The theoretical and numerical determination of the radar cross section of a finite cone

In this work, rigorous electromagnetic theory is used to determine the nose-on radar cross section of a perfectly conducting cone of finite height. The end cap of the cone is assumed to be a segment of a spherical surface with center at the apex of the cone. Numerical results have been obtained for a cone having a total apex angle of 30 degrees and for values ka ranging from 0.0259 to 5.18, where k = 2π/λ and a is the radius of the base of the cone. These data are compared with theoretical results obtained by using Siegel's Rayleigh method and by using Keller's modified geometrical optics, as well as with experimental results obtained by Keys. The comparisons are instructive below ka = 3.2, the apparent upper limit of validity of the present results.