Two-Dimensional Quantization Method for Phased-Array Scanning

This paper describes a method for controlling the phase shifters in an electronically scanned two-dimensional phased-array antenna with digital phase shifters. The control algorithm, referred to as two-dimensional quantization (TDQ), significantly reduces the beam-steering errors and the quantization sidelobes caused by the digital phase quantization for a two-dimensional array by increasing the effective phase resolution in the scan-plane direction, and improving the stair-step approximation to an ideal linear phase gradient. This is accomplished by independently adjusting the phases of elements in the plane perpendicular to the scan plane to obtain the desired effective phase gradient. Examples are given showing that a 32 by 32 element planar array with three-bit phase shifters using this method can achieve a beam-steering accuracy equivalent to an array with eight-bit phase shifters. This permits the use of phase shifters with fewer bits to achieve the same beam-steering accuracy, reducing the cost of the array.