Design of compact microstrip UWB power divider using square ring multiple-mode resonator

A new compact microstrip ultra-wideband (UWB) power divider using square ring multiple-mode resonator (SRMMR) is presented in this letter. The characteristics of the proposed square ring multiple-mode resonator are investigated by using even- and odd-mode analysis. Then, the UWB performance is achieved by introducing square ring multiple-mode resonator to the basic Wilkinson power divider. Finally, a new compact microstrip UWB power divider is designed and fabricated. The simulated and measured results indicate that it has a low insertion loss and good return loss performance at all the three ports, and a high isolation between the two output ports across the UWB bandwidth from 3.1 to 10.6 GHz with a small size of 0.46λg × 0.69λg, where λg is the guided wavelength at 6.85 GHz.