The equivalent circuit modeling and application in band-pass filter of spiral-shaped defect ground structure

In this article, the equivalent circuit applied lumped elements was proposed to characterize the transmission characteristics of the spiral-shaped defected ground structure (DGS). Parameters of the equivalent circuit were extracted based on three characteristic frequencies. To verify the feasibility of the equivalent circuit, a third order BPF were designed with two spiral-shaped DGSs and a microstrip resonator. Then, the proposed equivalent circuit was used to demonstrate the filter responses. The simulation results of the two filters showed good consistency with the analysis results. Finally, the third order BPF was fabricated and measured, the measured results agree well with the simulations. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:445–448, 2016