Compact Dual-Band Dual-Polarized Implantable Antenna for Biomedical Applications

A compact dual-band dual-polarized implantable antenna is investigated in this study for bio-telemetry in biomedical applications. It operates in the wireless medical telemetry service band (1.395-1.432 GHz) with an impedance bandwidth of 1.22-1.69 GHz and in the industrial, scientific, and medical band (2.40-2.48 GHz) with an impedance bandwidth of 2.08-2.59 GHz. Besides, circular polarization is obtained in the upper band with 3-dB axial bandwidth of 2.22-2.50 GHz. Meandering technology is utilized to realize miniaturization and the dimensions of the antenna are optimized to be <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5\times 6\times 0.4\text{ mm}^{3} (0.023 \times 0.028 \times 0.0019 {\lambda_{0}}^3, \lambda_0$</tex> is the wave length at 1.4 GHz) without introducing shorting-pins. Moreover, to better analyze the antenna tuning, equivalent circuits are constructed. Finally, for human safety, the specific absorption rate is analyzed.