Research on electromagnetic scattering characteristics of slits on aircraft

Slits are feeble sources among the various electromagnetic scattering sources on a traditional aircraft. But for the stealth military aircraft, scattering contribution of slits is remarkable since the main sources are heavily reduced. To analyze the scattering characteristics of slits at different polarizations, a slit was placed in the diagonal of a metal plate to weaken the influence of metal edges and the diagonal was placed from vertical to horizontal. By means of a series of radar cross section (RCS) testing, the polarization rules, width parameter influence, interval parameter influence, and other characteristics of slits are investigated. Experiments with different slit widths demonstrate two points: for HH polarization, when the slit width was less than a quarter of the wavelength, increase in slit width would considerably enhance the surface wave effect, but when it was greater than a quarter of the wavelength, its increase tended to reduce scattering; for VV polarization, the scattering of the test piece was close to a plate with no slit when the slit width was small and scattering was enhanced when the slit width was greater than half of the wavelength. Experiments with multi-slits show that interval parameters would have an impact on the RCS distribution and peak location by coupling the effect of individual slits. The influence of VV polarization was greater than HH polarization.