A Parallel-Crossed H-Plane Waveguide Eight-Port Hybrid and Its Application to a Planar Magic Tee

This paper presents a novel eight-port hybrid constructed of four parallel-crossed H-plane rectangular waveguides. First, a basic constitution theory is discussed and actually its circuit configuration is optimized based on the H-plane planar circuit approach. Then, some broadband versions are designed. The present eight-port hybrid, in addition to the advantage of a compact planar-structure, has the capability of handling very high power levels because the electric fields terminate only on the flat top and bottom surfaces. Next, a fully-planar magic tee (180-degree hybrid) is proposed using the eight-port hybrid with the four isolation ports terminated to two sets of complete reflectors. The fractional bandwidth is about 13 percent for a tolerance limit of 20-dB return loss and isolation, and the power-split imbalance stays within plusmn0.3 dB over the bandwidth. The validity of the design results is confirmed both numerically and experimentally.