Analysis and implementation of shorting pins in microstrip patch antenna for SAR reduction

Abstract

Specific absorption rate (SAR), is the safety measure to quantify human exposure to electromagnetic radiation from mobile phones and other wireless devices, which must be kept within the permissible levels to avoid various health concerns. This paper provides an experimental study on the effectiveness of SAR reduction using shorting pins, and its corresponding effects on antenna performance. A compact single-element microstrip patch antenna design using shorting pins with reduced SAR value is also presented. The surface current distribution on the patch can be modified by the strategic positioning of shorting pins to produce a broadband beam radiation pattern with a near-field null in the vicinity of the user’s direction. This completely minimizes the back lobes in the E-plane, with minor back lobes in the H-Plane, creating a deep null which reduces the SAR value without compromising the signal coverage. The antenna is fabricated and cross-verified by experimental evaluation in an anechoic chamber for return loss, gain, and radiation pattern.