Compact UWB Band-Pass Filter with Dual Notched Bands Based on Novel Defected Ground Structures

A compact ultra-wide-band (UWB) band-pass filter (BPF) with dual notch bands is presented using novel defected ground structures (DGS). A couple of triangle-ring resonators with four open-stubs fed by a couple of inter-digital coupled structures is developed to meet the UWB requirement of a uniform 3.1GHz to 10.6GHz full-band transmission response. Dual notch bands are generated for filtering out the interference caused by strong signals transmitted from 8/7 X-band systems whose down-link is from 7.25GHz to 7.75GHz and whose up-link is from 7.9GHz to 8.4GHz. The sharp rejection of down-link signals is achieved by etching the first ring DGS on the bottom ground plane. The other rejection of up-link signals is introduced by coupling resonance of the second and third ring DGSs etched on the bottom layer. Moreover, two pairs of ring-arc DGSs are used to achieve a wider upper stop-band. Further, through the surface current analysis, the rejection band and pass-band performances are testified. Eventually, the designed UWB BPF with dual notch bands shows a good pass-band performance from 2.5 to 9.9 GHz and the high stop-band rejection -15dB up to 23GHz from the simulated results.