Design of UWB filter based on multi short circuited stubs

A novel ultra-wideband (UWB) band pass filter (BPF) with a fractional bandwidth (FBW) of about 109% is proposed using microstrip line structure. The proposed UWB filter consists five short circuited stubs of quarter wave length are placed at λ₀/4 distance apart each other in feed line of 50 Ω impedance which exhibit a very wide bandwidth from 3.1 GHz to 10.67 GHz and high rejection in out of the UWB band. The proposed filter structure is simulated using GML 1000 substrate of dielectric constant 3.2 and height 0.762mm on Electromagnetic circuit simulator for UWB band of fractional bandwidth 109% at center frequency 6.85GHz. The simulated frequency response shows about zero dB insertion loss (S₂₁) and return loss (S₁₁) less than -20dB. Simulated frequency response is very close to standard UWB spectrum.