Dual-Band Filtering Power Divider Using Dual-Resonance Resonators With Ultrawide Stopband and Good Isolation

Abstract

In this letter, a novel compact dual-band filtering power divider (DB-FPD) is proposed. It consists of a U-shaped Wilkinson power divider, two pairs of dual-resonance resonators (DRRs), and a pair of spur lines. With the simultaneous use and appropriate design of the coupled feedlines, mixed electric and magnetic couplings between the DRRs and spur-lines with different lengths, multiple transmission zeros are produced which result in two passbands with desired power division, high-frequency selectivity, good isolation, and an ultrawide stopband. A prototype DB-FPD operating at 2.3 and 3.5 GHz with 3-dB fractional bandwidths of 8% and 6% is designed, fabricated, and measured. The measured responses agree well with the design simulations, exhibiting a stopband up to 13.8 GHz ( $6f_{0}$ ) with 20-dB rejection level.