The Research And Design Of UWB Microstrip Filters’ Miniaturization On Multi-mode Resonators

The miniaturization of UWB filter is needed for realizing industrialization ofmicrowave communication filter. This paper, based on a detailed analysis of multi-moderesonator UWB filter theory and design methods, studies the transmission characteristicsof the multimode resonator filter, and designs a high-band rejection of ultra-widebandfilters with low insertion loss, flat passband ripple and excellent transmissioncharacteristics.Firstly, this paper analyses the multi-mode resonator MMR resonance condition,design method, and introduces the design steps of multi-mode resonator to design UWBfilter.And according to the design steps of the filter, a UWB filter based on steppedimpedance resonators SIR is designed, and it is improved on this basis to strengthencoupling strength and improve the filter bandwidth by changing coupling mode.Secondly, a three mode resonator UWB filter is designed, the filter can basically meetthe design requirements, but harmonic suppression is poor in stopband. It is improved onthis basis of the three mode resonator filter to design a five mode resonator which it solvesthe problem that the harmonic suppression is poor in stopband, at the same time, improvesthe passband characteristics, and get a high performance UWB filter.Finally, the defected ground structure DGS is modeling and simulation throughhigh-frequency electromagnetic simulation software HFSS to conclude that the DGS hassingle-pole low-pass characteristics, slow wave effects and high impedance characteristics.The equivalent circuit of DGS is extracted, and combined with simulation software ADSto verify the correctness of the equivalent circuit. The effects of dumbbell type DGS’svarious parameters on the circuit transmission characteristics are analysed, at the sametime, the DGS structure will be applied to design a compact ultra-wideband filter based onDGS in five-mode filter.