: The time-dependent surface current density waveforms at various points on the surface of a perfectly conducting sphere illuminated by a plane electromagnetic wave are presented The incident plane wave has an impulsive or shock-type time dependence Current density waveforms in the E-plane (strong creeping wave) and H-plane on both the lit and shadowed sides of the sphere are shown On the illuminated side of the sphere, removal of the Kirchhoff or physical optics approximation for the surface current density permits a detailed examination of the deficiencies of this approximation for short times (high frequencies) From these results the form of a first order correction to the Kirchhoff current is suggested On the shadowed side of the sphere, the changing character of the current waveform is noted

Transient Current Density Waveforms on a Perfectly Conducting Sphere

: A basic process for producing three-dimensional isometric images of a radar target from measured multiple frequency scattering data has been modified to image targets with more complex geometrical shape from non-mutually orthogonal look angle data. Other modifications include changes in the use of the physical optics approximation beyond the shadow boundary, use of polarization diversity information, and estimates of the length to width ratio of the target are given and illustrated. Images produced using these modifications are presented. Recommendations for further research to provide a more versatile imaging procedure are made. The computer programs presently used in the imaging process are given in appendices of the final report. (Author)

J D Young

Papers

Target imaging from multiple frequency radar data