RCS Near Field Test Of X-Band Electrically Large Target

Radar Cross Section（RCS）is a key indicator for evaluating the good or bad stealth performance of weapon systems.In recent years,RCS testing technology has been an important technology researched by various countries.At present,the technical methods of RCS testing include far-field method testing technology,compact field method testing technology,and near-field method testing technology.However,the near-field test has the advantages of low cost,good confidentiality and high precision compared with the first two test methods.In addition,the X-band（8GHz-12GHz）is an important radar frequency band.In reality,many targets are electrically large in the X-band.Therefore,it is very meaningful and valuable to study the near-field test of the X-band electrically large-scale targets.This thesis mainly studies the near-field test of X-band electrically large size target RCS.After understanding the research trends of RCS near-field testing at home and abroad,the research goal of this topic is determined to realize the near-field testing of Xband electric large-scale target RCS in a small indoor space,and a test plan is given.In order to achieve this goal,this paper firstly analyzes the electromagnetic theories related to RCS testing.On the basis of these theories,the formula for conversion between near field and far field is deduced,and the testing method of one-dimensional circular sampling is determined.In the electromagnetic simulation software FEKO,two typical waveform incidents are set,and the near-field simulation is performed on the electrically large standard target to obtain the near-field original data.Using the derived formula,write a near-field data processing program to process the original data obtained by FEKO simulation,the obtained target RCS is basically consistent with the theoretical value,and under the same conditions,the extrapolation result of plane wave irradiation is better than the extrapolation result of spherical wave irradiation.Theoretical analysis of this result.Then,based on the simulation results of the previous two typical waveforms,the research on the test antenna is carried out.With the help of the HFSS design,a single Vivaldi antenna was fabricated with near-field distribution with approximately spherical wave characteristics.It is proposed to use the one-dimensional array of Vivaldi antennas to uniformly feed,and to synthesize the distribution characteristics of approximate plane waves in the near field based on Huygens principle.The design of the 16-element Vivaldi antenna is completed,and the quasi-single station transceiver system is designed based on the two sets of antennas.Finally,a low-scattering background test environment is built,automated test software is written,and the software and hardware equipment of the test system are integrated.The background interference was eliminated by the method of vector cancellation,and two sets of quasi-single-station test antennas were used to test a metal cylinder with a length of 400 mm and a diameter of 30 mm and a metal plate with a length of 500 mm,a width of 150 mm and a thickness of 2 mm.The test effect is good,and the test effect of the array antenna is better than that of the single Vivaldi antenna.The experimental results show that the test scheme can be used for the near-field test of the X-band electric large size target,the overall test curve is basically consistent with the theoretical curve,and there is a certain error at a specific angle.Finally,the factors that affect the test results are analyzed in many aspects.