LAUSR

A new compact ultra-wideband (UWB) bandstop filter with good performance is proposed. The proposed UWB bandstop filter is composed of two pairs of quarter-wavelength resonators, a high impedance main transmission line, a half-wavelength resonator, and an H-shaped multiple-mode ring resonator. The proposed H-shaped multiple-mode ring resonator is introduced to achieve three transmission poles appearing in the lower and upper passbands thus to improve the characteristics of selectivity. The proposed quarter-wavelength resonators and half-wavelength resonator are used to obtain four transmission poles showing up in stopband thus to improve the in-band suppression characteristics. To validate the design concept, a new compact UWB bandstop filter with high selectivity and good suppression is designed and fabricated. UWB stopband, low insertion losses, and good selectivity are achieved as demonstrated in both simulation and experiment.