Design of a Low Sidelobe Monopulse Array Antenna with Hybrid Feeding Structure

A low sidelobe monopulse array antenna with hybrid feeding structure is proposed. The array consists of four subarrays which employ 6 X 8 microstrip patch elements on the top layer. The feed network, which is hybrid feeding structure, is composed of 1 -to -48 microstrip power dividers on the top layer, microstrip to groove gap waveguide transitions and a gap waveguide-based monopulse comparator. The microstrip unequal power dividers are compact to achieve unequal amplitude distribution. And the monopulse comparator based on groove gap waveguide has low insertion loss. Hence, the array antenna achieves low sidelobe and high efficiency. The array antenna is designed with size of 400 X 320 mm(2). The simulated VSWR is less than 1.5 from 10.52 - 10.68 GHz, the simulated gain is 28.7 dBi at 10.6 GHz and the sidelobe level is less than -19 dB. The null depth in the difference pattern is less than -35 dB.