CA1075780A - Cb coupler - Google Patents
Cb couplerInfo
- Publication number
- CA1075780A CA1075780A CA277,323A CA277323A CA1075780A CA 1075780 A CA1075780 A CA 1075780A CA 277323 A CA277323 A CA 277323A CA 1075780 A CA1075780 A CA 1075780A
- Authority
- CA
- Canada
- Prior art keywords
- pass filter
- band pass
- housing
- antenna
- 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.)
- Expired
Links
Abstract
ABSTRACT OF THE DISCLOSURE
A coupler device is provided to enable a standard automobile AM/FM antenna to be effectively used as an AM/
FM/CB antenna. The coupler device includes a CB band pass filter between the antenna and CB transceiver with the CB
band pass filter being operable to exclude the AM/FM band.
An Am/FM band pass filter is located between the antenna and the AM/FM receiver with the AM/FM band pass filter being operable to exclude the CB band. Reactive elements are located between the CB band pass filter and the CB
transceiver with the reactive elements and the CB band pass filter operating together as a CB impedance matching network.
A coupler device is provided to enable a standard automobile AM/FM antenna to be effectively used as an AM/
FM/CB antenna. The coupler device includes a CB band pass filter between the antenna and CB transceiver with the CB
band pass filter being operable to exclude the AM/FM band.
An Am/FM band pass filter is located between the antenna and the AM/FM receiver with the AM/FM band pass filter being operable to exclude the CB band. Reactive elements are located between the CB band pass filter and the CB
transceiver with the reactive elements and the CB band pass filter operating together as a CB impedance matching network.
Description
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BACKGROUND OF TE~E INVENTION
The present invention concerns a novel device and method for using a standard automobile AM/FM antenna as an A~5/
FM/CB antenna.
Mobile citizen band (CB~ transceivers have become in-creasingly popular. In order to obtain most effective recep-tion and transmission, the CB transceivers have required the presence of a separate CB antenna mounted on the automohile in which the CB transceiver is located. The presence of such CB antennas has signaled CB transceiver thieves with respect to the probable location of a CB transceiver.
The alarming theft rate of CB transceivers has provi-ded a need for a means for hiding or disguising a CB antenna.
I have found that an efficient CB antenna can be provided using a standard automobile A~5/FM antenna of the rod or tele-scopic variety. I have also found that by using the principles of the present invention, a standard automobile A~5/FM antenna can be used as an A~5/FM/CB antenna, with the public being un-- aware that the standard AM/FM antenna is also being used as a CB antenna.
It is, therefore, an object of the present invention to provide a coupling system that will adapt a standard auto-mobile A~1/FM antenna to AM/FM/CB use.
A further object of the present invention is to provide a coupler which is capable of matching a standard AM/FM antenna to a CB transceiver with acceptable VSWR.
Another object of the present invention is to provide a standard automobile antenna which operates as a disguised CB
antenna.
Other objects and advantages of the present invention will become apparent as the description proceeds.
BACKGROUND OF TE~E INVENTION
The present invention concerns a novel device and method for using a standard automobile AM/FM antenna as an A~5/
FM/CB antenna.
Mobile citizen band (CB~ transceivers have become in-creasingly popular. In order to obtain most effective recep-tion and transmission, the CB transceivers have required the presence of a separate CB antenna mounted on the automohile in which the CB transceiver is located. The presence of such CB antennas has signaled CB transceiver thieves with respect to the probable location of a CB transceiver.
The alarming theft rate of CB transceivers has provi-ded a need for a means for hiding or disguising a CB antenna.
I have found that an efficient CB antenna can be provided using a standard automobile A~5/FM antenna of the rod or tele-scopic variety. I have also found that by using the principles of the present invention, a standard automobile A~5/FM antenna can be used as an A~5/FM/CB antenna, with the public being un-- aware that the standard AM/FM antenna is also being used as a CB antenna.
It is, therefore, an object of the present invention to provide a coupling system that will adapt a standard auto-mobile A~1/FM antenna to AM/FM/CB use.
A further object of the present invention is to provide a coupler which is capable of matching a standard AM/FM antenna to a CB transceiver with acceptable VSWR.
Another object of the present invention is to provide a standard automobile antenna which operates as a disguised CB
antenna.
Other objects and advantages of the present invention will become apparent as the description proceeds.
