Broadband Planar Filters with Enhanced Couplings Using Defected Ground Structures

In this paper a study of some microwave microstrip bandpass filters (BPF) using defected ground structures (DOS) is presented. This technique allows designs of tight couplings without the necessity of using very narrow coupling gaps. Based on the results of the study, four-pole cross-coupled planar microwave bandpass filters were designed, with a single or with two ground slots. Compared to similar microstrip filters without defected ground, the simulated performances of these novel structures indicate some technological advantages