Branch-Line Hybrid-Rings with Coupled-Lines

A branch-line hybrid-ring is composed of four quarter-wavelength transmission lines, and hence occupies a large area on printed circuitboards because of its loop structure. In this paper, a branch-line hybrid-ring which includes microwave C sections is proposed for size reduction. The perfect input match and isolation can be attained at a center frequency as in a normal hybrid-ring. No practical differences are found in the frequency characteristics between the normal network and the proposed one.