A Compact Balanced-to-Balanced Filtering Gysel Power Divider Using $\lambda _{g}$ /2 Resonators and Short-Stub-Loaded Resonator

In this letter, a compact balanced-to-balanced filtering power divider (FPD) is presented. It is composed of three half-wavelength resonators and a short-stub-loaded resonator (SSLR). Due to the intrinsic resonance characteristic of the half-wavelength resonator, the bandpass response and power dividing function for differential-mode signal are realized and the suppression for common-mode signal is also achieved. The SSLR is utilized as an extra isolation resonator to achieve high isolation between two output ports. A resister is also needed to load on the SSLR for adjusting its loaded quality factor (Q
_e
). For the demonstration of the design method, an FPD operating at 2.405 GHz has been fabricated and measured. The measured results validate the design method.