A Broadband Flexible Implantable Loop Antenna With Complementary Split Ring Resonators

In this letter, a novel flexible implantable loop antenna with complementary split ring resonators (CSRRs) is proposed and designed for biomedical telemetric applications. The antenna has a very wide bandwidth to cover the Medical Device Radiocommunications service (MedRadio 401-406 MHz) and Industrial, Scientific and Medical (ISM 433.1-434.8, 868.0-868.8, 902.8-928.0 MHz and 2.45 GHz) bands which support the functions of wireless data transmission, wireless power transfer and saving (wakeup receiver). It is optimized over a two-step design process for cylindrical implants for a robust communication over 2 m. The CSRRs are introduced to reduce the absorbed power inside the body and improve the antenna impedance matching. This results in a larger radiation efficiency, gain and transmission coefficient (over 2 dB in comparison with the structure without the CSRRs). The specific absorption rate (SAR) is also decreased significantly. Measurements in a pork phantom are conducted and a good agreement with the simulation results is demonstrated. This novel antenna could be an excellent candidate for a range of implantable applications.