E-Plane Forked Hybrid-T Junction

A novel rearrangement of the waveguides of a microwave hybrid-T junction has been investigated. This junction is formed by the intersection of four rectangular waveguides, two of which (conventionally E and H arms) are mutually perpendicular, cross-polarized, and have their centerlines in one symmetry plane of the junction; the remaining two waveguide arms are formed by symmetric E-plane bifurcation of the E-arm waveguide extended. This hybrid T possesses special advantages with regard to match and pulse power capacity. A special test fixture was constructed of 1.122- X 0.497-inch rectangular waveguide. Experimental design work was carried out over a 12 per cent range of frequencies from 8.5 to 9.6 kmc. The H-arm reflection was reduced to 2.6-db standing-wave ratio (swr) by simple shaping of the bifurcating element. Addition of conventional matching elements resulted in maximum reflections, within the above band, of 0.8 and 0.6 db swr in the H and E arms, respectively. The ultimate limitation on the E-arm power capacity, as fixed by the intensified electric field at the leading (rounded) edge of the center partition, was computed to be 2 db below uniform waveguide. Experimental corroboration has been obtained.