A Novel Metasurface-Based Monopulse Antenna with Improved Sum and Difference Beams Radiation Performance

This paper proposes a novel metasurface-based monopulse antenna. A multimode pyramidal horn with four ports is selected as the feed of the proposed monopulse antenna. The 3-dB couplers and the optimized waveguide phase shifters are employed to design the monopulse comparator. In order to obtain good sum and difference beams performance, metasurfaces are mounted on a bowl structure to radiate the electromagnetic wave from the sub-reflector. An experimental prototype of the proposed design has been fabricated and measured at Ku-band. The measured results show that the gain ratio between the sum and difference beams is 2.8 dB and 3.7 dB, respectively. More importantly, the peak gain of the sum beam at 16 GHz is 27.1 dB, without considering the loss of the comparator, with a corresponding aperture efficiency of about 41.4%. This indicates that the proposed structure is beneficial for improving the sum and difference beams performance of the monopulse antenna, which is suitable for tracking platforms.