Abstract:

An ultra-wideband (UWB) filter with a novel compact structure using dual-mode resonators is proposed. The passband ranges from 3.9~11.6 GHz, achieving about 99% fractional bandwidth (FBW). Two sharp attenuation poles can be located close to either side of the desired pass-band to improve the frequency selectivity. The other two attenuation poles can be set in the stopband of upper frequencies so as to reject the third resonant modes of dualmode resonators. The measured results demonstrate that the insertion loss is below 1.0 dB in the passband, and higher than 15.0 dB in the upper-stopband (12.0~19.5 GHz). Group delay variation in the passband is less than 0.5 ns. The measured result agrees well with the electromagnetic (EM) simulated result, demonstrating validity of the filter.

Key words: dual-mode resonator; ultra-wideband (UWB); attenuation pole; filter