Novel Approach For Center Frequency And Bandwidth Tuning In Multimode Resonator Based Microstrip Dual-Mode Bandpass Filter

Abstract

Abstract This paper demonstrates a novel approach for both center frequency and bandwidth tuning in dual mode Bandpass filter. The proposed filter is configured from a half wavelength multimode resonator structure. The Ultra-wide bandpass response of multimode resonator is extracted using an inter-digital feed structure which provides good input/output coupling. By deploying stepped admittance structure perturbation element in to the symmetrical plane of multimode resonator, dual-mode response is achieved with three upper stop band transmission zeros(TZs). The coupling between two degenerative mode frequencies is controlled by admittance ratio Y of stepped admittance structure. Changing admittance ratio(Y) of stepped admittance structure, results in change in even mode resonance frequency and location of three upper stop band transmission zeros while keeping odd mode frequency fixed. Proposed filter has size of 14mm*30mm.