Influence of phantom models on implantable antenna performance for biomedical applications

The performance variations of implantable antennas due to the influence of the phantom model dimensions, the shape or the implant depth is reported in this paper. Three 2D-square spiral PIFA prototypes operating in the Medical Device Radiocommunications Service (MedRadio) frequency band (401-406 MHz) and in the Industrial Scientific and Medical bands (866 MHz and 2.45 GHz) are presented and characterized to assess the influence of the surrounding tissues in the radiation features. The electromagnetic modeling is based on the finite-difference time-domain method. The dielectric properties of the skin have been taken as a reference for the parameters of phantom models while the Low-Temperature Co-fired Ceramic technology has been chosen for the substrate. The results show that some antenna features such as the gain, the efficiency or the radiation pattern are substantially modified when changing phantom dimensions or implant depth. Finally, the standardization of implantable antenna characterization is suggested in order to improve the comparison between prototypes.