Path loss compensated beam switchable antennas with spatially modulated zero-index metamaterial loading for 5G base stations

Abstract

To achieve a uniform illumination on the ground in the context of an indoor millimetre-wave 5G base station, path loss compensation is necessary. The gains of the antenna radiating at ±45° require an additional gain of 3 dB to compensate for the additional path loss to maintain the same link budget at those angles. Thus, to enhance the end-fire gain with minimal electrical footprint, spatially modulated zero-index metamaterial is proposed and integrated with a tapered slot antenna. The antenna post integration is analysed for the phase correction of the wavefront leading to a gain of 8.5 dBi and aperture efficiency of 77% at 28 GHz. A co-polarised vertical stacking topology is proposed to achieve path loss compensated beam switchable antennas with an angular coverage of ±65° and mutual coupling <30 dB throughout the band. Detailed simulated and measured results are presented and are in good agreement.