Performance Improvement of LC-Based Beam-Steering Leaky-Wave Holographic Antenna Using Decoupling Structure
Hyungcheol Kim, Sangwook Nam
Abstract
A liquid crystal-based beam-steering leaky-wave holographic antenna is designed with decoupling structure. Since the distance between elements in holographic antennas is inevitably small ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ < \!\!\!\lambda $ </tex-math></inline-formula> /5), the mutual coupling is strong and should be compensated for the accurate implementation of the excitation amplitude and phase of each element. The performance degradation of a holographic antenna due to mutual coupling is estimated and a decoupling structure is proposed, fabricated, and inserted into the designed antenna. The operating principle of the decoupling structure is explained with circuit model and the simulation confirms the enhanced gain and sidelobe performance when steered from −60° to 60° in 20° intervals. Compared to the antenna without the decoupling structure, the maximum improvement of the gain and the sidelobe level is 3.93 and 7.7 dB, respectively, in the simulation. The experimental results are consistent with the simulation results.