A Fast Phased Array System Calibration Method by Fully Utilising In-Built Beamformers

Abstract

The phased array system (PAS) plays an essential role in modern communications. However, the imperfection of active devices and feeding networks will cause amplitude and phase undesirability for each antenna element, further resulting in beam distortion and performance degradation. Hence, calibration is necessary to maintain desirable PAS operation. One well-known method is the rotating element electric field vector method as shown in [1]. By imposing an extra phase shift on the element to be calibrated, its amplitude and phase are numerically obtained through the measured amplitude variation of the E-field formed by the entire array. In [2] a power-only measurement method is enough to determine the element complex E-field change by shifting the element phase to pi/2 and turning off the element under test in two separate measurements. This paper introduces a novel alternative fast PAS calibration method incorporating phase rotation and amplitude attenuation into calibration practice. By iteratively measuring the array radiation power under system in-built beamformer control, including arbitrary phase shifting and specific amplitude attenuation applied to each element, the initial phase and amplitude for all elements can be solved.