A Broadband Low Sidelobe Waveguide Slot Monopulse Antenna Array With Reduced Structural Complexity

This paper presents a Ka‐band waveguide slot monopulse antenna array featuring broadband, low sidelobe level (SLL) and reduced structural complexity. A modified 1‐to‐4 backed cavity is proposed to form an unequal‐power 2 2 subarray, enabling element‐level amplitude tapering and phase compensation within a three‐layer metallic structure. The input‐port offset in the backed cavity provides a degree of freedom for unequal‐power division, while the compensation stubs mitigate the phase imbalance and maintain stable in‐phase radiation. By combining the unequal‐power 2 2 subarrays with a folded unequal‐power full‐corporate feeding network integrated with a planar Magic‐T, the proposed 2 16 linear array realizes broadband monopulse radiation without introducing additional metallic layers. A prototype is fabricated and measured, achieving a 17.1% relative impedance bandwidth from 32 to 38 GHz with −10 dB. Measured results demonstrate an H‐plane SLL below −20 dB and a difference‐beam null depth greater than 40 dB.