Study On Electromagnetic Scattering Computation And Experimentation Of Radar Stealth Targets

The counterwork between stealth and anti-stealth is an important field in modern electronic war. Study of radar target's electromagnetic scattering characteristics is the foundation to design stealth weapons and anti-stealth radar systems. In this dissertation, based on the potential of impulse radars to detect stealth targets, and the pulse signal's character of an impulse radar test system designed by ourselves, firstly stealth targets' wideband electromagnetic scattering characteristics in low frequency and electromagnetic scattering characteristics in time-domain are studied by using both theory prediction and chamber measurement, finally several outdoor experiments to detect stealth targets are performed by using the impulse radar experiment system.Theory prediction includes study on electromagnetic computing methods and electromagnetic scattering computation of radar stealth targets. Among lots of methods to predict electromagnetic scattering characteristics, the finite-difference time-domain (FDTD) method and its parallel mode are chosen as the primary method. In the part of study on electromagnetic computing methods, firstly basic principles of the FDTD and some key techniques are introduced. And the FDTD meshing technique based on facet models and the technique of producing coated grids based on the FDTD grids are put forward. Then, the alternating direction implicit finite difference time domain (ADI-FDTD) method is studied. The ADI-FDTD method is extended to dispersive media—isotropic plasma based on the PLJERC(Piecewise Linear JE Recursive Convolution) method. And the JEC-FDTD method for the magnetized plasma is studied. Then, according to author's own programming practice, some key techniques of the parallel FDTD method based on MPI (Message Passing Interface) are provided. The difference between the parallel JEC-FDTD and the parallel FDTD has been pointed out. The parallel JEC-FDTD method increases current density iteration, and increases some current density datum and electric field datum exchange in the interface.Among the lots of radar stealth technique, shape-stealth, radar absorbing material (RAM) and developing plasma-stealth have been analyzed. Their principles and the stealthy methods have been researched. Then the electromagnetic scattering characteristics of stealth targets have been gotten by the FDTD method, and the valuable conclusions have been deduced.In the indoor measurement aspect, the systems of frequency domain and time domain are introduced. The electromagnetic scattering characteristics of the representative targets are measured by the systems. And the calculated results and the measured results are analyzed. The results indicate: stealthy abilities of stealth targets are weak in low frequency.In the outdoor detection aspect, the characteristics of the impulse radar system have been introduced. And our structure for the impulse radar experiment system has been provided. Then the experiments of detecting stealth targets in the short-range and in the long-range have been successfully performed. These show that the impulse radar has anti-stealth potential.