Applicability of physical optics thin plate scattering formulas for remote sensing

The authors evaluate the applicability of simple formulas for scattering from flat plates that were developed using an extended physical optics (PO) procedure. These formulas take on especially simple forms (denote here as TPO) when the plates are electrically very thin. The authors consider circular plates (disks) and show that when the radius-to-thickness ratio (a/t) is large, the TOP formulas give accurate backscatter cross sections for all incident angles. The PO formulas are not usable for angles of incidence near or at edge-on to the flat surfaces of the disk. On the other hand, complex polarization rate information is lost with TPO. It has been argued elsewhere that TOP should hold even for electrically small disks provided a/t is large. The authors show that TPO gives results accurate (with some exceptions) to ~4% when a/t ~200 for Rayleigh disks. These results are obtained primarily by comparing TPO computational results with an exact numerical procedure