Tuning circuitry for a VHF television (TV) antenna tunes such antenna for signals corresponding to the TV channel selected and couples those signals to the tuning system of a television receiver. An antenna has a pair of signal terminals across which the tuning circuitry connects to form a resonance...http://www.google.fr/patents/US4339827?utm_source=gb-gplus-shareBrevet US4339827 - Automatic tuning circuit arrangement with switched impedances
Automatic tuning circuit arrangement with switched impedances
