Rain effects: E.M.E...
#1
Hi All,

Does anyone have any information about rain effects on Yagi arrays when used for E.M.E. on receive ?

During my 436 MHz observations of the Vela pulsar I notice when the antenna is wet there is a significant drop in received signal strength (during light rain the signal virtually disappears).  The antenna is a long Yagi (5.7 m).  I had thought that, while return loss is affected significantly, gain is less affected by water on the elements.  I have done some preliminary tests by keeping the driven elements dry, but the effect still seems to be there.  I ask for E.M.E. observations on this point as the loss of a few dB in sensitivity would be noticeable - just like my Vela pulsar observations.

Steve

Vela Pulsar observations...
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#2
hi.

To get some response you might have better luck using the email reflector service...

http://mailman.pe1itr.com/mailman/listinfo/moon-net

John
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#3
(12-01-2018, 08:06 AM)VK2FAK Wrote: hi.

To get some response you might have better luck using the email reflector service...

http://mailman.pe1itr.com/mailman/listinfo/moon-net

John

Thanks John.

Good idea.

Steve
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#4
Rain static QRM will obviously increase the SNR, you didn't mention if that was happening or not.
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#5
(12-01-2018, 10:40 AM)VK2KRR Wrote: Rain static QRM will obviously increase the SNR, you didn't mention if that was happening or not.

Hi Leigh,

As far as I can tell it is not rain static as it appears to persist after rain has stopped - but the antenna is still wet.   The antenna is pointing almost straight up so all elements (both polarisations) are essentially horizontal such that water hangs onto them.

Steve
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#6
Steve,

Perhaps this might go some way towards answering your question:

http://www.qsl.net/yu1aw/Misc/wetantenas.pdf

I have not read it yet myself, but from a cursory glance it appears very interesting.

Cheers,
Chas
VK3PY
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#7
(12-01-2018, 06:41 PM)VK3PY Wrote: Steve,

Perhaps this might go some way towards answering your question:

http://www.qsl.net/yu1aw/Misc/wetantenas.pdf

I have not read it yet myself, but from a cursory glance it appears very interesting.

Cheers,
Chas
VK3PY
Hi Chas,

Yes - that pretty much covers it.

Thanks !

Steve
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