-2-:, 1075~80 In accordance with the present invention there is provided a coupler device including a housing adapted for location within a moving vehicle, which comprises means for coupling the housing to a standard automobile A~l/FM antenna, means for coupling the housing to an AM/FM receiver, means for coupling the housing to a CB transceiver, a CB band pass filter located in the housing between the antenna coupling means and the CB transceiver coupling means, the CB band pass filter being operable to exclude the AM/FM bands, and an AM/FM
band pass filter located in the housing between the antenna coupling means and the AM/FM receiver, the AM/FM band pass filter being operable to exclude the CB band, the AM/FM band pass filter comprising a parallel inductance and capacitance forming a parallel resonance circuit and operable to be resonant at the CB band, and means for adjusting the AM/FM
band pass filter to tune it for resonance at the CB band.
In the illustrative embodiment, a CB band pass fil-ter is located in the housing between the antenna coupling means and the CB transceiver coupling means. The CB band pass filter is operable to exclude the AM/FM band. An AM/FM
band pass filter is located in the housing between the antenna coupling means and the AM/FM receiver with the AM/FM band pass filter being operable to exclude the CB band.
In one embodiment, reactive elements are located in the housing between the CB band pass filter and the CB trans-ceiver, with the reactive elements and the CB band pass filter operating together as a CB impedance matching network.
In the illustrative embodiment, means are provided for adjusting the CB band pass filter to adjust the tuning of --30 the circuit. Means are also provided for adjusting the reac- -tive elements to match the antenna impedance to the transceiver mpedance.
band pass filter located in the housing between the antenna coupling means and the AM/FM receiver, the AM/FM band pass filter being operable to exclude the CB band, the AM/FM band pass filter comprising a parallel inductance and capacitance forming a parallel resonance circuit and operable to be resonant at the CB band, and means for adjusting the AM/FM
band pass filter to tune it for resonance at the CB band.
In the illustrative embodiment, a CB band pass fil-ter is located in the housing between the antenna coupling means and the CB transceiver coupling means. The CB band pass filter is operable to exclude the AM/FM band. An AM/FM
band pass filter is located in the housing between the antenna coupling means and the AM/FM receiver with the AM/FM band pass filter being operable to exclude the CB band.
In one embodiment, reactive elements are located in the housing between the CB band pass filter and the CB trans-ceiver, with the reactive elements and the CB band pass filter operating together as a CB impedance matching network.
In the illustrative embodiment, means are provided for adjusting the CB band pass filter to adjust the tuning of --30 the circuit. Means are also provided for adjusting the reac- -tive elements to match the antenna impedance to the transceiver mpedance.
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.
A more detailed explanation of the invention is provided in the following description and claims, and is illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a view of a coupler device housing constructed in accordance with the principles of the present invention; and Figure 2 is a schematic circuit diagram of illustrative -3a-~ ~ I .
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circuitry used in the coupler device of Figure 1.
Referring to Figure 1, an illustrative coupling device constructed in accordance with the principles of the present invention is shown having a housing 10 which includes the appropriate electrical circuit elements. ~ousing 10 is adapted to be connected under the dashboard of an automobile and may use any suitable fastening means, including screws, bolts, or it may carry a Velcro patch which is connected to a Velcro patch fastened to the underside of the dashboard.
Housing 10 includes a standard automobile antenna con-nector 12 to which the conventional cable from an automobile AM/FM antenna is connected. The housing 10 is also coupled via cable 14 to a coaxial connector 16 which is connected to the standard female receptacle of a CB transceiver. Housing 10 is coupled via cable 18 to a male connector 20 which is connected to the standard female receptacle of an AM receiver or an AM/FM
receiver.
A knob 22 is provided for manually matching the antenna impedance to the transceiver impedance and a knob 24 is provided for manually adjusting the tunin~.
Referring to Fi~ure 2, a preferred circuit is shown therein for providing the electrical characteristics that are appropriate to achieve the objectives of the present invention.
The circuitry enclosed within the dashed lines is located within housing 10. Thus, a standard AM/FM antenna 30, mounted on the vehicle by means of mounting 32, is connected via line 12 to an AM/FM band pass filter 34 comprising an inductance 36 and a variable capacitor 38. AM/FM band pass filter 34 has electrical characteristics which serve to pass the AM/FM band but to ex-3~ clude the CB band. AM/FM hand pass filter 34 couples antenna 30 to the AM/FM receiver via cable 18 and connector 20 (Figure
.
A more detailed explanation of the invention is provided in the following description and claims, and is illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a view of a coupler device housing constructed in accordance with the principles of the present invention; and Figure 2 is a schematic circuit diagram of illustrative -3a-~ ~ I .
