A Size-Reduced Tri-Band Gysel Power Divider With Ultra-Wideband Harmonics Suppression Performance

In this paper, a size-reduced tri-band Gysel power divider (PD) with ultra-wideband harmonics suppression performance, simple structure, high-power handling capability, and independently controllable bandwidth is first presented. The three passbands are introduced by two tri-band biasing networks whose impedances can also be utilized to control the bandwidths of the three passbands independently. With the introduction of slow-wave transmission lines and coupled lines with series open-circuited stubs, a reduced size and ultra-wide stopband can be obtained, respectively. Detailed closed-form design equations are derived and validated with a design of PD operating at 2.0, 2.5, and 3.0 GHz. Also, two additional circuits are designed, simulated, and fabricated. One is utilized to obtain the optional range of the three passbands, and the other is to make a comparison with the proposed PD. All the measured results agree well with the corresponding simulated ones. Proper impedance matching, isolation, and a wider 3-dB fractional bandwidth can be obtained, which is 18.5%, 20.7%, and 13.0%, respectively, at each passband. In addition, more bands can be easily extended to the proposed PD by introducing more open-circuited stubs in the tri-band biasing networks.