Genetic Algorithm Optimisation of Jaumann Layers - Use of Resistive Sheets

  1. Saville, P.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
Multilayer stacks of resistive sheets spaced a quarter wavelength apart can be arranged to produce wideband Jaumann microwave absorbers. Absorber bandwidth increases with the number of resistive sheets and the resistance profile through the absorber determines its performance. In the past resistance profiles with an exponential or quadratic taper have been proposed and optimization routines have been used to obtain the optimum absorber design. Here, the Genetic Algorithm has been applied to the optimisation of absorber design, using bandwidth and reflectivity objective functions. The best absorber bandwidths were achieved with the bandwidth objective function for 1-7 layer absorbers. For an N-layer absorber there are many absorber designs that produce very similar bandwidths. This is true even for the “optimal” designs where a range of resistance profiles produce the same bandwidth. The shape of the optimal resistance profile depends on the resistance of the sheet nearest to the perfect electrical conductor. Generally the profiles follow an exponential curve, except for the outer layer. Absorber performance also depends on the spacer permittivity. Higher permittivity generally results in a narrower bandwidth, unless a protective spacer is applied to the outside of the absorber. Absorber designs that have a protective layer and higher permittivity values result in reflectivity profiles equal to an N+1 absorber, without a protective layer. This effect is limited to two or t

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Report Number
DRDC-ATLANTIC-TM-2005-123 — Technical Memorandum
Date of publication
01 May 2005
Number of Pages

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