Thinned coincident arrays for the direct measurement of the principal solution in radio astronomy

A new technique is described for the design of a thinned, linear, multiplicative array which directly measures the principal solution of a radio source distribution. The original filled multiplicative array with uniform element spacing l is first generalized to an array of N/sub 1/+1 subarrays each with M/sub 1/+1 elements. A thinning factor of 1/2 is shown to be possible if M/sub 1/=N/sub 1/. Finally, if each subarray is further divided into smaller subarrays until the smallest are simply two element interferometers, then the principal solution can be directly measured but with far fewer elements. Significant thinning factors are achieved when the array is very large. The method can also be used to measure the principal solution with planar arrays, with very strong thinning occurring for large arrays.