Control of bandstop response of cascaded microstrip low-pass-bandstop filters using arrowhead slots in backside metallic ground plane

In this paper, a new equivalent circuit and modeling method for a uniform arrowhead-defected-ground-structure slot are proposed for the design of a DGS-cascade lowpass or bandstop filter. The effect of the geometry of a defected ground structure (DGS) on the performance of the cascaded-LPF or BSF and the effect of the cascaded-method is also examined. The proposed LPF or BSF based on pi-arrowhead DGS slot is 70% shorter than a conventional LPF. Only three cells of the proposed structure are necessary for a 15-dB stopband at 6 GHz. The validity of the proposed equivalent circuit model is established by comparing their response to the full-wave EM simulation of several structures. Measured results show that the new designs exhibit better performance by suppressing ripples and enlarging stopband bandwidth