AOA measurement is a technique used to determine the direction from which a radio-frequency (RF) wave approaches an antenna array.

 To find the AOA, the phase-comparison (also known as phase interferometry) technique is often used.

 This approach, applicable in radar and direction-finding systems, accurately estimates the signal's arrival direction by calculating the phase difference of the signal as it is received by two or more spatially separated antennas.

 By analyzing these phase differences, the system can pinpoint the exact direction of the incoming signal.