I have been intrigued by Sporadic-E propagation since my youth and experiences with TV-DX-ing ( seen an earlier post that details those exciting days!) I don't know if anyone has a definitive answer as to just what causes Sporadic E, though there has been speculation ranging from thunderstorms to short, high bursts of energy from the sun to “just because” or “they just happen”.
In any event, they do occur and appear
to be the result of high ionization areas or clouds in the E layer
that appear sporadically ( hence the name). These openings result in
localized higher than normal maximum useable frequencies that can
affect signals beginning about 2 mHz up through the VHF range.
Activity up through six meters and up to about 70 mHz is fairly
common, though there have been occasions of Sporadic E extending up
into the FM broadcast band ( 88-108 mHz in the U.S.) or even
occasionally up into the 2 meter amateur band ( 144 mHz).
I have noticed the best Sporadic E
openings beginning in the month of May and extending throughout the
summer, to about mid August in North America. At least that is the
time frame I have made the most loggings by this mode. That is not to
say that such openings do not occur other times of the year. I have
noticed a few even in the dead of winter. Others may have noticed
more in other parts of the year. My observations might also have
been affected by the time I had available to look for them or just
lack of noticing.
I had begun tuning up through six
meters back in April, looking for beacon signals, but other than the
local ground wave available signals had not heard anything. I had
also begun checking DX Summit for such things.
It was just such a check that led me
to tune up to six meters this Sunday (18 May local time) I had not
been in front of the radios on Saturday because of a trip out of town
to one of the grandbaby's birthday party ( this IS just a hobby and
there ARE priorities!! :-) ). But after getting back late Saturday
night and before getting into bed about midnight ( the 200 mile
trip each way in one day is rather tiring) I did make a check of DX
Summit to see if there had been anything unusual. There I found a
number of entries of 6 meter activity that had continued not just
through the day but well into the night.
Sunday afternoon was the first time
that it became possible to get in front of the radios. Just a quick
tune through the band resulted in the “find” of a strong SSB
signal on 50140 in the form of AG6V at 2206 GMT, then going back down
the band, a very strong CQ on CW from XE2CQ ( nice call!) above S-9
on 50104 at 2211 GMT. Over the next few minutes the following
stations were heard. Times are, of course, GMT.
2212 AI6O 50097.14 CW 579QSB “CQ”
2216 AA4CF 50097.54 CW 559 “CQ”2219 KD4AOZ/B 50061.26 CW 559QSB BEACON
2222 K4TQR 50050.34 CW 569 BEACON
2227 N4LR/B 50068.42 CW 549 BEACON
2228 WN6K 50098.00 CW 559 “CQ” DM13
2230 N4KH 50097.4 CW 599QSB “CQ” EM64
2233 XE1RCS/B 50019.43 CW 549 BEACON EK09
2242 N4LR/B 50068.41 CW 569 BEACON EM73
Further tuning around at that time resulted in no new signals, but Sporadic E lived up to its name: signals would go from barely audible to over S-9 in seconds, stay up there perhaps a minute, then plunge to the edge of audibility.
By the way the set up for logging
these stations was the Icom R-75 in the wide cw bandwidth or the wide SSB bandwidth and
connected to an 80 meter sloper at the high end up about 45 feet,
sloping down toward the East. I am in Waco, Texas in EM11.
After an hour or so break, I came back
to the radio just to see if the band was still open. Surprisingly, it
was! Some signals were surprisingly strong, especially since I had
not set up the feedline for the antenna for VHF work. Normally for
day to day HF work the antenna comes to the shack in about a 175 foot
run of RG-8X routed out of the way around the edge of the yard. The
line loss at the lower HF frequencies is tolerable in that length of
line. Usually when I plan to listen on 6 meters, I disconnect the
longer line and run the shorter 75 foot line directly across the
yard, suspended across what is normally a walkway to reduce the
losses. Of course it cannot be left that way. Perhaps this summer
another support will have to sprout next to the shack window by the
house with a “proper” six meter antenna on it and a short length
of heliax to feed it.
This time, the Mexican and West coast
stations did not appear, and interestingly, some Texas stations only
moderate distances were heard. I am certain they were not coming
ground wave, but perhaps by Sporadic E back scatter. The distances
from Dallas, New Braunfels and San Antonio were far too short for
Sporadic E into Waco. I am not sure about one particularly strong
station heard from Brownsville at the far southern tip of the state.
Here are the loggings, again with
times GMT, and now past 7 PM local CDT and into May 19 GMT.
0047 KS4L 50095.6 CW 559 “CQ”
0053 W0OOG 50097.6 CW 549 “CQ”0054 AB4B 50095.27 CW 589 “CQ” EM64
0055 K5HTI 50125.6 USB 55
0056 K5HGX 50125.6 USB 55 EM11
0056 W9CAR 50125.6 USB 58/59 TN
0057 AB4B 50132.7 USB 57 “CQ”
0058 N4IM 50132.7 USB 54
0059 W4BAB 50145.7 USB 57
0104 AA9RN 50155.2 USB 57
0105 AB5EW 50150.2 USB 56 EL09
0105 W4BAB 50150.2 USB 57
0106 NE4TN 50150.2 USB 57
0108 W5QQ 50132.9 USB 55
0110 KA5GNM 50130.3 USB 58
0112 W4AQQ 50132.7 USB 58
0112 AB4B 50132.7 USB 58
0122 K4EJQ 50095.8 CW 599 RUNNING 1 KW AND 6 EL.
0123 AF5FM 50098.6 CW 579
0125 AB5EB 50150.5 USB 55 EL09
0129 W4VAS 50145.25 USB 56 EM74
0129 W4SOH 50145.25 USB 57 EM76
0131 K4MVL 50145.25 USB 57
0132 W3DP 50125.25 USB 57
0134 N9JED 50125.25 USB 55
0134 W4IMD 50125.25 USB 59+
0136 N4BAF 50135.15 USB 57
At this point, other activities required the listening session to end. I noticed on DX Summit the next day during daylight and early evening in Europe, many postings of stations working over similar or greater signals. I noticed several times stations calling CQ with no takers. Perhaps many people were unaware the opening was even occurring!
This is, indeed, Sporadic E season,
such as I enjoyed in my young days of TV DX-ing, but with six meters,
the band can appear open even when the Maximum Useable Frequency
would not be high enough to even put a single rolling bar through an
analog tv picture!
I would be very interested in hearing
some of your signals heard on six meters the past few days and in the
days to come. Just drop a note through comments. Include your email
address if you want ( it will not be posted, all comments are
reviewed before going up) and I will email you back with my personal
email address. I would be interested in hearing about the openings
and would also be happy to add your loggings to a future posting on
the blog! The same goes for DX on any other mode, as well...HF
amateur DX, Shortwave Broadcast, Medium Wave Broadcast, TVDX or
NDB's. Would love to hear from you!
73 and good listening!
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