Optically tunable liquid crystal phased array antenna for beam steering at X-band

A light-controlled liquid crystal phased array antenna operating at 10.5 GHz is proposed and experimentally validated. Unlike conventional electrically tuned phased arrays that require bias circuits, the proposed design employs an azo-doped liquid crystal whose dielectric constant is tuned via cis-trans isomerization under optical excitation. This method eliminates dependence on external voltage connections, thereby reducing power consumption, electromagnetic interference, and structural complexity. The antenna consists of a 1 × 2 microstrip patch array, a liquid crystal phase shifter, a power-splitting network, and a coupling feed structure. Measurements confirm stable impedance matching with S11 below −10 dB across the operating band. Under optical illumination, the antenna achieves a beam steering range of ±12° and a peak gain of 7.65 dBi. These results demonstrate the feasibility of all optical control in phased arrays, highlighting its potential for compact, reconfigurable, and interference-resistant applications in next-generation wireless communication and adaptive radar systems.