A Low Frequency Broadband 3-D Metamaterial Absorber

Radar absorbing materials can effectively suppress transmitted and reflected waves, so they are widely used in radar stealth, electromagnetic shielding, and wireless communications. Restricted by the electromagnetic dispersion characteristics of materials, it is difficult to improve the broadband low-frequency absorption performance of absorbing materials based on equivalent circuits. In this paper, a 3-D broadband metamaterial absorbing structure is designed by combining the principle of broadband antenna reciprocity with the equivalent circuit absorbing theory. The structure is mainly is divided into an orthogonal Vivaldi absorber and a multilayer impedance matching metamaterial structure. Under
$\boldsymbol{0}^{\circ}$
incident condition, the absorption rate is greater than 90% in the range of 0.48GHz to 11GHz, and the relative bandwidth of the absorption rate is 183%. At 0.5GHz, the overall thickness of the structure is
$\boldsymbol{0.17\lambda_{0}}$
.