Patent ID: 7878207

Claim:
A method comprising: generating a first waveform in an external device; driving an external antenna with the first waveform, wherein the external antenna has an asymmetrical loading profile; measuring a first value of an electrical parameter associated with the external antenna while the external antenna is driven with the first waveform; generating a second waveform in the external device, the second waveform having at least one different waveform parameter than the first waveform; driving the external antenna with the second waveform; measuring a second value of the electrical parameter while the external antenna is driven with the second waveform; and determining a location of an implanted object relative to the external antenna based on a difference between the measured first and second values of the electrical parameter, wherein the difference between the first and second values of the electrical parameter is caused at least in part by the asymmetrical loading profile of the external antenna.