A Review on DGS and Comparative Study of Filters with and Without DGS Technique

In recent years, there have been several new concepts applied to distributed microwave circuits. One such technique is defected ground structure or DGS, where the ground plane metal of a microstrip (or stripline, or coplanar waveguide) circuit is intentionally modified to enhance performance. Defected ground structure (DGS) for the microstrip line, which has period etched defects in the backside metallic ground plane, is one recent hotspot of microwave circuit design. This paper presents advantages of filters using DGS technique over PBG and EBG techniques and also demonstrates the approach to overcome the limitation inherent in conventional microstrip and strip line BPFs having parallel coupled lines and high-performance low-pass filter (LPF). And also presents the DGS element and characteristics, application of DGS and at last the disadvantages of DGS. DGS provides an excellent performance in terms of Ripples in pass-band, Sharp selectivity at cut-off frequency, spurious free wide stop-band. There is a comparison of photonic bandgap (PBG) and electromagnetic bandgap band (EBG) with DGS, where DGS has simple structure and potentially great applicability to design microwave circuits such as filters, couplers, amplifiers and oscillators.