Study On Terahertz RCS Scaled Measurements For Metal Targets Of Rough Surfaces And Dielectric Coatings

The scale-relation for radar cross section(RCS)in the terahertz(THz)spectrum is of vital importance for RCS scaling measurement and inversion technology theoretically.In the THz band,the wavelength is shorter,the contribution of surface roughness can no longer be ignored,and the properties of the dielectric material become more complicated.For the scale-relation of RCS in THz,work has been done as follows:For the RCS measurement technology,the pros and cons of the THz RCS measurement system are analyzed.Based on the traditional fixed-range gate method,a dynamic range gate method is proposed to better suppress clutter and improve the SNR.The effectiveness of the method is proved both by measurement and simulation experiments.In view of metal targets with rough surfaces,the influence of root mean square height on RCS of specular reflection is analyzed;two intervals of root mean square height are proposed,in which RCS changes characteristically;three intervals of root mean square height for scale-relation are studied.Based on Kirchhoff Approximation(KA),the method for predicting the RCS of specular reflection is proposed.RCS measurement experiments were carried out on some models.Simulation results and measurement results demonstrate the effectiveness and reliability of the proposed method.As for targets coated with dielectric material,the dispersion characteristics of permittivity are theoretically analyzed and verified by simulation.The applicability of undetermined physical scaling factor method in the THz band is verified.An alternative method for obtaining the key parameters of materials is presented,which provides a new way for conducting the undetermined physical scaling factor method.Simulation results prove the effectiveness of the proposed method.The work of this paper is of great significance for the detection and recognition of electrically large objects and the design of new stealth targets.