Miniaturized Triple-Band Circular- Polarized Implantable Patch Antenna for Bio-Telemetry Applications

This letter presents a triple-band antenna with circular polarization (CP) behavior embedded in a lossy tissue for bio-telemetry applications. The triple bands are the Industrial, Scientific, and Medical (ISM) (868-868.6 MHz and 2.4-2.4835 GHz) bands and the midfield band at (1.824-1.98) GHz. These bands are used for physiological information telemetry, power-saving, and wireless power transfer (WPT) in medical devices. CP behavior at three bands is the key feature of the designed implantable antenna, compared with literature dual-band CP antennas. Moreover, the size of the designed antenna is compact of 50.8 mm$^{3}$. Finally, the specific absorption rate (SAR) and link margin are calculated for the consideration of health safety and reliable communication aspects.