While Troll'ing the web ...
I came across this post , by G2AJV , note the reference to a alloy or
copper plate below the coil and earthed ..
this was the quantum leap from the counter wound systems that are suspect a
little like the CFA ... (anyone remember shifnell ?) that eliminated the
flash over at cross over .. as there is 'no' crossover and the need to
fabricate an array that was a mirror image of itself ..the conducting plate
acting as a mirror..
G ..
http://web.ukonline.co.uk/g3ldo/coil.htm
I have just read some recent correspondence on this net concerning the pros
and cons of placing the antenna-loading coil in the shack or at the base of
the vertical aerial wire. The loading coil is not just a matching device, it
is also a primary source of vector potential and it is the vector potential,
rather than its offspring, the magnetic and electric fields, which is the
fundamental source of electromagnetic radiation. It is therefore
advantageous to place the coil upright at the base of the antenna.
Furthermore, as a large component of the vector potential is locally
concentrated in this region, it may be possible to gain a few dBs by placing
an aluminium or copper plate, somewhat larger than the diameter of the
solenoid, a few centimetres under the solenoid, insulated from the earth but
it may be connected directly to the TX ground terminal. (It reflects the
vector potential instead of allowing it to be absorbed in the terrain, but
DON'T stand on the plate to adjust the solenoid whilst running at full power
!!!). I appreciate that some readers may not be au fait with vector
potential and perhaps its fundamental role deserves to be lightly aired in
the amateur radio journals.
Roger, G2AJV.
--------------------------------------------------
From: "Stewart Bryant" <[email protected]>
Sent: Sunday, December 07, 2008 6:26 PM
To: <[email protected]>
Subject: Re: !!!Re: LF: Re: E field active antennas
Andy Talbot wrote:
Simultaneous whole band Rx, flat response. And yes, it must be
simultaneous 2 - 30MHz
By all means come down and sort it out for us if you like. But mine
does the job perfectly.
Was only speculating if the helical winding might make any difference.
Andy
Please stop feeding the group troll.
Stewart
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16:55
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