Patent ID: 6889086

Claim:
A telemetry system for enabling transfer of message data from an implantable medical device to an external device, comprising: an implantable medical device; an external device; a transmitter and a transmitter antenna incorporated as part of the external device for transmitting a radio-frequency carrier signal to the implantable device; an implantable device antenna incorporated as part of the implantable device for reflecting the radio-frequency carrier signal; a tuning circuit incorporated as part of the implantable device for adjusting the impedance of the implantable device antenna in a time varying manner so as to phase modulate the radio-frequency carrier signal reflected therefrom in accordance with the message data; a receiver and a receiver antenna incorporated as part of the external device for receiving the phase modulated carrier signal reflected from the antenna of the implantable device and extracting the message data therefrom; and, wherein the transmitter and receiver antennas are linearly polarizing antennas orthogonal to one another and the implantable device antenna is elliptically polarizing.