Electrically Tunable Quasioptical Notch Filter Based on a Liquid-Crystal-Metastructure for the Short Millimetre-Wave Range

The experimental results on the development of a LC-based quasioptical notch filter with an electrically controlled rejection frequency operating in the range of 109−120 GHz are presented. At the optimal frequency of 113.14 GHz, the rejection depth as low as −37.4 dB at the bandwidth of 6.7 % and 0−3 V controlling voltage range are demonstrated. Applications of the developed device in single-pixel sub-THz imagers are discussed.