The Applied Study Of Microstrip Filter Using Ring Resonators

In recent years, along with the high development of wireless communication in business, Microwave RF circuit has been attracted more and more attention and also got many achievements. At the same time, as one of the important microwave components, the microwave filters also developed rapidly in recent years. Especially, the performances of microwave filter directly influences the performances of the receivers. So develop high performance, study miniaturized microwave filter is a hot topic in now a days.Firstly, this article introduced the principle and characteristic of the traditional closed-loop resonators and on this basis respectively carries on the resonance characteristics of the analysis to the direct coupling closed-loop resonators and the parallel coupling closed-loop resonators, results showed that the two resonators have the good selective characteristic for the frequency, this characteristic can be applied to the microwave filter design. Secondly, discussed the resonance characteristic of the open-loop resonators which have a gap, the resonance results indicated that the physical size of the gap had the very tremendous influence to the frequency choice. Finally, unifies the analysis result of the ring-like resonators and the principle of the stub-line filters, which causes the direct coupling ring-like resonators and the parallel coupling ring-like resonators as the elemental frame of the filter, and can be applied to the stub-line bandpass filter design, the new designing stub-line bandpass filters compare with the traditional microstrip bandpass filter, which have the wider band width, the lower intervene loss, the more smooth change in the frequency band, the steep transit belt and so on merits.In the filter structural design aspect, the structural size of ring-like resonator may determine by the center frequency, therefore use the ring-like resonant structure as a stub unit, this characteristic demonstrates the unique superiority in the design circuit structure aspect, has brought the convenience thoroughly for the microstrip filter designs. At the same time, using ADS (Advanced Design System) to simulate the electric circuits and optimist the design parameters, and can raise the design efficiency and the quality greatly, obtains the quite practical microstrip bandpass filter finally.The research results of this article have many reference values on the application of ring resonators in the microstrip filter, and improve the efficiency of the filter design. But in the process of the microstrip line filter research; there are some discontinuous questions which are in the bend and the gap as well as in the T-junction place need to be solved.