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Topic: Sporadic E propagation

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	Sporadic E propagation - Wikipedia, the free encyclopedia
		Sporadic E propagation is a relatively rare form of propagation where a radio wave bounces off a sporadic E cloud, notated as E
		in the E layer region of the ionosphere.
		The distance variability of Es propagation is due to cloud height and density.
	en.wikipedia.org /wiki/Sporadic_E_propagation (292 words)

	Ionosphere - Wikipedia, the free encyclopedia
		The E layer is the middle layer, 90 km to 120 km above the surface of the Earth.
		The vertical structure of the E layer is primarily determined by the competing effects of ionization and recombination.
		Sporadic E propagation is characterized by small clouds of intense ionization, which can support radio wave reflections from 25 – 225 MHz.
	en.wikipedia.org /wiki/Ionosphere (2874 words)

	TV-FM DX - Wikipedia, the free encyclopedia
		In this propagation method, when the signal encounters a rise in temperature in the atmosphere instead of the normal decrease (known as a temperature inversion), the higher refractive index of the atmosphere there will cause the signal to be bent.
		Sporadic E, also called E-skip, is the phenomenon of irregularly scattered patches of relatively dense ionisation that develop seasonally within the E region of the ionosphere and reflect and scatter TV and FM frequencies, generally up to about 150 MHz.
		Although Sporadic E can occur at any time of the year, the most active period is during the summer months, from early May to August (Northern Hemisphere), and early November to February (Southern Hemisphere).
	en.wikipedia.org /wiki/TV/FM_DX (5352 words)

	Sporadic E (Site not responding. Last check: 2007-10-13)
		Sporadic E is a form of propagation that can arise with little warning, and enable frequencies of 100 MHz and more to travel over distances of a thousand kilometres and more.
		In view of the fact that the sporadic E clouds occur at around the same height as the E layer, similar distances are achieved.
		This means that when sporadic E is being experienced, the area from which stations are heard will change over the life of the cloud.
	www.qsl.net /ta1dx/amator/sporadic_e.htm (528 words)

	Articles on sporadic E and 50 MHz Radio Propagation
		The term "sporadic E" is however a geophysical term denoting localized enhancements of the electron density in the E region of the ionosphere with a duration between seconds and several ten minutes.
		Those electron density enhancements may be observed quite often in the E region of ionosphere which is however not true for sporadic E forward scatter of VHF radio waves.
		Very dense sporadic E layers may exceed critical frequencies of 16 MHz but this models result in critical frequencies around 25 MHz (in 144 MHz sporadic E) or even 35 to 39 MHz (in 222 MHz sporadic E) which evidently no longer reflects the true ionosphere.
	www.df5ai.net /Material/articles.html (1992 words)

	Propagation: sporadic E skip (Es)
		Es has a set of characteristics which, when taken all together, set it apart from all other forms of DX propagation.
		In fact, a study we made of hundreds of Es receptions revealed that 950 miles is the optimum distance on channel 2, with distances lengthening slightly with each higher channel, up into the FM band.
		Es is very much a summertime phenomenon in the temperate latitudes, with peaks in June and July; very good openings also in May and August; and a sprinkling in late April and early September.
	www.ham.dmz.ro /radioamateur/propagation/sporadic-e-skip.php (951 words)

	Sporadic E (Site not responding. Last check: 2007-10-13)
		Sporadic E: Irregular scattered patches of relatively dense ionization that develop seasonally within the E region and that reflect and scatter frequencies up to 150 MHz.
		Note 1: The sporadic E is a regular daytime occurrence over the equatorial regions and is common in the temperate latitudes in late spring, early summer and, to a lesser degree, in early winter.
		Note 3: The sporadic E can sometimes support reflections for distances up to 2,400 km at frequencies up to 150 MHz.
	bopedia.com /en/wikipedia/s/sp/sporadic_e.html (111 words)

