Patent ID: 7437130

Claim:
A low frequency radio frequency transmitter adapted to adjust aerial impedance for a selected radio frequency signal, the radio frequency transmitter comprising: a tunable radio frequency signal generator having an impedance for generating a radio frequency signal in the range of approximately 520 kilohertz to approximately 1700 kilohertz; an aerial coupled to the tunable radio frequency generator to transmit the radio frequency signal, the aerial having an output voltage and an aerial impedance; an adjustable reactive element coupled to the aerial to match the impedance of the signal generator to the aerial impedance; a sampler coupled to the aerial to measure the aerial's output voltage; and an impedance adjusting apparatus coupled to the sampler and the adjustable reactive element, the impedance adjusting apparatus, responsive to the measured aerial output voltage and adapted to iteratively increase the impedance of the adjustable reactive element until the measured aerial output voltage ceases increasing thereby matching the aerial impedance to the radio frequency signal generator impedance.