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Author Topic: multi-band vertical plans  (Read 228 times)
KB7RGT
Member

Posts: 33




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« on: November 17, 2003, 03:11:59 AM »

I want to build a multiband HF vertical.  I have been unable to find a source for plans.  Any good ideas?

Tks, Steve, KB7RGT
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AC4FD
Member

Posts: 26


WWW

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« Reply #1 on: November 17, 2003, 09:07:37 AM »

ARRL Antenna Handbook!

Just a thought! Smiley

I know that they have several article regarding Multiband Verticals (as well as dipoles and other types).

Here is one article from ARRL's website that you can access even if you are not a member:

http://www.arrl.org/tis/info/pdf/7806016.pdf

If you are a member there are many more.

Good Luck!

AC4FD
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KA5N
Member

Posts: 4380




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« Reply #2 on: November 17, 2003, 12:19:40 PM »

You didn't mention how many bands you wish to use.  For a simple solution that works see
www.cebik.com/v20.html.  This describes an antenna that works well from 30-10 meters.  I have been using a similar setup for almost 15 years except I use an elavated groundplane cut for 20 meters with twin-ax feed rather than a vertical dipole.  A good antenna tuner is essential I use a TenTec 229 (current model is 238)with an internal balun.  Mine works well on 30,20,17,15,12, and 10 meters and I can make contacts on 40 meters.  For 160,80, and 40 meters a longer antenna or top loading is very important.
Some of the automatic tuners should also work well.
For $20 for aluminum tubing and $5 worth of wire you can't beat it for a vertical.
Gud luck Allen KA5N
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RobertKoernerExAE7G
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Posts: 1435




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« Reply #3 on: November 17, 2003, 04:01:55 PM »

Check out what is in the ARRL HandBooks, any year will do.

They are cheeeeeep on eBay.

73
Bob
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WB6BYU
Member

Posts: 13046




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« Reply #4 on: November 18, 2003, 04:18:27 PM »

You will find links to a lot of different antenna
projects here:

http://www.ac6v.com/antprojects.htm

The first think you want to ask yourself is, what bands
are you interested in, and what are the physical
constraints on the antenna?  For two or three bands,
parallel vertical elements will work well.  Actually
if you put some sort of plastic spreaders on a central
vertical support, you can hang wire radiators for all
the higher bands from it.  (Or hang all the wires from
a convenient tree branch if you have one.)  Using
multiple parallel elements is probably one of the
simplest methods to multi-band operation, and one of
the cheapest if you use wire elements.

Another approach is to use a single radiator with some
sort of matching network at the base for each band.
This is the approach used in the article recommended
in a previous post.  Generally the radiator length
shouldn't exceed 5/8 wavelength on the highest band for
optimum low-angle radiation, but this is a trade-off
since longer antennas work better on the lower bands.
(There was a follow-up article to the QST article
recommending a maximum radiator length of 20' for 10m,
and pointing out that adding a variable capacitor in
the matching system would make it easier to match on
some bands.)  These days, an autotuner bolted to the
base of the vertical whip will handle matching on all
bands for you if you don't want to have to walk out
to the base of the antenna to change bands.  For just
two or three bands, relay switching from the shack is
practical.)

Versions using home-made traps are possible, though
the mechanical complexity increases as you try to add
more bands.

Probably one of the most practical home-construction
multi-band verticals I've seen was a clone of a B & W
product.  This used three vertical radiators arranged
in a triangle, each of which worked on 2 bands.  They
were bolted to short sections of large-diameter PVC
pipe for spreaders, and made from electrical conduit
if I recall (though aluminum might be preferable.)
One element was a full quarter wave on 40 and 3/4 wave
on 15m (with some bits of capacitive loading).  The
same approach was used on the second element to cover
30 and 10m.  The last element was a quarter wave on
20m topped with a loading coil that resonated with the
top radiator on 80m.  The whole thing was about 30'
tall and, like most verticals, required a good set of
ground radials.  I'm sure I've seen a copy of the
article around on the web somewhere.


others were (I think) 80/20m and 30/10m, using a
full quarter (or 3/4) wave on the higher frequency
topped with a loading coil
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