A Broadband Monopulse Sum-difference Beam Feed Network with Compact Size of Ka-Band

In this letter, a broadband, compact sum-difference beam feed network based on substrate integrated coaxial (SICL) waveguide is proposed for millimeter-wave applications of Ka-Band. It contains four 3dB hybrid couplers and four two types of 90°phase shifters to form four 180°bridges. The measured result of proposed network fractional impedance bandwidth for |S11|<-10dB is 22.9% at a center frequency of 35GHz, along with a phase shift of approximately ±10° in operating band. Besides, the overall size of proposed network is only 20mm×20.7mm, which could be a good candidate for high-gain applications of Ka-Band.