A Compact Circularly Polarized Implantable Antenna at ISM Band for Healthcare Applications

In this paper, a coax-fed circularly polarized (CP) implantable patch antenna operating in 2.4 GHz (Industrial, Scientific and Medical ISM band) is proposed. A shorting pin and two L-shaped slots on the radiating patch are used to reduce the electrical size of the antenna. In order to enable circular polarization, four open ended stubs are added to the four corners of the radiating patch. Furthermore, two corners of the ground plane are truncated to enhance the circular polarization purity. A PEC shielding mechanism is placed around the periphery of the antenna to improve the gain and axial ratio performance. The proposed implantable antenna is simulated and optimized using CST Microwave Studio inside a skin box at 3 mm depth. The proposed implantable antenna demonstrates satisfactory performance in terms of impedance bandwidth, axial ratio and embedded gain performance.