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Ray diagram of sporadic E event
Sporadic E (abbreviated Es or SpE) is an unusual form of radio propagation using a low level of the Earth's ionosphere that normally does not refract radio waves.
Sporadic E propagation reflects signals off relatively small "clouds" in the lower E region located at altitudes of about 95~150 km (50~100 miles). The more conventional forms of skywave propagation in the ionosphere's higher F region refract off layers of electrons knocked off of gases by intense UV light, which are renewed on a fairly regular daily cycle. In both cases, the ionized material, when present, refracts (or "bends") radio signals back toward the Earth's surface creating a "bent pipe" path for radio signals.
The Es propagation often supports occasional long-distance communication during the approximately 6 weeks centered on summer solstice at very high frequencies (VHF), which under normal conditions can only propagate by line-of-sight.[1]
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"Sporadic E reference and resources". amfmdx.net. Archived from the original on 2007-06-24. Retrieved 2008-07-03.
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Es-Layer that occasionally may appear in summer may produce such SporadicEpropagation. A method of decreasing the skip zone is by decreasing the frequency...
may be impossible to use skywave at all, except during periods of Sporadic-Epropagation (from late spring through mid-summer). Skip contributes to noise...
allocations. One area of concern was the effects of tropospheric and SporadicEpropagation, which at times reflected station signals over great distances,...
indicators of SporadicE ionospheric propagation. According to IARU bandplans, the following 28 MHz frequencies are allocated to radio propagation beacons:...
absorption and reflection of the E-layer. Fellow of the Institution of Engineering and Technology (1975) SporadicEpropagation Journal of Atmospheric and Terrestrial...
summer months due to interference from foreign transmitters due to SporadicEpropagation thereby giving poor quality signals. Ambitalk addresses this interference...
entertainment, can be heard sporadically and in various modes on the shortwave bands. Pirate broadcasters take advantage of the better propagation characteristics...
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