H-Plane Crossed-Waveguide Hybrids

This paper presents a novel cruciform quadrature hybrid in H-plane rectangular waveguide, which is composed of two cross waveguides having two cylindrical metallic posts in the cross region, and one post at each input/output port. The former two posts produce directional nature in a signal flow, and the latter post achieves a matched state. Several basic hybrids are designed in this structure, and then a broadband one is successfully realized. Actually, a fractional bandwidth of about 28 percent is obtained with a tolerance limit for return loss and isolation of 20 dB, and the power-split imbalance stays within plusmn0.1 dB over the bandwidth. The validity of the design results is confirmed both numerically and experimentally. Furthermore, the advantage of the present hybrid is demonstrated by comparison with conventional hybrids