I've found that the G5RV is a decent antenna for 20M. For other bands,
simply stated, it works but other types of simpler wire antennas will easily
out perform it.
As a general rule, one shouldn't worry about coax loss on HF. Unless you
have some bad/defective coax, or a very long run (more than 100 ft) the loss
at HF, regardless of SWR, is nil. Most "antenna performance" issues are
related to and most often mistaken for radiation angle or take-off angle.
Many antenna configurations are best described as "cloud warmers". Most
think if the SWR is close to 1:1, the transmitter puts out the required
power they should be able to make contacts. Not necessarily so.
Here's a recent factual story. I have 2 wire antennas cut for the upper end
of 75M. Both coax fed with 1/2" Andrew hard-line (don't ask why), both
with 1:1 current baluns at the center. One is 40 ft high and is on the
tower at the house. The other is about 90 ft high and is on the tower at
the shop only some 200 ft from the house. Yesterday afternoon while at the
shop (high antenna) , listing to a QSO on 75M with 2 stations in South
Florida both were good copy. I decided to get into the QSO but for
technical reasons I went to the house to use that station. I couldn't hear
either of the South Florida stations. The difference, antenna height and
take off angle. The lower antenna works great for local contacts within 200
to 300 miles or less. The higher antenna skips over the local stuff but is
great in the 750 to 1500 mile range. Rule of thumb: local contacts, low
antenna. Long distant contacts, high antenna. Same band, same power.
As to verticals and radials, with any vertical radiator radials are
required. I don't care what anybody says. Radials are used to reduce
ground losses only. A driven ground at the base of the vertical is for
lightning protection only. Very low current flows through each individual
ground radial and since total current is divided between many then small
copper wire is OK. And yes, use copper. It is less prone to being
dissolved by salts in the soil. How many radials? 10 is better than none.
To get any further improvement one must go to 20 radials. To get further
improvement go to 40 and then 80 and so on. Get the picture? The radials
are parallel with ground resistance. Double the radials, cut the resistance
in half. It doesn't take long to get to the point of diminishing returns.
Ideally, about 50 to 60 is the correct number to get to the flat part of the
efficiency curve for fair soil. And they work better at or slightly under
the surface. Don't burry them too deep and normally, it's not advised to
put a driven ground at the end. And most agree that 1/4 wave radials are
adequate regardless of the height of the vertical radiator. If you are
using one of the "loaded" or short verticals that is in the 20 to 25 ft
tall range on 75M then 60 ft radials are needed. When using a single
vertical with radials, interlacing or connecting the radials together at the
ends or mid points is a waste of copper.
#14 insulated PVC solid copper wire from the local builder supply is great
for radials. It's about $12.00 / 500 ft. roll.
73
Bob K4TAX
----- Original Message -----
From: "Bwana Bob" <wb2vuf@gti.net>
To: <AC5E@aol.com>; <tentec@contesting.com>
Sent: Sunday, September 01, 2002 9:52 AM
Subject: Re: [TenTec] Vertical Ant. Question / Suggestion
>
>
> Guess I'm not alone. I had similar experiences with my G5RV. Mine was
> rigged as a horizontal inverted "V" because of space imitations. It
> worked fine on 20 meters, but on 10 meters it was really dead. A 10
> meter dipole in the attic outperformed it. I played with baluns and line
> isolators and tried running 450 ohm ladder line almost all the way to
> the shack, thinking that the coax was lossy. The kicker came when I put
> up a low (16 FT) inverted "L" cut for 80 meters as a backup antenna for
> traffic nets. The "L" was better than the G5RV. I took down G5RV and
> replaced it with a loop cut for 40 meters. The loop works fine on all
> bands, 40 and up. The inverted "L" is far better than the loop on 80
> meters, passable on 40 but no match for the loop above 40 meters. On 80
> meters the loop is really poor, as expected. (I don't know why magazine
> articles and ads show loops operated significantly below their resonant
> frequency. They just don't work at 1/2 freq, unless you open the
> opposite corner with a switch or stub).
>
> My antennas are really stealthy, especially the loop with its lower side
> running along my fence (secured with black plastic electric fence
> insulators). Shiny copper wire turns brown in a few weeks and blends in
> nicely with the trees.
>
> 73,
>
> Bob WB2VUF
>
> AC5E@aol.com wrote:
> >
> > Well, HiGain has a non automatic bandswitching vertical for around 90
bux,
> > and there are several other verticals that will get the job done as
well. I
> > worked 107 countries on 89 days on a Cushcraft R5, running a Paragon
> > barefoot. But remember that a vertical is a good antenna beyond 1,000
miles
> > or so, but contacts out to a few hundred miles get scarce and far
between.
> >
> > As far as that goes, the G5RV is a very decent 20 Meter antenna. The
problem
> > there is it's essentially a dummy load on 160 and 80, and fair to poor
on 40.
> > If you are looking for a monoband antenna you might think of repairing
or
> > replacing what you had.
> >
> > But if you really want a multiband stealth wire, why not try an Alpha
Delta
> > DX-CC. A little flat black color on the traps makes it essentially
invisible,
> > and that trap dipole did a far better job for me than anything else I
have
> > tried that I can shoehorn into my tiny back yard. I have had extended
75
> > Meter QSO's with both EI and ZL on the DX-CC running 5 watts, as well
as
> > plenty of other Q's on 40 and up.
> >
> > 73 Pete Allen AC5E
> > _______________________________________________
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> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
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