Radiowave propagation from a tissue-implanted source at 418 MHz and 916.5 MHz

Tissue-implanted ultra-high frequency (UHF) radio devices are being employe d in both humans and animals for telemetry and telecommand applications, Th is paper describes the experimental measurement and electromagnetic modelin g of propagation from 418-MHz and 916.5-MHz sources placed in the human vag ina. Whole-body homogeneous and semi-segmented software models were constru cted using data from the Visible Human Project. Bodyworn radiation efficien cies for a vaginally placed 418-MHz source were calculated using finite-dif ference time-domain and ranged between 1.6% and 3.4% (corresponding to net body losses of between 14.7 and 18.0 dB), Greater losses were encountered a t 916.5 MHz, with efficiencies between 0.36% and 0.46% (net body loss rangi ng between 23.4 and 24.4 dB), Practical measurements were in good agreement with simulations, to within 2 dB at 418 MHz and 3 dB at 916.5 MHz. The deg ree of tissue-segmentation for whole-body models was found to have a minima l effect on calculated azimuthal radiation patterns and bodyworn radiation efficiency, provided the region surrounding the implanted source was suffic iently detailed.