Substrate integrated waveguide(SIW) 3-dB narrow wall directional couplers for monopulse comparator application

The compact single-layer substrate integrated waveguide (SIW) 3-dB side-wall directional couplers with/without metallic dome for Ku-band monopulse comparator application are studied and demonstrated in this paper. These couplers with/without dome achieve ±0.35 dB/±0.7 dB power equality, -24.7 dB/-16 dB isolation, and -24.4 dB/-15 dB return loss, ±0.60 °/0.12 ° phase difference, respectively, over 17% bandwidth. Considering the bandwidth requirement and fabrication technique, the coupler without the dome is selected to integrate into the monopulse comparator. The monopulse comparator is fabricated and measured, indicating good performances for the Ku-band tracking system.