Local SAR estimation system using solid phantom and fixed E‐field probe

Abstract

AbstractWe propose a local Specific Absorption Rate (SAR) estimation system using solid phantom and fixed E‐field probe for application to portable wireless devices such as cell phones. This system is constructed from a solid phantom molded from a lossy dielectric and an electric field (E‐field) probe inserted into the phantom. The advantage of this system is the ability to easily measure in a relatively short time the local SAR with measurement deviations of about ±30% compared to the measurements made by the conventional technique using a liquid phantom. First, we perform numerical analysis using the finite‐difference time‐domain (FDTD) method in the basic parameter design to clearly show the effects of the size of the insertion hole for the E‐field probe in the solid phantom and the complex dielectric permittivity on the antenna input impedance and local SAR. Next, we develop a local SAR estimation system using solid phantom and fixed E‐field probe, and measure and evaluate the antenna input impedance and local SAR of two solid phantoms having different complex dielectric permittivities. We confirmed that their properties tend to nearly agree with the calculated results. Finally, we measure the local SARs of 32 portable phones using this system. We confirmed that compared to the measurements by the E‐field probe scanning method, the measurements of about 77% of the phones have deviations within 30%, and the target measurement accuracy during development could almost be achieved. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(9): 46–56, 2003; Published online in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/ecja.10082