Evaluation of SAR Reduction in Implanted Spherical Head Model Using RF Shield

Abstract

In this paper we propose to use radio frequency (RF) shield on dipole antenna to reduce Specific Absorption Rate (SAR) in the implanted spherical head model. RF Shields made of Ferrimagnetic material are used to suppress surface current on antenna. Conducting cylindrical implant of resonant length is embedded eccentrically into a head model and it is irradiated by dipole antenna (0.4 wavelength) at 900 MHz. Effect of wireless device on implanted head and SAR reduction techniques to minimize fears of Patients are discussed. Simulations are performed to find the effect of RF fields on implanted medical device by varying its parameters like length and location using CST-Microwave studio, the field simulation software. Paper includes numerical evaluation of the SAR reduction using RF shield and also analyzes the SAR data for shielding effectiveness. Drastic reduction in SAR was observed in case of Ferrite3 material of 1mm thickness when both implant location and length were varied. Simulation results will be useful for compliance testing of wireless communication devices. Keywords-SAR, SAR reduction factor (SRF), Dipole Antenna, Spherical Head, Implant and RF shield.