Fast and accurate SAR-testing of hand-held mobile telephones: Measurement technique, set-up and first assessment of accuracy

A new efficient technique for a fast(range of seconds) and accurate determi nation of the specific absorption rate (SAR) inside a homogeneous phantom i s proposed. To simulate the electric properties of human tissue, a solid ph antom material is used. In a fast scanning procedure, measurement of the el ectric field strength is carried out quasi-parallel using an array of elect ric field probes. This sensor matrix is mounted directly on the surface of the phantom. For a high accuracy of field determination, minimum field pert urbation caused by the probe array has to be achieved. Therefore, high-resi stive transmission lines are used for signal downlead. An efficient field t ransformation algorithm has been developed to determine the electric held s trength inside the phantom. Applying the new technique for SAR-testing of h and-held mobile telephones, random samples during production or even full t esting becomes possible for the first time. This leads to an enormous impro vement towards more safety for the consumers. In this paper, the new techni que is introduced and compared to the conventional testing procedure. The f irst prototype of a set-up is presented to be used for the design and optim sation of handset antennas as well as to check cellular phones with regard to safety limits. First assessment of accuracy and measurement examples are given.