Radiation Efficiency of Implanted Antennas: Evaluation of Antenna Encapsulation and Position in Different Canonical Body Models

In-body implanted antennas are one of essential components of various medical devices being developed in order to help in monitoring patient’s condition more directly. Human body is, however, a very hostile environment from electromagnetic point of view, since the body, when viewed as dielectric medium, has very high losses. To study how this effects the radiation properties, in this paper we focus on the analysis of radiation efficiency as a function of the size and the position of the implant inside the body. We compare two scenarios where the body is approximated with spherical and cylindrical body models which are commonly used in similar investigations. Results confirm that in both scenarios the size and the position of the implant have a major effect on the efficiency, however, the observations have to take into account the frequency since different loss mechanisms dominate for different frequencies.