This comment applies only to a counterpoise which is a good to excellent
ground radial field for 160, and resonant L's. It does not apply to L's
over FCP's or elevated radials resonant on 160.
To make a double L work over the aforementioned good to excellent 160 meter
ground radials, feed the two L wires in parallel, and leave them in
parallel. On 160 the 160L will show 20-40 ohms resistive, and the 80 L will
present a highly reactive Z, 5-10 ohms resistive and 400-800 ohms reactive.
The current will vastly prefer the 160 wire.
On 80, the 160 wire will show a feed Z which can a resistive component
anywhere from 600-3000 ohms resistive depending on frequency. The current
will flow to the 20-40 ohm resistive 80 L.
When you get away from the resonance center, the behavior will depend on
other factors because the voltages and currents will be so strange. To
examine that, a careful modeling of everything conductive around will be
needed to make enlightened SWAG.
This arrangement will not work for other high-performing non-resonant L
solutions for 160 and 80, and cannot be used in any simple configuration
(without relay switching of counterpoise and connected L wires) with FCP's
or simple 160 elevated radials.
73, Guy K2AV
On Mon, Oct 17, 2016 at 12:32 PM, Mike Furrey <mikefurrey@att.net> wrote:
> Hi Art,Yes, I have done that and am doing that. I use tall trees as
> supports and the 160 inverted L goes up one side of the tree then bent over
> horizontally to another tree over yonder. From the same feed point, the 80
> meter section goes up the other side of the same tree and the top actually
> folds over an upper limb down to the tie point. I have had the antennas
> separate and had them from the same feed point as I do now and I have not
> seen much, if any difference in performance. With 600 watts output I have
> about 165 countries on 160 and about 220 on 80 from a small suburban lot in
> Houston. I just installed the same antenna in TN and it has worked quite
> well there. I feed it through a ferrite bead balun and I have one elevated
> (up about 20') per band.Hope this helps. 73, Mike WA5POK
>
>
> On Monday, October 17, 2016 10:17 AM, Art Snapper <art@nk8x.net>
> wrote:
>
>
> I was considering adding a second vertical element to my 160 inverted L.
> This one would be roughly a quarter wave tall for use on 80.
>
> I tried modelling in Eznec, but wasn't comfortable with the results. I may
> have screwed it up.
>
> Has anyone tried it for real? Is it a big compromise on either band? Would
> a switch at the feedpoint have any benefit?
>
> My inverted L has about 50 radials.
>
> 73
> Art NK8X
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