Fresnel Zone Theory of VLF Coupling into the Earth-Ionosphere Waveguide.

VLF propagation over long paths does not fill the entire great circle arc between transmitter and receiver at the ionospheric altitude. It is blind to the appearance of the terminator over either station. This report concerns one method of calculating the spacial extent of these 'excitation...

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Bibliographic Details
Main Author: Bradford, W. R.
Other Authors: NAVAL ELECTRONICS LAB CENTER SAN DIEGO CA
Format: Text
Language:English
Published: 1971
Subjects:
Cybernetics
Radiofrequency Wave Propagation
Radio Communications
(*RADIO TRANSMISSION
THEORY)
(*RADIO RECEPTION
VERY LOW FREQUENCY)
(*INFORMATION THEORY
PROPAGATION)
RADIO TRANSMITTERS
RADIO RECEIVERS
WAVEGUIDES
IONOSPHERE
EARTH(PLANET)
DIURNAL VARIATIONS
INTERFACES
REFLECTIVITY
GREENLAND
NORWAY
EIGENANGLES
FRESNEL ZONES
RAY TRACING
Greenland
Norway
Thule
Online Access:http://www.dtic.mil/docs/citations/AD0892152
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0892152
Description
Summary:VLF propagation over long paths does not fill the entire great circle arc between transmitter and receiver at the ionospheric altitude. It is blind to the appearance of the terminator over either station. This report concerns one method of calculating the spacial extent of these 'excitation' regions. A ray is drawn from the transmitting station so its angle of incidence at the ionosphere is the real part of the eigenangle. Other rays in the plane of incidence intersect the ionosphere in a great circle arc. The Fresnel zone phase coherence criterion, + or - one quarterwave, is applied to limit the extent of this arc. The arithmetic mean of central angles from the transmitter to each end of the arc is a measure of the excitation region. Calculations are carried out for 12 eigenangles. These represent day and night profiles at three latitudes over water. The Thule-Norway path is also represented.

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