Design of Compact E-Plane Differential Phase Shift Circulators

Two types of X-band compact E-plane differential phase shift circulators employing two identical 3-dB directional couplers are designed. The 180° and 90° ferrite phase shifters are adopted in each type separately, a phase match section and a 90° dielectric phase shifter are added to satisfy phase relations. The second circulator is fabricated and measured. The size of the cross section is less than λ × 0.9 λ. The values of isolation and insertion loss compare with more than 15 dB and 0.3 to 0.5 dB, from 8.25 to 9.25 GHz.