Development of a new type of Dual Mode Triple Conductor Combline Resonators

Abstract

In this study, we present a novel improved type of combline resonator with dual mode characteristics. The proposed resonator consists of three metal conductors: an enclosure and two inner conductor posts. This architecture

provides two asynchronous resonance modes that can be used to implement dual band pass microwave filters. Such architectures can provide low-cost, compact and easy-to-manufacture dual-band filters compared to conventional dual mode resonator filters, with a further reduction in size due to the fact that one physical cavity provides two electrical resonators. In addition, the new cavity introduces an anti-resonance mode opposite to the two primary resonance modes; this mode can be used as a transmission zero inside the rejection band in dual band filters, which enhances the filter selectivity, while maintaining the simple and miniaturized internal structure. The results of the study and the simulation, which were conducted on the proposed dual mode resonator, showed an improvement in the quality factor with a reduction in the overall size of the resonator compared to conventional resonators, while maintaining the characteristic impedance of the resonator at the two frequencies of the two resonant modes, in addition to maintaining small changes in the two modes quality factors values as resonance frequencies change. The study also indicates an improvement in the isolation between the two resonance modes compared to the traditional dual mode resonators that provide good isolation, which is reflected in the stability of one of the resonator resonance frequencies when trying to tune the other. The implemented study also indicated that the location of the anti-resonance frequency remains constant with respect to the two resonance frequencies.