A W-Band High-Aperture-Efficiency Multipolarized Monopulse Cassegrain Antenna Fed by Phased Microstrip Patch Quad

In this letter, a W-band multipolarized monopulse Cassegrain antenna is proposed, in which a phased dual-polarized microstrip patch quad is employed to feed the hyperbolic subreflector. Due to the more even polarization distribution on the aperture of the quad, the high aperture efficiency of the Cassegrain antenna is achieved. Simulation results verify that the microstrip patch quad is qualified to work as the multipolarized monopulse feed source by adjusting phases and amplitudes among the four feed ports. The metallic structure of this W-band multipolarized monopulse Cassegrain antenna is fabricated by using high-precision milling machine to assure the design parameters. At 94 GHz, the integral gain is 39.6 dBi and the aperture efficiency is 51.9%. Measurement results demonstrate the proposed antenna has excellent polarization synthesis and polarized monopulse performances further.