An Ultrawideband Implantable Antenna With Hybrid Polarization for Human Health Monitoring

A miniaturized ultrawideband implantable antenna with hybrid polarization is proposed in this letter. The antenna has a surface size of 10 mm × 9.8 mm, which consists of a tree-shaped radiation patch and a horseshoe-shaped defected ground structure. Because of the specially designed radiation patch and defective ground plane, the implantable antenna has realized ultrawideband 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 GHz to 11.36 GHz (131%), and three wide axial ratio (AR) bandwidths of 4.4 GHz to 5.2 GHz (16.67%), 6.6 GHz to 8 GHz (19.18%), and 10.4 GHz to 10.8 GHz (3.77%) were obtained. Furthermore, the link budget analysis and specific absorption rate 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.