FDTD computation of the RCS of high permittivity cubes

The radar cross-section (RCS) of a dielectric cube of permittivity /spl epsi//sub r/=37.84 is computed with the finite-difference time-domain (FDTD) method and is compared with the measured RCS. When the surface of the dielectric is assumed to coincide with the surface of the cells designated as dielectric cells, then Yee´s FDTD obtains the RCS of a larger cube than expected. It is shown that a cell size adjustment of a half-cell on all the cube surfaces approximately corrects the computed RCS. A better correction is obtained by rederiving the equation used to update the tangential components of the electric field at the surface of the cube. It is shown that, when an effective permittivity is used for these surface components, the agreement with the measured RCS is improved.<>