SIW Pillbox Antenna for Monopulse Radar Applications

A multibeam pillbox antenna system incorporating monopulse phase comparison technique is proposed in the 24-GHz band. This low-profile antenna architecture combines the scanning capabilities of pillbox configurations and enhanced resolution of two-quadrant monopulse technique; this approach avoids mechanical orientation of the antenna system for tracking applications. The radiating panel consists of two subarrays of 23 slotted waveguides, with 8 slots per waveguide. The beam is scanned in E-plane over a field of view of ±40°, and sum/difference patterns are generated in H-plane. Around the design frequency, f = 24.15 GHz, the antenna gain varies between 25 and 21.5 dBi for the central and extreme beams, respectively. The measured null depth is better than -16 dB for all difference beam patterns. The antenna bandwidth for VSWR <; 2 (S
_ii
<; -10 dB) and isolation better than 10 dB (S
_ij
<; -10 dB) is equal to 4.5%.