Research On Calibration Volume Of Terahertz Radar Cross Section Measurement

Radar cross section(RCS)is an important parameter to evaluate the scattering characteristics of targets.The rapid and accurate analysis of RCS is vital for stealth design of aircraft,warship and missile.At present,the measurement of terahertz target RCS is mainly based on the relative measurement of a target and calibrator.However,the methods of terahertz-band calibrator mostly continue to use that in microwave-band,and the research on the calibrators for terahertz RCS measurement is relatively lacking.Therefore,based on the absorption and scattering of terahertz wave,we focus on the calibrator of terahertz scattering cross-section measurement.In this thesis,the RCS of terahertz band calibrator is studied by theoretical calculation and simulation,and the factors that affect the accuracy of terahertz band calibrator are analyzed.The simulation data is compared with the experimental measurement.The main research is as follows.The metal conducting sphere with the radius of 10 cm is adopted as a typical calibrator,and software CST is used as the simulation method to analyze the influence of factors such as different periodic roughness depth,different periodic scratch shape,the roughness in different regions and ellipsoid degree of the sphere on the RCS of the calibrator.The results show that at 440GHz,the larger the surface roughness of the calibrator sphere is,the smaller the RCS value is.On this basis,the influence of different coating materials and coating thickness on RCS is discussed.The results show that when the thickness of the surface coating is greater than half wavelength,the RCS value begins to oscillate,so the thickness of the surface coating should be controlled within a half wavelength.Furthermore,it is analyzed the influence of incident direction and polarization mode on RCS.The results show that both incident direction and polarization mode have little effect on RCS of terahertz calibrator.Based on the simulation results,the RCS of spherical calibrator with different surface roughness is measured by experiment,and the results are in good agreement with the simulation results,that further verifies the correctness of the theoretical results.In summary,the research above provides the calibrator basis and test for the high-precision measurement of different types of targets in terahertz band.It has the potential application for the study of terahertz target scattering characteristics.