Multibeam Pillbox Antenna Integrating Amplitude-Comparison Monopulse Technique in the 24 GHz Band for Tracking Applications

An amplitude-comparison monopulse slotted waveguide antenna array with a pillbox parabolic quasi-optical beamforming network is proposed in substrate integrated waveguide (SIW) technology in the 24 GHz band. The beamformer is illuminated by a cluster of horn pairs located in the focal plane of the pillbox reflector. Each horn pair is composed of two H-plane sectorial horns connected to a coupler. In-phase and out-of-phase operations of each horn pair allow radiation of the Σ and Δ beams along the antenna scanning plane (E-plane). At the design frequency of 24.15 GHz, the experimental results demonstrate an antenna field of view of ± 26°, with null depth better than -20 dB for all the measured Δ beams. The antenna gain varies between 21.6 and 20.5 dBi for the Σ beams and the measured input reflection bandwidth is about 2.4% for VSWR <; 2.