EM Absorber Design Based On PSO And Study Of Electric SE Of A Metallic Enclosure With Aperture

Shielding technology and electromagnetic wave absorber are often used to restrain EMI and reduce radar echo from anechoic chambers, aircraft and so on. To obtain an ideal absorber which is thin and has a low reflection coefficient within a wide band of frequencies, an improved PSO is applied to EM absorber optimal design. After the analysis of shielding effectiveness of a metallic enclosure with aperture, the best restrain result of resonance frequency has been realized by coating with absorber at the inside of the cavity. The contribution of the paper is listed as follows:(1) The optimal design of planar multilayered EM wave absorbers is presented. The optimization process is based on an improved PSO. Assumed that the number of layers is given, in order to obtain an ideal absorber which is thin and has a low reflection coefficient within a wide band of frequencies, the thickness of each layer needs to be optimized as well that each layer needs to be chosen from a given material database. The problem is a classical optimization problem and the optimal design is to find the optimal solution. PSO in comparison with most of optimization algorithms such as Genetic Algorithms is simpler and faster. But the basic form of PSO may not obtain the optimal solution with complex problems. An improved PSO is applied to this design. Simulation results show the validity and effectiveness of this design method.(2) Investigate the effects of apertures on the electric shielding effectiveness of a rectangular metallic enclosure with aperture by using transmission line theory and simulation FEKO. The electric shielding effectiveness were calculated as a function of frequency, enclosure dimensions, aperture dimensions, position which was not in the centre within the enclosure by employing a transmission line equivalent circuit approach. To prevent electromagnetic wave leakage, an ideal absorber is attached to the inner wall of the cavity. The results by FEKO show that the resonance has been restrained after coating with absorber.