Common-Mode Loss Mitigation of a Differentially Fed Eight-port On-antenna Power Combining Patch Implemented in a Scanning Phased Array

On-antenna power combining is an emerging topic of high interest, where high-power amplifiers (HPA) are directly connected to a multiport antenna. Compared to other on-circuit power combining technics, improved efficiency, higher radiated power, smaller associated monolithic microwave integrated circuits (MMIC) and enhanced heat dissipation are achieved. This technic can be used in addition to spatial power combination within an array, to further improve the radiated power. However, several of these multiport antennas result in a common-mode parasitic effect, only occurring when the beam is steered, which reduces the radiated power. This paper exposes this phenomenon through infinite array simulations and explains its origin. A solution to mitigate this problem is finally proposed.