λ/2 Microstrip rejection filter behavior due to ferrite thin film overlay in the absence of external magnetic field

Abstract

Purpose

To study nonreciprocal effects in microstrip components due to ferrite thin film overlay.

Design/methodology/approach

The possibility of obtaining non reciprocal characteristics in the X band microwave region in the absence of external magnetic field by a simple process of using Mg, Co, Zn ferrite thin films as in‐touch overlay over λ/2 microstrip rejection filter was investigated. Microstrip rejection filter is basically a reciprocal component. The ferrite thin films were deposited by electroless plating.

Findings

It was found that frequency, pH and ferrite overlay material dependent changes occurred and differences in forward and reverse loss also observed, in some cases greater than 30 dB. Owing to the overlay the rejection properties of the filter is lost and there is an increase in insertion loss. The best non reciprocal effects are seen at higher frequencies. The presence of permeability related effects like magnetostatic modes interfering with the normal propagation of the microstrip circuits might be causing the changes in the circuits.

Originality/value

There is scope for true planarisation of ferrite‐based components by using the ferrite in thin film form as in‐touch overlay.

Citation

Surve, V. and Puri, V. (2007), "λ/2 Microstrip rejection filter behavior due to ferrite thin film overlay in the absence of external magnetic field", Microelectronics International, Vol. 24 No. 1, pp. 35-39. https://doi.org/10.1108/13565360710725928