Constrained feed techniques for limited field of view scanning or time delay steering

Large arrays are often treated as arrays of smaller subarrays for the purpose of simplifying the array control and reducing the cost. Two major applications of subarray techniques are for limited field of view scanning and for time delay compensation of phase steered arrays. Although effective subarraying can be readily implemented using space feeds, it has remained very difficult to produce good pattern control with constrained feeds. This paper presents several new solutions to the problem, as applied to one dimensional arrays. The extension to two dimensional scanning can be accomplished by cascading the beamformer networks. It is expected that these techniques will enable the fabrication of low sidelobe arrays with very large constrained subarrays.