The Design Of Microwave Filter Based On DGS

DGS(Defected Ground Structure)is derived from Photonic Band-Gap (PBG) Structure,it’s a structure which is etching the nonperiodic or periodic defected pattern on the metalground plane of microwave transmission lines. Because DGS can influence the distributioninductance and capacitance of microstrip transmission line, it can be good at improvingperformance parameters of microwave circuit, and DGS can reduce the size of themicrowave circuits effectively. By using DGS equivalent circuit, the method of analyzingand designing microwave plane circuit is simpler, so many scholars pay attention to DGSand do deeply research and have accumulated a lot of valuable achievements.First DGS development’s history is introduced, and research situation is summarized inthis paper, then this paper also introduces two typical DGS structure about the dumbbellshape DGS and spiral DGS, which are analyzing compared with each others.DGS is derivedas a equivalent LC circuit by using dumbbell shape, and the equivalent circuit is verified byusing both the HFSS simulation software and ADS2009circuit simulation software.Secondly, this paper introduces the basic theory and design method of microwavefilters and three common kinds of microwave filters.Thirdly, the parameters of the classic dumbbell shape structure’s design are simulatedby using HFSS electromagnetic simulation software. And the classic dumbbell shapevarious design parameters are researched by using the LC equivalent circuit, then weunderstand how they affect the property of the microstrip’s transmittion. And a "E" DGSis proposed basing on the Analysis results, and simulated by using HFSS electromagneticsimulation software. Comparing with the classic dumbbell shape DGS we can find that"E"DGS has the lower resonant frequency for the same area, and prove that "E" DGS is veryuseful.Finally, DGS is used in the design of microwave low-pass filter, and improvesperformance of SIR’BPF, so it is proved that a new kind of effective and practical DGS wasput forward in this paper.