2016 Volume 13 Issue 11 Pages 20160425
A novel compact microstrip ultra-wideband (UWB) bandpass filter (BPF) is proposed using a multiple-mode resonator (MMR), aiming at transmitting signals in the whole UWB passband. The resonant frequencies of this MMR in the design are properly adjusted equally within the UWB passband. Then, two aperture-backed interdigital coupled-lines at the two sides are introduced for an effective enhancement of the capacitive coupling factor. Transmission zeros can be created at the lower and upper passband edges to improve the passband selectivity greatly. Finally, a microstrip UWB filter with good in-band filtering performance and sharp rejection skirts is simulated and fabricated with good agreement.