Wideband Loop Antenna With Split-Ring Resonators for Wireless Medical Telemetry

This letter presents a wideband flexible loop antenna with split-ring resonators (SRRs) for use in wireless medical telemetry. This design covers the entire MedRadio band (401-406 MHz) and four Industrial, Scientific, and Medical (ISM) bands (433.1-434.8, 868.0-868.8, and 902.8-928.0 MHz and 2.4-2.48 GHz). The SRRs improve the loop antenna return loss and reduce the power absorbed inside the human body over the multiband frequency ranges; they also result in increased radiation efficiency, gain, and transmission coefficient. A human body model has been used to study and optimize the antenna performance in a realistic environment and shows a reduction in specific absorption rate when the SRRs are used. Measurements are conducted in a tissue-simulating liquid phantom and show a good agreement with the simulations. This novel antenna could be used for a range of implantable applications such as wireless data transmission and wireless power transfer.