Research On Electromagnetic Scattering Characteristics Of Slits

Modern warfare, firstly, is a battle of high-tech electronics. Radar detection and stealth technology is one of the most important fields of electronic countermeasure. Stealth technology is the combination of reducing the observability of target with controlling the characteristic signals of target. As an important approach of strengthening attacking ability of modern weapons and protecting themselves, the most ultimate goal is to reduce the radar cross section of target. There are two basic approaches which are widely used:shape stealth design and radar materials which absorb radar wave.At present, with the increasing development of Radar Cross Section (RCS) reduction techniques, the influences of the primary scattering sources on the surfaces of objects have been controlled effectively. The discontinuous characters on the surface of objects, such as slits and steps, have a more and more big proportion in total scattering of objects. So investigating the scattering characteristics of feeble sources has been important direction of stealth technology and research on the wide band electromagnetic scattering characteristics of them has a great significance for evaluating the total RCS of target and reducing the RCS of target.Method of Moments (MOM) is an accurate and efficient algorithm, and its accuracy and efficiency have been proved. But for high frequency problem and complex structure, too dense grid of object will lead to dense impedance matrix and many unknown variables, so the computational efficiency will be very low. Asymptotic Waveform Evaluation (AWE) technique was adopted to obtain the current density at any frequency, point within the frequency range by the surface current density at given frequency point using MOM in this paper. Then the wide band RCS was calculated. The numerical results proved that wide band electromagnetic scattering characteristics of object could be precisely evaluated using MOM in conjunction with AWE, and the computational efficiency was considerably improved.In this paper the basic concept and significance of radar cross section was firstly introduced, and then the basic numerical methods for analyzing electromagnetic scattering problems and scattering problems of slits were summed up. Secondly, basic concept of method of moments, basis functions and testing functions were introduced. Then surface current density and radar cross section of two-dimensional conducting body in transverse magnetic field and transverse electronic field were calculated. Thirdly, surface current density and radar cross section of three-dimensional conducting body were discussed. And the method of fast calculation for matrix elements and singular integrands were introduced, then wide band RCS of perfect conducting cavity with different slits were calculated and the scattering characteristics of slits were obtained. Finally, basic concept of AWE technique was introduced and wide band RCS of perfect conducting plate with different slits were calculated, the numerical results were in good agreement with those of MOM.This paper discussed the wide band electromagnetic scattering characteristics of slits systematical and simplified the special models, the accurate and efficient calculation was obtained. This is very important and valuable for investigating the influences of slits to total scattering of object farther. It's also very important for evaluating the RCS of targets and reducing the RCS of targets.