US Patent 7936174 Coupling loop

A coupling loop or antenna is provided that can be used with a system that determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. In one embodiment multiple energizing loops energize an implanted sensor and a sensor coupling loop connected to an input impedance that is at least two times greater than the inductance of the sensor coupling loop receives the sensor signal.