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Re: LF: PA0RDT polarisation

To: [email protected]
Subject: Re: LF: PA0RDT polarisation
From: qrss <[email protected]>
Date: Tue, 21 Jun 2011 14:45:32 +0100
In-reply-to: <7C83B6E4275F422A83872B7E0134B689@Hugh>
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Hi Hugh

Let me get in before the experts and we can maybe all learn some more.

Polarisation is vertical, its a capacitive probe. Like all antennas it needs an earth or a counterpoise etc. Two identical PCB patches could be used as a dipole. As designed, yes, it uses the coax which can be earthed, I think the design details show it earthed prior to entering the shack. The coax picking up signals is true, again I think the design shows an isolating transformer. Positioning of an E-Probe for best performance is a case of much experimentation.

73 Eddie G3ZJO

On 21/06/2011 13:59, Hugh_m0wye wrote:
Hello Group,
My apologies if this topic has already been covered, but I have trawled back
through many LF E-mails and can't find any discussion of it.
I have been persuaded to build a PA0RDT miniwhip by Chris G4AYT, and I am
most impressed by its performance so far.
It is not yet in an ideal location, but the weather has not been brilliant
for out-door activities ...

My question is what is its polarisation ? And leading on from that what is
it acting "against"?
I have reaad that it is an E-field probe, but I assume that an E-field probe
is just a very short dipole.
So if the patch of pcb is one arm of the dipole, is the rest of the circuit board and the feed cable the other half of the dipole, and so does this then
form part of the antenna ?  In which case the instruction to place the
antenna outside the building is rather a strange one, as the coax feeder
would also be receiving signals right back to the radio in the shack.

I tried moving the coax around while the antenna was fixed, and it didn't
seem to have much effect on reception.
I would guess that when the antenna is mouted as described that it is most
sensitive to vertically polarised signals - but I don't think I have seen
that written down anywhere.

Your thoughts on this would be much appreciated - (or perhaps someone could
point me to where the discussion has already been archived :-)
73
Hugh M0WYE







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