Novel Ultra-Wideband Bandpass Filter Using Shorted Coupled Lines and Transversal Transmission Line

A novel ultra-wideband (UWB) bandpass filter using two shorted coupled lines and a 270° transversal transmission line is proposed. The two shorted coupled lines are utilized to realize 180° phase inversion, while a folded transversal transmission line of 270° is introduced to perform as another power transmission path. Good impedance matching, UWB passband and wider upper stopband can be achieved. One prototype is fabricated for demonstration, good agreement is observed between simulated and measured performances of the UWB filter, indicating a fractional bandwidth of 124.6% (3-11.6 GHz).