Compact microstrip band-pass filter for EMI reduction

Abstract

Compact microstrip band-pass filter design using parallel coupled lines is presented in this paper. The microstrip lines are calculated and constructed using CST studio with two input and output ports of the filter structure are printed over Defected Ground Structure (DGS).The proposed symmetrical structure offers a simple and compact design while exhibiting an improved stop-band characteristics in comparison to conventional coupled microstrip line filter structure. The simulation and measurements of 2GHz prototype band pass filter are presented. The measured result agrees well with the simulation data. Compared with conventional parallel coupled line band pass filter, the second, third and fourth spurious responses are suppressed; in addition, the size of the prototype filter circuit is reduced up to 20.8%.