A Low-Loss and Dual-Polarized Wideband Quasi-Optical Comparator at Terahertz Frequencies

This letter presents a low-loss, dual-polarized, easy-manufacturing, and wideband one-dimension al (1-D) quasi-optical comparator at terahertz (THz) frequencies. A novel comparator structure is first proposed and analyzed with wideband and low loss where a 3 dB splitter is introduced for dual polarization. To verify the proposed concept, a one-dimensional quasi-optical comparator prototype is implemented and experimented at THz frequencies. The measured bandwidth above 300 GHz is 20 GHz where the power in difference ports is lower than -19.7 dB for dual-polarized incident sum signal and the minimum value is -30 dB. According to the measured power in the sum port, the insertion loss of comparator is 0.26 and 0.46 dB for the horizontal and vertical polarizations, respectively. The realized good agreements between simulations and experiments indicate that the proposed quasi-optical monopulse comparator is an excellent candidate for monopulse antenna working at THz frequencies and higher frequencies.