip may be about one half guided wavelengths long at a mid-frequency of a predetermined frequency range. The total resonance length of each metal strip may be about 0.35 guided wavelengths to about 0.55 guided wavelengths long at a mid-frequency of a predetermined frequency range. The metal strips have a layout of: G-shape; an arcuate shape; substantially circular shape; G-shape with oppositely projecting stubs forming terminal ends of the metal strips; or a substantially triangular shape. The method may further comprise the steps of: forming a third bent metal strip for radiating energy coupled to at least one of the first metal strip and the second strip; and forming a fourth metal strip for radiating energy coupled to one of the first, second and third metal strips, the third and fourth metal strips being separated from each other for substantial portions of their lengths, a portion of at least one of the third and fourth metal strips partially surrounding a portion of at least the other one of the third and fourth metal strip, the first, second, third and fourth metal strips and the feedline being co-planar. In accordance with still another aspect of the invention, there is provided method of using an antenna. The method comprises the steps of: feeding RF energy via a feedline to first and second bent metal strips, the feedline and at least one of the first and second metal strips being co-planar, at least one truncated groundplane being adjacent to the feedline, the groundplane being truncated at or near a point where the feedlme is coupled to the first metal strip or the second metal strip; radiating the RF energy using the first bent metal strip; and radiating the RF energy using the second bent metal strip connected to the first metal strip, the first metal strip bending around the second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the metal strips for a substantial portion of the length of the first metal strip, the metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band. The method may further comprise the steps of: radiating the RF energy via a third bent metal strip coupled to at least one of the first and second bent metal strips; and radiating the RF energy via a fourth metal strip coupled to one of the first, second and third metal strips, the third and fourth metal strips being separated from each other for substantial portions of their lengths, a portion of at least one of the third and fourth metal strips partially surrounding a portion of at least the other one of the third and fourth metal strip, the first, second, third and fourth metal strips and the feedline being co-planar. In accordance with another aspect of the invention, there is provided an antenna, comprising: a first multi-band radiating element comprising a first bent metal strip for radiating energy, a second bent metal strip for radiating energy connected to the first metal strip, the first bent metal strip bending around the second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the metal strips for a substantial portion of the length of the first metal strip, the metal strips being laid out over an area in the range of 0.025 to 0.045 square guided wavelengths at a mid-frequency of the low band; a second multi-band radiating element that is similar to a mirror image of the first multi-band radiating element to form a dipole together with the first multi-band radiating element by supporting currents of opposite polarity to those in the first multi-band radiating element; and a feedline coupled to the first and second multi-band radiating elements. hi accordance with still another aspect of the invention, there is provided an antenna, comprising: first means for radiating energy; second means for radiating energy coupled to the first radiating means, the first radiating means bending around the second radiating means, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between the first and second radiating means for a substantial portion of the length of the first radiating means, the radiating means being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at the mid-frequency of the low band; and means for feeding RF energy to the first and second radiating means, the RF feeding means and at least one of the first and second radiating means being co- planar. The antenna may further comprise means for providing at least one truncated groundplane adjacent to RF energy feeding means. In accordance with yet another aspect of the invention, there is provided an method of installing in an electronic device with a conducting case a printed circuit board comprising at least one printed antenna in accordance with any one of the foregoing aspects. The method comprises the steps of: disposing the printed antenna of the printed circuit board outside the conducting case to enable radiation; and disposing the remaining components of the printed circuit board inside the conducting case to prevent electromagnetic interference. The conducting case may comprise a plurality of slots in which the printed circuit board is disposed. The method may comprise the step of providing a nonconducting cover or radome to cover the printed antenna. In accordance with another aspect of the invention, there is provided an electronic device comprising: a conducting case; and a printed circuit board comprising at least one printed antenna in accordance with any one of the foregoing aspects, the printed antenna of the printed circuit board disposed outside the conducting case to enable radiation, and the remaining components of the printed circuit board disposed inside the conducting case to prevent electromagnetic interference. The conducting case may comprises a plurality of slots in which the printed circuit board is disposed. The electronic device may comprise a non-conducting cover or radome to cover the printed antenna. These and other aspects of the invention are set forth in greater detail hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS Several embodiments of the invention are described hereinafter with reference to the drawings, in which: Figs. 1(a) and 1(b) illustrate an antenna suitable for two frequency bands; Fig. 2 lists parameter values for the antenna of Fig. 1; Fig. 3 is a graph of the measured input reflection coefficient versus frequency of the antenna of Fig. 1; Figs. 4(a), 4(b), and 4(c) are graphs showing the measured radiation patterns at 2.45 GHz, 5.25 GHz, and 5.78 GHz, respectively; Fig. 5 illustrates another antenna suitable for two frequency bands; Fig. 6 illustrates an antenna suitable for two frequency bands; Fig. 7 illustrates an antenna with more than two radiating strips employed in to obtain even better bandwidth or to cover more frequency bands; Fig. 8 has plan and side views of an antenna suitable for two frequency bands; Fig. 9 depicts a multi-band antenna array comprising four antennas of the type shown in Fig. 1 with suitable coupling; Fig. 10 depicts another multi-band antenna array comprising four antennas of the type shown in Fig. 1 with suitable coupling; Fig. 11 depicts an antenna with a coplanar waveguide (CPW) transmission line, suitable for two frequency bands; Fig. 12 depicts an antenna with two resonating slots, suitable for two frequency bands; Fig. 13 depicts a triple multi-band antenna on two stacked dielectric substrates; Fig. 14 comprises top plan, bottom plan, left elevation, and bottom elevation views of a ground-less multi-band antenna with two similar multi-band radiating strips formed on opposite sides of a substrate; Fig. 15 depicts an antenna comprising multi-band radiating elements formed on both the top and bottom surfaces of a substrate; Fig. 16 shows a dual multiband antenna on the same substrate; Fig. 17 shows another dual multiband antenna on the same substrate; Fig. 18 shows a further dual multiband antenna on the same substrate; Fig. 19 depicts another antenna comprising multi-band radiating elements on both the top and bottom surfaces of a substrate; Fig. 20 depicts an example of an antenna with a reflector; Fig. 21 depicts an antenna suitable for two frequency bands located between two substrates with truncated ground planes on the top surface of the upper substrate and on the bottom surface of the lower substrate; Fig. 22 illustrates a dipole antenna with two identical multi-band radiating elements formed on the same side of a substrate; Fig. 23 illustrates a dual multiband antenna with two identical multi-band radiating elements formed on the same side of a substrate in a diagonal manner relative to two corners of the substrate; and Fig. 24 illustrates another dual multiband antenna like the one of Fig. 23, but with different radiating elements and with one of the radiating elements rotated through 180 degrees; Fig. 25 illustrates another dual multiband antenna like the one of Fig. 24, but with different radiating elements; Fig. 26 is a block diagram of an electronic device comprising a printed circuit board with a printed antenna; and Fig. 27 shows a printed circuit board with a printed antenna installed in another electronic device with a conducting case. DETAILED DESCRIPTION Antennas and methods of manufacturing and using antennas are disclosed, h the following description, numerous specific details, including antenna dimensions, dielectrics, and the like are set forth. However, from this disclosure, it will be apparent to those skilled in the art that modifications and/or substitutions may be made without departing from the scope and spirit of the invention, hi other circumstances, specific details may be omitted so as not to obscure the invention. Where reference is made in any one or more of the accompanying drawings to steps and/or features, which have the same reference numerals, those steps and/or features have for the purposes of this description the same function(s) or operation(s), unless the contrary intention appears. Embodiments of the invention provide a multi-band and broadband, fully planar antenna. The basic antenna comprises multiple metal radiating strips, or elements, on one side and a trancated ground plane either on the same or on the other side of a continuous dielectric substrate. At least one radiating strip bends around at least one other radiating strip to conserve space. Each pair of radiating strips is laid over an area in the range of 0.025 to 0.045 square guided wavelengths (at the mid- band frequency of the lower band) to obtain near-optimal level of mutual coupling between the two strips. Further, the longer radiating strip is separated from the shorter radiating strip by a gap of at least 0.025 guided wavelengths (at the mid-frequency of the low band) for a substantial portion of the length of the longer metal strip, to generate strong radiation. Fully-planar means that all antenna metal features are on one or more parallel planes (e.g., the two surfaces of the substrate), and any connections between metal features on different planes can be made using standard planar printed circuit fabrication techniques. In basic configurations, radiating strips may be on the top surface of a substrate, e.g. as shown in Fig. 1, whereas in some extended configurations, radiating strips may be on both surfaces, e.g. as shown in Figs. 13-15 and 19. h other words, dielectric blocks, dielectric steps or dielectric discontinuities, metal features or metal connectors on dielectric edges, metal bends out of the parallel planes, and the like are not required. The fully planar configuration simplifies fabrication of the antenna and reduces fabrication cost, differentiating the embodiments of the invention from chip-type and bent-metal-type antennas. The fully planar antennas may be fabricated directly on a circuit board together with other printed circuit components simultaneously using the same standard microwave planar printed circuit fabrication method. This fully planar fabrication method does not require a separate process for antenna fabrication, or to connect the antenna to other printed circuit components. These fully planar antennas do not require mounting, surface mounting or bonding. Figs. 13, 15, and 19 illustrate embodiments that have plated via holes. Plated via holes are a technique commonly used in standard planar printed circuit fabrication technology to connect metal features on different planes. The whole antenna can be manufactured on a standard single-layer, or multilayer microwave substrate using standard planar printed circuit fabrication methods (i.e. etching, printing, milling). This can be done at low cost. This fabrication can be done at the same time other printed circuit components (not part of the antenna) are made on the same board or substrate, using the same fabrication method. Therefore, the cost of adding the antenna to the circuit is extremely low. Alternatively, the antenna may comprise metal strips and one or two metal sheets, that are held in place possibly using one or several pieces of insulating material. The insulating material may be a foam type material that has a dielectric constant close to unity, for example. Further, several embodiments of the invention require only one substrate layer (i.e. single-layer structure). Thus, multi-layer bonding is not required, although multilayer embodiments are possible (e.g. Fig. 13). If the antenna is made on a common FR4 substrate with a dielectric constant of 4.4, the total resonance length of each radiating strip may be about one quarter free- space wavelengths or one half guided wavelengths at the mid- frequency of the frequency range that the strip is expected to radiate strongly. However, the length can vary depending on the design and the dielectric constant of the substrate, e.g. from about 0.35 to about 0.55 guided wavelengths. The total resonance length of a strip is the length along the centerline of the strip from the strip end to the point where the strip is connected to the feedline (i.e. near the edge of the ground plane). This length ay include any tapered sections and parts of other strips. The wavelength of the field depends on whether the field is in air or in a dielectric. If the wave is completely in air, the wavelength is the free-space wavelength. If the wave is completely in the substrate, the wavelength is the guided wavelength, h the antennas, part of the field is in the air and the rest is in the substrate, if a substrate is used. Hence, both wavelengths are relevant. The embodiments of the invention satisfy increasing requirements for wireless communications capability in more than one frequency band using the same antenna. In particular, there is a requirement for compact and inexpensive antennas covering the 2.4-2.5 and 4.9-5.9 GHz frequency bands being used for wireless computer networks. The embodiments of the invention provide a compact antenna in the form of a defined pattern of electrical conductor (typically copper) formed (e.g., etched) on the surface of a dielectric substrate and fed by a single transmission-line element. The defined pattern produces an electrical performance in which the antenna radiates efficiently across all the 2.4-2.5 and 4.9-5.9 GHz frequency bands defined internationally for wireless data communications. The embodiments of the invention provide an antenna having a pattern of electrical conductor comprising two strips extending at an angle to each other from the single connection point and in which the longer of the strips bends around the shorter. The desired antenna performance and reduced antenna size are obtained by control of the form of the two strips. A multi-band radiating element comprises a pair of metal strips, as described hereinafter, in several embodiments, but may comprise more combinations of strips as well as different configurations of strips in other embodiments. Still further, the radiating element may comprise slots, in elecfromagnetically dual configurations of the strip antennas. By laying each pair of strips in an area in the range of 0.025 to 0.045 square guided wavelengths (at the mid- frequency of the low band), while leaving a gap of at least 0.025 guided wavelengths (at the mid-frequency of the low band) between the two strips for substantial portion of the length of the longer strip, near-optimal electromagnetic mutual coupling is obtained between the two strips. This electromagnetic mutual coupling leads to a loading effect on each strip by the other, resulting in an antenna with the required bandwidth in a small area. Spreading the strips over a larger area only makes the antenna physically larger, without significantly increasing the antenna bandwidth. On the other hand, making the strips too close throughout creates excessive mutual coupling leading to a reduction in antenna bandwidth, hi some configurations this results in the introduction of strong electromagnetic coupling between the open circuit ends of the two unequal length strips, which consequently are no longer independent radiators. Dual Band Antenna Figs. 1(a) and 1(b) illustrate an antenna 200 suitable for two frequency bands in accordance with an embodiment of the invention. Fig. 1(a) comprises plan and side views of the antenna 200, and Fig. 1(b) is an enlarged plan view of the antenna 200. The antenna 200 comprises first and second radiating strips 230 and 232, which are coupled to a feedline 220, disposed on the top surface of the substrate 210. The substrate 210 has a truncated ground plane on the bottom surface, indicated by shading and denoted by reference numeral 212. The side view of Fig. 1(a) shows the top surface of the substrate 212 on the left and the bottom surface of the substrate 212 to the right. Accordingly, for example, the truncated ground plane 212 on the bottom side is shown on the right side, hi Fig. 1, the metal components 220, 230, 232, 234 on the top surface are depicted with solid black fill, the substrate 210 with white fill, and the bottom ground plane 212 is depicted in plan view with gray dotted hatching and in side view with solid black (since it is made of metal and can be better seen with black fill than gray hatching in the side view). The gray hatching is used to depict the areas of the substrate 210, which is generally white, where the ground plane 212 is arranged on the bottom surface, as seen through the substrate 210. This fill/hatching scheme is used throughout the remainder of the drawings. The upper limit of the truncated ground plane 212 is depicted as forming a horizontal line, relative to the substrate 210 displaced from the upper horizontal edge of the substrate 210. The first and second radiating bent metal strips 230 and 232 and the feedline 220 are made of copper strips. While copper is typically used in such circuits, any suitable conducting material may be practiced without departing from the scope and spirit of the invention. Copper may be the base material, however, there may be a layer of another metal (e.g., gold) over the copper. The bent metal strips are preferably printed on the substrate. At the location where the feedline 220 joins the antenna strips 230, 232 (i.e., in the vicinity of the edge of the truncated groundplane), the width of the metal strip increases in a frustram shape to match the width W of the remainder of the bent metal strips 230, 232. This is indicated as "tapered section" 234 in Fig. 1(a). The foregoing description of the "frustram" applies to the other antennas described hereinafter. The feedline 220 may be printed on the substrate 210. The width W of the metal strips 230, 232 is greater than the width W_f of the feedline 220. The first bent metal strip 230 (that includes the tapered section) forms a first resonator section and generates the lower band (e.g. 2.4 - 2.5 GHz), and the second bent metal strip 232, in combination with the tapered section 234, forms a second resonator section that generate the higher band (e.g. 5-6 GHz), hi Fig. 1, the first bent metal strip 232 is substantially generally rectilinearly U-shaped, while the second bent metal strip 234 is substantially L-shaped, with the terminal ends of the strips 230, 232 being interlocking or otherwise in close proximity to each other, hi Fig. 1, the terminal ends are parallel to each other in a lengthwise manner. The two bent metal radiating strips 230 and 232 are separated from each other at one end for a large part of their lengths. As noted above, the strips 230 and 232 are also close to each other near the terminal portions of the bent strips, to strongly load each other by electromagnetic mutual coupling and hence improve the bandwidth of the antenna 200. The parameters Si, S , S₃, S₄, S₅, T, and d of one implementation of this embodiment are set forth in Table 300 in Fig. 2. The parameters Si, S₂, and S₃, define segment lengths of the U-shaped metal strip 230, and S₄, and S₅ define segment lengths of the second metal strip 232. The segments of each strip are essentially straight, elongated strips. The parameter d is the separation between segments Si, and S₅. The parameter T is the distance between the ground plane 212 and the segment S₄. The parameter W is the width of the segments Si, S , S₃, S₄, and S₅, and the parameter Wf is the width of the feedline 220. The parameter H is the thickness of the substrate 210. The parameters a and b are the separations between segments S₃ and S₅ and between S and S₄, respectively. This example design is based on a FR4 dielectric substrate. The parameter ε_r in Fig. 2 is the dielectric constant of FR4, shown as 4.4. The thickness of the metal strips is negligible, and therefore the total height of the antenna 200 is almost equal to the thickness of the substrate (H) that is 0.8mm. While a specific substrate has been noted in this implementation of the embodiment, antennas can be designed for other substrates, e.g. ceramic or RT-duroid having a different dielectric constant. Again, the free-space wavelength is the length of the wave if the wave is completely in air, and the guided wavelength is the wavelength if the wave is completely in the substrate. The parameters Li and L₂ are the total lengths of the first resonator section (i.e. first bent metal strip 230 including the tapered section 234) and the second resonator section (i.e., second bent metal strip 232 combined with the common tapered section 234), respectively. As indicated in the last row of Fig. 2, the length of the first resonator section is 0.20 free-space wavelengths or 0.42 guided wavelengths at the mid-frequency of the lower band and length of the second resonator section is 0.23 free-space wavelengths or 0.48 guided wavelengths at the mid-frequency of the upper band. As can be seen in Figs. 1(a) and 1(b), the ground plane 212 is located on the bottom surface of the substrate 210 beneath the feedline 220 on the top surface. The bent metal strips 230, 232 do not have a ground plane beneath those strips on the bottom surface of the substrate 210. The feedline 220 ends at the truncated ground plane 212. The radiating parts of the antenna, which include all metal parts outside the ground plane (i.e. two metal strips 230, 232 and the tapered section 234) are laid out over a rectangular region that is 10 cm long, 10 cm wide and has an area of 100 square millimeters. This area is equal to 0.03 square guided wavelengths (λι_g) at the mid-frequency of the low band (i.e. 2.54 GHz). hi the two-strip version of Figs. 1(a) and 1(b), the length of the section where the two strips are close to each other is approximately 0.1 guided wavelengths at the mid-frequency of the lower band- and approximately 0.2 guided wavelengths at the mid-frequency of the upper band, although the optimum value for the parameter may depend on the application. The separation between sections S₃ and S₅ , denoted by a in Fig. 1(b), is 0.06 guided wavelengths at the mid-frequency of the lower band. The separation between sections S and S₄, denoted by b in Fig. 1(b), is 0.085 guided wavelengths at the mid-frequency of the lower band. The antenna 200 is suitable for multi-band wireless and mobile communication systems. The antenna 200 may be fabricated on a thin (e.g., a thickness of 0.8 mm), inexpensive FR4 substrate using standard planar printed circuit fabrication methods. The antenna 200 may be fabricated with other printed circuit components of the wireless/mobile communication device on the same substrate or circuit board using the same fabrication technology simultaneously, without additional processes. The antenna 200 may be fabricated on other types of substrates (such as RT-Duroid, ceramic, etc.) as well, h that case, the antenna dimensions may be adjusted to account for the variation in the substrate dielectric constant. Alternatively, the antenna 200 may be fabricated without a physical substrate. The first metal strip 230, the second metal strip 232, and the feedline 220 may be fabricated out of a metal sheet. The ground plane 212 may be fabricated separately out of a metal sheet. These two parts of the antenna 200 may be held in place, in parallel to each other while leaving a uniform gap between them, possibly with the help of one or several pieces of insulating or dielectric materials. The insulating material may be a foam-type material that has a dielectric constant close to that of air or free space. The antenna dimensions should be adjusted to account for the variation in the dielectric constant. For each frequency band of operation, the antenna 200 of Fig. 2 has a resonance section or resonator. The resonance section for the lower band comprises the metal strip 230 with the tapered section 234. The resonance section for the upper band comprises the metal strip 232 and the tapered section 234. To conserve space, the resonant strip 230 is bent to form a shape of the letter U approximately (the shape may equally be refened to as C-shaped) and the strip 232 is bent to form the shape of the letter L. This bending also improves electromagnetic mutual coupling or loading between the two strips. The feedline 220 may be a standard 50-Ohm microstrip line over the ground plane 212. The antenna 200 has no ground plane directly below the radiating strips. The truncated ground plane 212 below the feedline 220 also serves as the ground for the radiating elements in the antenna 200 in Fig. 1. Two groundless embodiments of the invention are depicted in Figs. 14 and 22. Fig. 3 is a graph of the measured input refection coefficient magnitude versus frequency of the embodiment of Fig. 1. This parameter is less than-lOdB in a relatively narrow frequency band around 2.5 GHz and in a wide frequency band around 5-6 GHz. This means the antenna 200 shown in Fig. 1 operates well and is well matched to the 50-Ohm feedline 220 in these two frequency bands. Hence, this antenna is refened to as a dual-band antenna. The input refection coefficient magnitude of -10 dB conesponds to a return loss of lOdB and a voltage standing wave ratio (NS WR) of approximately 2:1. According to Fig.3, the antenna 200 shown in Fig. 1 is well matched in all four cirrrent IEEE WLAΝ bands, which are 2.4-2.5 GHz (IEEE 802.1 lb and 802.11 g), 4.90-5.09 GHz (IEEE 802.1 lj Japan), 5.15-5.35 GHz (IEEE 802.1 la U-ΝH lower and middle bands in USA) and 5.725-5.825 GHz (IEEE 802.1 la U-ΝII upper band in USA, etc.), and therefore the antenna 200 functions well in these four WLAΝ applications. The antenna 200 is capable of communicating in any or all of these WLAΝ bands, even simultaneously. For this reason, such antennas 200 are sometimes known as quad-band antennas in the literature. The antenna 200 in Fig. 1 can serve as the antenna in a multi-standard, global communication device such as a multi-standard WLAΝ PCMCIA card. The antenna 200 can also serve as an antenna for Bluetooth and HIPERLAΝ applications, for example. The measured gain of the antenna is 2.0 dBi at 2.45 GHz and 2.1 dBi at 5.25 GHz. These relatively low antenna gain figures indicate that the antenna radiates energy in almost all directions in both frequency bands. Figs. 4(a), 4(b), and 4(c) are graphs showing the measured radiation patterns at

