Achieving broad absorption bandwidth of the Co/carbon absorbers through the high-frequency structure simulator electromagnetic simulation

•Co/Carbon (Co/C) composites were prepared by facile hydrothermal and calculation process.•Modulating permeability of Co/C is achieved by adjusting the amount of Co2+.•The obtained Co/C composite exhibits a bandwidth of 5.8 GHz at a low thickness of 1.8 mm.•The electromagnetic simulated honeycomb made by Co/C shows an ultrabroad bandwidth of 11.6 GHz. [Display omitted] Confronting with increasing electromagnetic pollution, traditional microwave absorbing materials have their limitations, such as low yield and long preparation periods. At the same time, it is well established that electromagnetic simulation is an effective technology to enhance work efficiency, which can quickly explore the impedance matching conditions and electromagnetic characteristics to improve absorbing performance. Honeycomb structure has been widely used in the field of microwave absorption due to its light weight, high strength and heat resistance. This structure also possesses the advantages of multiple scattering, which is beneficial to microwave attenuation. In this work, Co/carbon (Co/C) particles with effective absorption bandwidth (EAB) (the band corresponding to the reflection loss value less than −10 dB) of 5.8 GHz were synthesized by a simple hydrothermal method. Whereupon through the high-frequency structure simulator (HFSS) electromagnetic simulation, Co/C absorbers with honeycomb structure were macroscopically designed, achieving an ultra-broad effective absorption bandwidth of 11.6 GHz. Herein, the effective combination of electromagnetic simulation and honeycomb structure design greatly improves the absorption bandwidth of Co/C. This work paves the way for designing microwave absorption materials with broad effective absorption bandwidth.