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,~
i~75~
circuitry used in the coupler device of Figure 1.
Referring to Figure 1, an illustrative coupling device constructed in accordance with the principles of the present invention is shown having a housing 10 which includes the appropriate electrical circuit elements. ~ousing 10 is adapted to be connected under the dashboard of an automobile and may use any suitable fastening means, including screws, bolts, or it may carry a Velcro patch which is connected to a Velcro patch fastened to the underside of the dashboard.
Housing 10 includes a standard automobile antenna con-nector 12 to which the conventional cable from an automobile AM/FM antenna is connected. The housing 10 is also coupled via cable 14 to a coaxial connector 16 which is connected to the standard female receptacle of a CB transceiver. Housing 10 is coupled via cable 18 to a male connector 20 which is connected to the standard female receptacle of an AM receiver or an AM/FM
receiver.
A knob 22 is provided for manually matching the antenna impedance to the transceiver impedance and a knob 24 is provided for manually adjusting the tunin~.
Referring to Fi~ure 2, a preferred circuit is shown therein for providing the electrical characteristics that are appropriate to achieve the objectives of the present invention.
The circuitry enclosed within the dashed lines is located within housing 10. Thus, a standard AM/FM antenna 30, mounted on the vehicle by means of mounting 32, is connected via line 12 to an AM/FM band pass filter 34 comprising an inductance 36 and a variable capacitor 38. AM/FM band pass filter 34 has electrical characteristics which serve to pass the AM/FM band but to ex-3~ clude the CB band. AM/FM hand pass filter 34 couples antenna 30 to the AM/FM receiver via cable 18 and connector 20 (Figure
-4-~07578~3 Antenna 30 is also connected to a CB band pass filter 40. Band pass filter 40 comPrises a series connected induct-ance 42 and variable capacitance 44. The CB band pass filter 40 has electrical characteristics which operate to pass the CB
band but to exclude the AM/FM band. A capacitor 46 is connec-ted in parallel with variable capacitor 44 to provide a vernier action to maintain the capacitance at a desired level. Thus, CB band pass filter 40 is a tuning coil having a capacitor 44 which acts to block the AM band and an inductor 42 which acts to block the FM band. Likewise, the ~I/FM band pass filter 34 is a resonant tank circuit formed of a parallelly connected inductance and capacitance which acts to block the CB band.
A CB impedance matching network 50 is provided including a variable capacitor 52 connected between capacitor 44 and cable 14 and a capacitor 54 connected between the junction 56 and ground. A capacitor 58 is connected in parallel to variable capacitor 52 to provide a vernier action to maintain the capaci-tance at its desired level during adjustment of capacitor 52.
The CB impedance matching network also includes CB band pass filter 40 cooperating with capacitors 52 and 54 with the arm of variable capacitor 52 being connected to match knob 22 for manual adjustment. Likewise, the arm of variable capacitor 44 is connected to channel knob 24 for manual tuning adjustment.
It is preferred that variable capacitor 38 be adjusted in the factory.
Antenna 30 ~.ay be a standard automobile AM/FM antenna which, as a rod, is generallv 31 inches in length or, as a telescopic antenna, telescopes from 22 inches to 54 inches.
Although no limitation is intended, an example of parameters which have been found to operate satisfactorily are as follows:
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Circuit Element Value Inductance 36 0.5 microhenries Capacitor 38 5-80 picofarads, nominally 47 picofarads Inductance 42 1.3 microhenries Capacitor 44 5-60 picofarads, nominally 50 picofarads Capacitor 46 27 picofarads Capacitor 52 5-60 picofarads, nominally 50 picofarads Capacitor 58 27 picofarads Capacitor 54 120 picofarads In operating the invention, the standard antenna lead is connected to antenna connector 12 of housing 10. Connector 20 is plugged into the AM/FM receiver receptacle and connector 16 is connected to the CB transceiver receptacle. Knobs 22 and 24 are varied to tune the system and match the impedance of the antenna to the impedance of the CB transceiver. Housing 10 is fastened to the underside of the automobile dashboard and the system is ready for use, with the standard automobile antenna being operable as an AM/FM/CB antenna.
Although a preferred embodiment has been shown, it is understood that in lieu of the capacitors being variable, the inductances could be variable. Alternatively, both the capaci-tors and inductors could be variable or, in one embodiment, the . circuit may be designed without variable elements. However, the circuit illustrated in Figure 2 is the preferred embodiment of the invention. Thus, it is to be understood that various modifications and substitutions may be made by those skilled in the art without departing from the novel spirit and scope of the present invention.
