Pattern and gain are the two most significant parameters. Due to the far field limitation, the two parameters are very difficult to measure for the large short wave phased array. A new approach based on the array's scattering parameter is presented to determine the radiation pattern of the array. With the measurement results of the element pattern in free space and the scattering parameter matrix, the array pattern is derived from the active-element pattern method. The element pattern is obtained by measurement of scaled model with VNA(vector network analyzer), while the scattering parameter matrix is gained by the intelligent scattering parameter tester. Referring to prior knowledge of the array such as geometry size, symmetry, the issue will be simplified further. The developed model is general which can be applied to an array of any size and configuration. Simulation results are given to demonstrate the advantages and validations of the scheme.