The influence of the user's hand holding a mobile phone to the ear on the peak spatial-average Specific Absorption Rate (psSAR) averaged over any 1 g and 10 g of tissue in the head is investigated. This study is motivated by recent reports that found substantial increases in psSAR by the presence of the hand in some cases. Current measurement standards prescribe the measurement of SAR in a head phantom without a hand present. The mechanisms of interaction between the hand and mobile phone models are studied. Simulations and measurements at 900 and 1800 MHz have been conducted to complement the understanding of the hand grip parameters leading to higher SAR in the head. Numerical simulations were conducted on four mobile phone models, and parameters such as the palm-phone distance and hand position were varied. Measurements of 46 commercial mobile phones were made, and the maximum psSAR with different hand positions and palm-phone distances was recorded. Both simulations and measurements have found increases in the psSAR in the head of at least 2.5 dB due to the presence of the hand. Furthermore, the psSAR is sensitive to the hand grip, i.e., the variations can exceed 3 dB.
This paper presents a novel method using multiple compact antenna test range (CATR) reflectors to perform simultaneous multiple angle measurements for 5G devices that are capable of beamforming in the millimeter wave frequency range. Four CATR reflectors and their respective feed antennas are arranged on a planar semicircle arc with the device under test placed on a positioner at the center of the arc. This arrangement is designed to generate four planar wavefronts with different incidences, realizing up to five pairs of angular spreads or four switched/simultaneous angles of arrival. The objective of this setup is to reproduce configurations involving multiple base-stations radiating from different directions. The initial target application is radio resource management (RRM) testing, where the execution of mobility procedures and radio link monitoring of a 5G millimeter wave device are evaluated. The reflectors create far-field conditions at the device under test for quiet zones up to 30 cm in diameter inside a portable system with a footprint of 3.25 x 1.4 meters. The applicability of the approach to RRM testing is demonstrated through measurements, performed with both sinusoidal and modulated signals, using horn antennas and commercial 5G devices. INDEX TERMS 5G mobile communication, antenna measurements, millimeter wave communications, MIMO, mobile radio mobility
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