Band-notched ultra-wideband bandpass filter design using multiple-mode resonator and stepped impedance stub loaded

A novel ultra-wideband (UWB) bandpass filter (BPF) with notched band is proposed in this paper. The filter is consisting of two symmetrical multiple-mode resonators (MMRs) connected to quarter-wavelength interdigital lines. This filter provides, in the passband, an insertion loss of 0.19 dB and a return loss greater than 22.6 dB. Furthermore, the filter occupies an area of 11.54 × 3.11 mm
²
. In this filter design, besides obtaining a uniform in-band transmission response, a notch band centered roughly 5.2 GHz is created by modifying one of two arms in the coupled-line sections. The simulation results are in satisfactory agreement with the measurement ones reported elsewhere. The proposed UWB-BPF presents good performance in terms of insertion loss, return loss, fractional bandwidth and compact size than those reported in the literature.