WO2002037607A1

WO2002037607A1 - Planar type wideband lpda antenna applied to vhf/uhf channel

Info

Publication number: WO2002037607A1
Application number: PCT/KR2001/000068
Authority: WO
Inventors: Dong-Sik Ahn
Original assignee: Maxwave Co., Ltd.
Priority date: 2000-11-03
Filing date: 2001-01-17
Publication date: 2002-05-10
Also published as: CN1468457A; AU2001228888A1

Abstract

A planar type wideband LPDA antenna has an UHF band of 470 MHz to 752 MHz and comprises: a nonconductive substrate board having a low dielectric and a small loss of an electromagnetic wave; and an antenna pattern arranged on the nonconductive substrate board and having a feed point for the supply of an electric power, the feed point being connected to a TV receiver module, the antenna pattern including an UHF dipole for an UHF band and a VHF dipole for a VHF band, the UHF dipole comprising a first dipole which is the longest dipole among the UHF dipoles and the VHF dipole comprising a second dipole for a high VHF channel, the second dipole being perpendicularly connected to one end of the first dipole.

Description

PLANAR TYPE WIDEBAND LPDA ANTENNA APPLIED TO NHF/UHF CHANNEL

TECHNICAL FIELD

The present invention relates to an antenna for a television receiver, and more particularly, to a planar type wideband LPDA(Log Periodic Dipole Array) antenna applied to VHF/UHF channels, connected to a television receiver or a TV receiver card of a computer for receiving television broadcasting signals and having a small sized planar shape.

BACKGROUND ART

Generally, antenna is connected to a television receiver in the interior of a room or a TV receiving card of a computer. V-shaped antenna is used for VHF band and a parabola or a loop-shaped antenna is used for UHF band.

These antennas, however, occupy a certain space and have a peculiar shape. To this end, they are out of harmony with the surrounding environments. Sometimes, these antennas may provide peoples with uncomfortableness in view of beauty.

Further, in a case that a viewer watches television broadcasting through a personal computer but dislikes to disclose such a watching to the public, the shape of the antenna plays an important role in user's selection. In spite of such a liking, it is not easy to change the shape of the antenna arbitrarily because the shape of the antenna affects largely on the performance of the antenna.

Moreover, the conventional antennas have an unsatisfactory yield of 3 dB or less.

DISCLOSURE OF THE INVENTION Therefore, it is an object of the present invention to provide a planar type wideband LPDA antenna adapted for VHF/UHF channels and having a compact size and superior performance.

It is another object of the invention to provide a planar type wideband LPDA antenna adapted for VHF/UHF channels and in harmony with the environment of the interior of a room or a desk where a television receiver or a personal computer is established.

According to one aspect of the present invention, there is provided a planar type wideband LPDA antenna adapted for VHF/UHF channel. The antenna comprises: a nonconductive substrate board having a low dielectric and a small loss of an electromagnetic wave; and an antenna pattern arranged on the nonconductive substrate and having a feed point for the supply of electric power, the feed point being connected to a TV receiver module. The antenna pattern comprises a UHF dipole for an UHF band of 470 MHz to 752MHz and a VHF dipole for a VHF band, the UHF dipole comprising a first dipole which is the longest dipole among the UHF dipoles, the VHF dipole comprising a second dipole for a high VHF channel, the second dipole being perpendicularly connected to one end of the first dipole. The second dipole has a length has a length corresponding to a difference between a length corresponding to half a wavelength of a central frequency, 195 MHz of the high VHF channels and one sided length of the first dipole.

Preferably, the antenna pattern has the same width with that of the longest dipole of the first dipole.

Preferably, the substrate board comprises a protective pad attached on the front surface and the rear surface of the substrate board.

Preferably, the protective pad is made of one material selected from a group consisting of paper, wood, vinyl, PVC, rubber and Teflon.

Preferably, the substrate board is 1 mm to 3 mm thick and the protective pad is 1 mm thick or less.

Preferably, the electric power supply terminal is coated with radom.

Preferably, the TV receiver module is established in an analog TV or a digital TV.

Preferably, the TV receiver module is a TV receiver card established in a computer.

Preferably, the antenna pattern is made of one material selected from a group consisting of gold, silver, copper and aluminum, and the antenna pattern has a thin film or tape shape.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

Fig. 1 is a schematic perspective view showing a connection status between a TV receiver card of a computer and an antenna of the present invention;

Fig. 2 is a schematic view showing an arrangement of when the antenna of Fig. 1 is applied to a television receiver;

Fig. 3 is a perspective view showing a structure and a connection status of the antenna in accordance with the present invention;

Fig. 4 shows an antenna array of the present invention;

Fig. 5 is a photograph of an antenna fabricated for an experiment;

Fig. 6 is a photograph of an antenna fabricated for a real use;

Fig. 7 is a graph showing a VSWR characteristic of the antenna of Fig. 5; and Fig. 8 is a graph showing a radiation characteristic of the antenna of Fig. 5.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention is in more detail described with reference to the accompanying drawings.

Fig. 1 and Fig. 2 show that a planar type wideband LPDA antennas for VHF/UHF band

of the present invention are applied to a personal computer and a television receiver, respectively. Especially, Fig. 3 shows a structure and a connection status of the antenna in

accordance with the present invention.

Referring to Fig. 1, a main body 20 of a personal computer is placed on a desk and is connected with a monitor 10 and a mouse 30. A planar type wideband antenna 100 for VHF/UHF band in accordance with the present invention is fabricated in a shape of a mouse pad.

The antenna 100 is connected to the main body 20 of the personal computer through a cable 150. In Fig. 1, reference numeral 108 indicates a radom for protecting a feed point

where the antenna 100 and the cable 150 are connected to each other. The feed point is for the supply of an electric power. Fig. 6 shows a photograph of the antenna fabricated in the

shape of the mouse pad and having the same dimension with the size of a real product.

Referring to Fig. 2, the antenna 100 is arranged at a place apart by a certain interval

from one side wall of a television receiver 40. Preferably, the antenna 100 is placed parallel to

a cabinet 50 for receiving articles such as video tape or compact disc. Although not shown in Fig.2, the antenna 100 is naturally connected to an input terminal arranged at the rear side of the television receiver 40 through a cable.

Referring to Fig. 3, the antenna comprises a substrate board 104. An antenna pattern is formed on the front surface and the rear surface of the substrate board 104. Protective boards 102 and 106 are disposed on the front surface of the substrate board 104 and the rear surface of the substrate board 104, respectively. The substrate board 104 and the protective boards 102 and 106 are made of nonconductive material having a low dielectric and a low

electromagnetic wave loss.

Preferably, the substrate board 104 and the protective boards 102 and 106 are made of

one material selected from a group consisting of paper, wood, vinyl, PVC, rubber and Teflon.

It is desirous that the substrate board is 1 mm to 3 mm thick and the protective boards are 1

mm thick or less.

The antenna array is electrically connected to the cable 150 at a feed point 105a and 105b. In order to prevent moisture from being penetrated, the feeding portion including the feedpoints 105a and 105b is coated with radome 108 as shown in Fig. 1. The radome 108 is preferably made of a material having the same property with those of the substrate board 104 and the protective boards 102 and 106 and is preferably 1 mm thick or less.

Returning to Fig. 3, the other end of the cable 150 is electrically connected through an

F-type connector 24 with a TV receiver module 22. Also, for harmony with the surroundings, it is preferable that the cable 150 has as small diameter as possible and the connector 24 has

as small size as possible.

Referring to Fig. 4, a design of the antenna pattern formed on the substrate board 104

in the antenna of the present invention is described in more detail.

It is the most important that the antenna has an gain of 7 db or more in a UHF band of 470 MHz to 752 MHz corresponding to TV channels of 14 to 60 and has a maximum matching in a VHF band of 174 MHz to 216 MHz corresponding to TV channels of 14 to 60. To this end, for designing the LPDA antenna, a material for the substrate board is firstly selected considering properties of material including dielectric and thereafter the gain is set to be over 7 dB in a design frequency range of 470 MHz to 750 MHz.

The antenna comprises: a plurality of UHF dipoles 104a for the use in an UHF band of

470MHz to 752 MHz; and a dipole 107 (referred to as second dipole) for the use in a VHF band, the second dipole being perpendicularly connected to one end of the longest dipole

(hereinafter referred to as first dipole) 104a of the UHF dipoles. In Fig. 4, a solid line indicates

a dipole pattern formed on a front surface of the substrate board 104 and a dotted line indicates a dipole pattern formed on a rear surface of the substrate board 104.

To obtain a length of the second dipole, there is first obtained a length (referred to as

first length) corresponding to half a wavelength of 195 MHz which is a central frequency of high VHF channels of channel 7 to channel 13. The first length as obtained is referred to as L_vhfd. Therefore, half of the first length, L_vhfd/2, corresponds to quarter of the wavelength of 195 MHz and is one sided length of the dipoles for high VHF channels. In a case that the substrate board is made of paper, the first length L_vhfd is 77 cm and one sided length of the first length is 38.5 cm.

Thereafter, there is obtained a difference between half of the first length, L_vhfd/2 and half (II) of one sided length of the first dipole, L_uMd/2. The obtained difference corresponds to

the one sided length (III) of the second dipole 107.

Thereafter, depending on the designed dimension, thin copper film or copper tape is

attached on both sides of the substrate. A power supply wire is thinly attached on a feed point

for the power supply and radomee of vinyl or paper is then attached.

Preferably, the antenna pattern is made of one material selected from a group consisting of gold, silver, copper and aluminum, and the antenna pattern has a thin film or tape shape. As aforementioned, on designing an LDPA antenna for UHF band matched with VHF band, there is no change in a length of straight line placed at both edges. Therefore, the antenna of the present invention does not show a specific variation in the impedance in

numerical analysis. In the design for the VHF channel matching, the impedance is matched and electrowave is received without any reflection but its efficiency becomes low since the

length of the straight line at both edges is smaller than the length of the dipole.

Fig. 5 is a photograph of an antenna fabricated by the above described method. In this embodiment, the antenna comprises a substrate board of paper which is 2.5 mm thick. A

copper tape having a thickness of 0.04 mm is attached on the front surface and the rear surface

of the substrate board. A vinyl is coated in a thickness of 0.3 mm on the front surface and the rear surface of the substrate board including the copper tape.

The antenna of Fig. 5 has a VSWR(Voltage Standing Wave Ratio) characteristic as shown in Fig. 7 and a radiation characteristic shown in Fig. 8.

As described previously, the planar type LPDA antenna of the present invention is an antenna for wideband and has a gain higher than the conventional dipole antenna or loop

antenna by 3 dB and more, to thereby show a superior performance upon receiving television broadcasting.

Also, since the antenna has very thin thickness, it can be fabricated in harmony with

the digital TV receiver to be spread in public as well as the analog TV receiver which is

currently used. For instance, the antenna is fabricated in a shape of book or picture frame in

harmony with the interior design and is established on table, wall, or furniture, or adjacent to

window where broadcasting signals are well received. For more higher sensitivity, the established direction of the antenna can be controlled.

Further, the antenna has an advantage in that the antenna is not easily recognized except a user because it is in harmony with the surroundings.

Especially, when a user receives the television broadcasting through the personal

computer, the user's privacy is protected because the others can not know whether the user is viewing the television broadcasting.

Furthermore, the antenna can be used as a signboard for advertisement because it has a planar shape.

While the invention has been described in connection with preferred embodiments,

variations and modifications will occur to those skilled in the art, and it is therefore understood that the invention herein is defined in the claims appended hereto.

Claims

WHAT IS CLAIMED IS:

1. A planar type wideband LPDA antenna adapted for VHF/UHF band, the antenna comprising: a nonconductive substrate board having a low dielectric and a small loss of an electromagnetic wave; and an antenna pattern arranged on the nonconductive substrate and comprising: a feed point for the supply of electric power, the feed point being connected to a TV receiver module; a UHF dipole for an UHF band; and a VHF dipole for a VHF band, wherein the UHF dipole comprises a first dipole which is the longest dipole among the UHF dipoles and the VHF dipole comprises a second dipole for a high VHF channel perpendicularly connected to one end of the first dipole, wherein the second dipole has a length corresponding to a difference between a length corresponding to half a wavelength of a central frequency of the high VHF channels one sided length of the first dipole.

2. The planar type wideband LPDA antenna of claim 1, wherein the substrate board comprises a protective pad attached on the front surface and the rear surface of the substrate board.

3. The planar type wideband LPDA antenna of claim 2, wherein the protective pad is made of one material selected from a group consisting of paper, wood, vinyl, PVC, rubber and Teflon.

4. The planar type wideband LPDA antenna of claim 1, wherein the substrate board is 1 mm to 3 mm thick and the protective pad is 1 mm thick or less.

5. The planar type wideband LPDA antenna of claim 2, wherein the feed point is

coated with radome.

6. The planar type wideband LPDA antenna of claim 1, wherein the TV receiver

module is established in an analog TV or a digital TV.

7. The planar type wideband LPDA antenna of claim 1, wherein the TV receiver module is a TV receiver card established in a computer.

8. The planar type wideband LPDA antenna of claim 1, wherein the antenna pattern is made of one material selected from a group consisting of gold, silver, copper and aluminum, wherein the antenna pattern has a thin film or tape shape.