non-dominated sorting genetic algorithm (nsga)

In this paper, a multilayer electromagnetic absorber is proposed in X band (8-12.4 GHz) frequencies. In the investigated absorber the electromagnetic characteristics of Nano-composite materials are obtain from previous studies. The analytical method of the transmission line method (TLM) is used to design of the proposed absorber. Performance of the proposed absorber is influenced by the properties of layers such as number of the layers, thickness of each layer, material of them, the layer arrangement and electromagnetic coefficients. Further, the modified local particle swarm optimization (MLPSO) method and non-dominated sorting genetic algorithm type two (NSGA-II) are employed to enhance absorption value and absorption bandwidth of the proposed structure with thin profile. The proposed multilayer configuration with 3mm thickness shows more than -18.5 dB absorption in X band frequencies. In this band, the maximum absorption value is about -57 dB for the proposed structure. Furthermore, the return loss of the proposed absorber is calculated by use of the numerical method of finite integration technique (FIT) in CST Microwave Studio (MWS). Finally, an error function is defined for comparison the analytical results with the numerical. According to this function,differences between these results are less than 5 percent over the X band frequencies.