2.45 GHz, 5.25 GHz, and 5.78 GHz, respectively. Each figure shows the normalized radiation patterns on two orthogonal planes, namely x-z and y-z planes, which are defined according to the coordinate system shown in Fig. 1(b). Figs. 4(a), 4(b), and 4(c) further indicate that the antenna 200 radiates energy in almost all directions at all measurement frequencies. The antenna 200 in Fig. 1 is therefore capable of forming a wireless communication link in any direction with another antenna. The angle shown in Figs. 4(a), 4(b) and 4(c) is the angle measured from the positive Z-axis, defined according to the coordinate system in Fig. 1(b). The angle of 0° conesponds to the direction of the positive z-axis, whereas the angle of 180° conesponds to the direction of the negative z-axis. While Fig. 1 depicts the metal strips 230, 232 of the antenna 200 forming an interlocking, rectilinear "U" shaped layout, other layouts of radiating strips such as triangular and circular shapes may be practiced without departing from the scope and spirit of the invention. Examples of such configurations are described hereinafter. Further, while only one multi-band metal strip antenna 200 is depicted on the substrate 210, multiple such antennas may in fact be implemented on the substrate 210 to provide multiple multi-band antennas, as described hereinafter with reference to other embodiments of the invention. The multiple, multi-band antennas on the same substrate layer can achieve antenna diversity (e.g., in wireless computer network PCMCIA cards, notebook computers, WLAN access points, base-station antennas, multiple-input-multiple-output (MIMO) systems etc.), independent transmission and reception, antenna anay function, or any other similar function. The antenna design shown in Figs. 1(a) and 1(b) performs well in all four IEEE 802.11 WLAN frequency bands (2.4-2.5 GHz, 4.9-5.09 GHz, 5.15 GHz - 5.35 GHz and 5.725 GHz - 5.825 GHz) cunently allocated for wireless communication systems. The bandwidth of the antenna 200 is wider than what is required for these four standards. The antenna 200 may be utilized as a quad-band antenna for IEEE 802.11 a, b, g, a+b, a+g, a+b+g, a+j, b+j, g+j, a+b+j, a+g+j or a+b+g+j systems for worldwide operation. The antenna 200 may also be utilized as an antenna for Bluetooth and HIPERLAN applications. The antenna 200 is only 0.8 mm thick and hence is thin enough to integrate into a PCMCIA wireless card (also called a PC card), for example, without increasing the thickness or width of the card at the antenna end (e.g. 5 mm thick and 54 mm wide). For a "clean" integration, the packaged height of the antennas may not exceed the 5 mm thickness of the PCMCIA card. Furthermore, the antenna 200 is small enough, so that two antennas can be included in a single PCMCIA card (for space/pattern/polarization diversity or other purposes) without increasing the width or height of the standard PCMCIA card. The embodiments of the invention can be scaled to other multi-band applications (such as mobile phones) and other frequency bands. The antennas can be integrated into other devices such as notebook computers, handheld computers, PDAs (e.g., Dell Axim, Compaq iPAQ, Palm Tungsten, O₂ XDA, etc.), security devices, game controllers, video cameras and digital cameras. Annular Dual Band Antenna Fig. 5 illustrates another antenna 600 suitable for two frequency bands. Fig. 5 comprises a plan and side view of the antenna 600. The antenna 600 comprises first and second C shaped radiating bent metal strips 630 and 632, which are coupled to a feedline 620, disposed on the top surface of a substrate 610. Here, the bent metal strips have a curved shape. A frusto-conical tapering portion 634 couples the feedline 620 to the metal strips 630 and 632. The bent metal strips 630 and 632 (including the tapering portion 634) are the radiating elements of the antenna 600. The substrate 610 has a truncated ground plane, denoted by reference numeral 612, on the bottom surface of the substrate. The first metal strip 630 is substantially longer than the second metal strip 632, forming about three-quarters of the circumference of an annular ring. The other metal strip 632 is an oppositely facing curved element disposed largely in the remaining quarter of the hypothetical annular ring, with at least a portion of its arc closely spaced relative to a terminal end of the metal strip 630. The first bent metal strip 630 has a larger radius in terms of the arc that the strip 630 defines than does the second bent metal strip 632. Both are connected together by a length of stripline coupled to the tapered portion 634. Again, the length of the section where the two strips 630, 632 overlap is approximately 0.1 guided wavelengths at the mid-frequency of the lower operating frequency range and approximately 0.2 guided wavelengths at the mid-frequency of the upper operating frequency range, although the optimum value for the parameter may depend on the application. This antenna 600 may be fabricated on a substrate using standard microwave printed circuit fabrication technology. Alternatively, the antenna 600 may also be fabricated without a substrate using metal sheets and strips, which are held in place with the help of insulating materials. Further Dual Band Antenna Fig. 6 illustrates an antenna 700 suitable for two frequency bands. In this drawing, the antenna 700 is substantially the same as that 200 in Figs. 1(a) and 1(b). Conesponding features in Fig. 6 have like numbers (7XX) compared to those (2XX) of Fig. 1. The antenna 700 comprises a truncated ground plane 712 on the bottom surface of the substrate, a feedline 720 and first and second bent metal strips 730, 732 with a tapered portion 734 having substantially the same configuration as that of Fig. 1. The antenna 700 differs from the antenna 200 of Fig. 1 in that the metal strips 730 and 732 each have a stub or orthogonally projecting portion adjacent the terminal end of the strip 230, 232 of Fig. 1. This and similar configurations can be practiced to make the antenna 700 shorter and wider. Triangular Dual Band Antenna Fig. 8 has plan and side views of an antenna 900 suitable for two frequency bands. This antenna 900 may be suitable for installation at the corners of a PCMCIA card or another electronic device with square corners, for example. The antenna 900 comprises first and second radiating bent metal strips 930 and 932, which are coupled to a feedline 920 by a tapered section 934, disposed on the top surface of a substrate 910. The substrate 910 has a truncated ground plane on the bottom surface, denoted by reference numeral 912. The overall form of the radiating strips is triangular. This embodiment varies in the anangement of the truncated ground plane 912 relative to the substrate 910 and the layout of the bent metal strips 930, 932. In Fig.l, the truncated ground plane 212 has an upper terminal edge forming a horizontal edge relative to the substiate 210 as depicted. In the antenna 900 of Fig. 8, the truncated ground plane has a terminal edge that runs diagonally from the lower left to the upper right across the substrate, so that a corner of the substrate 910 does not have a ground plane beneath the radiating strips 930, 932 and the tapered section 934. Other similar configurations are possible. The feedline 920 is depicted as being substantially vertical over most of its length and then angling to the left corner at a substantially 45° angle to connect to the tapered section 934. Other angles (35°, 40°, 50°, 55° for example) may be practiced. The first and second bent metal strips 930 and 932 (i.e., the radiating elements) and the feedline 220 are made of copper or any other conducting material. More preferably, the first radiating element 930, the second radiating element 932 and the feedline 920 are printed on the substrate 910. The feedline 920 ends at the truncated ground plane. The frustram shaped portion 934 of the radiating strips 930, 932 joins the feedline 920. The two bent metal radiating strips 930 and 932 are separated from each other for a large part of their lengths. Further, the bent metal strips 930 and 932 are close to each other near the terminal portions of the bent strips, to strongly load each other by electromagnetic mutual coupling and hence improve the bandwidth of the antenna

