Parallel- and cross-polarisation backscattering cross-sections of a conducting circular cylinder of finite length for a circularly polarised incident wave

Expressions for the backscattering cross-section of a perfectly conducting circular cylinder of finite length when a circularly polarised plane electromagnetic wave is incident on the cylinder at an arbitrary angle to the axis are derived for parallel-polarisation and cross-polarisation returned waves. It is shown that as ka sin α (where k=2 π/free-space wavelength, a=cylinder radius, α=angle with cylinder axis) increases to infinity, the backscattering cross-section formed by a parallel-polarisation returned wave, σ_pa, diminishes to zero, while that formed by a crosspolarisation returned wave, σ_cr, approaches the backscattering cross-section for a linearly polarised incident wave. Also, it is demonstrated that the ratio σ_pa/σ_cr becomes only a function of ka sin α, independent of the cylinder length, and therefore one can estimate a cylinder diameter by measuring the ratio σ_pa/σ_cr. Results of experiments to verify the theoretical results and to demonstrate the possibility of estimating a cylinder diameter are shown.