SUB MINATURE ANTENNA DESIGN FOR WIRELESS IMPLANTS

This paper describes the design, measurement and simulation of a sub-miniature loop antenna, suitable for wireless implant devices in the 900 MHz ISM and 402 MHz MICS radio bands. The difficulties of designing implant antennas are described, including how to minimise antenna detuning when it is placed inside the body, and how to manage areas of high-electric field strength through a combination of simulation and encapsulation design. Signal attenuation through the body and the effects on return loss are investigated using Ansoft HFSStrade models of two scenarios. In both cases fully featured body models are used with frequency dependent material parameters. The simulations confirm the trends seen in the measurements.