The Design of Planar Circulators for Wide-Band Operation

The stripline circulator used in microwave integrated circuits (MIC) is considered one of ferrite planar circuits (two-dimesional circuits). We investigated the optimum shape of a planar circulator for wide-band operation, perceiving the wider freedom of the planar structure in circuit design. The wide-band planar circulator, designed using the powerful contour-integral method is triangular shaped with slightly concave sides. The 20-dB isolation fractional bandwidth of the designed circulator is about 52 percent.