A SAR-Probe Calibration System Using A Reference Waveguide Antenna in Tissue-Equivalent Liquid

INTRODUCTION A SAR-probe is usually calibrated using a rectangular waveguide with a matching dielectric spacer below 3 GHz [1, 2]. However, the probe diameter is comparable with the aperture size of the waveguide above 3 GHz, and it can deteriorate the accuracy of the calibration. Therefore, an alternative calibration method using a reference antenna in the phantom liquid has been examined [3]. In the previous works, a prototype of calibration system has been manufactured and calibration factors of several SAR-probes have been determined below 2.45GHz [3]. In this method, the dipole-type antennas have been employed as the reference antenna for the frequency lower than 3 GHz. However, the element of this antenna is too short to manufacture above 3 GHz. Therefore, a waveguide-type antenna is designed as the reference antenna, and the SAR-probe is calibrated at 5.2 GHz.