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Propagation Question?


#1

Morning folks

Going to ask a question here on propagation.
Now Es or sporadic E causes big effects on VHF and UHF signals to travel great distances over the normal distance they travel, quite understand that.

But how low down the bands does it effect, 10m is well known to be effected by it as well 11mb.

Does it have effects on 20m and 15M due to last couple days experiences on air with currant down ward conditions. 
Some rum old signals been appearing such as F/AM738 giving me big signals on 15m and he,s only running 5w and five minutes laters hes disappeared into the noise, EA1/LU-049 signals big time both ways on 20m yet can not hear other Spanish Sota's.

Now and again get good signals from Scottish sotas on 20m normally not heard .And what caught me by surprise was the Welsh Sota on 20m GW/NW-076 on Saturday 324km north away from self here in SE Cornwall 

both good signals. Normally I expect this off 40m band.

So Gents and Ladies is this Es am experiencing or is it something else causing these rare moments..

Many thanks for your time and attention to this one

Karl


#2

We find that if the skip is short on 20m - say I can hear Don G0RQL in Devon or you perhaps (not back scatter - pure skip) then VHF Sporadic E is usually running on 6m and on 2m it can reach as far as Spain / EA8 / Italy.

73 Phil


#3

Hmm interesting stuff

Too me IF Es does effect 20 & 15, its seems to have reverse effect shortening the stations range between two stations. Like on 10m as 10 is well know for long path and DX and to hear more localised say Europeans here it’s Es as were getting at moment.

Hence the Es effect on VHF and UHF is lengthening the station range because its normally short in first place.

May have interesting theory, here love to see it proved or disproved
that,s the Wonders of Es propagation.

Karl


#4

I think short skip on 20 and 15 is caused by Es.

IIRC, Es hinders propagation on the lower HF bands, 80, 60 and 40, causing extreme QSB. It is rare on 2 metres and pretty well unheard of on 70 cm.

Brian


#5

Like that Brain, a theory being question with another added bit.
Very interesting point as to what you say its reverse on the Upper bands of VHF and UHF and increases range, there for reverse on lower bands shorting the range, For we know VHF and UHF signals pass through the F and F2 layers into space and are related to line of sight ruling.

Now you have mentions something here it hinders the prop on 80 60 and 40 might explain why I can’t hear Wales at the moment and usual stuff I hear on 40m AND The Europeans coming in so well during day time at the moment.

Thanks brain you have answered another question bugging me why 40 is so crap at moment.

Wicked

Any one else care to drop in on this rather interesting subject

karl


#6

Two good books for beginners:

Ionospheric Radio by Kenneth Davies
Propagation of Radiowaves, 2nd Edition, Edited by L. W Barclay

Both are university-level texts.