Genetically Optimized Two-Dimensional Fractal-Random Arrays

In has been known to antenna engineers that periodic arrays can be used to effectively suppress radiation pattern side-lobes with just a small number of elements but are more susceptible to effects from element failure. Random arrays on the other hand are more robust in terms of element failure but are not typically able to suppress side-lobe levels as effectively as their periodic counterparts. In an effort to design robust arrays which are able to effectively reduce side-lobe levels, a compromise was proposed that included both fractal and random features called the fractal-random array (Y. Kim and D.L. Jaggard, Proc IEEE., 74 (9), 1278-1280, 1996; D.H. Werner and R. Mittra, Frontiers in Electromagnetics., Ch. 3, 96-100, 1999). Fractals are objects that have a self-similar structure repeated periodically throughout their geometry produced by the repeated application of a simple Euclidian structure called the generator. In order to introduce randomness into a fractal-random array, one can randomly choose from several different generators and apply them at different stages of the fractal structure. In this way fractalrandom arrays can possess good qualities of both the periodic and random classes of arrays.