Design of wideband filtering power divider with high selectivity and good isolation

Abstract

A new microstrip wideband filtering power divider (FPD) is presented. By selecting proper coupling topology between a λ/4 short-ended microstrip transmission line and two multimode resonators, a wideband FPD is initially constructed. Meanwhile, by wisely introducing an isolation resistor between the resonators, good port-to-port isolation of the FPD is obtained. For validation, one prototype wideband FPD operating at 2.24 GHz with the fractional bandwidth of 32.1% is designed, fabricated, and measured. Results indicate that the presented FPD exhibits not only a high-frequency selectivity performance with the help of two out-of-band transmission zeros, but also better than 22.5 dB isolation within the entire operation band.