Effect of Spatially Uncorrelated Noise on the Maximum Array Gain Processor

Abstract

Several authors have shown that large array gains may be obtained by weighting individual elements with the optimum amplitude and phase factors. It is known that spatially uncorrelated noise, α, such as electronic noise, will decrease this maximum array gain. The purpose of this study is to obtain a quantitative value for this loss. Vertical, linear, equally spaced arrays from two to 10 elements are analyzed for both an isotropic and a surface generated noise field. Calculations on each array with elements spaced from one eighth to one wavelength have been made showing: (1) array gain as a function of the direction of “look” for several values of α, (2) array gain versus α for various spacing intervals, and (3) array gain versus the number of elements for given values of α. The loss of array gain increases as the number of elements increases for a given α. However, for the worst case of 10 elements spaced one-eighth wavelength apart, α could be 20 dB below the ambient noise level and still give much better results than conventional processing.