Scattering characteristics of surface roughness in frequency and incident angle dependent at millimeter-wave

The scattering energy of electromagnetic waves is dependent on the surface roughness, incident angles and complex refractive index etc. of materials. Because the millimeter-wave band has a short wavelength, the characteristics of scattering energy of radio waves are affected greatly by the surface roughness of materials. In this paper, the reflection characteristics of materials, especially surface roughness, are measured using the vector network analyzer. For the measured material, a cement block of construction materials is used. The complex refractive index of the cement block is extracted from the experimental data using the nonlinear least square method. The complex refractive index of cement block is deduced as n=2.2443-0.0597i at 28 GHz and n=2.1848-0.0475i at 38 GHz, respectively