CA2279219A1 - Multiple band antenna - Google Patents
Multiple band antenna Download PDFInfo
- Publication number
- CA2279219A1 CA2279219A1 CA002279219A CA2279219A CA2279219A1 CA 2279219 A1 CA2279219 A1 CA 2279219A1 CA 002279219 A CA002279219 A CA 002279219A CA 2279219 A CA2279219 A CA 2279219A CA 2279219 A1 CA2279219 A1 CA 2279219A1
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- CA
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- Prior art keywords
- antenna
- feed point
- frequency band
- length
- band
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
- H01Q5/30—Arrangements for providing operation on different wavebands
- H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
- H01Q5/314—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors
- H01Q5/321—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors within a radiating element or between connected radiating elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
- H01Q5/30—Arrangements for providing operation on different wavebands
- H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
- H01Q5/342—Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes
- H01Q5/357—Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes using a single feed point
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
- H01Q5/50—Feeding or matching arrangements for broad-band or multi-band operation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
- H01Q9/04—Resonant antennas
- H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
- H01Q9/32—Vertical arrangement of element
Abstract
The present invention provides an antenna system having one or more of the following characteristics or features:
Disguised Antenna System;
Dual band operation:
Broad band operation;
Isolation between transceivers to eliminate the need for change over switches or relays; and Built in broadcast coupler The foregoing can be provided by decoupling the antenna mast for multiple bands by use of a quarter wave decoupling stub or by the use of a frequency relative trap. As a result the antenna has multiple resonances simultaneously. The foregoing also can be accomplished by selecting antenna mast lengths that are harmonically related to provide a single element with multiple resonances without external devices. A diplexer comprising the combination of high and low pass filters and a broadcast coupler can be connected to the antenna feed point with transceivers operating in the different bands being connected to the high and low pass filters.
The simultaneous multiple resonances ensure a matched impedance at the antenna feed point so that when a communications device is connected by a length of coax to the antenna feed point the matched impedance will be maintained at the feed point regardless of the length of the coax.
Disguised Antenna System;
Dual band operation:
Broad band operation;
Isolation between transceivers to eliminate the need for change over switches or relays; and Built in broadcast coupler The foregoing can be provided by decoupling the antenna mast for multiple bands by use of a quarter wave decoupling stub or by the use of a frequency relative trap. As a result the antenna has multiple resonances simultaneously. The foregoing also can be accomplished by selecting antenna mast lengths that are harmonically related to provide a single element with multiple resonances without external devices. A diplexer comprising the combination of high and low pass filters and a broadcast coupler can be connected to the antenna feed point with transceivers operating in the different bands being connected to the high and low pass filters.
The simultaneous multiple resonances ensure a matched impedance at the antenna feed point so that when a communications device is connected by a length of coax to the antenna feed point the matched impedance will be maintained at the feed point regardless of the length of the coax.
Description
MULTIPLE BAND ANTENNA
CROSS REFERENCE TO A RELATED APPLICATION
Applicant hereby claims priority based on Provisional Application No. 60/094,917 filed July 31, 1998 and entitled "Multiple Band Antenna" which is incorporated by reference.
BACKGROUND OF THE INVENTION
This invention relates to the art of antennas for radios and communications equipment located in vehicles, and more particularly to a new and improved antenna system having multiple band, broad band operation.
There are many instances when it is desirable to operate commercial radio transmitters from a motor vehicle while remaining covert or undercover. There are times when the need to operate more than one band is also required. Another purpose for using one antenna installation has no covert application, however the cost factor does enter into the picture. One antenna installation costs half as much as two installations.
This is true financially and time wise also. There are several combinations that are standard:
Low Band/High Band Low Band/UHF Band High Band/UHF Band High Band/800 MHz to 900 MHz High Band/900 MHz to 970 MHz Uhf Band/800 MHz to 900 MH2 UHF Band/900 MHz to 970 MHz Cellular Band/PCS Band The foregoing band combinations are a partial list of the band combinations possible using these techniques, but should not be considered a complete listing. As new bands become available for communications these methods can be used to operate multiple bands from one antenna while remaining covert or less expensive.
SUMMARY OF THE INVENTION
The present invention provides an antenna system having one or more of the following characteristics or features:
Disguised Antenna System;
Dual band operation;
Broad band operation;
Isolation between transceivers to eliminate the need for change over switches or relays; and Built in broadcast coupler The foregoing can be provided by decoupling the antenna mast for multiple bands by use of a quarter wave decoupling stub or by the use of a frequency relative trap. As a result the antenna has multiple resonances simultaneously. The foregoing also can be accomplished by selecting antenna mast lengths that are harmonically related to provide a single element with multiple 2S resonances without external devices. A diplexer comprising the combination of high and low pass filters and a broadcast coupler can be connected to the antenna feed point with transceivers operating in the different bands being connected to the high and low pass filters.