900. The overall layout of the two metal strips 930, 932 is a triangular form. The first metal strip 930 has a short segment connecting to the frustram 934, which adjacent its opposite end has a second, longer segment at a roughly 45 degree angle relative to the first segment. The third segment of the metal strip 930 is ananged at a 90-degree angle relative to the terminal end of the second segment. The second metal strip 932 has a first segment substantially in line with the first segment of the first metal strip 930 and a second segment of the second metal strip 932 that is at a roughly 45 degree angle relative to the first segment. The third segment of the first metal strip 930 and the second segment of the second metal strip 932 are at least partially closely adjacent to each other. As can be seen in Fig. 8, the feedline 920 ends where the ground plane is truncated. The feedline 920 couples to the antenna strips 930, 932 through the tapered section 934 of the antenna strip 930, which are separated from the ground plane. This antenna 900 may be fabricated on a substrate using standard planar printed circuit fabrication technology. Alternatively, the antenna 900 may also be fabricated without a substrate using metal sheets and strips, which are held in place with the help of insulating materials. Multi-Band Antenna In further embodiments of the invention, more than two radiating strips may be employed in one antenna to obtain even better bandwidth or to cover more frequency bands. An antenna 800 comprising more than two radiating metal strips is depicted in Fig. 7. Again, conesponding features in Fig. 7 have like numbers (8XX) to those (2XX) of Fig. 1. The antenna 800 comprises a substrate 810, a ground plane 812 on the bottom surface of the substrate 810, a feedline 820, a first bent metal strip 830 and a second bent metal strip 832. Extending from the segment of metal strip 830 conesponding to segment S₃ of Fig. 1 are two strips 840 and 842, having an overall shape similar, but not quite the same as the letter "G". The third metal strip 840 is rectilinearly U-shaped and coupled adjacent to tapered section that is coupled to the feedline 820. The fourth straight metal strip 842 is displaced from the tapered portion 834 along the first metal strip 830 and projects in a horizontal manner inwardly into the U-shape of the third bent metal strip 840. The fourth straight metal strip 842 is closely spaced relative to the terminal end of the third strip 840. The antenna 800 comprises four coupled radiating strips 830, 832, 840, and 842. Each metal strip 830, 832, 840, 842 forms a resonator section and radiates well within a certain frequency band. The lengths of the four resonator sections may be different, and the antenna may consequently operate in four separate frequency bands. Alternatively, by adjusting the lengths of the metal strips 830, 832, 840, 842, some of these frequency bands may be made to overlap, giving a lower number of wider operating frequency bands. This antenna 800 may be fabricated on the substrate 812 using standard microwave printed circuit fabrication technology. Alternatively, the antenna 800 may also be fabricated without a substrate using metal sheets and strips, which are held in place with the help of insulating materials. Dual Multiband Antennas on the Same Substrate Fig. 16 shows an anangement 1700 of two parallel multi-band antennas 1760, 1762 on the same substrate 1710, again with a truncated ground plane 1712 on the bottom surface of the substrate 1710. The antennas 1760, 1762 have respective feedlines 1720 A, 1720B. The antennas 1760 and 1762 each have the same basic configuration as the antenna 200 of Fig. 1. While the metal strip layout of the antenna 1762 is nearly identical to that of the antenna 200 of Fig. 1, the other antenna 1760 is a minored copy of the antenna 200. The anangement 1700 also differs from the antenna 200 of Fig. 1 in that the truncated ground plane 1712 extends as a rectangular body between the antennas 1760 and 1762. Thus, the upper left and right comers do not have the ground plane 1712 beneath the radiating strips, in a substantially square shape in each upper comer. This and similar configurations of antenna pairs provide space diversity. Another antenna pair configuration 1800 is depicted in Fig. 17. In this case, two antennas 1860 and 1862 are orthogonally aπanged relative to each other and have respective feedlines 1820A and 1820B, which are bent at an upper end roughly 45 degrees relative to the large vertical portion of the respective feedline 1820 A, 1820B. Each antenna 1860, 1862 has the same basic configuration as that of the antenna 900 in Fig. 8 and is disposed in an opposite upper comer of the substrate 1810. The bottom ground plane 1812 has a largely triangular shape at one end, with each antenna 1860 and 1862 extending from a side of the triangle. The left side truncated ground plane for the antenna 1860 has an edge running from the lower left to the upper right, while the right side truncated ground plane for the antenna 1862 has an edge running from the upper left to the lower right. This and similar configurations provide space, polarization and pattern diversity. Still another antemia pair configuration 1900 is shown in Fig. 18, where one multi-band antenna 1960 is rotated 90 degrees with respect to the other 1962 on the substrate 1910. Each of these antennas 1960, 1962 has the same basic configuration as the antenna 200 of Fig. 1. The antenna 1962 is essentially identical as that 200 of Fig. 1. However, the other antenna 1960 differs in that the feedline 1920A has a ninety- degree bend in the feedline 1920A, while the feedline 1920B is a straight vertical line for the antemia 1962. Further, the substrate without a groundplane 1912 under the radiating metal strips is rectangular in shape. This configuration 1900 also provides space, polarization and pattern diversity. Relative rotation between the antennas by other angles (e.g. 60 degrees) may also be practiced. The antenna pairs 1700, 1800, 1900 shown in Figs. 16, 17 and 18 may each be fabricated, with other printed circuit components, on the same substrate or circuit board using the same fabrication technology simultaneously, without additional processes. Alternatively, these antenna pairs 1700, 1800, 1900 maybe fabricated without a physical substrate, out of metal sheets and strips, and maybe held in place possibly with the help of one or several pieces of insulating or dielectric materials. Extending the same idea further, more than two multi-band antennas can be made on the same substrate for more advanced diversity applications or other purposes. Fig. 23 illustrates another antenna pair configuration 2400 with two identical multi-band antennas 2460, 2462 on the upper surface of a substrate 2410. Each antenna 2460, 2462 has a respective feedline 2420A, 2420B. The feedlines 2420A, 2420B are bent at roughly 45 degree angles to the right and left, respectively, adjacent a diagonal edge of the truncated ground plane 2412 to connect to the respective antenna 2460, 2462. Each antenna is in an opposite upper comer of the substrate. The trancated ground plane 2412 has a frasto-conical shape. The layout of metal strips in the antenna 2460 is different from the layout of the strips in the antenna 200 shown in Fig. 1. hi antenna 200, the two strips 230, 232 are close to each other in the section near their terminations. This is done to obtain strong electromagnetic mutual coupling between the strips 230, 232. This terminal section contributes significantly to the overall electromagnetic mutual coupling between the two strips. In other sections, the two strips are separated by larger gaps, and hence, the electromagnetic mutual coupling between those sections is relatively weaker, hi antenna 200, the ratio a/d is equal to 7. Such a layout leads to a small antenna with a wide bandwidth, as shown in Fig. 3. The layout shown in Fig. 23 is an alternative way of achieving a similar but inferior result without a close section. As in Fig. 1, the radiating elements in Fig. 23 are laid out over an area less than 0.045 square guided wavelengths in the low band (i.e., less than 153 mm²), to save space as well as to enhance electromagnetic mutual coupling between the strips. However, in Fig. 23, the separation a has been reduced, the gap d has been increased, and other adjustments have been made to obtain a desirable bandwidth. In the antenna 2460, the separation a is 2mm or 0.034 guided wavelengths in the low band, d is 1.5mm, and the ratio a/d is 1.3. Due to increased d, this layout does not have a section that predominantly contributes to the overall electromagnetic mutual coupling between the two strips. The electromagnetic mutual coupling effect achieved by such a layout is not as beneficial as the effect in antenna 200 in Fig. 1. Therefore, the layout in Fig. 23 generally leads to larger antennas with less bandwidth. As an example, the radiating strips of the antenna 2460 takes up a rectangular area approximately equal to 0.04 square guided wavelengths (or 142 mm²) whereas the radiating elements of antenna 200 needs only a rectangular area of approximately 0.03 square guided wavelengths (or 100 mm²). The total bandwidth of the antenna 2460 is less than the total bandwidth of the antenna 200. Other new items that have employed in antenna 2460 are two short metal strip segments of uniform width (with lengths tl and t2) on either side of the tapered section. Such segments may be employed in other embodiments of the invention. Fig. 24 illustrates another antenna pair configuration 2500 with two antennas 2560, 2562 on the upper surface of the substrate 2510. Antenna 2560 depicts another layout with a wide, short second strip. Further, the longer strip is closer to the shorter strip along the sides of the shorter strip but the longer strip is separated from the terminal end of the shorter strip by a gap larger than 0.025 guided wavelengths at the mid-frequency of the low band. The radiating elements in antenna 2560 are laid over an area in the range of 0.025 to 0.045 square guided wavelengths at the mid-frequency of the low band. Another difference between Figs. 23 and 24 is that the radiating element 2560 is rotated 180 degrees relative to the conesponding radiating element 2460 of Fig. 23. Fig. 25 illustrates another antenna pair configuration 2600 with two antennas 2660, 2662 on the upper surface of the substrate 2610. The main differences between Figs. 24 and 25 are that the radiating elements have different layouts and the frusto- conically shaped portion of the truncated ground plane 2612 is skewed more to the right.

