Based on the impedance matching principle and electromagnetic wave propagating law, double-layer absorbers with impedance-matching structure were designed both theoretically and experimentally. Microwave absorbers were prepared by mixing a commercially available rubber with magnetic micropowder (MMP) and/or dielectric materials. The first layer, made up of MMP has large permeability and magnetic loss, while the second layer (matching layer), comprised of MMP and/or dielectric material, has frequency dispersion with the parameters of permittivity and permeability to match the incidence free space over a wide frequency range. Experiments showed that the matching layer plays a key role in the absorption. Electromagnetic parameters and thickness need to be controlled precisely to achieve high absorption. It was reasoned out that with increasing electromagnetic performance of matching layer, matching thickness will decrease. Tests showed that the reflectivity was below -10 dB for samples 1 and 2, and below - 8 dB for samples 3-6 in the frequency range of 8-18 GHz. Finally, mechanical characteristics were also investigated with tensile strength above 10 MPa, indicating that the materials may find practical use in the engineering of microwave absorbers.
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