[PDF] Ionospheric Modification By High Power Obliquely Propagated Hf Radio Wave Transmissions Part 1 Experimental eBook

Author : Gary S. Sales
Publisher :
Page : 44 pages
File Size : 36,63 MB
Release : 1986
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A special experiment was carried out using a high powered transmitter and a high gain rhombic antenna to heat the ionosphere at a distance of 1300 km from the transmitter. A Digisonde ionospheric sounder was located at the midpoint to sense any changes that might occur in the ionosphere at the heating cycle period of ten minutes. The measured phase data was processed using spectrum analysis in an attempt to detect this ten minute period. The results are not conclusive but there is some indication that the heating period was detected only during the nighttime in agreement with theoretical prediction. Keywords: Ionosphere; Modification; High frequency; Propagation.

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Page : 1028 pages
File Size : 42,57 MB
Release : 1994
Category : Aeronautics
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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Author : Chao Huang
Publisher : John Wiley & Sons
Page : 47 pages
File Size : 36,65 MB
Release : 2021-05-11
Category : Science
ISBN : 1119507553

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A comprehensive review of global ionospheric research from the polar caps to equatorial regions It's more than a century since scientists first identified the ionosphere, the layer of the Earth’s upper atmosphere that is ionized by solar and cosmic radiation. Our understanding of this dynamic part of the near-Earth space environment has greatly advanced in recent years thanks to new observational technologies, improved numerical models, and powerful computing capabilities. Ionosphere Dynamics and Applications provides a comprehensive overview of historic developments, recent advances, and future directions in ionospheric research. Volume highlights include: Behavior of the ionosphere in different regions from the poles to the equator Distinct characteristics of the high-, mid-, and low-latitude ionosphere Observational results from ground- and space-based instruments Ionospheric impacts on radio signals and satellite operations How earthquakes and tsunamis on Earth cause disturbances in the ionosphere The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals. Find out more about the Space Physics and Aeronomy collection in this Q&A with the Editors in Chief

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Page : pages
File Size : 21,18 MB
Release : 1981
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Powerful, high-frequency radio waves have been used to temporarily modify the ionosphere. Thermal and parametric interactions have led to a diverse range of observed phenomena, including generation of density striations and artificial spread-F, enhancements of electron plasma waves, production of extrathermal electron fluxes and enhanced airglow, modification of the D-region temperature and densities, wideband signal attenuation, and self-focusing and scattering of the electromagnetic waves. The physics of ionospheric modification by high-power radio waves is reviewed in the context of our current theoretical understanding; disturbance generation mechanisms are qualitatively described. In addition, results of recent experiments are summarized in which ionospheric irregularities are generated and their evolution and decay processes investigated in detail. The effects and potential controlled applications of these HF ionospheric modifications for various RF systems studies are discussed. The C3I scientific community provides an important motivation for these ionospheric modification studies; their increased interaction and active participation in experimental design and interpretation are encouraged.

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Page : 37 pages
File Size : 28,69 MB
Release : 1992
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A series of experiments were carried out during late May 1991 to investigate changes produced in the ionosphere by a high power HF transmitter operating at a frequency approximately two times the F-layer critical frequency. These high power oblique transmissions heated a region of the ionosphere some 1200km east of the Delano, CA Voice of America relay station, operating with an effective radiated power of 90 dBW. An HF probe signal was used to detect changes in the ionosphere as it passed through the modified region. The probe system, operating at a frequency very close to the heater frequency, frequently showed amplitude changes that correlate well with the ten minute on/off cycling of the high power transmitter. This preliminary study used several signal processing methods to detect these changes in the presence of strong polarization fading. The results indicate that the amplitude of the probe signal decreased by 2 to 3 dB, often within 15 to 30s after the high power transmitter was turned on.