A W-Band High-Gain Low-Sidelobe Circular- Shaped Monopulse Antenna Array Based on Dielectric Loaded Waveguide

In this paper, a high-gain low-sidelobe circular-shaped monopulse antenna array operating in W-band is proposed. The antenna array is distributed on a circular aperture, which maximizes the usage efficiency of area and is suitable for mounting on a rotating platform with limited space. By loading dielectric in the waveguide, more radiating slots can be arranged in the same physical length as compared to the hollow waveguide, which is beneficial to suppress the sidelobe level. The feed network and the sum-difference network are placed on different layers to reduce the overall size of the antenna. The proposed antenna structure ensures good electrical connection between the feed network and the radiation array, and has high mechanical strength. Besides, the antenna array is low profile and is easy to machine. The measured results show that at center frequency 93 GHz, the reflection coefficients of sum and difference ports are less than -15 dB, the maximal gain is 38.58 dBi, the sidelobe level is lower than -20 dB, and the sum-difference contradictions are less than 4 dB.