Dual-response synergy: Gradient-designed honeycomb microwave absorber with strong broadband absorption

With the development of electromagnetic detection technology, higher requirements are put forward for wave-absorbing materials. The honeycomb microwave absorber has the advantages of low cost, light weight, strong wave-absorbing ability and wide wave-absorbing band. However, it has a poor absorption capacity in the S and C bands and usually requires a large thickness to achieve a strong absorption capacity. In this study, we use a realistic and symmetric model to reveal the relationship between the absorption/reflection properties of honeycomb wave-absorbing materials and the absorber content and the number of impregnations. The surface of the honeycomb is covered with fiberglass board to reduce the reflectivity in the target band. Simultaneous controlled tuning of the 5 GHz and 12–14 GHz absorption peaks. And a dual-response synergistic gradient honeycomb sandwich structure (GHSS) is constructed using a low-reflective high-frequency response matching layer and a high-absorption low-frequency response absorber layer and adjusting the skin thickness to reduce the reflectivity. The gradient design improves the impedance matching between the honeycomb structure and air to enhance the absorption, and the dual-response synergy broadens the absorption band. The GHSS has comprehensive and effective absorption coverage in 2–18 GHz, with an average reflection loss of −18.8 dB. Average absorption up to −18.0 dB in S and C bands. The prepared lightweight and low-thickness composite honeycomb are expected to have a good application prospect in the field of electromagnetic wave absorption.