Circumferential distribution of scattering current and small hole coupling for thin finite cylinders

The scattering current induced on a thin finite conducting cylinder immersed in a"theta"-polarizedE-field is studied. Particular attention is paid to the circumferentially nonuniform mode as theE-field angle of incidence varies. This nonuniformity is shown significant (peak-to-average ratio of 3 dB at cylinder midlength) at certain incidence angles for wavelength long cylinders with diameters as small as0.067lambda. Also investigated is the relationship between scattering current and cavity response patterns for narrow thin-walled cylindrical cavities with small holes through which energy is coupled. It is demonstrated theoretically, with experimental verification, that the circumferential variation of scattering current strongly affects the fields within thin cylindrical cavities having apertures with small circumferential extents. It is noted, however, that for most thin-body radiation and scattering problems (in contrast with aperature coupling) only the uniform current mode is significant.