Results Of A High Power Oblique Incidence High Frequency Ionospheric Modification Experiment
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Results Of A High Power Oblique Incidence High Frequency Ionospheric Modification Experiment
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Author : Gary S. Sales
language : en
Publisher:
Release Date : 1989
Results Of A High Power Oblique Incidence High Frequency Ionospheric Modification Experiment written by Gary S. Sales and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with categories.
Preliminary Investigation Of Ionospheric Modification Using Oblique Incidence High Power Hf Radio Waves
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Author : Gary S. Sales
language : en
Publisher:
Release Date : 1986
Preliminary Investigation Of Ionospheric Modification Using Oblique Incidence High Power Hf Radio Waves written by Gary S. Sales and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1986 with categories.
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.
Ionospheric Modification By High Power Radio Waves
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Author :
language : en
Publisher:
Release Date : 1981
Ionospheric Modification By High Power Radio Waves written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1981 with categories.
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.
Ionospheric Modification With Obliquely Incident Waves Electron Heating And Parametric Instabilities
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Author : E. C Field (Jr)
language : en
Publisher:
Release Date : 1985
Ionospheric Modification With Obliquely Incident Waves Electron Heating And Parametric Instabilities written by E. C Field (Jr) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with categories.
Nearly all ionospheric modification experiments have been carried out with the modifying wave at vertical incidence. For many applications, however, the modifying wave would probably be at oblique incidence. This report identifies nonlinear phenomena tha could be caused by obliquely incident modifying waves. It concentrates on phenomena that might enhance or degrade the performance of high frequency (HF) radar or communications systems. The nonlinear processes that lead to ionospheric modification divide naturally into two categories: (1) ohmic heating, which alters temperature and hence, reaction rates, collision frequencies, and particle densities, and (2) generation of parametric instabilities, which causes a myriad of phenomena. As the incidence angle is increased, heating is affected by two competing trends. It is weakened by the increased path length, but is strengthened near caustics. A transmitter with a power-gain product on the order of 10 MW can launch and oblique wave strong enough to produce electric fields of several tenths of a volt per meter or more in the ionosphere. Such fields produce substantial temperature increases, which are initially concentrated near the caustics, but spread via heat conduction.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1995
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Aeronautics categories.
Ionospheric Heating With Oblique Waves Volume 2 Applications To High Frequency Radio Propagation
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Author : R. M. Bloom
language : en
Publisher:
Release Date : 1989
Ionospheric Heating With Oblique Waves Volume 2 Applications To High Frequency Radio Propagation written by R. M. Bloom and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with categories.
This volume presents numerical calculations of ionospheric electron density perturbations and ground-level signal changes for several electric field distributions produced by high-frequency (HF) transmitters. This volume applies theory developed in earlier work (Vol. 1) to the problem of possible self-effects of powerful obliquely incident radio waves. Using the results from this earlier work, we use field-driven changes in ionospheric electron density to calculate modified ambient refractive index profiles and the consequent effects on ground signal intensity for sample transmitters. Our calculations indicate that ground-level field-intensity changes of several dB might be produced by joule-heating of the ionosphere by intense oblique HF waves. Our results are extremely sensitive to the model ionosphere and therefore indicate that an experiment should employ the widest possible range of frequencies and propagation conditions. (RH).
Historical Overview Of Hf Ionospheric Modification Research
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Author : William E. Gordon
language : en
Publisher:
Release Date : 1990
Historical Overview Of Hf Ionospheric Modification Research written by William E. Gordon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with categories.
Radio waves have inadvertently modified the Earth's ionosphere since the Luxembourg observations of Tellegen in 1933 and perhaps since Marconi in 1901. The history of ionospheric modification by radio waves is reviewed, beginning with Marconi, describing the Luxembourg effect and its explanations, and its early use to deduce the properties of the lower ionosphere in the 1930s. 'ne measurements became more sophisticated in the 1950s, leading to the call for high-power high-frequency modification experiments in the upper ionosphere. Beginning in 1970, radio facilities became available of sufficient powers to induce changes in the ionospheric plasma detectable by a wide array of diagnostic instruments and techniques. A summary of these effects is presented based upon work up to 1990. These studies were originally motivated as a means of better understanding the natural ionosphere using a weak perturbational approach. However, a rich spectrum of nonlinear wave-plasma interactions was quickly discovered and ionospheric modification research became strongly motivated by issues in basic plasma physics. The ionosphere and near-Earth space are now exploited as an exceptional plasma laboratory-without-walls for the study of fundamental plasma processes requiring large spatial or temporal scales. Here we present a brief overview of these processes and phenomena, illustrated using results obtained from the Arecibo ionospheric modification facilities. The lessons learned and phenomena explored thus far offer many opportunities for controlling the ionospheric environment critical to many civilian and military telecommunications systems, both to disrupt systems normally operational and to create new propagation paths otherwise unavailable.
Nuclear Science Abstracts
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Author :
language : en
Publisher:
Release Date : 1974
Nuclear Science Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1974 with Nuclear energy categories.
Energy Research Abstracts
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Author :
language : en
Publisher:
Release Date : 1990
Energy Research Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Power resources categories.
Radio Science
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Author :
language : en
Publisher:
Release Date : 1993
Radio Science written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Radio meteorology categories.