Experimental Evaluation of a Millimeter-wave Fully-Connected Hybrid Beamformer with a Large Antenna Array

Current trends in developing cost-effective and energy-efficient wireless systems operating at millimeter-wave (mm-wave) frequencies and with large-scale phased array antennas for fulfilling the high data-rate demands of 5G and beyond has driven the needs to explore the use of hybrid beamforming technologies. This paper presents an experimental study of a wide-bandwidth millimeter-wave fully-connected hybrid beamformer system that operates at 26 GHz with 128 antenna elements arranged in a 16 × 8 planar array, 6-bit phase shifter, 6-bit attenuators and two separate radio frequency (RF) channels each capable of fully independent beamforming. The linearity, phase, and attenuation performance of the beamformer system between 25.5 GHz and 26.5 GHz are evaluated as well as the beamforming performance of a 128-element planar phased array at 26 GHz where the measured radiation patterns with and without amplitude tapering are compared.