Compact ultra-wideband notch-band bandpass filters using multiple slotline resonators

A novel extremely compact ultra-wideband (UWB) bandpass filter (BPF) with a notch band is presented.The multiple slotline resonators have been applied to construct the UWB BPF and implement the notch band within the UWB passband. Based on the transmission-line theory, the equivalent-circuit model of the proposed UWB notch-band BPF has been developed. The upper cut-off frequency and passband bandwidth of the UWB BPF, as well as the center frequency of the notched band can be adjusted by tuning the structural parameters. The proposed compact UWB notch-band BPF using multiple slotline resonators has been designed, simulated, and measured. The measured results agree with the simulated ones closely. The notched band centered at around 5.7 GHz has 10-dB rejection fractional bandwidths of about 2%. © 2012 Wiley Periodicals, Inc.