Study on thin-layer broadband metamaterial absorber based on composite multi-opening ring pattern of magnetic dielectric layers

Balancing the thickness and bandwidth of electromagnetic wave–absorbing materials has been a challenging task. In this study, a thin and broadband metamaterial absorber consisting of a frequency selective surface (FSS) layer compounded with a magnetic dielectric layer was proposed. The changes in the wave absorbing properties of the absorbers with different numbers of openings in the open circular structure and combinations of open circular rings were analyzed. After obtaining the optimum combination of patterns, the effect of parameter variations on the microwave absorption properties of metamaterial wave absorbers was investigated. The test results show that the optimized metamaterial absorber has a thickness of 1.7 mm, a simulated absorption bandwidth of up to 10.0 GHz, and a microwave reflection loss of less than − 10 dB in the frequency band of 8.0–18.0 GHz. The absorber was prepared and its reflection loss was measured. It is found that these test results have the same trend as the simulation results, which verifies the feasibility of the metamaterial absorber structure design; the proposed two-layer magnetic dielectric composite FSS structure improves the overall impedance matching, avoids the electromagnetic wave being reflected in the surface, and makes the electromagnetic wave enter the interior more; when the resonant absorption peak generated by the introduction of FSS is close to the absorption peak generated by the magnetic dielectric layer, continuous absorption will be achieved, which is the reason for the wide absorption band of the metamaterial absorber. This novel structure takes into account the characteristics of thin layer, broadband absorption, and polarization insensitivity, which has a potential application prospect in stealth technology.