As used herein, the terms "AM" and "F~" refer to the AM
and FM broadcast bands, respectively, the AM broadcast band presently being about 500 kilohertz to 1600 kilohertz and the .
~( . - , :
.: : -1~7~
FM broadcast hand presently being about 88 megahertz to 108 megahertz. The term "CB" refers to the citizens radio service, which presently is around 27 megahertz.
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band but to exclude the AM/FM band. A capacitor 46 is connec-ted in parallel with variable capacitor 44 to provide a vernier action to maintain the capacitance at a desired level. Thus, CB band pass filter 40 is a tuning coil having a capacitor 44 which acts to block the AM band and an inductor 42 which acts to block the FM band. Likewise, the ~I/FM band pass filter 34 is a resonant tank circuit formed of a parallelly connected inductance and capacitance which acts to block the CB band.
A CB impedance matching network 50 is provided including a variable capacitor 52 connected between capacitor 44 and cable 14 and a capacitor 54 connected between the junction 56 and ground. A capacitor 58 is connected in parallel to variable capacitor 52 to provide a vernier action to maintain the capaci-tance at its desired level during adjustment of capacitor 52.
The CB impedance matching network also includes CB band pass filter 40 cooperating with capacitors 52 and 54 with the arm of variable capacitor 52 being connected to match knob 22 for manual adjustment. Likewise, the arm of variable capacitor 44 is connected to channel knob 24 for manual tuning adjustment.
It is preferred that variable capacitor 38 be adjusted in the factory.
Antenna 30 ~.ay be a standard automobile AM/FM antenna which, as a rod, is generallv 31 inches in length or, as a telescopic antenna, telescopes from 22 inches to 54 inches.
Although no limitation is intended, an example of parameters which have been found to operate satisfactorily are as follows:
~.
~7S78(~
Circuit Element Value Inductance 36 0.5 microhenries Capacitor 38 5-80 picofarads, nominally 47 picofarads Inductance 42 1.3 microhenries Capacitor 44 5-60 picofarads, nominally 50 picofarads Capacitor 46 27 picofarads Capacitor 52 5-60 picofarads, nominally 50 picofarads Capacitor 58 27 picofarads Capacitor 54 120 picofarads In operating the invention, the standard antenna lead is connected to antenna connector 12 of housing 10. Connector 20 is plugged into the AM/FM receiver receptacle and connector 16 is connected to the CB transceiver receptacle. Knobs 22 and 24 are varied to tune the system and match the impedance of the antenna to the impedance of the CB transceiver. Housing 10 is fastened to the underside of the automobile dashboard and the system is ready for use, with the standard automobile antenna being operable as an AM/FM/CB antenna.
Although a preferred embodiment has been shown, it is understood that in lieu of the capacitors being variable, the inductances could be variable. Alternatively, both the capaci-tors and inductors could be variable or, in one embodiment, the . circuit may be designed without variable elements. However, the circuit illustrated in Figure 2 is the preferred embodiment of the invention. Thus, it is to be understood that various modifications and substitutions may be made by those skilled in the art without departing from the novel spirit and scope of the present invention.
As used herein, the terms "AM" and "F~" refer to the AM
and FM broadcast bands, respectively, the AM broadcast band presently being about 500 kilohertz to 1600 kilohertz and the .
~( . - , :
.: : -1~7~
FM broadcast hand presently being about 88 megahertz to 108 megahertz. The term "CB" refers to the citizens radio service, which presently is around 27 megahertz.
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Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A coupler device including a housing adapted for location within a moving vehicle, which comprises: means for coupling said housing to a standard automobile AM/FM antenna;
means for coupling said housing to an AM/FM receiver; means for coupling said housing to a CB transceiver; a CB band pass filter located in said housing between said antenna coupling means and said CB transceiver coupling means, said CB band pass filter being operable to exclude the AM/FM bands;
and an AM/FM band pass filter located in said housing between said antenna coupling means and said AM/FM receiver, said AM/FM band pass filter being operable to exclude the CB band, said AM/FM band pass filter comprising a parallel inductance and capacitance forming a parallel resonance circuit and operable to be resonant at the CB band; and means for adjust-ing said AM/FM band pass filter to tune it for resonance at the CB band.
means for coupling said housing to an AM/FM receiver; means for coupling said housing to a CB transceiver; a CB band pass filter located in said housing between said antenna coupling means and said CB transceiver coupling means, said CB band pass filter being operable to exclude the AM/FM bands;
and an AM/FM band pass filter located in said housing between said antenna coupling means and said AM/FM receiver, said AM/FM band pass filter being operable to exclude the CB band, said AM/FM band pass filter comprising a parallel inductance and capacitance forming a parallel resonance circuit and operable to be resonant at the CB band; and means for adjust-ing said AM/FM band pass filter to tune it for resonance at the CB band.
