Design of lightweight, broad-band microwave absorbers using genetic algorithms

A procedure for synthesizing multilayered radar absorbing coatings is presented. Given a predefined set of N/sub m/ available materials with frequency-dependent permittivities in /sub i/(f) and permeabilities mu /sub i/(f) (i=1,. . ., N/sub m/), the technique determines simultaneously the optimal material choice for each layer and its thickness. This optimal choice results in a screen which maximally absorbs TM and TE incident plane waves for a prescribed range of frequencies (f/sub 1/,f/sub 2/,. . ., f/sub N/f) and incident angles ( theta /sub 1/, theta /sub 2/,. . ., theta /sub N theta /). The synthesis technique is based on a genetic algorithm. The technique automatically places an upper bound on the total thickness of the coating, as well as the number of layers contained in it, which greatly simplifies manufacturing. In addition, the thickness or surface mass of the coating can be minimized simultaneously with the reflection coefficient. The algorithm was successfully applied to the synthesis of wideband absorbing coatings in the frequency ranges of 0.2-2 GHz and 2-8 GHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>