Reduction of mobile phone radiation exposure using multi-stopband frequency selective surface

Abstract

Here, a multi-stopband frequency selective surface (FSS), covering commercial frequency bands CDMA, GSM-900, GSM-1800, LTE-2200 MHz, Wi-Fi, and Bluetooth for mobile communication applications has been proposed employing a pair of concentric square ring patches as a unit cell. Possibilities of annular ring patch type FSS are explored first. Finally, the design comes up with a compact square ring patch type single layer FSS. It is also explored that by increasing the width of the inner ring, operating bandwidth can be enhanced to cover closely spaced commercial frequency bands in a single band. Thereby the mutual coupling between the closely spaced resonators for multiple bands can be minimized. The proposed design is flexible enough to tune the desired resonance frequency by changing the length of the individual ring resonators. The design concept has been formulated using linear polynomial regression (LPR) techniques and validated through proper measurement of the fabricated prototype. This FSS can be used as a mobile back cover to protect mobile users from harmful radiations.