A miniaturized pre select filter based on quarter-cut dielectric resonator

A 6-pole pre select filter based on quarter cut dielectric resonators has been designed and developed at C-band. This PSF is intended for the use in a satellite application where it will provide better than 120dBc rejection to the satellite transmit band. The PSF has a bandwidth of 60 MHz and synthesis of filtering function is done using chebyshev polynomials. The loading of hollow waveguide cavity with quarter cut dielectric resonator offers significant reduction in size with a little degradation in insertion loss compared to the hollow waveguide cavity. TM mode is used for the realization of the filter which offers wide spurious free window towards the higher side and being a dominant mode it does not impose any other propagating mode restriction towards the lower side of the pass band. Quarter cut dielectric resonator itself offers reduction in footprint compared to the full cylindrical dielectric resonator. Application of such a miniaturized resonator for the microwave filtering purpose is a very promising technique that results in the significant reduction in terms of weight and footprint of the filter. Realized filter shows almost 57% reduction in size and better than 69% footprint reduction compared to an equivalent invar waveguide PSF. Simulated and measured responses are in good agreement with each other and shows the efficacy of such resonators.