Radio-frequency coupler
First Claim
1. A radio-frequency coupler comprising:
- a first terminal for interconnection with a conventional automobile receiving antenna used for receiving rf transmissions within a first band of radio frequencies, a second terminal for interconnection with a receiver operating within the first band of radio frequencies and a third terminal for interconnection with a transceiver operating within a second band of radio frequencies different from the first band;
first and second rf transmission paths, the first rf transmission path extending between the first terminal and the second terminal and the second rf transmission path extending between the first terminal and the third terminal;
a first resonant circuit connected in the first rf transmission path and tuned to offer a first impedance to rf transmissions within the first band of frequencies but a second and higher impedance to rf transmissions within the second band of frequencies thereby to pass rf transmissions in the first band but substantially block those in the second band;
a second resonant circuit connected in the second rf transmission path and tuned to resonate at a frequency within the second frequency band thereby to offer a first impedance to rf transmissions within the first band of frequencies but a second and lower impedance to rf transmissions within the second band of frequencies so that rf transmissions within the second band are passed but those within the first band are substantially blocked; and
a third resonant circuit connected between the third terminal and electrical ground and tuned to resonate at a frequency outside the second band of frequencies whereby the second and third resonant circuits form a series-connected path between the first terminal and electrical ground and the impedance of the third resonant circuit at the second band of frequencies allows maximum rf energy within the second band of frequencies to be transferred between the antenna and the transceiver thereby permitting the conventional automobile receiving antenna normally used only for receiving rf transmissions within the first frequency band to also be used for sending and receiving rf transmissions within the second frequency band.
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Accused Products
Abstract
A radio-frequency coupler comprising a first terminal for interconnection with a conventional automobile receiving antenna used for receiving rf transmissions within a first radio-frequency band, a second terminal for interconnection with a receiver operating within the first radio-frequency band and a third terminal for interconnection with a transceiver operating within a second frequency band different from the first band. A first rf transmission path extends between the first terminal and the second terminal and a second rf transmission path extends between the first terminal and the third terminal. A first resonant circuit is connected in the first rf transmission path and tuned to pass rf transmissions in the first band but substantially block those in the second band. A second resonant circuit is connected in the second rf transmission path and tuned to resonate at a frequency within the second band so that rf transmissions within the second band are passed but those within the first band are substantially blocked. A third resonant circuit is connected between the third terminal and electrical ground and tuned to resonate at a frequency outside the second band. The second and third resonant circuits form a series-connected path between the first terminal and electrical ground and the impedance of the third resonant circuit at the second frequency band allows maximum rf energy within the second band to be transferred between the antenna and the transceiver thereby permitting the conventional automobile receiving antenna normally used only for receiving rf transmissions within the first frequency band to also be used for sending and receiving rf transmissions within the second frequency band.
26 Citations
9 Claims
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1. A radio-frequency coupler comprising:
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a first terminal for interconnection with a conventional automobile receiving antenna used for receiving rf transmissions within a first band of radio frequencies, a second terminal for interconnection with a receiver operating within the first band of radio frequencies and a third terminal for interconnection with a transceiver operating within a second band of radio frequencies different from the first band; first and second rf transmission paths, the first rf transmission path extending between the first terminal and the second terminal and the second rf transmission path extending between the first terminal and the third terminal; a first resonant circuit connected in the first rf transmission path and tuned to offer a first impedance to rf transmissions within the first band of frequencies but a second and higher impedance to rf transmissions within the second band of frequencies thereby to pass rf transmissions in the first band but substantially block those in the second band; a second resonant circuit connected in the second rf transmission path and tuned to resonate at a frequency within the second frequency band thereby to offer a first impedance to rf transmissions within the first band of frequencies but a second and lower impedance to rf transmissions within the second band of frequencies so that rf transmissions within the second band are passed but those within the first band are substantially blocked; and a third resonant circuit connected between the third terminal and electrical ground and tuned to resonate at a frequency outside the second band of frequencies whereby the second and third resonant circuits form a series-connected path between the first terminal and electrical ground and the impedance of the third resonant circuit at the second band of frequencies allows maximum rf energy within the second band of frequencies to be transferred between the antenna and the transceiver thereby permitting the conventional automobile receiving antenna normally used only for receiving rf transmissions within the first frequency band to also be used for sending and receiving rf transmissions within the second frequency band. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification