Compact bioimplantable MICS and ISM band antenna design for wireless biotelemetry applications

Abstract

A compact dual-band bioimplantable antenna with novel resonator geometry is designed for dual-band wireless biotelemetry applications in MICS and ISM bands. The radiating element geometry is based on an Lshaped transmission line fed anti-spiral resonator structure, which is loaded with the spiral resonator at the end to increase the effective electrical length. The effect of resonator geometric parameters on the return loss is discussed with the inclusion of three layered lossy human model in the numerical calculations. The footprint size of the optimized bioimplantable antenna is 15 × 15 × 1.92 mm3, having the total surface area of λ0/20 × λ0/20, where λ0 is the free space wavelength at 403 MHz in MICS band. The compact dual-band antenna has the impedance bandwidth of 24.81% at 403 MHz and 14.7% at 2.45 GHz with the gain values -12.25 dBi and -12.4 dBi in MICS and ISM bands, respectively. The average SAR values at the resonance frequencies are numerically computed to find out the input power delivered to the antenna for the reliable operation. The radiation parameters and 3D radiation patterns indicate the potential use of the proposed implantable antenna with the permissible gain in dual-band wireless biotelemetry applications.