Surface scattering effects are merely diffraction phenomena resulting from random phase variations induced on the reflected wave-front by microtopographic surface features. Intensity) is shift- invariant in direction cosine space paper toĮxplain some non- intuitive scattering behavior reported in the Paper it is emphasized that scattered radiance (not irradiance or Of the fact that this is basically a scalar treatment) by using theįresnel reflectance coefficients for the desired polarization. Hence, the dominant polarization effects are included (in spite The scattering function is normalized by the total reflectance of the Techniques considered to be more rigorous by many investigators. Of rough surfaces not accurately modeled by vector perturbations Is imposed, this STF can be utilized to predict the scattering behavior Since no explicit smooth surface approximation Gap between the traditional 'figure' and 'finish' errors, and (2) theĮxtremely large incident angles inherent to grazing incidence Wolter STF was generalized to include: (1) the effects of small-angle scatterĬaused by 'mid' spatial frequency surface irregularities which span the Space with respect to incident angle (this led to a modest followingĪmong the radiometric community of BRDF curves plotted in the Scattering data was shown to be shift-invariant in direction cosine To the understanding of image forming systems. The resulting model was analogous to, and anĮxtension of, the highly successful application of linear systems theory Transfer function (STF) that relates the scattering behavior to the Scatter phenomena was developed by considering it to be a scalarĭiffraction process resulting from random phase variations in the exit Over twenty years ago a linear systems approach to modeling surface We demonstrate that the customary paraxial limitation imposed in most scalar diffraction treatments is completely unnecessary and the resulting calculations for diffracted radiance (not irradiance or radiant intensity) are shift- invariant in direction cosine space In this paper we extend the H- S theory to include large incidence angles and scatter angles. Harvey later generalized this Harvey-Shack (H-S) theory to include the effects of small-angle scatter caused by 'mid' spatial frequency surface irregularities, and the extremely large incident angles inherent to grazing incidence Wolter Type I x-ray telescopes. In 1979 Harvey and Shack formulated a scattering theory in a linear systems format. The Beckmann-Kirchoff (B-K) scalar diffraction theory of surface scatter phenomena is valid for rougher surfaces but contains a paraxial (small-angle) assumption that limits its ability to accurately handle wide-angle scattering and large angles of incidence. However, not all applications of interest satisfy the smooth surface approximation. Some of these have links on this site accessable from the Groups button on the opening page.Ĭopyright © 1995-98 VE1CBF All Rights Reserved.Ĭreated: 1995.02.25 | Modified: 1998.11.The Rayleigh-Rice (R-R) vector perturbation theory agrees well with experimental wide-angle scatter measurements from 'smooth' surfaces for arbitrary incident angles. Prospective Amateurs in other countries should get in touch with their national organization. Please note that the links in the above table discuss aspects of amateur radio (specifically regulations) as they apply to Canada and the United States of America respectively. The American Radio Relay League Frequently Asked Questions Page. WD1V's Frequently Asked Questions about Amateur Radio. The Radia Amateurs of Canada Frequently Asked Question PageĪn Informative document for prospective Canadian Hams. While I could continue for some time here, there are a couple of sources that have already been very well done that should answer most of the questions one might have about HAM radio. It is a hobby open to all regardless of age, race, gender, creed, wealth, social status or disability, and in most nations of the world. It has activities and challenges for those with interests in electronics, radio reception and transmission, television, satellite communication, data communication, simple chatting with others around the world, building electronic projects, competing in skill testing events, providing community service, meeting other people, computers, and many more. Amateur Radio is a multifaceted hobby with something for almost everyone.
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