RAT-RACE HYBRID RINGS WITH A MICROWAVE CESAREAN-SECTION

A rat-race hybrid-ring which includes a coupled-line called microwave C-section is proposed for size reduction. The perfect input match, iso lation, equal power split and certain phase differences between two ou tput ports can be satisfied at center frequency as in a normal hybrid- ring. The size of the proposed circuit becomes smaller than that of a normal rat-race built up with a folded non-coupled 3/4-wavelength tran smission line, although the frequency characteristics are slightly dam aged by the electromagnetic coupling between two folded strips. Theore tical results based on the even and odd mode decomposition method are in good agreement with those of the experimental circuit fabricated at 1 GHz.