Antenna-User Interaction in MIMO-Enabled Laptops

Abstract

The operation of wireless personal communication terminals very close to the user inherently faces the problem of electromagnetic (EM) coupling between the device and the biological tissues. In this paper the effects of the electromagnetic antenna-human interaction is studied for a laptop MIMO antenna system, where four integrated antenna elements can operate simultaneously. Two points of view are considered: antenna performance and EM dosimetry. The first one addresses not only the degradation of the antenna performance but includes also the effect of the human proximity on the antenna characteristics, namely scattering matrix, Total Active Reflection Coefficient (TARC), radiation efficiency and envelope correlation between port signals. The exposure of the human tissues to EM radiation is expressed in terms of Specific Absorption Rate (SAR). These characteristics are evaluated as a function of the array excitation scheme (including phased array approach and MIMO-like signaling) and compared to simple scenarios where all the power is radiated only by one antenna element.