Theory and experiment of thin-film junction circulator

We have calculated the S-parameters and losses in ferrite-film-junction circulators using a new effective-field theory assuming TEM-like propagation. Conductivity loss dominates the dielectric and magnetic losses in Y-junction circulators fabricated on ferrite films with thicknesses less than 200 mu m. It is plausible to fabricate Y-junction thin-film circulator at X-band with insertion loss less than 0.5 dB if the film thickness is larger than 100 mu m, The quality of the conductor plane is important in reducing the overall insertion loss of the thin-film-junction circulator.