On Uncertainty Investigation of mmWave Phased Array Element Control with an All-on Method

Accurate control of complex excitation of array elements is key to ensure spatial discrimination capability of millimeter-wave (mmWave) phased array, e.g., beamforming to target signal directions and nulling toward interference signal directions. Element excitation uncertainties are typically evaluated in an “ on – off ” mode, where the element under test is enabled with other phased-array elements properly terminated. However, such an “ on – off ” method might lead to inaccurate results due to the fact that mmWave phased arrays are typically designed for an “all- on ” mode, where all array elements are enabled with proper complex excitations. Therefore, there is a need to accurately determine the array element excitation uncertainties in its typical operation mode, i.e., “all- on ” mode. In this letter, an “all- on ” method is proposed to enable accurate array element uncertainty investigation in the “all- on ” mode. The proposed algorithm is experimentally validated in a 4 × 4 mmWave phased-array experimental platform. The experimental results have shown that an amplitude deviation up to $\pm$ 0.1 dB and a phase deviation $\pm \text{1}^\circ$ can be achieved in the “all- on ” mode with the proposed method, compared to those up to $\pm$ 0.8 dB and $\pm \text{9}^\circ$ , respectively, for the conventional “ on – off ” method.