Limitations of Rayleigh Rice Perturbation Theory for describing surface scatter

For over three decades the Rayleigh Rice Perturbation Theory has been the method of choice for relating the surface power spectral density function (PSD) of smooth, clean, front surface reflectors to corresponding scatter patterns. This paper explores limitations with this traditional approach. In particular the annoying (anomalous) "hooks" at the high frequency (near grazing) end of a calculated PSD are investigated. In addition the smooth surface requirement is also probed for its limit. Experimental data involving different materials and wavelengths as well as variations in source polarization and incident angle are presented. The same data set is also used in a follow-on paper suggesting theoretical variations that may solve some of these issues.