Design of microwave filter

Abstract

Defected Ground Structure (DGS) is the technique for etching off the defected patterns in the metallic ground plane for the purpose of varies the bandgap characteristics and transmission characteristics. Convention DGS microwave filter consisted of a dumbbell sharp defected area and a narrow slot connecting together in the ground plane. It is similar to a simple L-C circuit. The proposed DGS microwave filter is composed of modified rotated-H sharp defected area and compensated microstrip line. The performance has been improved by that capacitive and inductive element variation. The designs are carried out by IE3D simulation software and in the experimental measurements a network analyzer is used. The L-C circuit model of the microwave filter has also been derived. The -20dB rejection bandwidth and selectivity are adopted for comparing the different results.