Use of Rod Reflectors for SAR Reduction in Human Head

Abstract

An improved version of the compensation method based on rod reflectors is presented. In this version, one or more metallic rod reflectors are installed near a transmitting antenna in order to create an additional field needed for decreasing the antenna's field inside the user's head, hence removing the need for auxiliary radiators. Both single and double rod reflectors are investigated. It is shown that using two rod reflectors, the field at the compensation point decreases by at least 7.5 dB in the frequency range of 850-2200 MHz. Using a single rod the reduction factor is above 5.4 dB in the same frequency band. Using the proposed rod-antenna structure with a single reflector, the peak specific absorption rate (SAR 1g ) and the total SAR measured at 1 GHz were reduced by 7.7 and 8.9 dB, respectively. With two reflectors, the SAR reduction factor for peak SAR (1 g) and total SAR levels were, respectively, 9.5 and 10.2 dB. The simulations and experimental results obtained so far show that the developed rod-antenna structures can be used as an effective method for SAR reduction. Index Terms-Antenna theory, compensation method, mobile antennas, near fields, reflector, SAR reduction.Motti Haridim received the M.Sc. degree in electrical engineering from the University of Washington, Seattle, WA, USA, in 1986, and the Ph.D. degree in electrical engineering from Technion-Israel Institute of Technology, Haifa, Israel, in 1992.Since 1994, he has been with the Faculty of Engineering at HIT-Holon Institute of Technology. During 2002During -2008, he was the Head of the Department of Communication Engineering at HIT. His research interests include the physical layer of communication systems, including optical communications, RF communications, antennas, and electromagnetic radiation. He has published more than 100 papers on theoretical and applied aspects of antennas, radiation, RF communications, and optical communications.Prof. Haridim is a Member of the management committees of the European COST Actions IC1102, TU1208, and IC1301. He is the Head of the Technologies and Engineering aspects of radiation, TNUDA-the Israeli national center for nonionizing radiation. He received number of prizes and research grants for R&D projects in the fields of antennas and radiation.

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