The multilayer structure design of magnetic-carbon composite for ultra-broadband microwave absorption via PSO algorithm

In this work, the multilayer magnetic-carbon composites were precisely constructed by the Particle Swarm Optimization algorithm to achieve an ultra-broadband electromagnetic wave absorbing (EMA) performance. Composite with different content of magnetic Fe3S4 hollow microspheres and carbon nanotubes were prepared as absorbing fillers to obtain four basic monolayer EMA materials. Based on their different electromagnetic parameters, various multilayer structures were designed and further simulated via the finite element method. In a series of designed EMA materials with intense absorption and broad bandwidth, a 2-layer model with 3.8 mm thickness was selected as an optimal structure, owning to its excellent simulation EMA property with a minimum reflection loss of −40 dB and an extended qualified bandwidth value of 11.7 GHz. According to the designed structural parameters, the 2-layer composite was successfully prepared and the measured results were in good agreement with the simulated properties, confirming the accuracy of the multilayer optimization. The FEM simulation analysis revealed that the high EMA performance of the multilayer composites is attributed to the enhancement of the electromagnetic loss capability as well as the improvement of broadband impedance matching between the material surface and air.