Radiation characteristics of ingested wireless device at frequencies from 430 MHz to 3 GHz*

In order to assess the compliance of high frequency ingested wireless devices (IWD) within the safety guidelines worldwide, the biological effects and the radiation efficiency of the IWD in a realistic human body model were studied using the Finite-Difference Time-Domain (FDTD) method. Simulations were carried out for three orientations of the IWD at seven positions in the human body model. Specific Absorption Rate (SAR), temperature rise, near field and far field characteristics were analyzed at frequencies from 430 MHz to 3 GHz. Results showed that the radiation intensity outside the body decreased with frequency. Furthermore, the orientation and position of the IWD, which gave maximum radiation efficiency, was frequency dependent. In our experiment, when the IWD was located at the front-most and back-most positions of the small intestine, the electric intensity outside the human body was maximum and minimum, respectively. The position influences the radiation efficiency of the IWD more than its orientation.