A Circular Triple-Mode Cavity Filter With Two Independently Controlled Transmission Zeros

摘要

The paper presents a new filter design based on circular triple-mode cavities that allow the realization of two transmission zeros. Each transmission zero is generated and controlled by a dedicated resonance. For relatively narrowband applications requiring a second order transmission zero, the circular cavity is left homogenous. For broadband designs, the separate frequencies of the resonances are tuned by a symmetrically inserted rectangular aperture. The approach is verified by two 3rd order filter designs at 11GHz. The introduced triple mode cavity can be used as a building block in the design of sophisticated higher order filters.