The results obtained by applying the current-distribution method to the problem of approximating the scattering cross section, when the transmitter and receiver are separated, are presented for several simple geometric configurations. The method is applied for the case in which the transmitter is located on the axis of revolution and the ratio l/λ is large, where l is a ``characteristic dimension'' of the body and λ is the wavelength. These results indicate that in most of the cases considered the cross section increases as the angle between the receiver and the transmitter increases.

The first two terms of Kline's asymptotic expansion are obtained for the scattering of a plane wave incident along the axis of a perfectly reflecting semi-infinite body of revolution. When this method is applied to the paraboloid the exact electromagnetic solution is obtained in closed form. The accuracy of the method of physical optics is studied by using the asymptotic expansion.

The value of the nose-on back scattering cross section of a semi-infinite cone is determined by the exact methods of electromagnetic and acoustical theory, and by physical optics. It is shown that, to the degree of approximation used, the electromagnetic value and the physical-optics value are equal. The acoustical value is found to be less than the electromagnetic value by a factor which depends only on the cone angle; both are proportional to the square of the wavelength. It is shown that the electromagnetic and physical-optics answers agree with experimental data to within a factor of two. The electromagnetic theory results obtained hold for the cases in which the half-cone angle is close either to 0 or to π/2.

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