Equivalent circuit for microstrip bandpass filter

Abstract

Filter is an electromagnetic device that is designed to select signals based on frequency response. Filter can be easily analyzed by the general theory of equivalent circuit which refers to a theoretical circuit that retains all of the electrical characteristics of a given circuit. Equivalent circuit simplifies calculation and facilitate the analysis of equivalent circuit. In this final project, it will be shown two types of equivalent circuit, they are equivalent circuit of microstrip bandpass filter (BPF) without defected ground structure (DGS) method and equivalent circuit of microstrip bandpass filter using defected ground structure (DGS) method. Equivalent circuit will be designed using a circuit software simulation. The procedure of simulation is conducted by determining the equivalent circuit comprised of lumped elements and then changing the value of each element, i.e. capacitor and inductor. The effects of varied element value are analyzed to investigate its relationship to the value of reflection and transmission coefficient of BPF, S11 and S12. Equivalent circuit of microstrip BPF without DGS method being modeled has a bandwidth of 3.9GHz ranges from 2.15GHz-6.05GHz. Equivalent circuit of microstrip BPF using DGS method being modeled has a bandwidth of 5.3GHz ranges from 1.9GHz-7.2GHz.