The Phased Array Is the Maximum SNR Active Array [Lecture Notes]

Active arrays are widely used in many sensing applications, including radar, sonar, and medical imaging. It is often stated without proof that the phased array maximizes the SNR at a given focal point over the class of possible active arrays. The proof here of this statement, under various conditions, provides new insight into the use of active arrays in diverse sensing applications. Courses that may benefit from this article include array signal processing, radar, sonar, and medical imaging.