Computationally Efficient Model for Uwb Signal Attenuation Due to Propagation in Tissue for Biomedical Implants

An analytical model which predicts the attenuation of ultrawide-band (UWB) signals as they traverse various inhomogeneous tissues is presented. The model provides a computationally efficient method of determining the frequency-dependent losses encountered by electromagnetic radio frequency (RF) signals used to communicate with biomedical implants. Classic transmission line theory is employed to generate an analytical representation which models the inhomogeneous tissue using layers of homogeneous material. The proposed model was verified experimentally with tests of both single and multilayer samples. A realistic abdominal implant scenario was also modeled and the predictions were verified using a commercially available 3D electromagnetic (EM) simulator. The results of this study indicate that for deep implants the higher frequency portion of the UWB spectrum is attenuated much more strongly than the lower end of the band. This implies that for robust communication UWB signals targeting biomedical implants should be limited to the lower portion of the spectrum.