A short-ended CRLH coaxial cavity resonator with zeroth-order resonance

This paper introduces a coaxial cavity resonator structure with a new configuration based on the composite right/left-handed transmission line (CRLH–TL). In order to create the CRLH–TL, the shunt inductance coils and the series capacitance gaps are added to a conventional half-wavelength short-ended coaxial cavity resonator. The final resonator is composed of three periodically connected CRLH unit cells. Through the adjustment of the diameter of the inserted coils and the gaps of created capacitances, the proposed resonator was able to support the desired zeroth-order resonance (ZOR) in the balanced mode. In order to verify the applicability of the proposed resonator to the CRLH metamaterial, a dispersion diagram and the constitutive parameters of a unit cell were determined using three-dimensional EM simulation. The resonant frequencies and quality factors associated with each resonance modes were then computed through eigenmode analysis for the overall resonator formation. In addition, the electromagnetic field distributions of the resonator at the ZOR frequency have been described and discussed. These results enable us to validate that the proposed CRLH coaxial cavity resonator can be utilized as a zeroth-order resonator based on the CRLH–TL structure. As a result the proposed resonator has a 69% reduction in size compared to traditional short-ended coaxial cavity resonators.