A W-Band Two-Dimensional Monopulse Sparse Array Antenna

A novel W-band 2-D monopulse sparse array antenna with suppressed sidelobe levels is proposed in this article. The 2-D monopulse antenna is composed of a radiation sparse array, an irregular interconnected waveguide -based network, a power divider network, and a sum–difference network. The sparse array uses a box-horn as the radiation element and is optimized based on the genetic algorithm, which exhibits low sparsity and low sidelobe levels. The whole aperture of the antenna is divided into four subarrays. To feed all the radiating elements that are randomly distributed in the subarrays with the same amplitude and equal phase, an irregular interconnected waveguide -based network and a power divider network are designed. Finally, a sum–difference network is connected to the end of the four subarrays to obtain the sum and difference radiation performance results for the monopulse antenna. A 2-D monopulse sparse array antenna with 32 radiating elements is fabricated and measured. The measured
$\vert \text {S}_{\mathbf {11}}\vert \le -10$
dB bandwidth of the antenna is over 6 GHz (from 90 to 96 GHz). At the center frequency, the maximal gain of the sum radiation pattern is approximately 24.0 dBi, with low sidelobe levels (both E-plane and H-plane) less than −19.0 dB. In addition, the null depth of the difference radiation pattern is less than −30.0 dB.