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Abstract. The radio refractive index of the atmosphere is governed by
the combination of atmospheric temperature, pressure and humidity. Over oceans,
humidity gradients can cause an effect known as the evaporation
duct. Such a duct has the property of trapping radio
waves between the sea surface and the top of the
duct, which can result in extended range or radio black
spots. The amount of channeling is dependent on the carrier
frequency, the duct structure and various transmitter and receiver properties
including antenna tilt and height above sea level. Knowledge of
the duct and how it affects propagation is therefore of
some importance to people using or designing maritime radio equipment
for use in maritime and littoral environments because it allows
disadvantages to be overcome while making use of the advantages
of extended range. This paper discusses research being undertaken at
James Cook University on duct height determination and propagation within
it. The paper also discusses current topical studies within the
International Telecommunications Union (ITU) on sharing between radar and satellite
links in the 13.75–14-GHz band and implications to this work
arising from a predominant duct.
Related topics:
communications systems, radar, command systems
View first page of "Kerans: Implications of Anomalous Propagation In The Evaporation Duct for Radars At X and Ku Band"
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