Design of balanced power divider with wide common‐mode suppression band

In this paper, a balanced power divider (PD) is designed and implemented in a three‐layer configuration. It consists of two tightly stacked microstrip Wilkinson PDs with a shared ground plane in the middle layer. With both dumbbell‐shaped and partially interdigital open‐ended slots embedded in the common ground, the designed balanced PD can yield a high common‐mode (CM) suppression level over a very wide frequency band without degrading the differential‐mode (DM) performance. A close examination of this design reveals that good CM suppression mainly comes from the blocking of the ground‐plane current path by the open‐ended slots in the ground plane. In addition, the proposed balanced PD also exhibits a very wide CM isolation band. A prototype of the proposed balanced PD is realized. The measured fractional frequency bandwidth for CM suppression is 68% and for CM isolation is 93%.