[Elecraft] searching for post by Wayne n6kr about counterpoise

[Walter Underwood]

The manual for the KXAT1 describes this antenna on page 9.

“...for backpacking use on 40/30/20 meters, a wire length of 24-28 feet will generally provide good results. For use on 30/20 m only, as little as 12 ft. can be used, and for 20 m only, as little as 8 ft. Avoid lengths which are close to a half- wavelength long or any multiple thereof, which will be out of the KXAT1's matching range. For example, you should avoid using close to 33' if 20 m operation is planned, or 46' if you'll be using 30 m.

Use a at least one ground radial, cut to at least 1/8th wavelength on the lowest band used (16' on 40 meters). When possible, use two or more radials, with one cut to 1/4 wavelength on each band.”

http://www.elecraft.com/manual/E740054%20KXAT1%20man%20rev%20B.pdf

The KX2 manual has slightly different recommendations on page 10.

"The wire tied to the red post (antenna hot lead) is attached to a tree or other tall support. The wire tied to the black post (radio chassis ground) is the equally important counterpoise, which is typically laid on the ground.

A length of about 25 feet for each wire, matched to the KX2’s output using an antenna tuner (see ATU, pg. 11) will typically provide good performance on 40-10 m."

http://www.elecraft.com/manual/E740282%20KX2%20owner%27s%20man.pdf

I’ve been using 26 feet in the air and 16 feet on the ground.

As for a single counterpoise/radial, there will be more radiation in the direction of the radial. The radial reduces ground losses in that direction. The directions without radials will have more ground loss and thus less signal. 

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Sep 8, 2018, at 6:50 AM, Tom McCulloch <thom2 at att.net> wrote:
> 
> This is probably NOT what you are looking for but it's about random length antennas...it goes back to Jan 29, 2017.
> 
> hope this helps:
> 
> I'd call an ad-hoc antenna that works on multiple bands with an ATU a "Kinda-Random Antenna" (KRA). (Apologies to linguistic purists.)
> 
> A simplified definition might be:
> 
>  A. long enough to work within the maximum limits of the ATU's L-network on the lowest band used
>  B. presents a reasonably low impedance on all bands used (e.g., doesn't look like an end-fed half-wave)
> 
> ATUs have limited monotonicity and granularity, as well as stray impedances, so in practice there is a third criteria:
> 
>  C. tunable on each band used despite specific L-network idiosyncrasies
> 
> This third criteria is the hardest one to predict for a given ATU design, as the idiosyncrasies vary with PCB layout and actual component values. They may only impact the highest bands, or for a particular antenna, the bands on which Q is the highest. For our ATU designs, we try to minimize strays and keep the network monotonic by using tightly toleranced capacitors and toroidal inductors.
> 
> While a wide range of wire lengths will meet the requirements of a "KRA" in the field, we've found from experience that something in the 25'-28' range works on all bands from 40 meters up, and roughly twice this for 80 meters up. Since it's impossible to predict the effect of ground losses, obstructions, deployed wire angles, etc., you may occasionally need to add or remove wire to obtain resonance on all bands used.
> 
> 73,
> Wayne
> N6KR
> 
> 
> Tom
> 
> WB2QDG
> 
> K@ 1103
> 
> 
> On 9/6/2018 11:57 PM, JEROME SODUS wrote:
>> Hello,
>> 
>> 
>> I want to re-read a post that Wayne n6kr made about a wire-antenna tossed up a tree and the location of a counterpoise; this was relative to portable operating a kx2 or kx3, if I recall correctly.
>> 
>> 
>> But my archive search has come up empty.
>> 
>> 
>> My recollection is he recommended placing the counterpoise in a direction opposite to the wire-antenna.
>> 
>> I need to verify that recollection.
>> 
>> Hopefully someone has saved that post.
>> 
>> TIA for any help.
>> 
>> 73 Jerry km3k
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> 
> -- 
> 
> I'm happy to be anywhere -- Keith Richards
> 
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