Multiple Multi-Layer, Multi-Band Antennas on Multiple Stacked Layers of Substrates Still further, multiple multi-layer, multi-band antennas can be employed on multiple stacked layers of substrates, for example, to cover even more frequency bands. A triple multi-band antenna 1400 on two stacked dielectric substrates 1410,

1411 is depicted in Fig. 13. One multi-band antenna 1460 and the common feedline may be printed on the top surface of the first substrate 1410 (indicated by solid black fill), and the second multi-band antenna 1462 may be printed on the bottom surface of the first substrate 1410 or the top surface of the second substrate 1411 (indicated by solid dark gray fill). A third multi-band antenna 1464 may be made on the bottom of the second substrate 1411 (indicated by gray dotted hatching). Each of the antennas 1460, 1462, 1464 has the same basic configuration as that of the antenna 200 shown in Fig. 1 but their dimensions may be different. The second and third antemias 1462, 1464 may be coupled to the common feedline with plated via holes 1440, or another coupling mechanism through the substrates 1410, 1411. A truncated ground plane 1412 may be formed on the bottom surface of the first substrate 1410, the top surface of the second substrate 1411, or the bottom surface of the second substrate 1411. The configuration 1400 in Fig. 13 can be extended to a larger number of substrate layers and a larger number of multi-band antennas. The side view of the antenna 1400 clearly indicates a gap between the bottom antenna 1464 and the truncated ground plane 1412 (see the right edge). The three antennas may differ in shape and/or size and may overlap each other in alignment. For example, in Fig. 13, the three antennas 1460, 1462 and 1464 have the same configuration, but different sizes. Multi-Band Antenna with Coplanar Waveguide Feedline Fig. 11 shows a multi-band antenna 1200 where all metal features and the truncated ground plane 1212 are on the same plane on the top surface of a dielectric substiate 1210. The ground plane 1212 is split into two parts to allow space for the long central metal strip 1220 that feeds the antenna 1200. This metal strip 1220 is separated from the two parts of the ground plane 1212 by two slots 1250 on either side of the strip 1220. The central metal strip 1220, the two slots 1250, and the two parts of the ground plane 1212 together form the feed transmission line generally known as a coplanar waveguide (CPW). The radiating strips 1230, 1232 in this antenna 1200 are similar to those shown in Fig. 1. The main difference is the location of the truncated ground plane 1212, which is now on the same plane as all other metal features 1220, 1230, 1232. In this embodiment, the feedline 1220 is substantially wider than the feedline of the above embodiments and is wider than the width of the bent metal strips 1230, 1232 that are the radiating elements. Consequently, the tapered portion between the feedline 1220 and the bent metal strips 1230, 1232 is inverted relative to the above embodiments. Any multi-band antenna with a ground plane on the lower surface (e.g. shown in Figs. 1, 5, 6, 7, 8, 9, 10, 13, 15, 16, 17, 18, 19, 23, 24 and 25) can be subjected this conversion, by splitting and moving the ground plane to the same surface that contains the feedline. As a result of this conversion, the input transmission line becomes a coplanar waveguide instead of a microstrip line. The width of the metal strip of the feedline and the slots may be adjusted to achieve a desirable characteristic impedance (e.g. 50 Ohm). In general, the metal strip of a 50-Ohm coplanar waveguide transmission line is wider than that of a 50-Ohm microstrip transmission line. The antenna 1200 in Fig. 11 may be fabricated by printing or etching all the metal features and the ground plane 1212 on one side of the substrate 1210. The antenna 1200 in Fig. 11 may also be fabricated without a substrate, using metal strips and two sheets, which may be held in place using insulating materials. Electromagnetically "Dual" Multi-Band Antennas The Electromagnetic "dual" of an antenna is obtained by applying the Principle of Duality in Electromagnetics, that is, by replacing metal features by slots and slots by metal features. Fig. 12 shows the dual 1300 of the multi-band antenna 1200 shown in Fig. 11.

