Dual-Wideband Filtering Power Divider With Good Isolation and High Selectivity

A new microstrip dual-wideband filtering power divider (FPD) is presented in this letter. The proposed device is mainly composed of a resonator loaded quarter-wavelength (λ /4) three-line coupled structure and a modified isolation network. To illustrate the design principle of the proposed FPD, equivalent circuits of the structure under the even-/odd-mode excitations are provided with the derived design equations. For demonstration, a prototype dual-band FPD operating at 2.3 and 3.64 GHz with 3-dB fractional bandwidths of 36.5% and 22.3% is designed, fabricated, and tested. Results indicate that the new FPD exhibits both good isolation and high frequency selectivity within the whole operation band.

I. Introduction

In recent years, designing highly integrated multifunction microwave circuits has become an effective approach to meet the demands for compact and low-cost radio frequency devices. Among them, the filtering power divider (FPD) characterized with both the functions of power division/combination and frequency selectivity has been attracting more and more attention.