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 ±0.1 dB and a phase deviation ±1° can be achieved in the “all-on” mode with the proposed method, compared to those up to ±0.8 dB and ±9°, respectively, for the conventional “on-off” method.