Terahertz Target Near-Field RCS Measurement And Error Depressing Technology

The terahertz wave has the advantages of broader band and high resolution and has an extensive potential in future development for military use such as space target detection and for civil use such as security check.The terahertz electromagnetic scattering characteristic measurement is the base of the development of terahertz technology and is also one of research hotspots in terahertz field.Therefore,this paper,based on the RCS measurement and error depression,mainly studies the RCS measurement's technology,the RCS measurement error depression,the evaluation and the near-field error correction.Aiming at the RCS measurement technology,this paper mainly studies the definition and acquiring of RCS and the measurement system which is used in the paper's experiment.At first,according to the definition of classical RCS and broad band RCS,this paper infers the calculation expression of RCS which is measured under the linear frequency modulation signal.Then,it introduces the RCS measurement system which is based on the microwave frequency doubling technology,and analyzes its performance from structure and theory.Then,this paper introduces the RCS calibration and designates the calibration target.At last,it uses the electromagnetic calculation software CST and calculates the standard target's RCS which can be used for measurement result's verification.Aiming at the RCS measurement error depression and evaluation,this paper mainly studies the measurement error signal transform domain depression and error evaluation indexes.At first,it analyzes the source of the measurement error and adopts the corresponding measures including the vector field subtracting method and software distance gate method to depress the measurement error.Then,it puts the evaluation indexes which are based on the subsection statistics and uses the indexes for evaluating the RCS measurement error.Aiming at the RCS measurement error which is caused by the near-field effect,this paper mainly studies three kinds of near-field correcting technologies.At first,this paper analyzes the near-field effect on the RCS measurement result.And then,it establishes an near-field measurement model and processes the measurement result with Melin smoothing method,cylinder field correcting method and inverse synthetic aperture method.At last it evaluate the corrected results and indicates its validity.