Doppler-surface mapping technique for characterisation of spinning cylinders illuminated by radar

The objective of this paper is to present a new Doppler-surface mapping (D-map) technique for understanding the backscattering characteristics of broadside illuminated electrically large spinning cylindrical radar targets. The D-map technique utilises new results that indicate that for nominally axi-symmetric rotations, an asymmetric and discrete line Doppler spectrum will always be present. In essence these frequency spectra are mapped to the target surface and represented In the form of a scattering half angle. Two classes of target (metallic and dielectric) are studied at rotation rates between 1Hz and 8Hz. The technique has practical relevance since from knowing the scattering angle and target dimensions, it is possible to determine the area of the target surface contributing to the backscattered response. It is found that the target scattering angle is invariant with rotation speed. However, the scattering angle for the dielectric cylinder is 50% greater than for the metallic cylinder suggesting that the technique could be used to discriminate between targets with differing electrical (material) properties or surface roughness characteristics.