	Estimated range of distances for sporadic E propagation modes
		With over 55 years of sporadic E DX logs and observations, we now have a very large database of information which gives us a very good idea regarding what distances are possible on the VHF band.
		One factor as to the maximum distance propagated by sporadic E is the height of the Es cloud.
		The main factors that set the minimum and maximum distance limits for Es DX reception are geometry of the earth, Es cloud electron density, the number of Es clouds, and Es ionization height.
	www.geocities.com /toddemslie/Es_distances.html (1694 words)

	Argentina on VHF! (Site not responding. Last check: 2007-10-13)
		E skip happens when ionization in the E layer of the stratosphere becomes dense enough to reflect VHF signals back to earth.
		E skip could have enabled our signals to reach the Caribbean, and from there, TE propagation extended the reach to South America.
		The signals were very similar to Sporadic E signals, some times S9+40, other times at the noise floor, with lots of rapid fluctuation in signal strength and clarity.
	n5xu.ae.utexas.edu /news/oct1998/node3.html (510 words)

	Sporadic-E (ES) - FinnKristensen (Site not responding. Last check: 2007-10-13)
		The behavior of mid-latitude sporadic E is unpredictable, and when you start to believe that correlations and observations are fact, sporadic E will surprise you with an inexplicable result.
		This is opposite of normal F region propagation, where the quantity and intensity of propagation at higher frequencies is directly related to the amount of sunspots.
		Es backscatter is not well understood, and little scientific study of the phenomenon as it applies to us as DX'ers has been done.
	www.oz4vv.dk /index.php?option=com_content&task=view&id=27&Itemid=51 (5297 words)

	Sporadic-E Reference and Resources (Site not responding. Last check: 2007-10-13)
		Sporadic E is an unpredictable natural phenomenon the occurs in the E region of the ionosphere.
		While sporadic E is unpredictable, numerous correlations and observations have been made, by amateurs and scientists alike.
		For example, sporadic E is known to have a diurnal pattern, peak near the solstices, and occur more frequently in latitudes closer to the equator.
	www.amfmdx.net /fmdx/sporadic-e.html (813 words)

	Propagation
		Typical path propagation found on the six metre band are path enhancements due to atmospheric inversion layers, although not as greater effect as on higher frequency bands, ionospheric refraction via the F2 layer at about 200Km in altitude and the mysterious Sporadic Es which are clouds of ionized air at around 100Km in altitude.
		E propagation is not un-common on the six metre band but it’s not a daily event, so we need to use a bit of science and have a strategy to take advantage of this effect.
		Sporadic Es are from a minimum of about 800km to a maximum of about 2400km with the optimum distance being around 1500km.
	members.optusnet.com.au /vk3ysf/DX.htm (788 words)

	High band 175-220 MHz TV DX via sporadic E
		In practice, it is difficult to know of a possible propagation path for the highest frequency, because of the geometric restrictions imposed, and unless the DXer and the transmitter are in precise relative positions, the DX station will not be heard.
		The optimum sporadic E propagation path distance is approximately 1,240 miles (2,000kms), which is the same for bands 1, 2 & 3 (Australian channels 0-11).
		The maximum single hop distance for Sporadic E DX is about 1,430 miles (2,300kms), a geometric restraint based on an average height of E-layer ionization of approximately 65 miles (105kms).
	www.geocities.com /toddemslie/highbandspe.htm (1698 words)

	Your Heading Goes Here
		Other closely related propagation modes are sometimes confused with temperate-zone sporadic-E. Long duration meteor scatter is often difficult to distinguish from true sporadic-E. When the MUF is just below 50MHz, for example, random meteors may elevate the MUF to a useful level for a few tens of seconds at a time.
		The resulting sheets, or sporadic E clouds, may attain the required ion density to serve as a reflecting medium for VHF radio waves.
		Sporadic E clouds observed by rocket-borne instruments and back-scatter experiments have been found to be 50 to 100km in diameter, 2 to 4 km thick and 95 to 115km in altitude.
	www.uksmg.org /sporade.htm (3032 words)

