Phase Modulation Technique for Four-Dimensional Arrays

A novel type of four-dimensional array based on phase modulation technique named phase-modulated arrays (PMAs) is proposed in this letter. The antenna elements of PMAs are modulated by an amplitude-phase function. During each modulation period, the antenna is successively connected with two different delay lines selected by the switch and radiates in two different phases, which would generate additional equivalent phase excitations at the center frequency. By controlling the operation sequence of the two delay lines, the static excitations can be completely replaced by the dynamic ones. Therefore, beam steering can be realized at the center frequency without phase shifters. To verify its performance, PMAs are applied to synthesize low sidelobe level beam-steering patterns without phase shifters and attenuators. Simulation results illustrate that PMAs can meet the design requirement and simplify the structure of the array greatly.