Thick film fin-line isolators for the R-band

Ba-hexaferrite isolators have been made for the R-band using the finline technique. As far as is known this is the first time these isolators were made using a thick film of Ba-hexaferrite and mounted in the E-plane of a metal wave guide housing. The preparation of a thick film of ferrimagnetic paste using Ba-hexaferrite powder containing 5 wt.% glass is described. A low-cost, simple screen-printed process for deposition of hexaferrite films on an Al₂O₃ substrate was used. The transmission properties of these isolators were measured. The frequency ranges were determined where the isolation was more than 20 dB. The experimental results show that it is possible to make these devices without using an external magnet because hexaferrites can simulate the effect of a large external bias field