	Basics of Radio Wave Propagation
		The differential particle directional flux j (E,w) denotes the number of particles of energy E per unit energy interval, per unit area, per unit time, per unit solid angle of observation, passing through an area perpendicular to the viewing direction; the angle w is the angle between the viewing direction and the local magnetic field.
		For propagation along the direction of the magnetic field, it is the mode in which the electric vector rotates in the same sense that an electron gyrates freely about the field.
		For propagation along the direction of the magnetic field, it is the mode in which the electric vector rotates opposite to the direction of an electron gyrating freely about the field.
	ecjones.org /propag.html (16958 words)

	Your Heading Goes Here
		With E layer propagation it would appear that the rule is valid - most obvious when the signals to North America decline, if not disappear on 28MHz, at the times when the band opens on 50MHz, much the same as F layer propagation.
		I believe that we are, for the most part, unable to see (hear) the E layer propagation, which is bringing in the weak long range signals due to the very strong Sporadic E signals that are masking them.
		On the subject of night time Es, I suggest that although the sun may have set at a location, as far as the E layer is concerned it is still daylight, or in a few extreme cases the E layer is so excited, it does not have time to die.
	www.uksmg.org /elayer.htm (1446 words)

	A Seven-Year Study of 50-MHz Sporadic-E Propagation - Aug 1972 CQ - p. 66
		W3ASK, Propagation Editor, CQ uring the early 1960's the author's interest in sporadic-E (Es) propagation on the amateur 50 mHz band was aroused considerably by two articles appearing in CQ and written by Morgan and Dorothy Monroe
		Using procedures described by the Monroe's, an intensive study of 50 mHz Es propagation was undertaken at WA5IYX during the period January 1, 1964 through December 31, 1970.
		The diurnal, or hour-to-hour variation in Es propagation is shown in fig.
	home.swbell.net /pjdyer/cq/cq7208a.htm (1777 words)

	DX: Studying The E-Skip Phenomenon - Chris Kadlec
		The propagation which I experienced in October 1987 involving E-assisted TEP to Botswana had some flutter which the southerly stations did not note to any extent and may have been due to the fact that I was located at the northerly extremity of the path.
		Fortunately, the propagations differ sufficiently from one another that by combining a little experience with the descriptions to follow, you should seldom have any difficulty assigning one definite propagation mode to each DX catch.
		Sporadic E skip (Es): Es has a set of characteristics which, when taken all together, set it apart from all other forms of DX propagation.
	www.beaglebass.com /dx_tv_index.htm (7125 words)

	Identifying Unique and Specific Propagation Modes in the Over-the-Horizon SuperDARN Radar Reflections
		Finally, the OTH research radar data are shown to be a useful tool for propagation predictions in conjunction with the propagation forecasts for the SFI and K-Index levels.
		From the figure above, as an electron cloud propagates away from a magnetic pole, each individual electron within the cloud is trapped along a respective magnetic flux line so that the electron cloud expands reducing the total ion density proportional to the square of the distance from the magnetic pole.
		Dense ion clouds formed by the convergence of the magnetic flux lines near the magnetic poles are believed propagate equatorward under the influence of Atmospheric Gravity Waves for each of these propagation modes (note: Atmospheric Gravity Waves are large wavelength neutral pressure waves extending into the thermosphere and not Einstein's gravity).
	ecjones.org /radar.html (1396 words)

	DX Radio - July 2002 DX News
		Propagation - Overnight tropo to the north, in the morning tropo to the West of England and Wales.
		Propagation - Some meteor overnight, then again a weak Sporadic E to Spain and Portugal at the bottom of the band.
		Propagation - Weak Sporadic E to Italy the bottom of the band in the afternoon which then moved to Spain.
	www.dxradio.co.uk /dx200207.html (662 words)

