Shifted Base Mode Character of Array Antenna with Failed Elements

The failed elements will cause unacceptable pattern distortion for the phased array antenna, such as massive MIMO array antennas. This paper presents the base mode character of the array with failed elements. Firstly, the origin of the far filed measurement is mathematically shifted to the position of each element of the array one by one. Then each shifted far field can be represented with some orthogonal modes. The base mode character behaves a sharp gap compared with its adjacent modes while the shifted position is located on the failed element. This shifted base mode character of array antenna with failed elements can be utilized to fast diagnose the array antenna with several failed elements.