Design of implantable antenna on the dielectric/ferrite substrate for wireless biotelemetry

A miniature and broadband implantable antenna is designed for wireless biotelemetry in the medical implantable communications service (MICS) frequency band (402-405 MHz). To minimize antenna size and enhance bandwidth, a meandered planar inverted-F antenna (PIFA) structure is adopted on a dielectric/ferrite substrate. The potential of the proposed antenna is verified through a prototype fabrication and measurement with 2/3 human muscle-emulating material environment. Good agreement is observed between the simulation and measurement in terms of resonant characteristics and gain radiation patterns of the antenna. The measurement shows broad bandwidth (return loss of 10 dB) of 226 MHz and maximum gain of -27.7 dBi at 403.5 MHz. Analysis of 1-g SAR distribution is conducted to satisfy the specific absorption rate limitation (1.6 W/ kg) of the American National Standards Institute.