Design of reconfigurable liquid crystal holographic antenna fed by a slow-wave rectangular waveguide

The purpose of this paper is to develop a novel design method for reconfigurable liquid crystal holographic antennas (LC-HAs) to suppress electromagnetic (EM) leakage and mutual coupling between radio frequency (RF) channels. The antenna is composed of tunable liquid crystal (LC) radiators and the feeding waveguide, which are coupled to each other through air slots opened on the upper wall of the waveguide. The slow wave is realized by a broken nail structure mounted on the lower wall of the waveguide. Attributed to the ingenious multimode-resonant antenna element design, the extremely high amplitude tuning efficiency of the antenna element is achieved under the limited LC volume. Attributed to the ingenious multimode-resonant antenna element design, the extremely high amplitude tuning efficiency of the antenna element is achieved under the limited LC volume, which enables the proposed LC-HA to reach a scanning angle of −60° to + 60°, and the gains of 12.5 dB – 15 dB over the whole scanning angle. Holographic algorithm is used to realize beam scanning. Numerical simulation results are highly consistent with the preset angle of the algorithm, indicating that the working mechanism and design method of the proposed antenna are reasonable and proper. An antenna prototype is fabricated and measured. The experimental results are consistent with the simulation results. This paper provides a novel design method for reconfigurable LC-HAs fed by a slow-wave rectangular waveguide, which has an advantage over existing microstrip-fed or gap-waveguide-fed LC-HAs in suppressing EM leakage and mutual coupling between RF channels.