tongaloa (?)
I have (also) used the vertical loop for many years, but I don't
think you should feed it with the twisted 450 Ohm line to
opposite corners as Dave just described in his N4PC loop.
I installed my vertical loops (separate antennas for 40 and 80m)
in a delta configuration with the flat side on the bottom and the
point on the top. Some might argue that it would perform better
when mounted with the flat section on top - I would agree, but
then you need two masts. As I built mine, I only needed 1 mast.
I fed the antenna in the lower corner (either corner) with an
electrical quarter wavelength of RG9 (70 Ohms) and then random
length of RG-213.
The beauty of this antenna is that it requires less horizontal
space than a dipole and it doesn't need gillions of radials like
good verticals do.
On the air results:
Again, compared to a standard dipole (no traps and no balun -
just an RF choke at the feedpoint), when working JA from EU, the
JA was typically 1 S-Unit stronger on the loop, but the EU QRM
was about 4 or 5 S-Units louder on the dipole. So, it made
copying the DX station significantly better on the loop than on
the dipole.
This antenna serves an entirely different purpose than the
horizontal loop we were speaking about in the previous posts on
80M LOOP. The horizontal loop was for short range (say, under
1000 miles) and the vertical loop was for long-haul DX.
The 40m version covered the whole European band (7000 to 7100).
The 80m versioned had to be lengthened or shortened when changing
between the CW or SSB portions of the band. I simply inserted a
piece of wire in the middle of the horizontal leg (which was
reachable on a step ladder). You can adjust the rope support of
the corner opposite the feedpoint to compensate for added or
reduced length (let the loop slide through the corner insulator
in that corner - don't fasten it). The slight difference in
lengths of the two diagonal sides in non-critical.
This version of the loop antenna has been described in detail by
DL1BU, the (ex)technical director for the CQDL magazine in the
April, 1979 issue.
Finally, to be exact, the feedpoint was not exactly in the corner
but rather 1.5m (40m) and 3m (80m) up the diagonal leg.
I never ran any tests of this antenna against a good vertical. I
only compared it to dipoles, but at many locations. The results
were always as I described above. The 40m version fits easily in
any city lot.
73
Rick
-----Original Message-----
From: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com]On Behalf Of tongaloa
Sent: Monday, March 15, 2004 5:49 PM
To: tentec@contesting.com
Subject: Re: [TenTec] 80M LOOP
Dave wrote:
> I have kept the Paul Carr modeling and installation of 80 mtr
loop
> with phasing line twisted (450 Ohm line) between opposite
corners -
> its bit less than 1 wavelength - he did not lose any multi band
> performance.
>
> Dave K8BBM
dave-
Would be interested in seeing if for a vertical plane loop.
-bob
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