Publici ge I hour per response. including the time for rvewing instructions. searching existing dat es. -6-S
AUTHOR(S)Akira
SUPPLEMENTARY NOTESThe view, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy, or decision, unless so designated by other documentation.
12a. DISTRIBUTION /AVAILABILITY STATEMENT 12b. DISTRIBUTION CODEApproved for public release; distribution unlimited.
ABSTRACT (Maximum 200 words)This final report summarizes our study of the propagation and scattering characteristics of waves in geophysical media. We have conducted theoretical and experimental studies of enhanced backscattering from very rough surfaces, millimeter wave and optical experiments on scattering from random media, vector radiative transfer studies including rough surface effects, and pulse scattering from rough surfaces.
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THE VIEW, OPINIONS AND/OR FINDINGS CONTAINED IN THIS REPORT ARE THOSE OF THE AUTHOR(S) AND SHOULD NOT BE CONSTRUED AS AN OFFICIAL DEPARTMENT OF THE ARMY POSITION, POLICY, OR DECISION, UNLESS SO DESIGNATED BY OTHER DOCUMENTATION.
I. STATEMENT OF THE PROBLEMS STUDIEDFor the past years, we have been conducting extensive basic research on millimeter and optical wave propagation and scattering in geophysical media. These media include hydrometeors, fog, hail, smoke, dust, turbulence, ice, snow, and vegetation which often severely affect communication and target detection in the atmosphere. We have been successful in making substantial contributions in this field. On the basis of our extensive background and capabilities, we proposed to conduct theoretical and experimental studies on wave characteristics in such random media. We conducted carefully controlled millimeter, microwave, and optical experiments so that the experimental results could be compared with theoretical predictions. We also proposed to conduct theoretical and numerical studies in conjunction with experimental studies. The studies included coherent and incoherent fields, beam waves, pulse waves, backscattering enhancement, depolarization, angular and range resolutions, vector radiative transfer, and target identification. This basic information should be useful in clarifying the wave characteristics in the actual geophysical environments and their effects on communications, radars, lidars, polarimetric radars, and target resolution and identification.
II. SUMMARY OF MOST IMPORTANT RESULTS
A. Enhanced Backscattering from Very Rough SurfacesWhen the rms height of a rough surface is of the order of a wavelength and the correlation distance is such that the rms slope is close to unity, the surface is called a "very rough surface" and at present this is outside the range of applicability of conventional theories. However, in this range of parameters, enhanced backscattering takes place, and this has attracted considerable attention among workers in geophysics and surface optics. We have conducted extensive studies on this problem --th...