Design of a Pin-loaded Wideband Implantable Antenna with Circular Polarization

In this paper, a pin-loaded circularly polarized antenna that operating at the 2.45-GHz industrial, scientific, and medical (ISM) band is designed for biomedical applications. Its circularly polarized wave is generated by the loading of vias and two arc-shaped open slots, where the two slots have different lengths to achieve better axial-ratio (AR) performance. Besides, the antenna size is miniaturized by loading two pairs of patches at the inner edge of annular ring. In addition, we loaded a notch on the ring near the feed point to improve the matching performance and achieve a wide impedance bandwidth. This proposed structure shows a simulated impedance bandwidth of 9.7% and a wide AR bandwidth of 15.9%. Finally, the radiation patterns and specific absorption rate performance of the antenna are characterized, showing it a satisfying candidate for implantable applications.