http://elecraft.85.s1.nabble.com/dipole-antenna-efficiency-tp458071p458074.html
I understand many G5RV's are getting replaced with these antennas. I
300' of wire on each side, all in a 100' on each side package. Have had
good luck with it. Their shortest is a bit over 70'.
> Shaun, Dohn, and All,
>
> Your proposal to wrap wire around pipe will probably end up being a "bust".
> In essence, you would just be loading a coil, and it would be very
> inefficient as a radiator. Some have tried to use a "helical" approach in
> order to shorten the overall length, but again that doesn't work all that
> well either. An example would be using the old "Slinkey" wire toys that we
> all probably had at one time or another. Those can work, after a fashion,
> but are generally poor performers.
>
> I disagree about the G5RV also. That is not a very good antenna,
> notwithstanding the huge amount of use those antennas get. The problem is
> that the G5RV was never intended to be an "all band" antenna, and it is a
> performer on all but a couple of bands. Unless you use a tuner, you will be
> very unhappy with the results you get with a G5RV design, particularly with
> modern rigs that don't have the advantage older tube-type transmitters had
> with pi-network coupling. The warts that a G5RV has is well documented,
> and the latest thing I remember reading about it was in a recent issue of
> Sprat--the Spring 2007 issue. Therein is a discussion by ex-ZS6BKW, who is
> famous for originating much of the variations for the G5RV that are in use
> today. Paraphrasing his own words, don't expect much from a G5RV unless you
> at least use a tuner!
>
> Unless you want to put up some sort of trap dipole, or a multi-band
> vertical, your best option is to get a decent tuner and put up a dipole with
> balanced line feeders. The 88 foot antenna described by L.B. Cebik on his
> website (www.cebik.com), is an excellent choice for a simple antenna that
> will work well on 80 meters through 10 meter. You can shorten that to 44
> feet if you want to give up 80 meters. That will fit in just about anyone's
> backyard, unless you live in a condo. The higher you get it, the better it
> will work. Just don't use coax, or the losses will eat you alive! You can
> coax feed an antenna that is resonant with good results. But when you try
> to use it on a higher frequency (like using an 80 meter coax fed antenna on
> 40 meters), the results turn to mush. The same antenna fed with balanced
> line through a tuner will work substantially better at higher frequencies.
> The resonant antenna (130 feet on 80) works better than the 88 foot antenna
> does on 80, but the 88 foot version (or the 44 foot version) is intended to
> standardize your radiation pattern, and is still a decent performer on 80
> meters.
>
> Another option would be a remotely tuned vertical on your roof. Dr.
> Megacycle (KK6MC), suggested this to me not long ago when he visited my
> shack. His advice was to put up a 22 foot vertical, remotely tuned, and
> using balanced feedline. This would give you pretty decent performance from
> 40 meters through 10 meters. You would need as many radials (random length)
> as possible. This was a suggestion as an alternative to my R7 vertical,
> which is a pretty good performer, but perhaps not as good as the suggested
> alternative. I haven't tried that yet, but I'd like to. I'm sure the
> suggestion is a good one.
>
> This may be more than you wanted to hear, but it seemed as if you were
> struggling to come up with a solution. Hopefully it helps some in that
> process. If wire antennas, or verticals, are just not practical for you,
> you might want to try a mini-loop. These aren't nearly as efficient as a
> good wire antenna, but they are quite small, and the results can often
> surprise you. Besides, they are fun to build!
>
> Dave W7AQK
>
>
>
> ----- Original Message -----
> From: "Dohn" <
[hidden email]>
> To: "'Shaun Oliver'" <
[hidden email]>;
> <
[hidden email]>
> Sent: Friday, January 04, 2008 2:50 AM
> Subject: RE: [Elecraft] dipole antenna efficiency
>
>
> > Shaun,
> >
> > For materials needed vs. radio theory, you just can't beat a G5RV antenna.
> > IMHO I've used mine with my K1, K2 and several home brew projs and it
> > works
> > great time and again. Yes, you want to get the center up there a ways.
> > Say
> > around 35-40 feet, but the payoff was good for me. There are a number of
> > sites out there that have good versions of a very old, classic antenna.
> > Very few parts (all of which can be made with junk around the house. Very
> > little investment for a sound payoff.
> >
> > Dohn N8EWY
> >
> > -----Original Message-----
> > From:
[hidden email]
> > [mailto:
[hidden email]] On Behalf Of Shaun Oliver
> > Sent: Thursday, January 03, 2008 9:20 PM
> > To:
[hidden email]
> > Subject: [Elecraft] dipole antenna efficiency
> >
> > Hi all,
> > if I were to make a dipole, would coiling it round a piece of plastic
> > piping decrease the efficiency of the thing? I intend on making one for
> > 40 meters, one for 80 meters, and one for 10 meters. I've worked out
> > that1 meter of piping will suffice for each leg of each antenna.
> > thanks in advance.
> > shaun
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