System-based modelling and synthesis of defected ground structure resonators and filters

摘要

This paper describes a method for the system modelling and synthesis of defected ground structure (DGS) resonators based on the singularity expansion method (SEM). The analytical expressions of the transfer functions for three types (dumbbell-shaped, C-shaped and meander-shaped) of DGS resonators are formulated. The physical poles of the DGS structures are extracted utilising a pole-energy-based matrix pencil (MP) scheme. Afterwards, the transfer function expressions are utilised to develop an accurate equivalent lumped-element circuit for the three types of DGS resonators. A systematic synthesis method using the generalised transfer function of the resonators is proposed to design a meander-shaped DGS dual-bandpass filter. Good agreement is observed between the transfer function model of the system and the computed frequency domain data of the synthesised DGS filter. The developed procedures of system-based modelling and synthesis are general and can be used systematically to synthesise multipart DGS filter structures.