Patent ID: 8081043

Claim:
In an RF communication system in which an external transmitter electromagnetically couples a signal of predetermined frequency, f c , to a receiver separated by an air gap from the transmitter, a method for dynamically shifting a resonant frequency, f R , of a tuning circuit of the receiver to better match the f c of the transmitted signal, the tuning circuit comprising an antenna and a capacitor, a capacitance of which can be varied in a selected one of first and second directions, the method comprising the steps of: (1) selecting one of said first and second directions; (2) capturing a first current response of the tuning circuit to the signal transmitted by the transmitter; (3) varying the capacitor in said selected first or second direction; (4) comparing the captured first response to a second current response of the tuning circuit to the signal currently transmitted by the transmitter; (5) if the comparison made in step 4 indicates that the second current response is weaker than the captured first response, selecting the other of said directions; and (6) returning to step 2.