Abstract: For strong coupling active phased array, the array cells exist two kinds of radiation pattern, common mode and differential mode, in order to reduce common mode interference radiation on the transmitting system, this article embarks from the theory of odd even mode, against the radiation pattern of the antenna unit decomposition to obtain the odd mode im pedance and radiation power, its significance lies in the realization of the strong coupling array ports two kinds of active im pedance separation, which provide the theoretical support for unit port matching; This article finally 3X3 strong coupling ar ray, for example, in a 180 degree hybrid balun to separate odd mode and even-mode for coupling antenna, and carries out the impedance matching design, the experimental results show that this method is effective in reducing the system commonmode interference, and gives a reference value of EMC analysis and engineering application for general active array.