Compact Dual-band Filtering Power Divider with Low Loss and High Isolation Based on Open-Circuited Stepped-impedance Resonators

Abstract In this paper, a novel, compact, and high-performance dual-band filtering power divider is presented. The proposed circuit is constructed from a dual-band power divider and open-circuited stepped-impedance resonators. The dual-band power divider is realized by using two-section impedance transformers. To achieve the filtering function, three open-circuited stepped-impedance resonators are attached to three ports of the dual-band power divider to create a transmission zero between two operating bands. The proposed dual-band filtering power divider has a compact size, ease of fabrication, and high performance in terms of low insertion loss, high isolation, and good return losses. In order to validate the design concept, a dual-band filtering power divider operating at 1 GHz and 2.3 GHz with the size of 0.26 λg×0.23λg is designed, fabricated, and measured. The experiment results show that the dual-band filtering power divider has better than 37.1 dB isolation, 23.3 dB return loss, and 3.49 dB insertion loss at two central frequencies. The measured fractional bandwidths (|S11| < -14 dB) are 30.7% for the first passband and 13.8% for the second.