Design and evaluation of a compact antenna for implant-to-air UWB communication

A compact, printed, capsule-shaped ultrawideband (UWB) antenna for biomedical implants is presented. The 10-dB return loss bandwidth of the proposed antenna is 3.5-4.5 GHz, which covers the recently proposed UWB for biomedical applications. The antenna matching has been optimized using CST Microwave Studio and verified by measurements. An optimized feed mechanism to reduce guided wavelength, as well as integration with other electronics, has been considered in the antenna design. Radiation performance has been evaluated on an impulse-based UWB transmitter/receiver testbed to show that the antenna is usable in biomedical applications, such as capsule endoscopes. The antenna has been tested both in free space and with tissue loading.