[TowerTalk] Conclusion, G5RV vs. Dipole
n4kg@juno.com
n4kg@juno.com
Mon, 16 Oct 2000 20:54:03 -0600
> He (G5RV) also (mistakenly in my view) believed that on the
> bands other than 20 meters, part of the antenna was "folded"
> into the open-wire "stub." N7WS
THAT explains where all of these "mythical beliefs" came from.
BAD SCIENCE gets published and it never dies. N4KG
IMHO, his (G5RV) best recommendation was to use open wire
line all the way to a balanced antenna tuner. N4KG
Additional comments follow related paragraphs. de N4KG
On Mon, 16 Oct 2000 n7ws@azstarnet.com writes:
>
> At 11:20 AM 10/16/00 -0600, n4kg@juno.com wrote:
> >
> >Unless I am mistaken, there is a HUGE misunderstanding
> >of how the G5RV antenna works.
>
> And how!
>
> >
> >The ONLY way it could act as a Top Loaded Vertical is for
> >the currents in each side of the balanced transmission line
> >to be EQUAL and flowing in the SAME direction. If that were
> >the case, they could be tied together or replaced by a single
> >wire and attached to the two sides of the horizontal wires at
> >the top. I do NOT believe that is the case.
>
> Actually, that is *exactly* what Varney proposed in his original
> 1958 RSGB Bulletin article.
>
> >
> >IF the feed is indeed as a split balanced dipole of various
> >electrical lengths, then the ladderline is acting as a balanced
> >transmission line with EQUAL but OPPOSITE currents in
> >each side and it does NOT radiate.
> >
> >As a balanced dipole, it acts as:
> >
> >3/8 wave (short ) dipole on 80M
> >3/4 wave (long) dipole on 40M
> >2 Half Wave dipoles in phase on 30M (Voltage Node feed)
> >3 Half Wave Long Wire on 20M (current Node at feed)
> >(almost) 2 Full wave LW's in phase on 17M (near voltage node)
> >9/4 wave LW on 15M (neither current nor voltage node at feed)
> >5/2 wave LW on 12M (current node at feed)
> >Two 2WL LW in phase on 10M (voltage node at feed)
> >
> >BTW, as originally designed, the ladderline was meant as
> >an impedance transformer that provided a reasonable SWR
> >on SOME bands (but NOT ALL) without the need for a tuner.
>
> No, the "stub" as Varney called it, was meant as a 1/2 wavelength
> feeder on
> 14 MC/s (the notation of the day). Varney alternatively proposed an
> open-wire feeder from the antenna to the a.t.u. As a matter of fact,
> he actually recommended this for the bands other than 20 meters.
>
> He also (mistakenly in my view) believed that on the bands other
> than 20
> meters, part of the antenna was "folded" into the open-wire "stub."
>
> It continues to amaze me that hams practically worship the idea of
> an
> "all-band" antenna, where "all-band" means that by hook or crook, a
> "match"
> can be achieved at the input to the transmission line. At the same
> time,
> they will tout the "gain" achieved by some number of half-waves,
> while
> totally ignoring the fact that the "gain" achieved is often in the
> wrong
> direction.
>
> I just don't get it.
YEP, some people actually believe that 1 WL
CCS(?) antennas (1WL of wire, broken into
multiple sections coupled by some "magical"
capacitor value have Gain in ALL directions.
(The only way to get gain in ALL is directions
is by means of an AMPLIFIER.) The myths
never die! :-) N4KG
>
> Wes Stewart, chief operator at N7WS
>
> ps. With shameless immodesty, I direct you to:
> http://www.azstarnet.com/~n7ws/ladder.htm
> for some more of my thoughts on related material.
>
>
> >
> >de Tom N4KG
>
>
>
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