Microwave Behaviour of Bi 2 O 3 , TiO 2 and γ-Fe 2 O 3 Thick Film Overlays on Microstrip Rejection Filter

The paper reports the preliminary studies on the effect of thick film overlays of Bi 2 O 3 , TiO 2 and γ-Fe 2 O 3 materials on microstrip rejection filters. Variation of resonant frequency and quality factor of the rejection filter with overlay thickness are studied. It is observed that resonant rejection frequency and quality factor decrease smoothly with increase in the overlay thickness for Bi 2 O 3 & TiO 2 with logarithmic relation; but for γ-Fe 2 O 3 after a particular thickness, resonant rejection abruptly disappears and its variation is slightly orientation dependent.