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AGARD-LS-196

AGARD-LS-196
  • Version
  • 216 Downloads
  • 16.71 MB File Size
  • 1 File Count
  • April 26, 2016 Create Date
  • April 26, 2016 Last Updated
Scroll for Details

Propagation Modelling and Decision Aids for Communications, Radar and Navigation Systems
AGARD-LS-196 Propagation Modelling and Decision Aids for Communications, Radar and Navigation Systems
Any communications radar or navigation system that relies on
the propagation of electromagnetic (e.m.) waves between an
emitter and a receiver is affected by the environment in which
the waves propagate. An understanding of this environment.
and the way in which it affects propagation. is essential for an
assessment and prediction of system performance.
The medium through which the waves propagate has a direct
influence on propagation. in the HF and Inwcr frequency
bands. the ionosphere (the ionised region of the atmosphere
extending from about 85 to llllllllrm trhoéve the Earth's
surface) has the greatest effect. while at frequencies from VHF
to optical. the troposphere (the non-ionised. lower part of the
atmosphere. extending from the surface up to the tropopausc
at a height of IO—IS km) dominates. Variations in the
refractive index of the medium deter inc how the waves
deviate from the straight line paths that they would have in
free space. These effects can be exploited (for example to
provide communications far beyond the horizon) or can be a
source of system performance degradation (as for example in
the formation of radar coverage holes). Attenuation of the
signal also occurs in the ionosphere and the troposphere. and
scatter from particulates (such as rain. fdg and smoke) can be a
significant impairment. particularly on electro-optics systems.
The Earth's surface also affects svstnm performance. The
effect may be direct. by means of diffraction and scatter where
the Earth‘s bulge or terrain features intrude into the
propagation path. or it may be indirect. due to the influence of
the Earth's surface on the local meteorology and hence on the
refractive index structure of the lower atmosphere.
The propagation medium varies in both time and space. and on
various scales. The spatial scales of interest range from
thousands of kilometres for global communications via the
ionosphere to less than a metre for the effects of atmospheric
turbulence on optical systems. Time scales range from many
years (solar cycle effects on ionospheric propagation) to hours
or even minutes (the scale of weather phenomena).

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AGARD-LS-196

AGARD-LS-196
  • Version
  • 216 Downloads
  • 16.71 MB File Size
  • 1 File Count
  • April 26, 2016 Create Date
  • April 26, 2016 Last Updated
Scroll for Details

Propagation Modelling and Decision Aids for Communications, Radar and Navigation Systems
AGARD-LS-196 Propagation Modelling and Decision Aids for Communications, Radar and Navigation Systems
Any communications radar or navigation system that relies on
the propagation of electromagnetic (e.m.) waves between an
emitter and a receiver is affected by the environment in which
the waves propagate. An understanding of this environment.
and the way in which it affects propagation. is essential for an
assessment and prediction of system performance.
The medium through which the waves propagate has a direct
influence on propagation. in the HF and Inwcr frequency
bands. the ionosphere (the ionised region of the atmosphere
extending from about 85 to llllllllrm trhoéve the Earth's
surface) has the greatest effect. while at frequencies from VHF
to optical. the troposphere (the non-ionised. lower part of the
atmosphere. extending from the surface up to the tropopausc
at a height of IO—IS km) dominates. Variations in the
refractive index of the medium deter inc how the waves
deviate from the straight line paths that they would have in
free space. These effects can be exploited (for example to
provide communications far beyond the horizon) or can be a
source of system performance degradation (as for example in
the formation of radar coverage holes). Attenuation of the
signal also occurs in the ionosphere and the troposphere. and
scatter from particulates (such as rain. fdg and smoke) can be a
significant impairment. particularly on electro-optics systems.
The Earth's surface also affects svstnm performance. The
effect may be direct. by means of diffraction and scatter where
the Earth‘s bulge or terrain features intrude into the
propagation path. or it may be indirect. due to the influence of
the Earth's surface on the local meteorology and hence on the
refractive index structure of the lower atmosphere.
The propagation medium varies in both time and space. and on
various scales. The spatial scales of interest range from
thousands of kilometres for global communications via the
ionosphere to less than a metre for the effects of atmospheric
turbulence on optical systems. Time scales range from many
years (solar cycle effects on ionospheric propagation) to hours
or even minutes (the scale of weather phenomena).

FileAction
AGARD-LS-196 Propagation Modelling and Decision Aids for Communications, Radar and Navigation Systems.pdfDownload 
17,005 Documents in our Technical Library
2449551 Total Downloads

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Newest Additions

NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
AA-CP-20212-001
AA-CP-20212-001
ADPO10769 Occurrence of Corrosion in Airframes
The purpose of this lecture is to provide an overview ...
MIL-STD-1759 Rivets and Rivet Type Fasteners Preferred for Design
The purpose of this book form standard is to provide ...
MIL-STD-810G Environmental Engineering Considerations and Laboratory Tests
This standard contains materiel acquisition program planning and engineering direction ...