A Novel Wideband Bandpass Power Divider With Harmonic-Suppressed Ring Resonator

A simple stub-loaded ring resonator is presented as a novel wideband bandpass power divider with good in-band responses and out-of-band harmonic suppression. The first two resonances of the ring resonator are excited and employed to construct a wideband passband. By adjusting the length of loaded open stubs, four transmission zeros can be generated in the lower and upper stopbands. After installing three coupled-line sections at one input port and two output ports along the ring, additional two in-band poles and one upper-stopband transmission zero are further introduced. Subsequently, total five transmission zeros are utilized to improve the passband selectivity and suppress the high-order harmonic. In addition, a single resistor is properly placed between two output ports to ensure the isolation. Finally, a prototype power divider is fabricated and verified experimentally with attractive bandpass features.