Research Of DGS Technology Applied In Microstrip Filter's Design

Defected Ground Structure (DGS) is a nonperiodic structure proposed in recent years, which means machining various shapes of etching on the ground plane. This paper aims at: deep research of this structure, discuss the utility of existent equivalent circuit of DGS; analyze the traditional dumbbell shaped DGS particularly; search for novel DGS with good character, and apply it in design of microstrip coupled line microwave filter.With reading and studying mass of references, this paper summed up development of DGS, study hotspot and relatively mature theory of this field; summarize several types of DGS with comparisons; have study and research on several important equivalent circuits of DGS, discussed it's good qualities and bad qualities with 3-D full-wave simulations and circuit simulations; particularly analyzed and discussed effect of changing several parameters of dumbbell shaped DGS.Based on study and analyze of dumbbell shaped DGS, proposed three types of novel DGS, and discussed its performance with full-wave simulation. The results of simulation shows that the proposed DGS have more acute frequency character, less attenuation of pass-band, and smaller dimension compared with traditional dumbbell shaped DGS, and this proved the utility of proposed DGS. Summarized traditional design methods of filters, discussed study hotspots and problems in recent years, summarized existent study of filters with DGS. By use of proposed DGS, gained additional pole of coupled line filter, and finally improved its performance. Fabricated a filter with discussed method, measured it and analyzed the results. According the results of measurements, the filter with proposed DGS had great improvements on performance compared with traditional filter, and it also have great improvements on circuit area compared with prior studies on filters with DGS. What's more, the design of the filter again proved the utility and practicability of proposed DGS.