Electrically Small Multimodal 3D Beamforming MIMO Antenna for PHY-Layer Security

Abstract

This work proposes an electrically small 3D beam- forming antenna for PHYsical Layer (PHY-layer) security. The antenna comprises two layers of stacked patch structures, and is a five-mode five-port MIMO system operating around 1.85 GHz with electrical size ka = 0.98 and radiation efficiency of up to 55%. By studying the properties of the excited modes, phase and amplitude control allow for unidirectional beam scanning towards any direction around the elevation and azimuth planes. PHY-layer security is investigated using the directional modu- lation (DM) technique, which transmits unscrambled baseband constellations symbols to a pre-specified secure direction, while simultaneously spatially distorting the same constellations in all other directions. Bit Error Rate (BER) calculations reveal very low values of 2 × 10−5 for the desired direction of the legitimate receiver, with BER< 10−2 beamwidths of 55◦ and 58◦ for the azimuth and elevation planes, respectively.