A transponder (14) for communicating with an interrogator (12) has a high Q-factor resonant circuit (34) of frequency f.sub.1 for receiving RF powering signals. The transponder also has a tuning circuit (56,58) which when in electrical communication with the resonant circuit (34) is operable to form...http://www.google.de/patents/US5287112?utm_source=gb-gplus-sharePatent US5287112 - High speed read/write AVI system
