Design of Out-of-Phase Filtering Power Divider Based on Slotline and Microstrip Resonator

Abstract

A new design of filtering power divider (FPD) with a pair of highly isolated out-of-phase outputs is presented. By combining the conventional slotline–microstrip transition with microstrip resonators, the proposed FPD is initially constructed. Owing to the field conversion from the slotline to the microstrip line, two signals with equal magnitude and 180° phase difference are simultaneously obtained at two output ports. Specifically, to isolate two output ports, a new isolation network composed of a microstrip line and a grounded resistor is loaded on the differential symmetrical plane. By adopting the even-/odd-mode analysis method, the working principles for both of filtering and isolation are explained with design equations. For demonstration, two prototypes of out-of-phase FPDs operating at 3.4 GHz with 3-dB fractional bandwidths of 8% and 18% are designed, fabricated, and tested, respectively. The simulated and measured results are displayed to verify the theoretical design equations.