The metal pattern of the antenna 1300 is the "inverse" of "negative" of the metal pattern of the antenna 1200 in Fig. 11. This means, metalized areas of antenna 1300 conespond to non-metallized areas of antenna 1200 and vice versa. However, the feedline dimensions need to adjusted to achieve the same characteristic impedance, e.g. 50 Ohms. The radiating elements of this antenna 1300 are the resonating slots in the metal sheet 1312. The input transmission line of this antenna 1300 comprises two metal strips 1330 side by side and may be connected and matched to a microstrip or other common transmission line using a transmission line coupler or adapter. Between the two metal strips 1330 is formed a slot 1350 that is the dual of the metal feedline 1250 of Fig. 11. Bent slots 1310 replace the bent metal strips 230 and 232 of Fig. 1. Likewise, a tapering slot conesponding to the tapering metal portion 234 of Fig. 1 couples the slot 1350 and the bent slots 1310. Metal sheet 1312 is located where the dielectric without a ground plane is in the antenna 200. The bent slots 1310 are formed in the metal sheet 1312. The slot antenna 1300 has the dual shape of the antenna 200 of Fig. 1. The two-strip transmission line 1330 is shown in Fig. 12 as an example. Any other type of transmission line (e.g. microstrip line, coaxial line) may be used as the feedline in place of the two strips 1330. This antenna 1300 may be fabricated by printing or etching all metal features on one side of a substrate. The antenna 1300 may also be fabricated without a substrate, for example by cutting the antenna out of a metal sheet and holding the cut pieces in place with the help of insulating materials. Linear Array of Multi-Band Antennas Aπays of multi-band antennas maybe employed, for example, to increase the directivity or gain for applications such as wireless computer network access points and mobile phone base-station antennas. Fig. 9 shows an example linear array 1000 of multi-band antennas 1030, 1032,

1034, 1036. The anay 1000 comprises four multi-band antennas 1030, 1032, 1034, 1036 ananged along a straight line, but other numbers of multi-band antennas can be practiced. Each of the antennas 1030, 1032, 1034, 1036 has the same basic configuration as that of the antenna 200 of Fig. 1 in terms of the first and second bent metal strips. This anay 1000 has an almost omni-directional radiation pattern (that is similar to the pattern of a single antenna) on the x-z plane and a narrower radiation pattern on y-z and x-y planes. Again, the anay 1000 has a truncated ground plane 1012. Although a standard corporate feed system 1020 is shown in Fig. 9, many other known feed systems can be employed. The feed system 1020 comprises a single feedline at the bottom of the ground plane 1012, which branches into two feedlines. Each of those branches in turn separates into two further branches coupling to each of the antennas 1030, 1032, 1034, 1036. The feed system may include feedlines of different widths for impedance matching. Phase shifters may be introduced to change the direction of the main beam of the anay 1000. Alternatively, each antenna 1030, 1032, 1034, 1036 maybe connected to separate transceivers to form a Multiple Input Multiple Output (MEVIO) system. The separation between individual multi-band antennas 1030, 1032, 1034, 1036 in the anay 1000 maybe adjusted to change the shape of the radiation pattern and/or to adjust the mutual coupling between the radiating elements. This antenna anay 1000 may be fabricated on a substrate using standard planar printed circuit fabrication technology. Alternatively, the antenna anay 1000 may also be fabricated without a substrate using metal sheets and strips, which are held in place with the help of insulating materials. Planar Anay of Multi-Band Antennas Planar anays or two-dimensional anays of multi-band antennas may be employed, for example to obtain nanow radiation patterns on three orthogonal planes. A 2x2 planar (two-dimensional) anay 1100 comprising four antennas 1130, 1132, 1134, 1136 on a substrate 1110 is shown in Fig. 10 as an example, but other numbers of multi-band antennas may be practiced. The truncated ground plane 1112 has a cross-like shape and each antenna 1130, 1132, 1134, 1136 is positioned in one of the comers of the substrate without a ground plane beneath on the bottom surface. The feedline 1120 has a largely T-shape, where each end of the horizontal ends of the T again branch vertically (as depicted in Fig. 10) to connect to the respective antenna 1130, 1134 on the one hand and the respective antenna 1132 and 1136 on the other hand. This anay 1100 has a nanower (more directed) beam on all x-z, y-z and x-y planes. Other types of feed systems 1120 may be employed. Phase shifters may be introduced to change the direction of the beam. Alternatively each antenna 1130, 1132, 1134, 1136 may be connected to separate transceivers. This antenna anay 1100 may be fabricated on a substrate using standard planar printed circuit fabrication technology. Alternatively, the anay 1100 may also be fabricated without a substrate using metal sheets and strips, which are held in place with the help of insulating materials.

Multi-Band Antenna with a Reflector Antennas may be employed over reflecting surfaces to block radiation in certain directions and to enhance radiation in other directions. The reflector may have different shapes such as planar, comer or curved. Any of the multi-band antennas described in this application may be combined with a reflector. The reflector may be an artificial magnetic wall, which behaves like a theoretical magnetic conductor, designed to reflect waves at one or more operating frequencies of the antenna. Fig. 20 shows a multi-band antenna 2100 placed over an artificial planar magnetic wall reflector 2172, as an example. The antenna 2130 has the basic form of the antenna 200 of Fig. 1 in this example. There is a truncated ground plane 2112 on the bottom surface of the substrate. The artificial magnetic wall 2172 of the type shown in this example is also known as a High-hnpedance Surface, Metallic Electromagnetic Structure, Electromagnetic Band Gap (EBG) structure or Frequency Selective Surface (FSS). The wall may be fabricated by printing or etching metal patches 2180 on one or more substrate surfaces and connecting the patches 2180 to a ground plane 2186 using plated via holes 2184. Each patch 2180 and the via 2184 form a "mushroom" shape. Any other type of planar, curved, comer reflector that functions as an artificial magnetic wall may be practiced. If any of the multi-band antennas described herein is to be fitted on to a parallel conducting surface, an artificial magnetic wall may inserted between the antemia and the conducting surface. This prevents the electric field of the antenna, which is nearly parallel to the conducting surface, from being "short-circuited" by the conducting surface. The artificial magnetic wall reflects the field back before the field hits the conducting surface. A magnetic wall reflects electromagnetic waves with a phase of 0 degrees (like an "open-circuit" end of a transmission line), whereas an electric wall such as a conducting sheet reflects electromagnetic waves with a phase of 180 degrees (like a "short-circuit" end of a transmission line.) Ground-Less Multi-Band Antennas Multi-band antennas disclosed hereinbefore are monopole antennas, where the ground of the feedline also serves as the ground for the radiating elements. Each of these antennas can be converted to a truly ground-less dipole version, where two identical or almost identical multi-band radiating elements of positive and negative polarities are made to radiate together forming a dipole. Fig. 14 shows a ground-less or dipole-type multi-band antenna 1500 where the two similar multi-band radiating elements 1560, 1562 are formed on the opposite sides of a dielectric substrate 1510. The radiating elements 1560, 1562 each comprise bent metal strips having the configuration of the bent metal strips 230, 232 of the antenna 200 of Fig. 1. The radiating element 1560 on the top surface is depicted with solid black fill, while the radiating element 1562 on the bottom surface of the substrate 1510 is depicted with gray dotted hatching, so as to distinguish the two visually. However, the two radiating elements 1560, 1562 are in fact made of conductive metal, which may be the same metal (e.g., copper). The feedline 1520 of this antenna 1500 comprises two metal strips 1520A, 1520B, one on each side of the substrate 1510. The feedline strips 1520A, 1520B are coupled to the respective multi-band radiating elements 1560, 1562 on the same side of the substrate 1510. The two drawings on the top show the plan and side view of the antenna 1500. This plan shows the first multi-band radiating element 1560 on the left side of the substrate 1510 and the feedline 1520A on the top surface or plane 1 in dark black. The feedline 1520A bends to the left as depicted. The "image" multi-band element 1562 on the bottom surface or plane 2 is shown with gray shading. The feedline 1520B bends to the right as depicted, with the radiating element 1562 on the right side of the substrate 1510. The drawing in the middle shows the "image" multi- band element 1562 and the feed strip 1520B on the bottom surface or plane 2 in gray dotted hatching. The lower drawing shows another side view of the antenna 1500. The two-strip feedline 1520 of this antenna 1500 may be connected and matched to a standard transmission line (e.g., a microstrip transmission line) using a transmission line adapter. Another type of a transmission line, such as a coaxial line, may be used instead of the two-strip feedline shown in Fig. 14. When a coaxial line is used, the outer conductor of the coaxial line is connected to one multi-band radiating element and the inner conductor of the coaxial line is connected to the other multi-band radiating element (through a hole in the substrate if a substrate is used.) Fig. 22 illustrates another ground-less or dipole-type antenna 2300 with two identical multi-band radiating elements 2360, 2362 formed on the same side of a substrate 2310, side by side. Each radiating element 2360, 2362 has the configuration of the antenna shown in Fig. 1. The radiating elements 2360, 2362 are fed through two parallel metal strips formed on the same side of the substrate 2310, separated by a gap, each of which is connected to each multi-band radiating element 2360, 2362. The feedline of this antenna maybe connected and matched to a standard transmission line (e.g., a microstrip transmission line) using a transmission line adapter. Another type of a transmission line, such as a coaxial line, may be used instead of the two-strip feedline shown in Fig. 22. If a coaxial line is used, the outer conductor of the coaxial line is connected to one multi-band radiating element and the inner conductor of the coaxial line is connected to the other multi-band radiating element. Dual-Band Antenna with One Strip on the Opposite Surface The antenna shown in Fig. 1 has two metal radiating strips on the top surface. One of these metal strips can be made on the bottom surface instead, as shown in the antenna 1600 of Fig. 15. The antenna 1600 has a feedline 1620, a taper section, and a first bent metal strip 1630 on the top surface of the substrate 1610. The truncated ground plane 1612 is on the bottom surface of the substrate 1610. The second bent metal strip 1632 is disposed on the bottom surface of the substrate 1610 and may be coupled to the first metal strip 1630 and the feedline 1620 using a plated via hole 1640 through the substrate 1610. The overall shape of the antenna 1600 viewed in plan view is the same as that of the antenna 200 of Fig. 1. Plated via holes are commonly used in microwave planar printed circuit fabrication technology to connect metal features on different surfaces. This antenna may be fabricated on a substrate using standard microwave planar printed circuit fabrication technology. Antenna with Multi-Band Radiating Elements on Both Surfaces The antenna shown in Fig. 1 has two metal radiating strips on the top surface, which form one set of multi-band radiating elements. Another set of multi-band radiating elements, with the same or different dimensions, may be formed on the bottom surface of the substrate. Fig. 19 depicts an antenna 2000 comprising two multi-band radiating elements 2060 and 2062, with the same or different dimensions, formed on both the top and bottom surfaces of a substrate 2010. The multi-band radiating element 2060 has the same basic configuration as the bent metal strips 230 and 232 in Fig. 1, but flipped horizontally, coupled to a tapered section and a feedline on the top surface of the substiate 2010. The truncated ground plane 2012 is disposed on the bottom surface of the dielectric substrate 2010. The second multi-band radiating element 2062 on the bottom surface of the substrate 2010 is depicted with gray dotted hatching. The second multi-band radiating element 2062 may be connected to the first multi-band radiating element 2060, or the common feedline, using a plated via hole 2040 through the substrate 2010. Each of the multi-band radiating elements 2060, 2062 has two resonator sections, and hence, the antemia 2000 in Fig. 19 has four resonator sections altogether. The lengths of the four resonator sections may be different and then the antenna 2000 may operate in four separate frequency bands. Alternatively, by adjusting the lengths of the resonator sections, some of these frequency bands may be made to overlap, giving less number of wider operating frequency bands. This antenna 2000 may be fabricated on a substrate using standard planar printed circuit fabrication technology. Antenna with Two Ground Planes Additional truncated ground planes can be added to any multi-band antenna with a single ground plane, to shield the feedline and the microwave circuit

