Micromechanically Tunable Slotline as Part of the Filter Based on the Coplanar Waveguide with Defected Ground Structure

Abstract

A new equivalent model of the defected ground structure for the CPW based filter is presented. The defected ground structure is considered as a short-ended slotline stubbed in the ground electrodes of the CPW line. Calculation of the filter's S-parameters could be performed by using the equivalent parameters of the line, such as effective dielectric permittivity and characteristic impedance. Both effective dielectric permittivity and characteristic impedance are obtained by using 2D finite element method applied to the cross-section of the line. Two ways for tuning slotline equivalent parameters are proposed. The simulation results of the proposed equivalent model are in good agreement with the 3D simulations. Such a method could be applied for the structures with various geometries and electro-physical parameters.