LAUSR

An improved phase modulation technique based on four-dimensional (4-D) antenna arrays is proposed in this letter. The modified control unit consists of two single-pole double-throw switches and four different delay lines (0, 0.5 π, π, and 1.5π). Each control unit connects the feeding network with the array elements. This structure generates nonuniform phase and amplitude excitations at the carrier frequency without using conventional phase shifters and attenuators. It allows the arbitrary angle beam-steering and beamforming by adjusting the time scheme of the switches. It is worth pointing out that all the switches are always in the “on” states to improve the radiation efficiency.