RESEARCH STUDIES RELATED TO MAPPING, GEODESY AND POSITION DETERMINATION
Final technical rept. 19 Dec 1961-18 Dec 1962
MIDWEST RESEARCH INST KANSAS CITY MO
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A feasibility study was undertaken to determine whether it was possible to deduce the index of refraction profile along some path in the atmosphere from physical measurements made external to that path. This problem was solved and it was demonstrated that it was possible to make this remote measurement of the index-of-refraction profile using a quantity called the transient reflection coefficient of the atmosphere. When an electromagnetic wave propagates into a medium of changing index-of-refraction, a certain portion of the incident energy is reflected back toward the source. The ratio of the reflected energy to the transmitted energy is called the reflection coefficient of the atmosphere. It was first shown that this reflection coefficient, which is a function of the frequency of the inci dent wave, is uniquely determined by the index-of refraction profile. In addition, it was demon strated that if the value of the reflection co efficient were known for all frequencies, then it would be possible to reconstruct the index-of refraction profile. Because the index-of-refrac tion profile changes with time, the reflection coefficient is also a time variable. Consequently, in order to determine the value of the reflection coefficient at all frequencies, it would be necessary to make a large number of simultaneous measurements each at a different frequency. Such a system, although feasible, would not be practical. It was because of this objection that the concept of a transient reflection coefficient was introduced.
- Atmospheric Physics
- Cartography and Aerial Photography
- Target Direction, Range and Position Finding