Theoretical modeling of microstrip thin-film circulators

We have calculated the S-parameters and losses in ferrite film junction circulators using a new effective-field theory assuming TEM-like propagation. At X-band conductivity loss dominates the dielectric and magnetic losses in Y-junction circulators fabricated on low-loss ferrite films with thicknesses less than 200 /spl mu/m. Our calculations compare closely with experiments.