The Design of Planar Circulators for Broad-Band Operation

The stripline circulator used in MIC is considered one of ferrite planar circuits. We investigated the optimum shape and operation condition of the planar circulator for broad-band operation, perceiving the wider freedom of the planar structure in circuit design. The wideband planar circulator, designed using the powerful contour-integral method, is triangularly shaped with wide coupling ports. The 20 dB isolation fractional bandwidth of the designed circulator is about 50 percent. Experimental results are also presented.