A Compact Fish Spear-Shaped UWB BPF with Dual Notch Bands Using SSIR Resonator

A compact and novel ultra-wideband (UWB) bandpass filter with dual notch band characteristics is presented in this paper. The ultra-wideband characteristics of the presented bandpass filter are obtained from a fish spear-shaped multimode resonator (MMR). The dual notch bands are realized by introducing shorted-stepped impedance resonator (SSIR) near the fish spear-shaped MMR. By varying the dimensions of the SSIR resonator, the frequencies of the notch bands can be tuned. To validate the present design approach, the proposed filter is fabricated and measured. The measured results match well with simulated ones. The measured passband of the proposed filter is from 3.67 to 11.34 GHz, with two notches at 5.31 and 8 GHz. The design BPF has passband insertion loss of 1.5 dB and return loss better than 12 dB in the passband. The proposed filter with has a compact size of 24.6 mm × 9.25 mm.