Design of a bandpass filter using multimode resonators for ultra-wideband application

A new technique is developed for designing a microstrip bandpass filter (BPF) with a 3-dB fractional bandwidth of 100%. The BPF is suitable for ultra-wideband (UWB) wireless applications. The design utilizes two multimode resonator(MMR) filter connected both in cascaded and back to back. In order to achieve ultra wide bandwidth, sharp roll off and low insertion loss(IL) back to back connection makes an important role which increases the coupling dramatically. An experimental filter is fabricated and the measured result shows insertion loss of -2.2 dB throughout the 3dB pass band of 6.54 GHz. Also a good agreement between the measured and simulated results are observed.