Investigation of bimodal paramagnetic filter

Analytical expressions are proposed for the working attenuation and phase response of a bimodal microwave paramagnetic filter. The bandwidth of the filter is found to increase as the amount of paramagnetic material until the bandwidth of the cavity is reached, which is determined by its Q-factor. This relationship makes it possible to select the optimum amount of material as a function of the requirements for the filter, whether the narrowest possible bandwidth, or minimum losses. A number of paramagnetic bimodal filters are investigated with center frequencies between 5 and 10 GHz. Comparison between the calculated and experimental curves within the passband of the filter indicates that the expressions for the working attenuation and phase response agree closely.