Wideband Beamforming for Hybrid Phased Array Terahertz Systems

The large bandwidth at terahertz (THz) and the large number of antennas in massive MIMO result in the non-negligible spatial wideband effect in time domain or the corresponding beam squint issue in frequency domain. For a phased array based hybrid transceiver, beam squint makes the accurate beamforming an enormous challenge since an analog beamformer/combiner cannot generate frequency-dependent phase shift constitutionally. In this paper, we propose a virtual sub-array based wideband hybrid beamforming approach to eliminate the impact of beam squint. By dividing the whole array into several virtual sub-arrays, a wider beam is generated and provides an evenly distributed array gain across the whole operating frequency band. Analytical and numerical results demonstrate the effectiveness of the proposed wideband beamforming approach.