An E-Band Beam Sharpening Antenna Based on Monopulse Comparator

An E-band antenna module and corresponding beam sharpening method is proposed to achieve high azimuth resolution for front-looking real aperture radar application. To achieve high angular resolution with a small antenna aperture size, a solution involving real beam and super-resolution is investigated. A monopulse antenna is developed to produce two coprime channels, which are essential for the subsequent beam sharpening in digital domain. A dual-aperture horn antenna and a monopulse comparator that make up the monopulse antenna are designed respectively, and the experimental prototypes are fabricated and tested. Experimental results show the antenna module can operate in the 75 to 80 GHz band, more than 20 dBi gain and 12 degrees half power azimuth beamwidth can be maintained in the sum-patterns, and the null-depths are lower than -20 dB in the difference-patterns. Based on the measured sum and difference patterns, an azimuth super-resolution processing based on two-channel deconvolution is implemented. The simulation results show the sharpening ratio can achieve 12 dB with 0 dB signal-noise-ratio and truncated half power beamwidth. Theoretically, the azimuth super-resolution of 0.8 degrees can be achieved with 20 mm aperture size. The corresponding achievements are valuable in the follow-up E-band civil front-looking imaging system.