Reconfigurable quad-band filter based on reactance transform method for wideband cognitive sensor applications

Next Generation wireless systems should be equipped with a wideband filters that can handle wideband signals of different communication standards. In case of cognitive wireless systems, it should be a reconfigurable/tunable multiband filter so that it can sense the different parts of radio spectrum for opportunistic usage. In this work, a reconfigurable quad-band bandpass filters based on lumped element topology is presented. The approach allows passband bandwidth to be reconfigured. The filter exhibits narrower and wider states. Each state has good selectivity as it features multiple transmission zeros, the advantage is that reactance transformed based filters increases the number of transmission zeros. Each band on each state keep the same center frequency with reconfigurable bandwidth. The reconfigurable quad-band filter exhibit a wider stop-band bandwidth for all bands.