THEORY AND EXPERIMENT OF THIN-FILM JUNCTION CIRCULATOR

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