Design and realization of microstrip filters with new defected ground structure (DGS)

In this paper, various microstrip filters, such as bandpass (narrow/wideband) filters, dual band bandpass filter and lowpass filters, are designed with new metal strips loaded defected ground structure (DGS). In this proposed DGS, metal strips are introduced in connecting slot of dumbbell shaped DGS (DB-DGS). This new DGS is an improved version of conventional (dumbbell-shaped) DGS with enhanced characteristics of filters. With this new metal strip loaded DB-DGS, a bandpass (narrow-band/wide-band) filters, dual-band bandpass filter and lowpass filters, are designed with improved characteristics. The entire proposed filters are designed and fabricated with the same substrate area using 50 Ω, λg/4 microstrip line which is very compact to conventional microstrip filters. For validation of proposed designs, all fabricated filters are measured in Rohde and Schwarz Vector Network Analyzer 1127.8500 and also compared with circuit simulated results. All the simulations are carried out in HFSS V10 and ADS2006A.