Modeling stepped U-slot DGS microstrip line

摘要

This paper presents an equivalent circuit model for a stepped U-slot defected ground structure (DGS). For a stepped U-slot DGS, the defected structure is simply modeled using a short-circuited stepped impedance coplanar waveguide (CPW) combined with a gap capacitor. The proposed circuit model is advantageous in its ability to accurately control the ratio (=f(s1)/f(r)) of the fundamental resonance frequency (f(r)) to first spurious resonance frequency (f(s1)) by changing the impedance and the electrical length of the CPW in each step. By using this property, two types of resonators with normalized first spurious resonance frequencies (=f(s1)/f(r)) of 4 and 2 were designed and fabricated. Good agreement between the EM simulations and the experimental results were achieved. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:583-587, 2016