Bias-Free Optically Controlled Pattern-Reconfigurable Planar Antenna

An antenna-level bias-line-free, optically controlled pattern-reconfigurable planar antenna for wideband sub-6 GHz applications is presented. The proposed antenna consists of four tapered-slot radiating units arranged in a compact planar configuration and excited through a reconfigurable feeding network incorporating four light-dependent resistors (LDRs). By selectively illuminating LDRs using aligned LEDs, the corresponding feed arms are activated without DC-bias lines embedded in the antenna itself, enabling pattern switching while avoiding a complicated biasing network. The antenna supports ten radiation states, including four principal directions (0°, 90°, 180°, and 270°), four diagonal directions (45°, 135°, 225°, and 315°), and two dual-beam excitations (0°/180° or 90°/270°). Measured results show impedance matching over 3.3-6.7 GHz for all states (at -10 dB |S₁₁| reference), with a realized gain of 5.8-6.3 dBi and a total radiation efficiency of 86-90% across the operating band. The proposed approach offers a compact, wideband, and practically implementable platform for bias-free pattern reconfiguration suitable for coverage and interference adaptation in sub-6 GHz wireless systems.