Phase-Shifter-Free Reconfigurable Array Architecture Using Phase Modulation---Part II: Applications and Measurements

Part II investigates phase modulation as a low-complexity alternative to conventional phase shifters in pattern-reconfigurable antenna arrays. In the proposed architecture, phase formation originates from the direct reconfiguration of the driven radiation current and the induced parasitic current within each radiating element. This is achieved through a dual-phase control mechanism that independently tunes the intrinsic and deflection phases using separately biased PIN diodes integrated into the feeding branches and parasitic comb structures. The resulting discrete phase states provide a phase tuning range of up to 116° and enable subarray-level beamforming without continuous element-wise phase synthesis. Based on this concept, a 6-element discretized subarray is developed as the fundamental beamforming unit, offering three fixed beam states with simplified bias control. By adopting subarray-level beam-state selection, an 8×24 sparse dual-polarized array is constructed, enabling wide-angle two-dimensional scanning (±60° azimuth, ±10° elevation) while significantly reducing the number of RF chains. Despite the reduced channel count, the proposed architecture maintains comparable channel capacity, as validated through simulations and measurements, demonstrating its practicality for large-scale base station antenna arrays.