Design of UWB bandpass filter for wireless communication applications

An Ultra Wide Band, band pass filter (BPF) with a fractional bandwidth (FBW) of about 110% is developed using a microstrip transmission line structure, comprising of bent short-circuited stubs separated by bend connecting lines. This approach resulted in a compact structure and it exhibited a selective filtering characteristic equivalent to a 9-pole Chebyshev filter. The insertion loss and return loss in the UWB band are found to be 0.45 dB and 11 dB respectively and a group delay of about 0.4 ns over the band. Experimental and theoretical filter parameters are found to agree well.