A novel compact ultra-wideband filter with wide stopband

A novel ultra-wideband filter with wide stopband is developed in this paper. The filter is based on the shunt stub-loaded bandpass structure. In order to suppress the upper-band spurious response, lowpass sections are embedded into the shunt stub-loaded bandpass filter. The good performance in passband and stopband is achieved. The design is successfully verified by both simulation and measurement. The designed filter has an ultra-wide multiple-octave bandwidth (2.2–10.2GHz) and a wide stopband which is up to 20GHz. Due to its simple structure and compact size, the ultra-wideband bandpass filter introduced in this paper is suitable for portable applications.