Importance

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Abstract

A method of matching the resonant frequency of an antenna resonant circuit (18, 46) to the output frequency of a transmitter output stage (26), the method includes the step of providing a powering signal from the transmitter output stage (26) to the antenna resonant circuit (18, 46). The method further includes the step of receiving at the antenna resonant circuit (18, 46) the powering signal, the antenna resonant circuit (18, 46) comprising a tuning circuit (48). The tuning circuit (48) is operable to variably modify the resonant frequency of the resonant circuit (18, 46). At its output the antenna resonant circuit (18, 46) provides a phase correlation signal having a known relationship to the frequency difference between the resonant frequency and the powering signal. A phase comparator (60) then receives the powering signal and the phase correlation signal and correspondingly adjusts the resonant frequency of the resonant circuit (18, 46) based upon the known phase relationship. Other devices, systems and methods are also disclosed.

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First Claim