A Novel Spurline Bandstop Filter Using Defected Ground and Defected Microstrip Structures

In this paper, an improved spurline bandstop filter (BSF) using defected ground structures (DGS) and defected microstrip structures (DMS) is proposed. This method is based on the increment of the slow-wave factor (SWF) when DGS and DMS cells are successfully applied to enhance the out-of-band characteristics of the spurline bandstop filters. By using this method, the proposed filter has a stopband from 3.9 to 5.2 GHz with S
₂₁
less than -20 dB and the maximum rejection level of 62 dB.