A new numerical method to improve the stopband of compact lowpass filter employing Defected Ground Structure(DGS)

In this paper, we present an effective technique for second harmonic suppression in a compact microstrip LPF by using a multilayer structure and several non uniform arrowhead shaped DGSs in the ground plane. The transfer function of the proposed very compact structure shows wide rejectband and sharp roll off in the transition domain. The equivalent circuit elements are extracted using simple circuit analysis method [1]. The measured results are in good agreement with the simulated results, both displaying an excellent filtering functionality of the proposed lowpass filter.