[Elecraft] Small QRP antenna

[Fred Jensen]

Ron is correct ... however my experience is that the rig, headphone 
cable, power cable from the battery, and me [holding the KX1] is more 
than sufficient.  For mine at home, it is fed with about 25 ft of coax, 
the shield of which serves that purpose.

If you attempt to model it with NEC-2, and all you care about are the 
radiation patterns, you don't need a counterpoise in the model.  While 
NEC-2 *really* doesn't like a source connected to the end of a wire, it 
only affects the source impedance values.  If you want those to be 
reasonably accurate and real, a short wire is necessary ... anything 
over a few feet seems to work just fine and is in no way critical.

Fred K6DGW
Sparks NV DM09dn
Washoe County

On 12/28/2016 3:43 PM, Ron D'Eau Claire wrote:
> While the efficiency as a radiator of a half wave end fed wire is relatively
> unaffected by the "ground" return, some sort of "ground" is needed to keep
> the whole rig from floating up to the RF potential at the end of the
> antenna. Often a hunk of wire roughly 1/4 wave long thrown on the ground is
> adequate.
>
> I too have had excellent results with them.
>
> 73 Ron AC7AC
>
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Fred
> Jensen
> Sent: Wednesday, December 28, 2016 12:57 PM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] Small QRP antenna
>
> The Summits On The Air crowd, at least one of whom "runs" up mountains, has
> had very good luck with end-fed half-waves.  The transformer weighs next to
> nothing, and the rest is just wire. Requires no counterpoise, very ground
> insensitive since it's fed at a voltage node.  Also because of that, you
> need no coax, just an adapter between rig and transformer.
> The higher you can get the middle [current node] the better, but it will
> work very well with just about any elevation on the far end.
>
> For 40, it's about 67 ft of wire, and is a full-wave on 20 and will work
> well there.  My KX1, when I still had it, had no problem finding a match.
> My HOA-Stealth here at home is an 80-10 EFHW strung about 6 ft high along
> the top of a wooden fence.  Works surprisingly well.
>
> Fred K6DGW
> Sparks NV DM09dn
> Washoe County
>
> --Northern California Contest Club
> --CU in the Cal QSO Party
> --7-8 Oct 2017
>
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