[Elecraft] The "Kinda Random Antenna" (was: Random wire lengths for antennas)

[Barry]

Wayne,
     I know what you are saying and agree. In very simple terms, if you 
can load it, it will radiate. That was a position that a writer with the 
nom de plume of Kurt N Sterba too in a book he wrote. By the physical 
law of conservation of energy, it all has to go somewhere. And, that 
could be heat or radiation. In his book he claims to have loaded a 
shopping cart and talked to people.

     Yes, you can do these things as long as you make good connections 
and the tuners can handle it. All of the discussion is how to pick a 
length that the tuner will accept. Once there, physics takes over. And 
just to prove my point, and yours, I just worked the CQ 160 CW contest. 
My antenna was a vertical 20 meter dipole center fed with open wire. My 
radio is a K3s. I worked across this country, Canada, and some DX with 
this 33' wire antenna that by all rights should have been over 200'. I 
would have done better, but my local power company added another 
handicap, line noise. Bottom line: Throw some wire up and see if it can 
be loaded. If yes, go for it.

73,
Barry
K3NDM

------ Original Message ------
From: "Wayne Burdick" <n6kr at elecraft.com>
To: "Tom McCulloch" <thom2 at att.net>
Cc: "Elecraft Reflector" <elecraft at mailman.qth.net>; 
"KX3 at yahoogroups.com" <KX3 at yahoogroups.com>
Sent: 1/29/2017 12:40:58 PM
Subject: [Elecraft] The "Kinda Random Antenna" (was: Random wire lengths 
for antennas)

>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
>
>
>On Jan 29, 2017, at 7:55 AM, Tom McCulloch <thom2 at att.net> wrote:
>
>>  I guess we need an alternate definition of "random" ;-)
>>
>>  Tom
>>
>>  wb2qdg
>
>
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