Design And Research Of Microstrip Dual-band Filter And Diplexer Using SIR Stub Loaded Resonators

Microwave dual-band filter and diplexer are key components of the wireless dual-band communication system, its miniaturized high performance has become one hotpot. The use of dual- mode resonator can be reduced the number of the resonator by half, resulting in a compact filter configuration, and therefore has been widely used in the filter design.First, in this paper, resonance characteristic of SIR stub loaded dual- mode resonator and coupling characteristic of the parallel-coupled microstrip line which used aperture compensation have in-depth research. And designed a second order dual-band filter using the dual- mode resonator. Its two passband center frequency can control independently, but the bandwidth controlled by the same variable. Also it has large size. Second, in order to reduce the size introduced defected ground resonator and designed another second order dual-band filter using this resonator. Such a filter, its passband center frequency and bandwidth can control independently. And this filter structure is compact, size is only half of the previous structure. Third, based on the SIR stub loaded dual- mode resonator proposed a novel quadruple- mode resonator and analyzed its resonance characteristic by odd-even mode analysis method. Also designed a second order dual-band filter using the novel quadruple- mode resonator. And its passband center frequency and bandwidth can control independently and structure is compact. Finally, based on the SIR stub loaded dual- mode filter transmission zero controllable characteristics, designed the continuous diplexer and discontinuous diplexer which center frequency ratio is less than 1.1.