Hybrid Analog-Digital Beamforming System with Quad-Steerable Beams based on Programmable Transmitarray

A hybrid analog/digital beamforming system generating four independent steerable beams is presented. A quad-focal-source programmable transmitarray operating on the frequency band 24 – 31 GHz is optimized and demonstrated. The proposed antenna system is based on an array of 400 programmable unit-cells with a 1-bit phase resolution. Four 10-dBi pyramidal horn antennas are used to illuminate the transmitarray aperture. Inter-beam interference is mitigated numerically by applying an amplitude and phase precoder. This hybrid precoding techniques can be used to implement spatial division multiplexing in a multi-user system.