Miniaturized coaxial cavity dual-band filter based on center-loaded short-circuit stub dual coaxial resonator

A miniaturized coaxial cavity dual-band filter based on center-loaded short-circuited stub half-wavelength resonator is proposed in this paper. Two degenerate modes of the dual coaxial resonator are split by adopting a method of loading short-circuited stubs in the center of the dual coaxial resonator, and two passband filters are designed by using two degenerate modes. The filter is designed by using a dual-mode resonator with a short-circuited branch loaded in the center of the resonator, which can reduce the number of corresponding resonators and thus achieve the goal of filter miniaturization. A dual-mode dual-band coaxial cavity filter with center frequencies of 1.175 GHz and 1.34 GHz was fabricated and measured with relative bandwidths of 3.7% and 2.3%, respectively, and the insertion loss in the passband is less than 2.1 dB. The measured results show good agreement with the simulations.