Dual-polarized wide-oblique-incidence-angle wideband radar absorbing structure based on anisotropic impedance matching theory

Abstract In this paper, a dual-polarized wide-oblique-incidence-angle (DP-WOIA) wideband radar absorbing structure (RAS), composed of the geometric gradient dielectric loaded with asymmetric resistive sheets, is proposed. To achieve the DP-WOIA absorption performance, an anisotropic asymmetric impedance matching theory is presented, serving as a design guide for this structure. For comparison, the RAS with symmetric resistive sheets is also presented. Numerical and experimental results demonstrate that both transverse electric (TE) and transverse magnetic polarized waves exhibit excellent wave-absorption performance in the frequency range from 3.84 GHz to 18 GHz over an ultra-wide oblique incidence angle from 0° to 65°. Compared with the RAS loaded with symmetric resistive sheets, the anisotropic electromagnetic characteristics achieved by asymmetric resistive sheets mitigate the impedance mismatches for TE polarized waves under oblique incidence, resulting in the desired DP-WOIA wideband absorption effect. The underlying physical mechanisms of the RAS’s impedance-matching behavior are analyzed through anisotropic transmission line theory and equivalent impedance distributions. This proposed RAS is anticipated for use in wideband absorption applications with extremely oblique incidence.