(connected to the feedline) from antenna radiation or for any other purpose. Fig. 21 depicts a multi-band antenna with two identical ground planes 2212, 2213. This is obtained by placing an additional substrate 2210 with a truncated ground plane 2213 over the multi-band antenna 200 shown in Fig. 2. Hence the printed circuit board has two layers. The feedline, located on the internal surface of the two-layer printed circuit board, is now sandwiched between two substrates and two ground planes 2212, 2213. Such transmission lines are known as strip lines.

A Printed Antenna in an Electronic Device with a Conducting Case An antenna, or several antennas, printed on a single layer or multi-layer printed circuit board may be used in an electronic device with a conducting case or shield (such as a computer or video camera) as follows. The printed circuit board is installed in the device such that the antenna section of the printed circuit board is outside the conducting case; the rest of the printed circuit board is inside the conducting case. This is achieved by making a slot in the conducting case, such as the slots available in the back of most desktop computers. Two embodiments of such an anangement are shown in Figs. 26 and 27. As the antenna is outside the conducting case, the antenna can radiate freely and form links with other wireless devices around. As the rest of the circuit board is within the conducting case, any undesirable radiation emitting from the radio frequency components or digital components of the printed circuit board are shielded by the conducting case and are not able to radiate. Hence, electromagnetic interference to other electronic devices is prevented. For better antenna performance, the electromagnetic effects of the conducting case may be accounted for in the antenna design and testing. The conducting case may form a part of the antenna ground. The exposed antenna section of the printed circuit board may be covered using a non-conducting cover or radome, made out of plastic or other material, to protect the antenna from accidental damage, to improve the aesthetic appeal or for any other reason.

Fig. 26 shows a printed circuit board with a printed antenna 2720 installed in a box shaped electronic device 2710 with a conducting case, such as a personal desktop computer 2700. In this embodiment, the circuit board 2715 has multiple layers (not shown). The antenna 2720 is printed on an internal surface of the printed circuit board 2715, like the antenna shown in Fig. 21. There is a truncated ground plane on each external surface of the printed circuit board 2715. The truncated ground plane on the front surface is indicated by hatching. The truncated ground plane on the back surface is not shown, to avoid complexity. One or both ground planes may be electrically connected to the conducting case 2710 of the device 2700. The antenna 2720 is designed such that the truncated ground planes and the conducting case serve as a ground for the antenna 2720. h this embodiment, the antenna feed has a stripline configuration, like in the antenna in Fig. 21. The feed strip is on an internal surface and is directly connected to the antenna 2720 (shown hatched). The two truncated ground planes on the two surfaces serve as grounds for the stripline feed.

More than one antenna may be printed on the same printed circuit board, for installation in an electronic device with a conducting case, using the method described above. Multiple antennas printed on the same printed circuit board may be identical or different. Such multiple antennas may be used to provide multiple communication services in one circuit board, such as WLAN (including Wi-Fi IEEE802.11), Bluetooth, WiMax (IEEE 802.16), PCS, UWB, broadband wireless, and other wireless services. They may also be used to improve signal quality for a given communication service using multiple antenna/channel techniques such as antenna diversity and MIMO.

Fig. 27 shows a printed circuit board 2815 with a printed antenna 2820 installed in another electronic device 2800 with a conducting case 2810, such as a camera. In this example, the case of the device 2800 has been designed to allow space for the antenna 2820. In this embodiment, the space is allowed in a comer but other locations are also possible. The printed circuit board 2815 is installed in the device 2800 such that the antenna section 2820 of the printed circuit board 2815 is outside the conducting case 2810; the rest of the printed circuit board 2815 is inside the conducting case 2810. This is achieved by making a slot in the conducting case 2810. The exposed antenna section 2820 of the printed circuit board 2815 may be covered using a non-conducting cover or radome, made out of plastic or other material, to protect the antenna 2820 from accidental damage, to improve the aesthetic appeal or for any other reason.

Applications The embodiments of the invention may address the rapidly emerging wireless communication standards such as IEEE 802.11a, 802.11b, 802.1 lg and 802.1 lj, for example. These standards operate respectively over allocated frequencies with the ranges approximately 2.4 to 2.5 GHz and 4.9 to 5.9 GHz. These frequency bands are approximately in the ratio of 1 to 2 and may have different fractional bandwidths. The LEEE bands are "unlicensed" in that a user is not required to apply for an individual license to transmit or receive within those bands. Embodiments of the invention may be practiced in "Ambient Intelligence" devices, where short-range wireless communication between sensing and controlling units is an aspect of an environment. Much of this communication activity takes place in one, or the other, or both, of the 2.4-2.5 and 4.9-5.9 GHz bands. Another wireless application field already requiring capability at frequency bands in an approximate ratio of 1 to 2 is mobile communication or mobile telephony. GSM mobile or cellular phone systems operate around 900MHz, 1800MHZ and 1900MHz; Digital Cellular Systems (DCS) operate around 1880 MHz, PCS systems around 1900 MHz, and Universal Mobile Telecommunication Services (UMTS) around 2000 MHz. A single multi-band antenna that operates in 890-960 MHz and 1700-2200 MHz may cover all these standards. The embodiments of the invention are scalable to these and other frequency bands. In other words, the embodiments of the invention can be made to operate in other multiple frequency bands by scaling their physical dimensions and other parameters. They may be practiced in cellular telephone handsets making them smaller and/or thinner than cuπent telephone handset antennas. Still other applications may be practiced, for example Bluetooth (2.4GHz) and GPS (1.575 GHz). The invented antenna has multi-band operation and covers all IEEE 802.1 la, 802.1 lb, 802.1 lg and 802.1 ljWLAN bands in all parts of the world, as well as HIPERLAN bands, for worldwide use. The antenna also has the flexibility to be designed for other frequency bands. The return loss (-20 log|sn|) in one or more embodiments is better than lOdB over the required frequency bands, and the E and H-plane antenna patterns are wide and relatively smooth. The antenna response involves two well-defined bands, rather than a continuous broadband response offers additional protection to intermodulation interference from any strong radio signals at frequencies outside the desired two bands. The antenna pattern may simply be printed as an extended part of the required transceiver circuit structure in microstrip, coplanar waveguide or other printed/etched format. The physical accuracies required are no more than are achieved in standard printed circuit fabrication technology. There is no additional step involved in the antenna such as a soldering a joint, or surface mounting. The compactness of the antenna produces a small physical form size easily permitting dual antennas for diversity within the width of a standard PCMCIA card, or within a small space of a laptop, handheld etc. The simple printed structure and compact size permits a PCMCIA implementation which extends only a small distance from the computer housing and whose very small thickness with no bulging means that if placed in the lower PCMCIA slot, the device does not interfere with access to the upper slot. Thus, the single feed, multi-band antenna has: • Low incremental cost, • Small thickness, • Compact size with acceptable dimensional tolerances • Wide radiation pattern, and • Well defined bandwidth response The foregoing is attractive to a system integrator, because the antenna design is essentially just the dimensions of the pattern to be etched onto the circuit board substiate. Additional components and manufacturing steps are not required. The antenna is low cost, since the antenna can be manufactured using standard planar printed circuit fabrication technology and use inexpensive circuit boards. The antenna is thin, since the antenna is printed on a circuit board that may be less than 1 mm thick. This permits it to be accommodated easily inside a 5mm thick PCMCIA card without a "swollen" end. The area of the antenna may be less than 10 mm x 10 mm. Hence two antennas can be accommodated in an area that is significantly smaller than the area used by cuπent PCMCIA cards. In other words, quad-band (IEEE 802.11 a+b+g+j) WLAN PCMCIA cards designed with the embodiments of the invention are not only thinner, but also be shorter than cunent cards. Longer cards are inconvenient and their use is limited in busy locations. As an example, one PCMCIA card in the market has an antenna extension (i.e., the protruding part of the card that pops out of the computer when the card is inserted into a PCMCIA slot in the computer) that is 32 mm long and 13 mm thick. With an embodiment of the invention, this section can be reduced to about 12 mm in length and 5 mm in height (i.e. the same as the rest of the card). Thus, the volume of this disruptive section may be reduced by about 85% (or a factor of about 7) with the embodiments of the invention. The antenna requires no ground plane directly underneath the radiating elements, unlike microstrip patch antennas. The design is not based on an infinite ground plane assumption, and hence does not suffer from the radiation pattern degradation due to ground plane truncation. On the other hand, when the theoretically infinite ground plane of a microstrip antenna is truncated to accommodate the antenna inside a PCMCIA card, the radiation pattern on the horizontal plane becomes weaker. The antenna is flexible and can be integrated into all types of devices such as notebook computers, handheld computers, mobile phones, digital cameras, video cameras, portable game controllers, wireless security devices, and multi-purpose devices. Antenna dimensions can be scaled to make it operate at different frequency bands. Triple or other multi-band operation may be practiced. In the foregoing manner, a number of antennas and methods manufacturing and using antennas have been disclosed. The detailed description provides prefened exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the detailed description of the prefened exemplary embodiments provides those skilled in the art with enabling descriptions for implementing prefened exemplary embodiments of the invention. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