	DX Radio - Full archive
		Propagation - Sporadic E opening to Italy up to 108 MHz in the early afternoon for a few minutes, followed by a later opening to Croatia which stayed near the bottom of the band.
		Propagation - Sporadic E to Eastern Europe, the after a little gap E's at the bottom of the band to Italy before the skip lengthened to Greece.
		Propagation - First Sporadic E of the year, and it was to Greece and Italy.
	www.dxradio.demon.co.uk /dxarchive.html (6750 words)

	DX Radio - 2003 DX News
		Propagation - Sporadic E briefly to Italy in afternoon.
		Propagation - Sporadic E to Italy, but fairly brief and confined to low end of band.
		Propagation - Brief Sporadic E to Italy in mid-afternoon.
	www.dxradio.co.uk /dx2003.html (1226 words)

	K9SE E-Layer Propagation Assessment Page
		Sporadic-E propagation at 144 MHz and higher is much less frequent than at 50 MHz.
		Another mode of long-distance propagation at 144 MHz is by scatter from field-aligned irregularities (FAI).
		User feedback pertaining to actual propagation conditions and whether or not these programs provided correct analysis is requested.
	mywebpages.comcast.net /k9se (283 words)

	TV FM DXing
		It is not surprising that the FCC thought that TV and FM frequencies would be immune from long distance propagation, because the conditions that produce it are irregular, comparatively rare events.
		It is possible to track the movement of a sporadic-E "cloud" by noting the locations of stations that fade in and out on a frequency as the cloud moves.
		Tropo propagation is caused by temperature inversions in the troposphere, the region of the atmosphere closest to Earth where all weather takes place.
	www.dxing.com /tvfmdx.htm (1304 words)

	ARRLWeb: The K7RA Solar Update (Site not responding. Last check: 2007-10-13)
		On the k1six.com link, the dates may be a bit confusing, because the title says the graph covers the period from 1995 to present, but the dates along the X axis run from early May to the present.
		It illustrates when sporadic E propagation across the Atlantic is the most common--in late June and early July.
		He has personally logged more than 3000 FM broadcast stations via sporadic E, and a few hundred of those were 1450-1500 miles distant.
	www.arrl.org /news/stories/2005/08/19/2 (506 words)

	Propagation Studies Committee of the Radio Society of Great Britain
		To promote and encourage research by amateurs and listeners into radio propagation, whether to expand their own understanding or to publish the results to the amateur community or, even more desirably, a wider professional audience.
		The current problem was a lack of propagation on the 6 and 10m bands and the consequent difficulty in finding interesting topics for discussion.
		A monthly report on 28 and 50MHz propagation sponsored by the Propagation Studies Committee.Its purpose is to report, analyse and discuss propagation on the 28 and 50MHz bands and its relationship to solar-geophysical events.
	www.keele.ac.uk /depts/por/psc.htm (7115 words)

	The BeamFinder radio propagation analysis software
		This type of "problem" also occured in the May 20, 2003 analysis resulting in a second paper which deals with predictions on double hop sporadic E propagation on very high frequencies.
		BeamFinder says, for example, we may expect 144 MHz QSOs between the southern tip of Norway and the island of Crete and we may also expect similiar dx QSOs between northern Germany and the Caspian Sea.
		Surprisingly, this is no prediction at all because this type of very long distance propagation was indeed reported in recent years - it was actually reported more than once, in fact.
	www.beamfinder.net (629 words)

	ARRLWeb: W1AW Bulletin ARLP035 (2005) (Site not responding. Last check: 2007-10-13)
		It illustrates when sporadic-E propagation across the Atlantic is the most common, in late June and early July.
		Doug Allen, W0AH of Woodland Park, Colorado wrote to say that receiving FM and TV stations from over 1000 miles away via sporadic-E propagation is fairly common in the summer.
		For more information concerning radio propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service propagation page at, http://www.arrl.org/tis/info/propagation.html.
	www.arrl.org /w1aw/prop/2005-arlp035.html (385 words)

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