Antenna development, link budget analysis and specific absorption rate evaluation in ultra-wideband implant communications

In this study, the authors developed an ultra-wideband (UWB) planar loop antenna for implant communication, and confirmed its usefulness by comparing its designed and measured reflection and transmission characteristics. With the planar loop antenna as the implant transmitting antenna, then they calculated the implant path loss and specific absorption rate (SAR) using the finite difference time domain method together with an anatomical human body numerical model. Moreover, through a link budget analysis based on the calculated path loss with selection diversity, they derived the transmitting power required to achieve a specific bit error rate performance, and clarified the corresponding local SAR with respect to the international safety limits. As a result, the UWB implant communication is found to be feasible at a data rate as high as 40 Mbps under the SAR safety limits.