Coincident arrays for the direct measurement of the principal solution in radio astronomy

Multiplication techniques are used on a single array to synthesize a product pattern (effectively the product of the voltage patterns of two coincident arrays), which yields the principal solution when it scans a source distribution. A formula for the array-element weighting coefficients is obtained. The behavior of these coefficients for various array sizes is investigated. It is also shown that by using the same weighting coefficients with two separated arrays (forming the "elements" of an interferometer) one can synthesize a large aperture which also yields the principal solution. The output signal-to-noise performance of the coincident system is compared to that of the compound interferometer having almost the same power pattern. The improvement factor IF defined as the quotient of the output signal-to-noise ratios of the coincident system and the compound inteferometer, is shown to be always greater than unity and increases for increasing noise levels and array sizes.