What makes you think the wire isn't doing the bulk of the radiating just
because it drags across the ground? Actual RF ground is usually some
distance below the surface, sometimes several feet.
There is a way to prove me wrong on all of this. Connect two AX1's to a
Tee connector coming directly out of the rig. Position them vertically
so that they act like a vertical dipole. Use the rig's antenna tuner
to make sure full power is getting to the combination. Have somebody
measure the signal strength at different positions around a circle some
distance from the rig/antenna.
Now replace the lower AX1 with the recommended 13' piece of wire, again
using the antenna tuner to hopefully feed the same amount of power to
the AX1. Take the same signal strength measurements ... again around
the circle in order to try to take into account any directionality of
the wire if it isn't mostly vertical.
If the AX1 by itself was doing most of the radiating the 2nd AX1 would
be a better counterpoise than the wire. That's not debatable.
73,
Dave AB7E
On 8/27/2019 4:07 PM, Wayne Burdick wrote:
I'm generally walking when I use the AX1 (pedestrian mobile, or /PM). It isn't
possible to elevate the radial under these circumstances; it drags on the
ground. The whip is the radiator.
Wayne
N6KR
On Aug 27, 2019, at 3:05 PM, David Gilbert <[email protected]> wrote:
I'll try not to beat this into the ground here, but I think the physics here is
important.
As K9YC said in his reply to you, equal currents go in both directions from the
feedpoint ... to the AX1 and to the counterpoise wire. That's simply physics,
and it's true unless currents on the shield of the coax cause imbalance ... in
which case the coax is doing a bunch of radiating.
Now then, what is important is what happens to those equal currents. It doesn't matter
if one side of the feedpoint is the AX1 or if it is the "counterpoise" wire ...
they are both simply loads as far as the feedpoint is concerned. Read that again ... it
is THE critical concept.
Current generates a radiated field. That is simple physics. Resistive loss dissipates energy
instead of radiating it. That is also basic physics. To a lesser extent, current distributed over
a longer length is a more effective radiator than a shorter length even disregarding impedance
concerns. Consequently, a short, lossy "load" is going to radiate less RF than a longer,
less lossy "load". Straighter is better than snaky. All of that is fact.
Unless you have a very short counterpoise wire it is going to try to do a
better job of radiating RF than the AX1 if you give it a chance. Keep it as
straight as possible and keep it clear of ground and other RF dissipating
structures.
That doesn't mean that the AX1 isn't serving a very useful purpose. It is. It is
allowing you to feed current into the "counterpoise" wire with a reasonable
feedpoint impedance. That's critical. But it doesn't mean that the AX1 is doing the
bulk of the radiating unless you aren't using a counterpoise at all.
Hope this helps. 73,
Dave AB7E
On 8/27/2019 2:29 PM, Grant Youngman wrote:
I’m not saying that an elevated counterpoise won’t work with the AX1, just that
I’m having trouble getting my head around considering the wire as the main
radiator, and the AX1 as a counterpoise???
Grant NQ5T
KX3 (8342)/KXPA100
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
