PO and PTD analyses in polarization prediction for plane wave diffraction from a large circular disk

The authors investigate plane-wave diffraction by a large flat disk, 10 wavelengths in diameter, in order to check the accuracy of PO (physical optics) and PTD (physical theory of diffraction) analyses. The excellent accuracy of the PTD is demonstrated. However, the PO is shown to result in excessive errors in cross-polarization prediction. The principal errors in the PTD are identified as the effects of secondary diffraction.<>