Compact UWB bandpass filter with notched band using multiple-mode resonator

In this paper, a compact ultra-wideband (UWB) bandpass filter (BPF) with notched band is proposed. The basic quintuple mode UWB bandpass filter is based on stub loaded multi-mode resonator (MMR) and two interdigital coupled lines. Two embedded slotline based split-ring resonators (SRRs) are introduced in the ground plane near the I/O feed lines in order to generate the notch band around 8.7 GHz. The design BPF has passband insertion loss of 1.6 dB, return loss greater than 12 dB and fractional bandwidth of 110 %. The proposed filter with has a compact size of 22.22 mm × 13.13 mm.