Fast and Accurate SAR-Testing of Hand-held Mobile Telephones: Measurement Technique, Set-up and First Assessment of Accuracy

摘要

A new efficient technique for a fast (range of seconds) and accurate determination of the specific absorption rate (SAR) inside a homogeneous phantom is proposed. To simulate the electric properties of human tissue, a solid phantom materialis used. In a fast scanning procedure, measurement of the electric field strength is carried out quasi-parallel using an array of electric field probes. This sensor matrix is mounted directly on the surface of the phantom. For a high accuracy of field determination, minimum field perturbation caused by the probe array has to be achieved. Therefore, high-resistive transmission lines are used for signal downlead. An efficient field transformation algorithm has been developed to determine the electric field strength inside the phantom. Applying the new technique for SAR-testing of hand-held mobile telephones, random samples during production or even full testing becomes possible for the first time. This leads to an enormous improvement towards more safety for the consumers. In this paper, the new technique is introduced and compared to the conventional testing procedure. The first prototype of a set-up is presented to be used for the design and optimisation of handset antennas as well as to check cellular phones with regard to safety limits. First assessment of accuracy and measurement examples are given.