[Elecraft] Small QRP antenna

[Wes Stewart]

Except for what I'm about to say, what Jim says in his first sentence is true, 
which of course includes his post:-)

The velocity of propagation in a wire, near to, on, or below the ground is 
different from the same wire in free space.  How different?  Most people don't 
know, don't care or couldn't determine it if they wanted to.  But it has been 
shown that for these radials, especially when few in number, efficiency actually 
/improves /when their lengths are less than 1/4 lambda. See: "Experimental 
Determination of Ground System Performance for HF Verticals...", by Rudy 
Severns,* N6LF, QEX, Jan/Feb 2009 pp 48-52.

* I can't recommend highly enough Rudy's work on vertical antennas. 
http://rudys.typepad.com/  He writes this stuff faster than I can read it.

Wes  N7WS

On 12/29/2016 11:58 AM, Jim Brown wrote:
> Nothing in this post is true. Optimum length for a counterpoise is a quarter 
> wave. Radials are a form of counterpoise, and their optimum length is also a 
> quarter wave. More radials reduce ground losses. Failing to provide an 
> adequate counterpoise will cause the antenna's return current to flow on your 
> coax, which makes the rig hot with RF. That's not much of a problem with 5W, 
> but it can be a very big deal with 100W or more.
>
> Of course, it does depend on what you mean by "much" and "minimal." Inadequate 
> counterpoise or radial systems can easily reduce you signal by 6 dB. That's an 
> S-unit, and it reduces your 5W signal to 1.25W.  I wouldn't call that minimal 
> or "not much."
>
> 73, Jim K9YC
>
> On Thu,12/29/2016 7:30 AM, Fred Moore wrote:
>> With an end fed 1/4 wave you only need a counterpoise that is about .05
>> wave length.  it can be the coax or another counterpoise. Although a
>> counterpoise has some effect on radiation pattern of a quarter wave
>> radiator, it is minimal.   You won't see much improvement in performance
>> by going above .05 wave length..  it's not worth the trouble to increase
>> the counterpoise length..