Generation of sum and difference patterns using fractal subarrays

In this letter, we explore the potential for the application of fractal subarrays to the generation of sum and difference patterns. For the purposes of this investigation, a standard planar array is decomposed into two subarrays: one in the form of a Sierpinski carpet, and the other consisting of its complement. A methodology is then introduced for feeding the two subarrays in order to produce either a sum or a difference pattern. A particular example is considered in which directive gain plots are obtained for both the sum and difference modes of a 27×27 planar array.