The calculation of radar cross sections of three-dimensional obstacles
coated with lossless/lossy dielectric layers is considered. The solutions of Maxwell’s equations are obtained by a finite-volume time domain
unstructured grid method developed from the previous study. The computed
time domain solutions are transformed to frequency domain to determine
the bistatic radar cross sections of the obstacles. Exact solutions of coated spheres are used to validate the numerical method. Two important issues in achieving low radar echoes are investigated, the suppression of low strength surface traveling wave and the inlet duct design. A lossy coating on an ogive is shown to suppress surface traveling waves. By using appropriate boundary conditions the radar echoes from the inside surfaces of inlets can be isolated and calculated. Radar cross sections of straight and serpentine inlets with and without lossy linings are computed and compared.