CLAtMS We claim: 1. An antenna, comprising: a first bent metal strip for radiating energy; a second bent metal strip for radiating energy connected to said first metal stiip, said first metal strip bending around said second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between said metal strips for a substantial portion of the length of said first metal strip, said metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band; a feedline coupled to at least one of said first and second bent metal strips, said feedline and at least one of said first and second metal strips being co-planar; and at least one truncated groundplane adjacent to said feedline, said at least one groundplane being truncated at or near a point where said feedline is coupled to said first metal strip or said second metal strip.

2. The antenna according to claim 1, wherein said feedline, said first metal strip and said second metal strip are co-planar.

3. The antenna according to claim 2, wherein said truncated ground plane is co-planar with said first metal strip, said second metal strip, and said feedline.

4. The antenna according to claim 1, further comprising insulation material joining said truncated ground plane, said first metal strip, said second metal strip, and said feedline together.

5. The antenna according to claim 1, further comprising at least one more truncated groundplane adjacent to the feedline, the groundplanes being truncated at or near a point where the feedline is coupled to the first metal strip, the second metal strip, or both.

6. The antenna according to claims 1, further comprising a dielectric substrate, wherein said first metal strip, said second metal strip, and said feedline are formed on planar surfaces of said dielectric substrate.

7. The antenna according to claim 6, wherein said truncated ground plane is disposed on the same planar surface of said dielectric substrate relative to said feedline.

8. The antenna according to claim 6, wherein said truncated ground plane is disposed on an opposite planar surface of said dielectric substrate relative to said feedline.

9. The antenna according to claim 6, wherein said truncated ground plane has an edge substantially parallel to an edge of said dielectric substrate.

10. The antenna according to claim 6, wherein said truncated ground plane has an edge substantially diagonal relative to two edges of said dielectric substiate.

11. The antenna according to claim 6, wherein said dielectric substrate is a multi-layer microwave substrate.

12. The antenna according to claim 11, wherein at least two truncated groundplanes are on different dielectric layer surfaces.

13. The antenna according to claim 6, further comprising a plated via formed through said substrate coupling said first and second metal strips, said first and second metal strips being formed on opposite planar surfaces of said dielectric substrate.

14. The antenna according to claim 1, wherein said truncated ground plane is co-planar with said feedline.

15. The antenna according to claim 1, wherein said antemia is manufactured using standard microstrip circuit fabrication methods.

16. The antenna according to claim 1, wherein the total resonance length of each metal strip is about one-quarter, free-space wavelength long at a mid- frequency of a predetermined frequency range.

17. The antenna according to claim 1, wherein the total resonance length of each metal strip is about one half guided wavelengths long at a mid-frequency of a predetermined frequency range.

18. The antenna according to claim 1, wherein the total resonance length of each metal strip is about 0.35 guided wavelengths to about 0.55 guided wavelengths long at a mid-frequency of a predetermined frequency range.

19. The antenna according to claim 1, wherein said metal strips have an overall layout selected from the group consisting of: a G-shape; an arcuate shape; a substantially circular shape; a G-shape with oppositely projecting stubs forming terminal ends of said metal strips; and a substantially triangular shape.

20. The antenna according to claim 1, wherein said metal strips have stubs extending orthogonally from the respective terminal portion of said metal strips.

21. The antenna according to claim 1, wherein at least one of said first and second metal strips comprises a tapered section of metal matching the width of said at least one metal strip to the width of said feedline.

22. The antemia according to claim 1, further comprising: a third bent metal strip for radiating energy coupled to at least one of said first and second metal strips; and a fourth metal strip for radiating energy coupled to one of said first, second and third metal strips, said third and fourth metal strips being separated from each other for substantial portions of their lengths, a portion of at least one of said third and fourth metal strips partially suπounding a portion of at least the other one of said third and fourth metal strip, said first, second, third and fourth metal strips and said feedline being co-planar.

23. The antenna according to claim 1, wherein said antenna comprises a multi-band and broadband, fully planar antenna.

24. The antenna according to claim 1, further comprising a reflector coupled to said antenna.

25. A multi-band antenna system comprising: at least two antennas, each comprising: a first bent metal strip for radiating energy; , a second bent metal strip for radiating energy connected to said first metal strip, said first metal strip bending around said second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between said metal strips for a substantial portion of the length of said first metal strip, said metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band; a feedline coupled to at least one of said first and second bent metal strips, said feedline and at least one of said first and second metal strips being co-planar; and at least one truncated groundplane adjacent to said feedline, said at least one groundplane being trancated at or near a point where said feedline is coupled to said first metal strip or said second metal strip.

26. A wireless electronic apparatus, comprising: a housing; an RF circuit disposed within said housing; at least one antenna coupled to said RF circuit and disposed within said housing, said antenna comprising: a first bent metal strip for radiating energy; a second bent metal strip for radiating energy connected to said first metal strip, said first metal strip bending around said second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between said metal strips for a substantial portion of the length of said first metal strip, said metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band; a feedline coupled to at least one of said first and second bent metal strips, said feedline and at least one of said first and second metal strips being co-planar; and at least one truncated groundplane adjacent to said feedline, said at least one groundplane being truncated at or near a point where said feedline is coupled to said first metal strip or said second metal strip.

27. The wireless electronic apparatus according to claim 26, wherein said apparatus is selected from the group consisting of: a cellular telephone; a wireless LAN card; a PC wireless LAN card; a PCMCIA wireless LAN card; a Cardbus wireless LAN card; a Wi-Fi wireless LAN card; a WiMax wireless communication card; a multi-standard wireless communication card; a computer; a printer; a wireless mouse; a computer peripheral; a PDA; an electronic organizer; an electronic memory device; an electronic or optical storage device; a wireless network access point; a cellular telephone base-station; a wireless game controller; a wireless security device; a home appliance with wireless interface; a wireless headset; a wireless communication PCI card; a USB-connected device with wireless interface; a wireless network integration (NIC) card; a SDIO card with wireless interface; a camera with a wireless interface; a video camera with a wireless interface; a multi-purpose device with a wireless interface; and an electronic device with a wireless interface. 27. An antenna, comprising: a plurality of radiating elements, each radiating element comprising a first bent metal strip for radiating energy, and a second bent metal strip for radiating energy connected to said first metal strip, said first metal strip bending around said second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid- frequency of a low band for said radiating element between said metal strips for a substantial portion of the length of said first metal strip, said metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid- frequency of said low band for said radiating element; at least one feedline coupled to said radiating elements, at least one of said radiating elements and said at least one feedline being co-planar; and at least one truncated groundplane adjacent to said feedline, said groundplane being truncated at or near a point where said feedline is coupled to at least one of said first and second metal strips.

28. The antenna according to claim 27, wherein said truncated ground plane is co-planar with said feedline.

29. The antenna according to claim 27, further comprising insulation material joining said truncated ground plane, said radiating elements and said feedline together.

30. The antenna according to any one of claims 27, further comprising a dielectric substrate, said radiating elements and said feedline being formed on at least one planar surface of said dielectric substrate.

31. The antenna according to claim 30, wherein said truncated ground plane is disposed on the same planar surface of said dielectric substrate as said feedline.

32. The antenna according to claim 30, wherein said truncated ground plane is disposed on an opposite planar surface of said dielectric substrate relative to said feedline.

33. The antenna according to claim 31, wherein said truncated ground plane is co-planar with said feedline.

34. The antemia according to claim 30, further comprising at least one plated via through said substrate coupling at least two of said radiating elements formed on opposite planar surfaces of said dielectric substrate.

35. The antenna according to claim 27, wherein said antenna is manufactured using standard microstrip circuit fabrication methods.

36. The antenna according to claim 27, wherein the total resonance length of each metal strip is about one-quarter, free-space wavelength long at a mid- frequency of a predetermined frequency range for said radiating element.

37. The antenna according to claim 27, wherein the total resonance length of each metal strip is about one half guided wavelengths long at a mid-frequency of a predetermined frequency range for said radiating element.

38. The antenna according to claim 27, wherein the total resonance length of each metal strip is about 0.35 guided wavelengths to about 0.55 guided wavelengths long at a mid-frequency of a predetermined frequency range for said radiating element.

39. The antenna according to claim 27, comprising three radiating elements and two dielectric substrates, one of said radiating elements disposed on a top surface of a first dielectric substiate, another of said radiating elements disposed on a bottom surface of a second dielectric substrate, and the remaining radiating element disposed on at least one of a bottom surface of said first dielectric substiate and a top surface of said second dielectric substrate.

40. The antenna according to claim 39, further comprising at least one plated via through said substrates coupling said three radiating elements.

41. The antenna according to claim 27, wherein said plurality of radiating elements is arranged substantially linearly in at least one dimension.

42. The antenna according to claim 27, wherein each radiating element is disposed in a comer of a dielectric substrate in at least one dimension.

43. The antenna according to claim 42, wherein said radiating elements are triangularly shaped in overall form.

44. The antenna according to claim 43, wherein said truncated groundplane has diagonal edges demarcating said comers without said groundplane beneath said radiating elements, said comers being triangular in form.

45. The antenna according to claim 27, further comprising a plurality of dielectric substrates, said radiating elements disposed on at least two surfaces of said plurality of substrates.

