[UK-CONTEST] Propagation OT

Thu Dec 27 19:41:57 EST 2007

Good to know that someone is aware of the phenomenon anyway. Better not 
quote the calls of those "denyers" for the sake of propriety if no other 
;-)

Logically, the occurrence at the winter solstice might indicate that it 
is not due to intense illumination of the E layer around the summer 
solstice as we have perhaps traditionally thought, because as we know it 
doesn't really start until late April and is usually gone by early 
September, at which times the radiation levels must be hugely more than 
at the winter solstice. Also we know I think ( tho' I am a newbie in VHF 
terms) that it is not more intense at sunspot maxima, indeed the really 
DX paths to e.g. JA and particularly KL7 have been better during the 
current sunspot minimum, although they never penetrated the barrier to 
my antennas :-( .

One conclusion might be that radiation levels are sufficiently intense 
at all times of the year, but that some opposing effect is at a minimum 
around the time of both solstices, although more obvious during the 
summer period. Could this perhaps be some kind of geomagnetic effect 
such as we know and love ( NOT) in F layer HF propagation. Is there e.g. 
any evidence that Es is inhibited during the geomagnetic disturbances 
that occur so regularly during sunspot maxima? Sadly my own experience 
at 6m is too recent to opine on the matter, but I am not aware that this 
is a known factor affecting e.g. 10m, with which OF NFD operators like 
myself are so familiar.

More questions than answers, but there must surely be some propagation 
gurus amongst contest operators?

73

Clive
GW3NJW

Darrell G0HVQ wrote:
> "I had read that in the USA that they have  worked inter-state Es around the 
> winter solstice on 6m, although several eminent 6m ops on this side had 
> never heard of it. " .....
>
> Wonder which 6m ops you've spoken to, because this 6m (& 10m) op knows that 
> the winter Es season is regular as clockwork, just like the summer one, 
> though of lesser duration & intensity ;-) I work stations every year on 6m 
> and 10m via this mode, usually only catch 1 or 2 openings though, that 
> typically last a few hours. The 'season' can start around late Nov and go on 
> into early Jan.
>
> Don't ask me to explain it, but it's there every year around the winter 
> solstice, usually after dark too unlike the summer occurences which mostly 
> occur in the daytime. Guess we don't notice it so much when there are more 
> sunspots, due to other forms of propagation.
>
> Yesterday's opening was interesting as, despite opening to the East from the 
> UK on the higher bands, it seemed to extend propagation to the west on 20m 
> (either that or it was a coincidence) - rather than closing at or before 
> dusk, 20m and 17m were open to the US a couple of hours after darkness fell.
>
> Has anyone really got to the bottom of what causes Es? I've read various 
> conflicting theories over the years, none of which was really conclusive.
>
> 73
> Darrell G0HVQ
>
>
> ----- Original Message ----- 
> From: "Clive Whelan" <clive.whelan at btinternet.com>
> To: "UK Contest Reflector" <uk-contest at contesting.com>
> Sent: Thursday, December 27, 2007 7:31 PM
> Subject: [UK-CONTEST] Propagation OT
>
>
>   
>> Well not as OT as QSLs and RSGB HQ move,- that's my excuse!
>>
>> How on earth can we explain Es propagation this evening extending from
>> 50Mhz all the way down to 14Mhz by 19:00z?
>>
>> I abhor the whole cluster ethos, but I have to admit that I was alerted
>> to this phenomenon by a local cluster watcher who reported spots for 10m
>> around 18:15z. Sure enough, flip the rx to 10m, and with the antenna
>> cranked down to 15ft and pointed due West, there were S9 DLs. I tune the
>> rx to 50Mhz, forgetting that the antenna was still the HF beam ( pointed
>> West at 15ft), and there was an OM and a gignormous S9 DL station. When I
>> twig the antenna error, I listen on the 2 el 6m quad, and the band is
>> full of Russian(?) video signals, but strangely no beacons. Where is the
>> quad pointing? Good question, but in the pitch black here out in the
>> sticks I have no idea until I go downstairs and switch on the outside
>> light; probably it's unimportant.
>>
>>
>> Now we all know that Es occurs around the summer solstice ( +/-) and we
>> can see the logic in that. I had read that in the USA that they have
>> worked inter-state Es around the winter solstice on 6m, although several
>> eminent 6m ops on this side had never heard of it. Well, it's here today
>> alright. What on earth is the technical basis for this when the sun is
>> overhead about as far South of the equator as it can get, and therefore
>> in theory can be exerting little influence on the E layer in highish
>> latitudes in the Northern hemisphere. Oh yes, after dark to boot!
>>
>>
>> Methinks Es is not quite what it seems, but what it really is I confess
>> I have no idea. My brain is hurting now, so I think I'll see if there
>> are any mince pies left in the pantry; perhaps that's help? ;-)
>>
>>
>>
>> 73
>>
>>
>>
>> Clive
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