3o The simultaneous multiple resonances ensure a matched impedance at the antenna feed point so that when a communications device is connected by a length of coax to the antenna feed point the matched impedance will be maintained at the feed point regardless of the length of the coax.
The following detailed description of the invention, when read in conjunction with the accompanying drawings, is in such full, clear, concise and exact terms as to enable any person skilled in the ' art to which it pertains, or with which it is most nearly connected, to make and use the invention.
1o BRIEF DESCRIPTION OF THE DFAwiNGs Fig. 1 is a schematic diagr;sm of a multiple band antenna system according to the present invention;
Fig. 2 is a schematic circuit diagram showing the antenna of Fig. 1 in combination with a diplexer and a pair of transceivers.
Fig. 3 is a schematic diagram of an alternative embodiment of the antenna in the system of Fig. 1;
Fig. 4 is a schematic diagram of another alternative embodiment of the antenna in the system of Fig. 1;
Fig. 5 is a schematic diagr,3m of another embodiment of the antenna in the system of Fig. 1; and Fig. 6 is a schematic circuit diagram further z5 illustrating the antenna of the present invention.
The antenna system of the present invention can be 3o made to be dual band using one or more of the following methods illustrated in Figs. 1-5. Referring f~.rst to Fig. 1, an antenna 20 is provided with a quarter wavelength coaxial decoupling stub 12 at the highest frequency band. The antenna 10 :has a primary section designated 14 which is resonant at the highest frequency band and has a length of a quarter wavelength at that highest frequency. The antenna 10 also has a secondary section designated 16 which is resonant at the lowest frequency band and has a length of a quarter wavelength at that lowest frequency. The coaxial section 12 opens up the antenna 10 so that the secondary portion 16 has a negligible effect on the feed point 18 when the antenna sections 14 and 16 approach resonance. Section 12 also lowers the resonant frequency of section 16 such that the electrical length of section 16 appears longer than its physical length. The foregoing arrangement makes the antenna mast 10 have multiple resonances simultaneously.
There is no frequency relationship and no harmonic relationship between the highest and lowest resonances.
The antenna ground or reference plane is designated 2C
in Fig. 1.
Thus, the antenna mast 10 can be decoupled for multiple bands through the use of quarter wave decoupling stubs 12. This will provide an antenna system that will function on multiple bands. In order to make this antenna 10 covert the mast can be cast into a fiberglass or other non metallic composite resin material. This will provide an antenna with dual band covert capability. In order to make this type of antenna dual band broad band and provide isolation between transceivers 22 and 24, a diplexer 26 must be used as shown in Fig. 2_ The diplexer should consist o=
three filter sections. The two primary filters should be built up using one high pass filter 30 and one low pass filter 32. These filters are connected together at the antenna port on feed point 18 and connected to the transceivers 22, 24 at the non-common end. The broadcast output is taken from the output of the low _ 5 pass filter 32 via a second low pass filter 36. When the original high and low pass filters are designed they should be designed to provide a minimum of approximately 36 Db isolation and an SwR (standing wave ratio) not ;
exceeding 2:1 across both bands. Actual isolation will depend upon receiver sensitivity and transmitter power.
The broadcast coupler low pass filter 36 must provide at least approximately 40 Db between the high end of the FN
broadcast band and the low end of the communications 1o band. Actual isolation will depend upon transmitter power and receiver sensitivity. The broadcast coupler provides a high degree of isolation and low insertion loss at the broadcast band. It may be viewed as a band pass filter to pass the broadcast signal and designed with low capacitance elements to minimize AM loss of signal.
The antenna system of the present invention advantageously solves the problem that in modern automobiles it is not possible to physically locate the matching networks at the base of the antenna. In the antenna system of the present invention, the diplexer 2E;
can be connected to antenna feed point 18 by a length of coax and therefore situated in a physically convenient location in the automobile. By having antenna 10 resonant at both frequencies this ensures a matched impedance at feed point 18 so that there always will be a matched condition regardless of the length of the coa=:
connecting the diplexer 26 or similar communications device to the teed point 18. In other words, having thr matched impedance at feed point 18 makes the length of the coax less relevant.
In order to have the foregoing antenna system broad band, wherein diplexer 26 is connected to teed point 18 by a length of coax, shown by the broken line 38 in Fig. 2, the length of the coax 38 and the characteristics of the high and low pass filters 30 and 32 are adjusted to complement each other. This enables the antenna systEm to achieve broad band performance at both frequencies simultaneously.
Figs. 3~5 illustrate alternative approaches whereby I
the antenna system can be made dual band. In particular, a second method of obtaining the dual band operation is the use of frequency selective traps in the l0 mast to provide a dual frequency resonance. These traps can be either coils and capacitors or coaxial cable properly inserted and connected in the antenna structure. The use of the diplexer will provide the necessary isolation and broad banding. The filter will also provide the output port for the broadcast radio.
