Propagation: sporadic E skip (Es)

   
 
ham | what is new | links
 Welcome to Www.Hampedia.net  submit to reddit
23 February 2017, 12:33 UTC 


SDR


ELAD
SDRplay

Transceivers


Kenwood
Midland
Yaesu
Alinco
Icom
Other

Antennas


M2
Par
Gap
Sirio
Araki
Maco
Nil-Jon
Maldol
Comet
Hustler
Nagoya
Watson
Hy-Gain
Dressler
Cue Dee
Solarcon
Diamond
Cushcraft
Quicksilver
Moonraker

Power supplies


Powerbox
Kenwood
Diamond
Samlex
Mascot
Daiwa
Yaesu
Alinco
Icom
H&H

Rotators


M2
CDE
Yaesu
Create
Kenpro

Antenna tuners


MFJ
LDG
SGC
Icom
Yaesu
Mizuho
Dentron
Kenwood
Sommerkamp
Barker & Williamson

Repeaters


GME
Icom
Zodiac
Kenwood

Transverters


Microwave Modules
Tokyo Hy-Power
SSB Electronics
Tecnostudi
Kenwood
Yaesu
Minix

Meters


Diamond
Comet
Bird
MFJ

Ham resources


Propagation:
  Sporadic E skip (Es)
  Backscatter
  Tropo
  Meteor Scatter (MS)
  F2 Skip
  Aurora
  Trans-equatorial scatter (TE)
  Lightning scatter (LS)

Propagation
by Glenn Hauser 
News

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. It builds up from low frequencies to a certain maximum usable frequency (MUF) which may vary widely from minute to minute, and opening to opening. Es always hits the lower frequencies first. It may or may not get above channel 2. Of course, if the skip is coming from a sparsely populated area, there may be no channel 2 transmitter --- so check channels 3 and 4 as well. A good opening will not stop at channel 6, but may continue upward into the FM band which begins immediately above channel 6. An extraordinary opening may even continue into the aeronautical band above 108 MHz, through the "2 meter" (144 MHz) ham band, past the heavily-populated 2-way mobile bands, even up to channel 7 --- 180 MHz! An Es opening reaching channel 7 is a rare treat; high-band (TV channels 7-13) Es may even poke a channel or two above 7. Usually, highband Es can be ruled out when the skip is not extending above channel 6 into the FM band.

In general, as Es distances shorten on the low band and FM, the opening is becoming more intense and the MUF goes up. As experienced Dxers can attest, Es at 1000 miles is much more common than Es at 600 miles. The usual minimum distance for Es is about 500 miles. 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 occurs when patches in the E layer of the ionosphere, about 65 miles above ground, become ionized. This layer normally refracts shortwave and mediumwave signals but is transparent to VHF radiation. The cause of Es ionization is not precisely known; some researchers connect it with low pressure areas and thunderstorms. However, it has no direct connection with surface weather, and the novice's association of Es with regular clouds in the sky is completely erroneous.

For once thing, the Es patch must be at approximately the midpoint between the transmitter and receiver, far beyond the visible horizon. Sometimes the patches remain fairly stationary, but usually they move at speeds up to several hundred miles per hour, more or less in a straight line. This means that one station after another will come in, with quite a lot of interference as they overlap.

They will probably be in a rough geographical progression, but not in a straight line. One can plot the midpoints on a map, and by correlating observations with other DXers viewing at the same time from other angles, pin down the Es patch with a degree of accuracy. This can prove useful in determining probable target areas (PTAs).

Long single hops of Es can reach about 1500 miles. Double-hop or cloud-to-cloud hop Es often occurs during the summer when more than one Es patch may be active simultaneously, in different parts of the continent. The two patches, the station, and you must all be along the same line. However, not too many stations are identified by double-hop Es for several reasons:

(1) Interference: the TV and FM bands are so congested in North America that there are usually stations on the air near the double-hop path midpoint, severely interfering with further stations.

(2) The earth is a rather poor reflector of VHF signals, but this it must do at the midpoint. Double-hop Es where the midpoint is water (an ocean or Great Lake) is much more efficient.

(3) The patch with the lower MUF is the controlling factor. For this reason, there's much more double-hop Es on channel 2 than on channel 6 or FM.

Es is very unpredictable, but we do know this much! 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. It can occur on any day of the year; these are known as off-peak openings. The winter solstice also brings a minor peak in December and January, as if some of the Es' fury were "bleeding over" from the southern hemisphere where, of course, the summer peak is in progress. The winter and off-season openings are most likely in the early evening hours. During the main "season", Es may start early in the morning and continue all day, into the night, but it likes to take a breather around mid-morning and mid-afternoon, and seldom lasts much past midnight. If you don't want to miss an Es opening, try checking once or twice an hour just before ID time, or tune a VHF radio paging channel.

Es can be very strong with lots of fading and interference. But strong signals may rival those of local stations and even interfere with them. Es may build up rapidly, over the course of a few minutes, but usually it decays more slowly. Weak openings in which the MUF hovers around TV channel 2 may tantalize you as stations fade in and out.
Es is more likely in southern areas during the off-season, but northerners should not assume that subzero temperatures or snowstorms rule out any DX! Closer to the equator, Es becomes more and more a year-round, daily phenomenon. "Diurnal Es" may provide a weak, scattery signal virtually every day over an Es-distance path. Other strange things happen, such as Es reception at double-hop distances but with the signal bouncing from one path to another without touching ground in between.

 


CB Equipment


President
Midland
Uniden
Zodiac

 Power amplifiers


Beko
Icom
Alinco
Drake
Yaesu
Daiwa
Collins
Kenwood
DanAmps
Ameritron
Autophon
Eto/Alpha
Command Technologies
E.F.Johnson
Dentron Radio Co.

FRS/GMRS


Bell
GPX
ENC
Tekk
Icom
Sony
Alinco
Drake
Cobra
Maxon
Vertex
Conair
Uniden
Jenson
Ranger
Midland
Whistler
Magnum
Unwired
Coleman
Motorola
Audiovox
Memorex
Columbia
Samsung
Standard
Kenwood
Cherokee
Panasonic
Freetalker
Vtech Vtalk
RadioShack
Fanon Courier
Sharper Image
General Electric
Oregon Scientific

PMR446


Sommerkamp
FreeQuency
Goodmans
Kenwood
Lafayette
President
Binatone
Motorola
Multicom
Albrecht
Maycom
Topcom
Xtreme
Ondico
Telcom
Maxon
Vertex
Zodiac
Yaesu
Cobra
Alinco
Icom
Alan
ITT