The interaction between the human body and the electromagnetic (EM) fields produced by a handheld communication device, such a cellular phone, is regulated around the world according to different safety standards. The fundamental dosimetric quantity used to quantify the level of exposure is the Specific Absorption Rate (SAR) [1]. Different organizations such as International Commission on Non-ionizing Radiation Protection [2], Institute of Electrical and Electronic Engineers (IEEE) [1] have setup exposure limits for SAR level. Many studies have been reported in the literature regarding the modeling of RF exposure levels from cellular phones, like in [3]. The compliance of a device to the exposure limit is determined by following the guidelines described in IEEE measurement standards [4], [5]. The compliance assessment process can be quite complicated and time consuming, due to the many different test conditions that have to be considered and the slow speed of the measurement equipment. Depending on the frequency, use configuration of the device and form factor the SAR values can vary significantly from test case to test case even for the same device. From a practical point of view a priori knowledge of which test configurations are more favorable in terms of SAR is very useful. During the design and the qualification of the device, in fact, one could focus only on the worst case configurations, thus avoiding redundant measurements. This paper shows that for a particular form factor, indicated as clam shell, where the phone is made of two halves that rotating around a hinge, one of the required test condition, described as tilt position, always provides lower SAR values. Different frequency, antenna locations and antenna types have been considered. The results obtained with the well-known Finite Difference Time-Domain (FDTD) method have been validated with measurements.
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