On the Validity of Physical Optics for Narrow-band Beam Scattering and Diffraction from the Open Cylindrical Surface

The exact formulas for the induced electric surface current (in the scattering phenomenon) and the equivalent electric surface current (in the diffraction phenomenon) on the open cylindrical surface due to an arbitrary narrow-band beam have been shown in their closed-form expressions within the context of the cylindrical harmonics, which gives information about the validity of the Physical Optics (PO) approximation. Both the Electric Field Integral Equation (EFIE) and the Magnetic Field Integral Equation (MFIE) are used to find the induced (equivalent) electric surface currents in the context of the cylindrical harmonics. The numerical example of the scattering and diffraction of the Hermite Gaussian beam from the open cylindrical surface is shown. The result is useful for the evaluation of the validity of the PO approximation in the cylinder-like surface.