An Ultrawideband Implantable Antenna With Hybrid Polarization for Human Health Monitoring

A miniaturized ultra-wideband (UWB) implantable antenna with hybrid polarization is proposed in this paper. The antenna has a surface size of 10×9.8 mm2, which consists of a tree-shaped radiation patch and a horseshoe-shaped defected ground structure (DGS). Because of the specially designed radiation patch and defected ground plane, the implantable antenna has realized ultra-wideband characteristics. By adding a superstrate to the antenna system, the circular polarization has been introduced to the antenna. A prototype of the antenna was fabricated and measured when it was buried inside a ground pork environment. The simulated and measured results show a fairly good agreement. A measured impedance bandwidth from 2.33 to 11.36 GHz (131%), and three wide axial ratio (AR) bandwidths of 4.4-5.2 GHz (16.67%), 6.6-8 GHz (19.18%), and 10.4-10.8 GHz (3.77%) were obtained. Furthermore, the link budget analysis and specific absorption rate (SAR) were further analyzed. It seems that the proposed antenna has a wide bandwidth, which covers the bands of the ISM, 5G, WiMAX, Wi-Fi, and satellite communication.