A Novel Monopulse Antenna Based on Quasi-Optical Technology at Sub-millimeter Wavelengths

In this paper, a novel monopulse antenna operating at sub-millimeter wavelengths is firstly proposed and developed based on quasi-optical (QO) technology. The developed monopulse antenna is composed of spherical thin lens, ellipsoid mirrors, plane mirrors, quasi-optical sum-difference comparator, and dielectric prisms. The parameters of quasi-optical elements are determined by using Gaussian-Beam theory. Then, the antenna configuration is simulated and further optimized by finite-difference time-domain (FDTD) method. The simulated results show good sum-difference performance, with the sidelobe levels below −10.0 dB and the null-depth approximately −35.0 dB at the center frequency of 375 GHz. A prototype of the proposed monopulse antenna is fabricated and measured. The measured results have a good agreement with the simulated results in the near-field test process. This type of QO monopulse antenna may be used as an excellent candidate for tracking system over 300 GHz.