$K$ -Band Phase Discriminator Using Multiport Downconversion for Monopulse Tracker

In this letter, K-band phase discriminator based on multiport downconversion for monopulse tracking system is presented. The proposed architecture adopts multiple six-port junctions to individually process elevation and azimuth difference signals delivered from a multibeam antenna feed network. To produce accurate 2-D angular information, elevation and azimuth difference channel path calibration by reflection-type phase shifters and attenuators are also used. The proposed hybrid multiport junction was implemented with microstrip passive circuits and GaAs monolithic microwave integrated circuits. The performance was verified at the satellite downlink frequency of 20 GHz by successful generations of quadrature I/Q signals according to elevation or azimuth difference signal variations.