Based On The Impedance Of The Half-wavelength Resonator Dual-band Filter Design

This paper just focus on the design of coupling structure of dual-band filter.On the basis of analyzing the synthesis theory of resonators coupled dual-band filter and the structure of tapered impedance resonators,mainly studying the application of the tapered impedance resonator coupling structure in the dual-band filter.Firstly,from discussing the filter theory of resonator coupling structure, provide the dual-band filter basing on impedance resonators structure a theoretical basis.On the basis of in-depth analysis of the traditional SIR features,probe a new structure for designing dual-band filters-the tapered impedance resonator.By theory and simulation,tapered impedance resonators have advantage in reflection coefficient and insertion loss over traditional SIR,and discuss several small structures of tapered impedance resonators.Using the small structure, design an open-loop second-order dual-band filter basing tapered impedance resonators,which frequency is 2.45/5.35GHz.Detailedly research the relationship between the position of first and second passband and the width and length of loading tapered line,and through the introduction of transmission zeros over the stopband of filters, improve the absorption depth of stopband.In order to further enhance the stopband rejection characteristics,and optimize the rectangular coefficient,design a dual filter using fourth-order cross-coupled topology which frequency is 2.4/5.05GHz.Basing on cross-coupling theory and the theory of symmetric feed structure,design a dual-band filter with high rejection on stopband and smaller reflection coefficient on passband.Test results coincide with the simulation results,so verify the correctness of the design.