Study On W-band Low-profile Integrated Monopulse Feeder Antenna

94 GHz atmospheric window is located in W band,and its atmospheric attenuation is small,making it ideal for radar applications.For long-distance,high-resolution applications,the hybrid reflector antenna composed of the reflector and the monopulse feeder is a good choice to achieve ranging and angle measurement.Therefore,in some radar systems with strict profile limitation,the low-profile integrated monopulse feeder is the key component.In this paper,the research on the low-profile integrated monopulse feeder is carried out,and its contents are divided into the following two aspects.1)A dual circular-polarized low-profile integrated monopulse feeder at W band is proposed.The radiation part is a compact 2×2 SIW longitudinal slot array with higher circular polarization efficiency.The monopulse comparator for the dual circular polarization consists of the SIW directional couplers and the corresponding phase shifters.Finally,based on single-layer PCB technology,the W-band dual circular-polarized low-profile monopulse feeder is fabricated and tested,and a matching reflector antenna is designed and fabricated.The measured results show that the SUM-beam gain of the reflector antenna is 35.6 dBi at 94 GHz,the broadside axis ratio is 1.5 dB,the DIFF-beam null depth is less than –20dB.2)A broadband low-profile integrated monopulse feeder at W band is studied.The radiation part is a 2×2 broadband stepped horn array;the broadband low-profile monopule comparator consists of two kinds of broadband low-profile waveguide magic tees.Finally,based on the MEMS process,the W-band broadband low-profile integrated monopulse feeder antenna is fabricated and tested.The measured results show that the relative frequency bandwidth of the feeder antenna can reach 21.7%,the measured SUM-beam gain range in working band is from13.5dBi to 14.9dBi,the DIFF-beam null depth is less than –28.5dB.