Scattering cross section of rough metallic spheres at terahertz frequencies

At terahertz frequencies, the detailed fine structures on target's surface can be compared with the wavelength, and the dispersive dielectric property of metals becomes obvious. Then, it is naturally thought that scattering characteristics of metallic spheres will exhibit a special phenomenon when compared with the situation in microwave band or infrared. Thus, a novel method of scattering modeling and calculation is proposed based on a full-wave approach for rough spheres at terahertz frequencies. The influence of the surface roughness and dielectric parameters of metal spheres on the scattering characteristics is evaluated by the proposed calculation method. With the further analyzing, it is clarified that the backscattering characteristics of metallic sphere can be depicted by Rayleigh region, resonant region, optical region, rough attenuation region, scattering enhancement region and ultraviolet transparent region with the increase of frequencies. Both the frequency dispersion and the rough surface decide the scattering characteristics of the metallic sphere, and also determine the frequency positions and amplitude levels of the rough attenuation region and scattering enhancement region.