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This is a semi-annual overview of this e-mail reflector 'group'.
Welcome to the 'Propagation' e-mail reflector (an opt-in-subscription
e-mail 'mailing' list, free-of-charge). This is a discussion 'group'
primarily focused on the science of getting a radio signal from one
location to another. The main focus is the long distance (DX) propagation
of shortwave radio signals. However, it is also acceptable to discuss
propagation of longwave, mediumwave, as well as VHF and above radio
signals.
This discussion list is available and accessible to any person who is
interested in exchanging ideas, and discussing the propagation of radio
waves. Included are the topical areas of space weather (and the affect on
radio propagation), ionospheric science, geomagnetic science, and to some
degree, weather phenomenon as it may affect the propagation of radio wave.
Radio propagation is the behavior of radio waves when they are
transmitted, or propagated, from one point on the Earth to another, or
into various parts of the atmosphere. Like light waves, radio waves are
affected by the phenomena of reflection, refraction, diffraction,
absorption, polarization and scattering.
Radio propagation is affected by the daily changes of water vapor in the
troposphere and ionization in the upper atmosphere, due to the Sun.
Understanding the effects of varying conditions on radio propagation has
many practical applications, from choosing frequencies for international
shortwave broadcasters, to designing reliable mobile telephone systems, to
radio navigation, to operation of radar systems. Radio propagation is also
affected by several other factors determined by its path from point to
point. This path can be a direct line of sight path or an over-the-horizon
path aided by refraction in the ionosphere. Factors influencing
ionospheric radio signal propagation can include sporadic-E, spread-F,
solar flares, geomagnetic storms, ionospheric layer tilts, and solar
proton events.
Radio waves at different frequencies propagate in different ways. The
interaction of radio waves with the ionized regions of the atmosphere
makes radio propagation more complex to predict and analyze than in free
space. Ionospheric radio propagation has a strong connection to space
weather. A sudden ionospheric disturbance or shortwave fadeout is observed
when the x-rays associated with a solar flare ionize the ionospheric
D-region. Enhanced ionization in that region increases the absorption of
radio signals passing through it. During the strongest solar x-ray flares,
complete absorption of virtually all ionospherically propagated radio
signals in the sunlit hemisphere can occur. These solar flares can disrupt
HF radio propagation and affect GPS accuracy.
On-topic posts to this e-mail reflector include detailed reports and
summaries of past and current solar (space weather) and geophysical
(geomagnetic) events, as well as forecasts of space and geophysical
weather as related to radio signal propagation and for establishing
communication circuits. Additionally, it is acceptable to discuss reports
of station-to-station conditions and analysis, contest results that reveal
propagation conditions, discussions of antennas and related propagation
topics involving antenna engineering, and transmission modes, noise, and
so on.
Please do not post questions about general topics like equipment wanted
and/or for sale, e-mail addresses needed, DX QSL routes, and so forth.
NOTE: DO NOT USE THIS REFLECTOR TO POST COMPLAINTS, PERSONAL CRITICISMS,
ATTACKS, ETC AGAINST OTHER LIST MEMBERS. VIOLATORS OF THIS POLICY WILL BE
REMOVED IMMEDIATELY WITHOUT NOTICE.
HOWEVER: this is a somewhat scientific forum, and therefore is available
for the exchange of ideas, as well as the challenge by interested
individuals of current ideas, new theories, and the critical examination
of data and the interpretation of that data. EXPECT PEER-REVIEW of your
science!
Above all, be considerate of all other subscribers, both in your tone,
your tact, as well as be considerate of those who have bandwidth
limitations, in which case please edit your replies by removing any text
that is not needed to give reference to your response (in other words,
only quote the very minimum that is needed for clarity).
Whether you are a beginner, or an expert, we all welcome you, and
encourage you to participate by asking questions on radio signal
propagation, space weather, and by submitting your ideas, insights, and
reports. Thank you for joining in.
You may make changes to your subscription to this list, by browsing to the
following URL:
<http://lists.contesting.com/mailman/listinfo/propagation>
-- the Moderator, Tomas Hood (NW7US)
http://sunspotwatch.com/
--
Tomas Hood, NW7US
Hamilton, Montana
http://sunspotwatch.com/
http://nw7us.us/
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