Gradient-Based Beam Peak Search for Over-the-Air Testing of mmWave Phased Arrays

It is essential to measure the transmit and receive capabilities of the millimeter-wave (mmWave) phased arrays in the beam peak direction, which are represented by the metrics effective isotropic radiated power (EIRP) and effective isotropic sensitivity (EIS) in the standardization, respectively. However, it often necessitates the time-consuming 3-D antenna radiation pattern measurements to identify the beam peak directions. To speed up the beam peak search procedure for mmWave phased arrays, a novel gradient-based method is proposed in this work. A coarse-and-refined strategy is further introduced to improve the reliability and robustness of the method. The proposed solution can be directly deployed in existing antenna measurement setups, and it can significantly reduce the measurement time while maintaining the measurement accuracy. The effectiveness and robustness of the proposed solution is validated by both numerical simulations and experimental measurements.