Impedance matching characteristic parameters of microwave absorbing materials for specular reflection and non-specular scattering suppression

The impedance matching characteristic parameters (IMCPs) of microwave absorbing materials for specular reflection under oblique incidence and surface wave attenuation are first proposed and defined. A microwave absorbing sheet was fabricated and its electromagnetic parameters were measured. The specular reflection suppression characterized by reflection loss and non-specular scattering suppression described by surface wave attenuation constants were studied with the change in thickness, polarization, and incident angle. The present results demonstrate that the definition of IMCPs for both specular reflection and non-specular scattering is effective. Meanwhile, the curves of IMCPs share the same shape and have the same peak frequency in specular reflection and non-specular scattering cases. In addition, Brewster angle properties are also consistent with the IMCPs under oblique incidence. Thus, this work develops a pathway for the design of microwave absorbing sheets suppressing both the specular reflection and non-specular scattering by adjusting the IMCPs.