2. A coupler device as described in Claim 1, and further including reactive elements located in said housing between said CB band pass filter and said CB transceiver coupling means, said reactive elements and said CB band pass filter operating together as a CB impedance matching network.
3. A coupler device as described in Claim 1, said CB
band pass filter comprising a series connected inductance and variable capacitance.
band pass filter comprising a series connected inductance and variable capacitance.
4. A coupler device as described in Claim 2, said reactive elements comprising a variable capacitance connected between said CB band pass filter and said CB transceiver coupling means, and a capacitor connected between the CB band pass filter-variable capacitor junction and ground.
5. A coupler device as described in Claim 1, means for adjusting said CB band pass filter to adjust the tuning of the circuit.
6. A coupler device as described in Claim 2, means for adjusting said reactive elements to match the antenna impedance to tne transceiver impedance.
7. A coupler device including a housing adapted for location within a moving vehicle, which comprises: means for coupling said housing to a standard automobile AM/FM antenna;
means for coupling said housing to an AM/FM receiver; means for coupling said housing to a CB transceiver; a CB band pass filter located in said housing between said antenna coupling means and said CB transceiver coupling means, said CB band pass filter comprising a series connected inductance and variable capacitance, said CB band pass filter being operable to exclude the AM/FM bands; an AM/FM band pass filter located in said housing between said antenna coupling means and said AM/FM receiver, said AM/FM band pass filter comprising a parallel inductance and variable capacitance, said AM/FM band pass filter being operable to exclude the CB band; and reac-tive elements located in said housing between said CB band pass filter and said CB transceiver, said reactive elements and said CB band pass filter operating as a CB impedance matching network.
8. A coupler device as described in Claim 7, in which said reactive elements comprise a variable capacitance con-nected between said CB band pass filter and said CB
means for coupling said housing to an AM/FM receiver; means for coupling said housing to a CB transceiver; a CB band pass filter located in said housing between said antenna coupling means and said CB transceiver coupling means, said CB band pass filter comprising a series connected inductance and variable capacitance, said CB band pass filter being operable to exclude the AM/FM bands; an AM/FM band pass filter located in said housing between said antenna coupling means and said AM/FM receiver, said AM/FM band pass filter comprising a parallel inductance and variable capacitance, said AM/FM band pass filter being operable to exclude the CB band; and reac-tive elements located in said housing between said CB band pass filter and said CB transceiver, said reactive elements and said CB band pass filter operating as a CB impedance matching network.
8. A coupler device as described in Claim 7, in which said reactive elements comprise a variable capacitance con-nected between said CB band pass filter and said CB
Claim 8 - Continued transceiver coupling means, and a capacitor connected between the CB band filter-variable capacitor junction and ground.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US72737176A | 1976-09-27 | 1976-09-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1075780A true CA1075780A (en) | 1980-04-15 |
Family
ID=24922384
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA277,323A Expired CA1075780A (en) | 1976-09-27 | 1977-04-29 | Cb coupler |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1075780A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5258728A (en) * | 1987-09-30 | 1993-11-02 | Fujitsu Ten Limited | Antenna circuit for a multi-band antenna |
| AU708446B2 (en) * | 1995-04-28 | 1999-08-05 | Toko Kabushiki Kaisha | Antenna sharing apparatus |
| GB2490145A (en) * | 2011-04-20 | 2012-10-24 | Frontier Silicon Ltd | A DAB (RTM) receiver module, including tuneable impedance matching circuitry, for retrofitting DAB radio to a car |
-
1977
- 1977-04-29 CA CA277,323A patent/CA1075780A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5258728A (en) * | 1987-09-30 | 1993-11-02 | Fujitsu Ten Limited | Antenna circuit for a multi-band antenna |
| AU708446B2 (en) * | 1995-04-28 | 1999-08-05 | Toko Kabushiki Kaisha | Antenna sharing apparatus |
| GB2490145A (en) * | 2011-04-20 | 2012-10-24 | Frontier Silicon Ltd | A DAB (RTM) receiver module, including tuneable impedance matching circuitry, for retrofitting DAB radio to a car |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |