[Elecraft] dipole antenna efficiency

[David Yarnes]

----- Original Message ----- 
From: <N2EY at aol.com>
To: <k0pp at acninc.net>; <elecraft at mailman.qth.net>
Sent: Saturday, January 05, 2008 7:28 AM
Subject: Re: [Elecraft] dipole antenna efficiency


> In a message dated 1/4/08 4:34:29 PM Eastern Standard Time, 
> k0pp at acninc.net
> writes:
>
>
>> I've never understood the popularity of the G5RV.  It's
>> achieved a sort of "cult" following.
>
> It's an ingenious compromise antenna for several bands, that's all.
> Actually, just a ~102 foot dipole with a matching system that gives
> "low" (but not unity!) SWR on several HF bands, so that a simple
> ATU can match it.
>



Well, it depends on what your definition of "low" is.  The SWR is below 2:1 
on only 1 band--20 meters.  On others it goes to 5:1 or more on most of the 
non-WARC bands, and is almost unusable on 30  and 17 meters.  That is, 
unless you use a tuner!  Use of a tuner is really the big bone of contention 
usually.  This antenna has been described as not requiring a tuner, when it 
really does need one for the most part.  Even Varney anticipated that as he 
has discussed in several articles.

Another problem is that, although Varney described his antenna sufficiently, 
so many variations have been born (but still are called "G5RV's"), in an 
attempt to improve the SWR on one band or another, that the "real G5RV" 
isn't even described that much anymore.  SWR can be improved on various 
bands, but usually at the expense of the SWR on another band.  Cebik 
describes a pretty good variation on his website.  As I understand it, 
Varney's objective was primarily to add 20 meters to an antenna that would 
also load acceptably on 80.  But he never intended for this to be a 
"tunerless" antenna from 80 through 10 meters.

Dave W7AQK