Compact microstrip balanced phase shifter with common-mode suppression

Balanced phase shifter (BPS) plays an important role in differential beamforming networks and phased array antenna systems due to the capabilities of differential-mode (DM) phase shift and common-mode (CM) suppression. The compactness of BPS also becomes highly demand for its benefit to miniaturize the system. The reported BPSs can be classified into symmetric type and asymmetric type according to the structure features and analysis method. In this paper, the two types of the state-of-the-art BPSs are presented and discussed. Two symmetric and asymmetric type cases designed by our research group are introduced for demonstration.