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Date: Tue, 21 Jun 2011 14:45:32 +0100
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Subject: Re: LF: PA0RDT polarisation
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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 point me to where the discussion has already been archived :-)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
>
>
>
>