46. The antenna according to claim 27, wherein said radiating elements have at least two sizes.

47. The antenna according to claim 27, wherein said radiating elements have different configurations.

48. The antemia according to claim 27, wherein said radiating elements are each disposed along a line.

49. The antenna according to claim 27, wherein said radiating elements are each disposed along a curve.

50. The antenna according to claim 27, wherein said radiating elements are each disposed on a planar surface.

51. The antenna according to claim 27, wherein said radiating elements are each disposed on a curved surface.

52. The antenna according to claim 27, wherein said radiating elements are uniformly spaced.

53. The antenna according to claim 27, wherein said radiating elements are non-uniformly spaced.

54. The antenna according to claim 27, further comprising a reflector coupled to said antenna.

55. A wireless electronic apparatus, comprising: a housing; an RF circuit disposed within said housing; an antenna coupled to said RF circuit and disposed within said housing, said antenna comprising: a plurality of radiating elements, each radiating element comprising a first bent metal strip for radiating energy, and a second bent metal strip for radiating energy connected to said first metal strip, said first metal strip bending around said second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band for said radiating element between said metal strips for a substantial portion of the length of said first metal strip, said metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band for said radiating element; at least one feedline coupled to said radiating elements, at least one of said radiating elements and said at least one feedline being coplanar; and at least one truncated groundplane adjacent to said feedlme, said groundplane being truncated at or near a point where said feedline is coupled to at least one of said first and second metal strips.

56. The wireless electronic apparatus according to claim 55, wherein said apparatus is selected from the group consisting of: a cellular telephone; a wireless LAN card; a PC wireless LAN card; a PCMCIA wireless LAN card; a Cardbus wireless LAN card; a Wi-Fi wireless LAN card; a WiMax wireless communication card; a multi-standard wireless communication card; a computer; a printer; a wireless mouse; a computer peripheral; a PDA; an electronic organizer; an electronic memory device; an electronic or optical storage device; a wireless network access point; a cellular telephone base-station; a wireless game controller; a wireless security device; a home appliance with wireless interface; a wireless headset; a wireless communication PCI card; a USB-connected device with wireless interface; a wireless network integration (NIC) card; a SDIO card with wireless interface; a camera with a wireless interface; a video camera with a wireless interface; a multi-purpose device with a wireless interface; and an electronic device with a wireless interface.

57. A multi-band antenna system, comprising: two or more antennas each comprising: a plurality of radiating elements, each radiating element comprising a first bent metal strip for radiating energy, and a second bent metal strip for radiating energy connected to said first metal strip, said first metal strip bending around said second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band for said radiating element between said metal strips for a substantial portion of the length of said first metal strip, said metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band for said radiating element; at least one feedline coupled to said radiating elements, at least one of said radiating elements and said at least one feedline being coplanar; and at least one truncated groundplane adjacent to said feedline, said groundplane being truncated at or near a point where said feedline is coupled to at least one of said first and second metal strips.

58. An antenna, comprising: a feedline; and a metal sheet coupled to said feedline, said metal sheet having a first bent metal slot for radiating energy formed therein and a second bent metal slot for radiating energy formed therein and coupled to said first radiating slot, said first slot bending around said second slot, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between said slots for a substantial portion of the length of said first slot, said slots being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band.

59. The antenna according to claim 58, further comprising a reflector coupled to said antenna.

60. A wireless electronic apparatus, comprising: a housing; an RF circuit disposed within said housing; an antenna coupled to said RF circuit and disposed within said housing, said antenna comprising: a feedline; and a metal sheet coupled to said feedline, said metal sheet having a first bent metal slot for radiating energy formed therein and a second bent metal slot for radiating energy formed therein and coupled to said first radiating slot, said first slot bending around said second slot, leaving a separation of at least 0.025 guided wavelengths at a mid- frequency of a low band between said slots for a substantial portion of the length of said first slot, said slots being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band.

61. The wireless electronic apparatus according to claim 60, wherein said apparatus is selected from the group consisting of: a cellular telephone; a wireless LAN card; a PC wireless LAN card; a PCMCIA wireless LAN card; a Cardbus wireless LAN card; a Wi-Fi wireless LAN card; a WiMax wireless communication card; a multi-standard wireless communication card; a computer; a printer; a wireless mouse; a computer peripheral; a PDA; an electronic organizer; an electronic memory device; an electronic or optical storage device; a wireless network access point; ^' a cellular telephone base-station; a wireless game controller; a wireless security device; a home appliance with wireless interface; a wireless headset; a wireless communication PCI card; a USB-connected device with wireless interface; a wireless network integration (NIC) card; a SDIO card with wireless interface; a camera with a wireless interface; a video camera with a wireless interface; a multi-purpose device with a wireless interface; and an electronic device with a wireless interface.

62. A multi-band antenna system comprising: two or more antennas each comprising: a feedline; and a metal sheet coupled to said feedline, said metal sheet having a first bent metal slot for radiating energy formed therein and a second bent metal slot for radiating energy formed therein and coupled to said first radiating slot, said first slot bending around said second slot, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between said slots for a substantial portion of the length of said first slot, said slots being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band.

63. A method of manufacturing an antenna, said method comprising the steps of: forming a first bent metal strip for radiating energy; forming a second bent metal strip for radiating energy connected to said first metal strip, said first metal strip bending around said second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between said metal strips for a substantial portion of the length of said first metal strip, said metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band; forming a feedline coupled to said first and second strips, said feedline and at least one of said first and second metal strips being co-planar; and forming at least one truncated groundplane adjacent to said feedline, said groundplanes being truncated at or near a point where said feedline is coupled to said first metal strip or said second metal strip.

64. The method according to claim 63, further comprising step of providing a planar, dielectric substrate, wherein said first metal strip, said second metal strip, and said feedline are formed on at least one surface of the dielectric substrate.

65. The method according to claim 64, wherein all metal components are on said two surfaces of said dielectric substrate.

66. The method according to claim 63, wherein the total resonance length of each metal strip is about one-quarter, free-space wavelength long at a mid- frequency of a predetermined frequency range.

67. The method according to claim 63, wherein the total resonance length of each metal strip is about one half guided wavelengths long at a mid-frequency of a predetermined frequency range.

68. The method according to claim 63, wherein the total resonance length of each metal strip is about 0.35 guided wavelengths to about 0.55 guided wavelengths long at a mid-frequency of a predetermined frequency range.

69. The method according to claim 63, wherein said metal strips have a layout selected from the group consisting of: G-shape; an arcuate shape; substantially circular shape; G-shape with oppositely projecting stubs forming terminal ends of said metal strips; and a substantially triangular shape.

70. The method according to claim 63, further comprising the steps of: forming a third bent metal strip for radiating energy coupled to at least one of said first metal strip and said second strip; and forming a fourth metal strip for radiating energy coupled to one of the first, second and third metal strips, said third and fourth metal strips being separated from each other for substantial portions of their lengths, a portion of at least one of said third and fourth metal strips partially sunounding a portion of at least the other one of said third and fourth metal strip, said first, second, third and fourth metal strips and said feedline being co-planar.

71. A method of using an antenna, said method comprising the steps of: feeding RF energy via a feedline to first and second bent metal strips, said feedline and at least one of said first and second metal strips being co-planar, at least one truncated groundplane being adjacent to said feedline, said groundplane being truncated at or near a point where said feedline is coupled to said first metal strip or said second metal strip; radiating said RF energy using said first bent metal strip; and radiating said RF energy using said second bent metal strip connected to said first metal strip, said first metal strip bending around said second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between said metal strips for a substantial portion of the length of said first metal strip, said metal strips being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band.

72. The method according to claim 71, further comprising the steps of: radiating said RF energy via a third bent metal strip coupled to at least one of said first and second bent metal strips; and radiating said RF energy via a fourth metal strip coupled to one of said first, second and third metal strips, said third and fourth metal strips being separated from each other for substantial portions of their lengths, a portion of at least one of said third and fourth metal strips partially sunounding a portion of at least the other one of said third and fourth metal strip, said first, second, third and fourth metal strips and said feedline being co-planar.

73. An antenna, comprising: a first multi-band radiating element comprising a first bent metal strip for radiating energy, a second bent metal strip for radiating energy connected to said first metal strip, said first bent metal strip bending around said second metal strip, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between said metal strips for a substantial portion of the length of said first metal strip, said metal strips being laid out over an area in the range of 0.025 to 0.045 square guided wavelengths at a mid-frequency of said low band; a second multi-band radiating element that is similar to a minor image of said first multi-band radiating element to form a dipole together with said first multi-band radiating element by supporting cunents of opposite polarity to those in the first multi-band radiating element; and a feedline coupled to said first and second multi-band radiating elements.

74. An antenna, comprising: first means for radiating energy; second means for radiating energy coupled to said first radiating means, said first radiating means bending around said second radiating means, leaving a separation of at least 0.025 guided wavelengths at a mid-frequency of a low band between said first and second radiating means for a substantial portion of the length of said first radiating means, said radiating means being laid out over an area of about 0.025 to about 0.045 square guided wavelengths at said mid-frequency of said low band; and means for feeding RF energy to said first and second radiating means, said RF feeding means and at least one of said first and second radiating means being coplanar.

75. The antenna according to claim 74, further comprising means for providing at least one truncated groundplane adjacent to RF energy feeding means.

76. A method of installing in an electronic device with a conducting case a printed circuit board comprising at least one printed antenna in accordance with any one of claims 1-24, 27-54, 58, 59, and 73-75, said method comprising the steps of: disposing said printed antenna of said printed circuit board outside said conducting case to enable radiation; and disposing the remaining components of said printed circuit board inside said conducting case to prevent electromagnetic interference.

77. The method according to claim 76, wherein said conducting case comprises a plurality of slots in which said printed circuit board is disposed.

78. The method according to claim 75 or 76, comprising the step of providing a non-conducting cover or radome to cover said printed antenna.

79. An electronic device comprising: a conducting case; a printed circuit board comprising at least one printed antenna in accordance with any one of claims 1-24, 27-54, 58, 59, and 73-75, said printed antenna of said printed circuit board disposed outside said conducting case to enable radiation, and the remaining components of said printed circuit board disposed inside said conducting case to prevent electromagnetic interference.

80. The electronic device according to claim 79, wherein said conducting case comprises a plurality of slots in which said printed circuit board is disposed.

81. The electronic device according to claim 79 or 80, comprising a nonconducting cover or radome to cover said printed antenna.