Electrical signal separating device having isolating and matching circuitry

An isolating and matching device to enable the heating element means of a motor vehicle electrically heatable window, not designed specifically to be an antenna or aerial and essentially aperiodic and non-resonant at VHF frequencies, to be used as a broad-band VHF receiving aerial, said device being interconnected between terminal leads of said heating element and an aerial feeder circuit of a receiver and having input leads for connection to a motor vehicle D.C. power supply and an aerial terminal for connection to said aerial feeder circuit, comprising in combination:

• isolating circuitry coupled with said terminal leads of said heating element and with said motor vehicle D.C. power supply to permit passage of heating current from said power supply to the said heating element while isolating or blocking passage of RF signals from said heating element to the said power supply, and means including matching circuitry means for effectively matching the impedance of said heating element to an aerial input impedance of the said aerial feeder circuit to thereby effect efficient VHF signal reception, said matching circuitry means including input circuit means operatively connected with said terminal leads of said heating element for bringing the said heating element to series resonance near the center of the VHF band to thereby provide efficient broad-band VHF reception;
• whereby, via said isolating and matching device, said motor vehicle electrically heatable window forms together with said input circuit means a series resonance in the VHF band and becomes usable as an efficient broad-band VHF receiving aerial.