Thus, antenna 10' shown in Fig. 3 is provided with a parallel resonant circuit 40 comprising capacitor 42 and inductor 44 tuned to the highest band. The primary section 14' between resonant circuit 40 and feed point 18' is resonant at the highest freguency band and has a length of a quarter wavelength at that highest frequency. The secondary section 16' between feed point 18' and the opposite end of antenna 10' is resonant at the lowest frequency band and has a length of a quarter wavelength at that lowest frequency. Antenna 10" shown in Fig. 4 is provided with a coaxial trap 46 tuned to the highest band. Trap 46 is tuned by selecting the length of coax that is wound or unwrapped to form the trap. The primary section 14' between coaxial trap 46 and feed point 18" is resonant at the highest frequency band and has a length of a quarter wavelength at that highest frequency. The secondary section 16" between feed point 18" and the opposite end of antenna 10" is resonant at the lowest frequency band and has a length _ 7 of a quarter wavelength at that .lowest frequency. The antennas 10' and 10" would be connected at the feed points 18' respectively, and 18" each to a diplexer comprising the combination of high and low pass filters S and broadcast couplers in a manner similar to the system of Fig. 2. Likewise each diplexer can be located remote ' from the antenna, being connected by a length of coax, in a manner similar to that of the system of Fig. 2, and each antenna 10', IO" can be made broad band in a manner similar to that described in connection with Fig. 2.
In the antenna system illustrated in Figs. 1-4, there is no need for any harmonic relationship between the multiple resonances. A third method of providing the necessary multiple band operation is to use antenna mast lengths that are harmonically related to provide a single element with multiple resonances without external devices. An example of this method would be a 1/4 wave antenna mast for VHF Band and 3/4 wave mast for UHF
Band. Thus, in the antenna 50 shown in Fig. 5, the mast length designated 52 is a quarter wavelength at the lowest frequency band and the mast length designated 54 is an odd multiple of a quaxter wavelength at the highest frequency band. Accordingly, in contrast to th<_ antennas illustrated in Figs. I-4, the antenna 50 of Fig. 5 has need for a harmonic relationship which is the odd harmonics 3, 5, 7, 9, etc. For example, the quarter_ wavelength mast at 150 MHZ would. require a three quarte~~
wavelength mast at the other band which is three times the lowex frequency or 450 MHZ, or a five quarter wavelength mast at the other band which is five times the lower frequency or 750 MHZ, etc.
As in the embodiments of Figs. I-3, antenna 50 would be connected at the feed point 56 to a diplexer comprising the combination of high and low pass filters _ g and a broadcast coupler. Likewise, antenna 50 and the diplexer can be at different physical locations with the remotely located diplexer being connected by a length of coax to the feed point 56, and antenna 50 can be made broad band in a manner similar to that described in connection with Fig. 1.
In the embodiments of Figs_ I-S the broadcast radio and broadcast coupler 36 can be omitted so that the antenna is operated with only the pair of transceivers.
Furthermore, the system could be operated by transmitting on one of the freQuency bands and receiving on the other frequency band. This would be done mainly at low power to avoid interference, low power being defined by the isolation parameters of the diplexer. As further alternatives, the system could be operated with receivers on both frequency bands or with transmitters on both frequency bands. By way of example, the antenna system of the present invention could enable the broad band antenna to be located on a tower with a single coax' connecting the antenna feed point to a diplexer and transmitters or receivers located at the base of the tower_ This would avoid the need to provide a pair of expensive coax sections on the tower as has been done it prior art arrangements.
The various methods shown and described in connection with Figs. 1-5 are different ways of achieving multiple resonance in the antenna of the present invention. In an effort to meet all of the criteria stated above it is necessary to use one of the multi band techniques shown. The need for broad banding requires the diplexer to be designed to be a matching filter as well as an isolation filter. This means the common (antenna) port is not normally 50 ohms across the entire bandwidth of both of the bands, but requires 9 _ i correction to a nominal SO ohms by the action of the filter. The need for isolation between both receivers and or transmitters along with the broadcast cannot be forgotten. In addition, while the antenna according to the present invention has been described in connection with the dual resonances, multiple resonance, i.e.
three, four, etc. are intended to be included within the scope of the present invention. For example, for three bands the antenna is tuned at the highest of the three i0 bands arid at the next highest band. The resonance of the lowest band is established by the overall length of the monopole. The physical length of the antenna is slightly less as modified by the coaxial stub or the like.
The present invention is illustrated further by the following example of the circuit of Fig. 5. Antenna 60 is similar to antennas 10, 10', 10" or 50 shown in Figs. 1-4. The antenna feedpoint 62 is connected either directly or through a section of coax 64 to a diplexer similar to that of Fig. 2. The diplexer, in turn, includes high aid low pass filters for the high band (UHF)and low band (vHF)transceivers 70 and 72, respectively, and another low pass filter or broadcast coupler for the broadcast radio 74. The high pass ~5 filter for transceiver 70 comprises variable capacitors 76, 78, 80 and 82 each of which can have a magnitude ranging from 0.1-8 picofarads and inductors 84, 86 and 88 each having a magnitude of 15 nanohenries . The low pass filter for transceiver 72 comprises inductors 90, 92 and 94 which can have magnitudes of 40, 22 and 106 nanohenries, respectively, and capacitors 96 and 98 each having a magnitude ranging from 0.5 to 14 picofarads.
The low pass filter for broadcast radio 74 includes the combination of capacitor 100 and inductor 102 together i - 10 - ;
with the network of inductors 104, 106, 108, 110 and 112, variable capaciters 114, 116, 118 and capaciters 120, 122, 124 and 126. Capaciter 100 can have a magnitude of 5, 6 picofarads and inductor I02 can have a S magnitude of 88 nanohenries. Inductors 104, 106, 108, 110 and 112 can have magnitudes of 20, 94, 158, 158 and 20 nanohanries, respectively. Variable capaciters 114, 116 and 118 each can have a magnitude ranging from 0.1-8 picofarads. Capaciters 120, 122, 129 and 126 can have magnitudes of 24, 48, 57 and 48 picofarads, ;
respectively. The foregoing dual based antenna, diplexer, transceivers and broadcast radio is an example of an illustrative arrangement installed in a vehicle wherein the antenna is disguised for covert operation.
The foregoing inductor and capaciter values are approximate and are adjusted for each vehicle type.
It is therefore apparent that the present invention accomplishes its intended objectives. While embodiments of the present invention have bee:n described in detail, that has been done for the purpo~;e of illustration, not limitation.
I
CROSS REFERENCE TO A RELATED APPLICATION
Applicant hereby claims priority based on Provisional Application No. 60/094,917 filed July 31, 1998 and entitled "Multiple Band Antenna" which is incorporated by reference.
BACKGROUND OF THE INVENTION
This invention relates to the art of antennas for radios and communications equipment located in vehicles, and more particularly to a new and improved antenna system having multiple band, broad band operation.
There are many instances when it is desirable to operate commercial radio transmitters from a motor vehicle while remaining covert or undercover. There are times when the need to operate more than one band is also required. Another purpose for using one antenna installation has no covert application, however the cost factor does enter into the picture. One antenna installation costs half as much as two installations.
This is true financially and time wise also. There are several combinations that are standard:
Low Band/High Band Low Band/UHF Band High Band/UHF Band High Band/800 MHz to 900 MHz High Band/900 MHz to 970 MHz Uhf Band/800 MHz to 900 MH2 UHF Band/900 MHz to 970 MHz Cellular Band/PCS Band The foregoing band combinations are a partial list of the band combinations possible using these techniques, but should not be considered a complete listing. As new bands become available for communications these methods can be used to operate multiple bands from one antenna while remaining covert or less expensive.
SUMMARY OF THE INVENTION
The present invention provides an antenna system having one or more of the following characteristics or features:
Disguised Antenna System;
Dual band operation;
Broad band operation;
Isolation between transceivers to eliminate the need for change over switches or relays; and Built in broadcast coupler The foregoing can be provided by decoupling the antenna mast for multiple bands by use of a quarter wave decoupling stub or by the use of a frequency relative trap. As a result the antenna has multiple resonances simultaneously. The foregoing also can be accomplished by selecting antenna mast lengths that are harmonically related to provide a single element with multiple 2S resonances without external devices. A diplexer comprising the combination of high and low pass filters and a broadcast coupler can be connected to the antenna feed point with transceivers operating in the different bands being connected to the high and low pass filters.
3o The simultaneous multiple resonances ensure a matched impedance at the antenna feed point so that when a communications device is connected by a length of coax to the antenna feed point the matched impedance will be maintained at the feed point regardless of the length of the coax.
The following detailed description of the invention, when read in conjunction with the accompanying drawings, is in such full, clear, concise and exact terms as to enable any person skilled in the ' art to which it pertains, or with which it is most nearly connected, to make and use the invention.
1o BRIEF DESCRIPTION OF THE DFAwiNGs Fig. 1 is a schematic diagr;sm of a multiple band antenna system according to the present invention;
Fig. 2 is a schematic circuit diagram showing the antenna of Fig. 1 in combination with a diplexer and a pair of transceivers.
Fig. 3 is a schematic diagram of an alternative embodiment of the antenna in the system of Fig. 1;
Fig. 4 is a schematic diagram of another alternative embodiment of the antenna in the system of Fig. 1;
Fig. 5 is a schematic diagr,3m of another embodiment of the antenna in the system of Fig. 1; and Fig. 6 is a schematic circuit diagram further z5 illustrating the antenna of the present invention.
The antenna system of the present invention can be 3o made to be dual band using one or more of the following methods illustrated in Figs. 1-5. Referring f~.rst to Fig. 1, an antenna 20 is provided with a quarter wavelength coaxial decoupling stub 12 at the highest frequency band. The antenna 10 :has a primary section designated 14 which is resonant at the highest frequency band and has a length of a quarter wavelength at that highest frequency. The antenna 10 also has a secondary section designated 16 which is resonant at the lowest frequency band and has a length of a quarter wavelength at that lowest frequency. The coaxial section 12 opens up the antenna 10 so that the secondary portion 16 has a negligible effect on the feed point 18 when the antenna sections 14 and 16 approach resonance. Section 12 also lowers the resonant frequency of section 16 such that the electrical length of section 16 appears longer than its physical length. The foregoing arrangement makes the antenna mast 10 have multiple resonances simultaneously.
There is no frequency relationship and no harmonic relationship between the highest and lowest resonances.
The antenna ground or reference plane is designated 2C
in Fig. 1.
Thus, the antenna mast 10 can be decoupled for multiple bands through the use of quarter wave decoupling stubs 12. This will provide an antenna system that will function on multiple bands. In order to make this antenna 10 covert the mast can be cast into a fiberglass or other non metallic composite resin material. This will provide an antenna with dual band covert capability. In order to make this type of antenna dual band broad band and provide isolation between transceivers 22 and 24, a diplexer 26 must be used as shown in Fig. 2_ The diplexer should consist o=
three filter sections. The two primary filters should be built up using one high pass filter 30 and one low pass filter 32. These filters are connected together at the antenna port on feed point 18 and connected to the transceivers 22, 24 at the non-common end. The broadcast output is taken from the output of the low _ 5 pass filter 32 via a second low pass filter 36. When the original high and low pass filters are designed they should be designed to provide a minimum of approximately 36 Db isolation and an SwR (standing wave ratio) not ;
exceeding 2:1 across both bands. Actual isolation will depend upon receiver sensitivity and transmitter power.
The broadcast coupler low pass filter 36 must provide at least approximately 40 Db between the high end of the FN
broadcast band and the low end of the communications 1o band. Actual isolation will depend upon transmitter power and receiver sensitivity. The broadcast coupler provides a high degree of isolation and low insertion loss at the broadcast band. It may be viewed as a band pass filter to pass the broadcast signal and designed with low capacitance elements to minimize AM loss of signal.
The antenna system of the present invention advantageously solves the problem that in modern automobiles it is not possible to physically locate the matching networks at the base of the antenna. In the antenna system of the present invention, the diplexer 2E;
can be connected to antenna feed point 18 by a length of coax and therefore situated in a physically convenient location in the automobile. By having antenna 10 resonant at both frequencies this ensures a matched impedance at feed point 18 so that there always will be a matched condition regardless of the length of the coa=:
connecting the diplexer 26 or similar communications device to the teed point 18. In other words, having thr matched impedance at feed point 18 makes the length of the coax less relevant.
In order to have the foregoing antenna system broad band, wherein diplexer 26 is connected to teed point 18 by a length of coax, shown by the broken line 38 in Fig. 2, the length of the coax 38 and the characteristics of the high and low pass filters 30 and 32 are adjusted to complement each other. This enables the antenna systEm to achieve broad band performance at both frequencies simultaneously.
Figs. 3~5 illustrate alternative approaches whereby I
the antenna system can be made dual band. In particular, a second method of obtaining the dual band operation is the use of frequency selective traps in the l0 mast to provide a dual frequency resonance. These traps can be either coils and capacitors or coaxial cable properly inserted and connected in the antenna structure. The use of the diplexer will provide the necessary isolation and broad banding. The filter will also provide the output port for the broadcast radio.
Thus, antenna 10' shown in Fig. 3 is provided with a parallel resonant circuit 40 comprising capacitor 42 and inductor 44 tuned to the highest band. The primary section 14' between resonant circuit 40 and feed point 18' is resonant at the highest freguency band and has a length of a quarter wavelength at that highest frequency. The secondary section 16' between feed point 18' and the opposite end of antenna 10' is resonant at the lowest frequency band and has a length of a quarter wavelength at that lowest frequency. Antenna 10" shown in Fig. 4 is provided with a coaxial trap 46 tuned to the highest band. Trap 46 is tuned by selecting the length of coax that is wound or unwrapped to form the trap. The primary section 14' between coaxial trap 46 and feed point 18" is resonant at the highest frequency band and has a length of a quarter wavelength at that highest frequency. The secondary section 16" between feed point 18" and the opposite end of antenna 10" is resonant at the lowest frequency band and has a length _ 7 of a quarter wavelength at that .lowest frequency. The antennas 10' and 10" would be connected at the feed points 18' respectively, and 18" each to a diplexer comprising the combination of high and low pass filters S and broadcast couplers in a manner similar to the system of Fig. 2. Likewise each diplexer can be located remote ' from the antenna, being connected by a length of coax, in a manner similar to that of the system of Fig. 2, and each antenna 10', IO" can be made broad band in a manner similar to that described in connection with Fig. 2.
In the antenna system illustrated in Figs. 1-4, there is no need for any harmonic relationship between the multiple resonances. A third method of providing the necessary multiple band operation is to use antenna mast lengths that are harmonically related to provide a single element with multiple resonances without external devices. An example of this method would be a 1/4 wave antenna mast for VHF Band and 3/4 wave mast for UHF
Band. Thus, in the antenna 50 shown in Fig. 5, the mast length designated 52 is a quarter wavelength at the lowest frequency band and the mast length designated 54 is an odd multiple of a quaxter wavelength at the highest frequency band. Accordingly, in contrast to th<_ antennas illustrated in Figs. I-4, the antenna 50 of Fig. 5 has need for a harmonic relationship which is the odd harmonics 3, 5, 7, 9, etc. For example, the quarter_ wavelength mast at 150 MHZ would. require a three quarte~~
wavelength mast at the other band which is three times the lowex frequency or 450 MHZ, or a five quarter wavelength mast at the other band which is five times the lower frequency or 750 MHZ, etc.
As in the embodiments of Figs. I-3, antenna 50 would be connected at the feed point 56 to a diplexer comprising the combination of high and low pass filters _ g and a broadcast coupler. Likewise, antenna 50 and the diplexer can be at different physical locations with the remotely located diplexer being connected by a length of coax to the feed point 56, and antenna 50 can be made broad band in a manner similar to that described in connection with Fig. 1.
In the embodiments of Figs_ I-S the broadcast radio and broadcast coupler 36 can be omitted so that the antenna is operated with only the pair of transceivers.
Furthermore, the system could be operated by transmitting on one of the freQuency bands and receiving on the other frequency band. This would be done mainly at low power to avoid interference, low power being defined by the isolation parameters of the diplexer. As further alternatives, the system could be operated with receivers on both frequency bands or with transmitters on both frequency bands. By way of example, the antenna system of the present invention could enable the broad band antenna to be located on a tower with a single coax' connecting the antenna feed point to a diplexer and transmitters or receivers located at the base of the tower_ This would avoid the need to provide a pair of expensive coax sections on the tower as has been done it prior art arrangements.
The various methods shown and described in connection with Figs. 1-5 are different ways of achieving multiple resonance in the antenna of the present invention. In an effort to meet all of the criteria stated above it is necessary to use one of the multi band techniques shown. The need for broad banding requires the diplexer to be designed to be a matching filter as well as an isolation filter. This means the common (antenna) port is not normally 50 ohms across the entire bandwidth of both of the bands, but requires 9 _ i correction to a nominal SO ohms by the action of the filter. The need for isolation between both receivers and or transmitters along with the broadcast cannot be forgotten. In addition, while the antenna according to the present invention has been described in connection with the dual resonances, multiple resonance, i.e.
three, four, etc. are intended to be included within the scope of the present invention. For example, for three bands the antenna is tuned at the highest of the three i0 bands arid at the next highest band. The resonance of the lowest band is established by the overall length of the monopole. The physical length of the antenna is slightly less as modified by the coaxial stub or the like.
The present invention is illustrated further by the following example of the circuit of Fig. 5. Antenna 60 is similar to antennas 10, 10', 10" or 50 shown in Figs. 1-4. The antenna feedpoint 62 is connected either directly or through a section of coax 64 to a diplexer similar to that of Fig. 2. The diplexer, in turn, includes high aid low pass filters for the high band (UHF)and low band (vHF)transceivers 70 and 72, respectively, and another low pass filter or broadcast coupler for the broadcast radio 74. The high pass ~5 filter for transceiver 70 comprises variable capacitors 76, 78, 80 and 82 each of which can have a magnitude ranging from 0.1-8 picofarads and inductors 84, 86 and 88 each having a magnitude of 15 nanohenries . The low pass filter for transceiver 72 comprises inductors 90, 92 and 94 which can have magnitudes of 40, 22 and 106 nanohenries, respectively, and capacitors 96 and 98 each having a magnitude ranging from 0.5 to 14 picofarads.
The low pass filter for broadcast radio 74 includes the combination of capacitor 100 and inductor 102 together i - 10 - ;
with the network of inductors 104, 106, 108, 110 and 112, variable capaciters 114, 116, 118 and capaciters 120, 122, 124 and 126. Capaciter 100 can have a magnitude of 5, 6 picofarads and inductor I02 can have a S magnitude of 88 nanohenries. Inductors 104, 106, 108, 110 and 112 can have magnitudes of 20, 94, 158, 158 and 20 nanohanries, respectively. Variable capaciters 114, 116 and 118 each can have a magnitude ranging from 0.1-8 picofarads. Capaciters 120, 122, 129 and 126 can have magnitudes of 24, 48, 57 and 48 picofarads, ;
respectively. The foregoing dual based antenna, diplexer, transceivers and broadcast radio is an example of an illustrative arrangement installed in a vehicle wherein the antenna is disguised for covert operation.
The foregoing inductor and capaciter values are approximate and are adjusted for each vehicle type.
It is therefore apparent that the present invention accomplishes its intended objectives. While embodiments of the present invention have bee:n described in detail, that has been done for the purpo~;e of illustration, not limitation.
I
Claims (15)
1. A dual band antenna comprising:
a) an antenna mast having a feed point at one end;
b) a quarter wavelength coaxial decoupling stub on said antenna mast and tuned to the highest frequency band;
c) said antenna having a primary section between said stub and said feed point which is resonant at the highest frequency band and which has a length of a quarter wavelength at the frequency of the highest frequency band; and d) said antenna having a secondary section between said feed point and the opposite end of said antenna which is resonant at the lowest frequency band and which has a length of a quarter wavelength at the frequency of the lowest frequency band;
e) so that said antenna has multiple resonances simultaneously.
a) an antenna mast having a feed point at one end;
b) a quarter wavelength coaxial decoupling stub on said antenna mast and tuned to the highest frequency band;
c) said antenna having a primary section between said stub and said feed point which is resonant at the highest frequency band and which has a length of a quarter wavelength at the frequency of the highest frequency band; and d) said antenna having a secondary section between said feed point and the opposite end of said antenna which is resonant at the lowest frequency band and which has a length of a quarter wavelength at the frequency of the lowest frequency band;
e) so that said antenna has multiple resonances simultaneously.
2. The antenna of claim 1, wherein a diplexer comprising the combination of high and low pass filters and a broadcast coupler is connected to said antenna feed point.
3. The antenna of claim 2, wherein transceivers operating in said highest frequency band and in said lowest frequency band are connected to said high and low pass filters, respectively.
4. The antenna of claim 1, wherein the simultaneous multiple resonance ensure a matched impedance at said antenna feed point so that when a communications device is connected by a length of coax to said antenna feed point the matched impedance will be maintained at said feed point regardless of the length of the coax.
5. A dual band antenna comprising:
a) an antenna mast having a feed point at one end;
b) a frequency selective trap on said antenna mast and tuned to the highest frequency band;
c) said antenna having a primary section between said trap and said feed point which is resonant at the highest frequency band and which has a length of a quarter wavelength at the frequency of the highest frequency band; and d) said antenna having a secondary section between said feed point and the opposite end of said antenna which is resonant at the lowest frequency band and which has a length of a quarter wavelength at the frequency of the lowest frequency band;
and e) so that said antenna has multiple resonances simultaneously.
a) an antenna mast having a feed point at one end;
b) a frequency selective trap on said antenna mast and tuned to the highest frequency band;
c) said antenna having a primary section between said trap and said feed point which is resonant at the highest frequency band and which has a length of a quarter wavelength at the frequency of the highest frequency band; and d) said antenna having a secondary section between said feed point and the opposite end of said antenna which is resonant at the lowest frequency band and which has a length of a quarter wavelength at the frequency of the lowest frequency band;
and e) so that said antenna has multiple resonances simultaneously.
6. The antenna according to claim 5, wherein said frequency selective trap comprises a parallel resonant circuit tuned to the highest frequency band.
7. The antenna according to claim 5, wherein said frequency selective trap comprises a coaxial trap tuned to the highest frequency band.
8. The antenna of claim 5, wherein a diplexer comprising the combination of high and low pass filters and a broadcast coupler is connected to said antenna feed point.
9. The antenna of claim 8, wherein transceivers operating in said highest frequency band and in said lowest frequency band are connected to said high and low pass filters, respectively.
10. The antenna of claim 5, wherein the simultaneous multiple resonances ensure a matched impedance at said antenna feed point so that when a communications device is connected by a length of coax to said antenna feed point the matched impedance will be maintained at said feed point regardless of the length of the coax.
11. A dual band antenna comprising a mast having a feed point at one end and an opposite end, said antenna having a length between said feed point and said opposite end selected to be one quarter wavelength at the lowest frequency band and an odd multiple of a quarter wavelength at the lowest frequency band and an odd multiple of a quarter wavelength at the highest frequency band so that said antenna has multiple resonances which are harmonically related.
12. The antenna of claim 11, wherein said lowest frequency band is the VHF band and said highest frequency band is the UHF band.
13. The antenna of claim 11, wherein a diplexer comprising the combination of high and low pass filters and s broadcast coupler is connected to said antenna feed point.
14. The antenna of claim 13, wherein transceivers operating in said highest frequency band and in said lowest frequency band are connected to said high and low pass filters, respectively.
15. The antenna of claim 11, wherein the simultaneous multiple resonances ensure a matched impedance at said antenna feed point so that where a communications device is connected by a length of coax to said antenna feed point the matched impedance will be maintained at said feed point regardless of the length of the coax.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US9491798P | 1998-07-31 | 1998-07-31 | |
| US60/094,917 | 1998-07-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2279219A1 true CA2279219A1 (en) | 2000-01-31 |
Family
ID=31186111
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002279219A Abandoned CA2279219A1 (en) | 1998-07-31 | 1999-07-30 | Multiple band antenna |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US6266026B1 (en) |
| CA (1) | CA2279219A1 (en) |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US7176278B2 (en) * | 2001-08-30 | 2007-02-13 | Biorexis Technology, Inc. | Modified transferrin fusion proteins |
| EP1309103A1 (en) * | 2001-10-31 | 2003-05-07 | Nokia Corporation | Antenna system for GSM/WLAN radio operation |
| GB2416922B (en) * | 2004-07-30 | 2009-03-04 | Motorola Inc | Antenna for use in a mobile radio communication device |
| EP1796211A1 (en) * | 2004-09-22 | 2007-06-13 | Niigata Seimitsu Co., Ltd. | Antenna for portable terminal and portable terminal |
| TW200921996A (en) * | 2007-11-05 | 2009-05-16 | Mitac Technology Corp | Transmission line loaded dual-band monopole antenna |
| US8144060B2 (en) * | 2008-06-02 | 2012-03-27 | 2Wire, Inc. | Multiple feedpoint antenna |
| US20100013731A1 (en) * | 2008-07-21 | 2010-01-21 | Harold James Kittel | Coaxial cable dipole antenna for high frequency applications |
| US20100127952A1 (en) * | 2008-11-25 | 2010-05-27 | Motorola, Inc. | Dual helix, dual pitch antenna for wide frequency bandwidth |
| US8774067B2 (en) * | 2009-11-17 | 2014-07-08 | Nokia Corporation | Antenna impedance stabilization with stabilization load in second antenna circuitry |
| US8957822B2 (en) | 2012-09-13 | 2015-02-17 | ImagineCommunications Corp. | Operation of an antenna on a second, higher frequency |
| US20140273887A1 (en) * | 2013-03-15 | 2014-09-18 | Motorola Mobility Llc | Tunable ila and dila matching for simultaneous high and low band operation |
| US20160204520A1 (en) * | 2015-01-08 | 2016-07-14 | Qualcomm Incorporated | Multi-band antenna with a tuned parasitic element |
| CN105576378B (en) * | 2015-12-17 | 2018-11-13 | 京信通信系统（广州）有限公司 | A kind of dual-band antenna, dual polarization dual-band antenna and isolation element preparation method |
| US10468743B2 (en) | 2016-01-07 | 2019-11-05 | United States of America as represented by the Federal Bureau of Investigation, Dept. of Justice | Mast mountable antenna |
| USD798847S1 (en) | 2016-01-07 | 2017-10-03 | The United States of America as represented by the Federal Bureau of Investigation, Dept. of Justice | Antenna |
| US10374311B2 (en) | 2017-12-13 | 2019-08-06 | Motorola Solutions, Inc. | Antenna for a portable communication device |
| US11228094B2 (en) * | 2018-04-05 | 2022-01-18 | Huawei Technologies Co., Ltd. | Antenna arrangement with wave trap and user equipment |
| CN111313155B (en) * | 2018-12-11 | 2021-11-19 | 华为技术有限公司 | Antenna and communication apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3950757A (en) * | 1975-03-12 | 1976-04-13 | Beam Systems Israel Ltd. | Broadband whip antennas |
| NL181388C (en) * | 1978-03-22 | 1987-08-03 | Philips Nv | AERIAL DEVICE FOR A NUMBER OF SIMULTANEOUS TRANSMITTER RECEIVERS. |
| US4509056A (en) * | 1982-11-24 | 1985-04-02 | George Ploussios | Multi-frequency antenna employing tuned sleeve chokes |
| JPS6477205A (en) * | 1987-06-27 | 1989-03-23 | Nippon Denso Co | Shared antenna equipment for vehicle |
| US5311201A (en) * | 1991-09-27 | 1994-05-10 | Tri-Band Technologies, Inc. | Multi-band antenna |
| US5451968A (en) * | 1992-11-19 | 1995-09-19 | Solar Conversion Corp. | Capacitively coupled high frequency, broad-band antenna |
| US5798736A (en) * | 1995-03-28 | 1998-08-25 | Mcdonnell Douglas Corporation | Antenna system having a plurality of fundamental resonances |
| GB9520018D0 (en) * | 1995-09-28 | 1995-12-06 | Galtronics Uk Ltd | Broad band antenna |
| US5995065A (en) * | 1997-09-24 | 1999-11-30 | Nortel Networks Corporation | Dual radio antenna |
-
1999
- 1999-07-30 CA CA002279219A patent/CA2279219A1/en not_active Abandoned
- 1999-07-30 US US09/364,478 patent/US6266026B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US6266026B1 (en) | 2001-07-24 |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |