Stuart,
Excellent story.
Having moved several times due to my career, I was in many clubs. I
introduced the "Lazy Loop" to each club at field day. Each time it was put
up in addition to what they already had (the first year), and put up the
second year as the only antenna. Our clubs run only one transmitter.
In general the shape of the loop makes no difference on the low bands, but
it does make a difference on the high bands.
On the high bands, for us, the 4-sided loop was clearly better than the
3-sided loop.
Here's why. At about 33' of height, the 80m (long) loop exhibits low angle
of radiation with very distinct major lobes off of its 4 corners. The lobe
across from its feedpoint is strongest but only slightly. Here in Europe,
we need two main beam headings: NW for working stateside, and NE for
working Asia. By feeding in the SE corner, this places the strongest lobe
in the direction of stateside, but you still have a strong lobe towards
Japan.
How well does it work?
All the clubs I introduced this to were running directional antennas. The
first one had a Fritzel FB-33 triband beam, the second one had a 2 element
tri-band Quad, the third one had a Hygain TH-3. All were mounted at 10m
height (33 ft.). This was the same height as the loop. In all three
locations, the loop performed on par with the beam/quad to the DX countries
- but, we didn't have to rotate the loop, didn't need a rotator, and didn't
have to have an army of guys to push up a heavy tower. 4x 10m long aluminum
poles were erected within one hour.
As a result, all three clubs switched to running only the 80m (long) lazy
loop, fed with openwire.
I typically used a DECCA KW EZEE Match for matching it.
When I moved to Munich in 1983, I introduced it to a 4th club, who loved it,
but then the DARC changed the field day rules and specified that the most
common class (100w) could only have 1 single elevated mast or pole, with a
maximum height of 15m and one (wire) antenna. Beyond that there was an
"open" class where anything goes, but most clubs stayed out of that because
it was too much work. This was the death sentence for the lazy loop in Field
Day.
We followed with another antenna not shown in the books. We installed a
long dipole about 60 to 70m long and fed it with openwire. We also broke
each up with insulators and jumpers to shorten it for daytime work. 2 years
later we added a second, shorter dipole under the main dipole, but fed it in
parallel to the main wire dipole, with a common feedline. This has remained
"the killer FD antenna" till this day for that class.
Yes, wires are fun. Now that I'm retired, I'm spending 8 hours per day
playing with wires.
73
Rick, DJ0IP
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Stuart
Rohre
Sent: Thursday, July 11, 2013 1:36 AM
To: tentec@contesting.com
Subject: Re: [TenTec] OCF antennas evolution
Rick, I am fine with loops also, even 270 foot or larger.
Our club used up to 1024 foot horizontal loop for Field Days some years ago
when we had a large sports field. Each year for several, we would make
various loop lengths. We had a small one of only 100 some feet each side,
and others between the BIG one and this "small" one.
Something 300 odd feet around was the one easiest for us to put up, using
some lighting poles at the sports field in those days. BUT, all our loops
needed 3 corners supported, (or four).
We did more of the 3 corner versions. The IDEZ (Zepp) could be supported at
its center by one mast, and the ends tied off in tree limbs at relatively
low heights. It was placed for best effect to ham population centers which
was a compromise with the loops. We ran up to
5 loops one year for 5 stations.
We did research and find that with a lightweight ladder, able to reach up to
what we found was a workable height for Field Day antennas, (20
feet) we could quickly run a loop legs as three straight runs with a pigtail
at each wire end. The pigtails were joined by wire nuts, and we were done
in record time. Trying to use one piece of wire to do three or four sides
was too labor intensive in our hot climate.
We are mostly doing simpler 88 foot to 135 foot inverted Vees now, again due
to labor time. We have opted to set up the morning of the Field Day, thus
must do what antennas we can, in about 3 hours. This June we had 9 antennas
up. The 88 foot has been very good year before this, and so so with bad
conditions on 20m June 22. Did better on June 23, as the CME effects
cleared out. WE also had a bad mike on June 22 that was not discovered
until later.
Antennas are fun and low cost when you make them locally, as we do.
We are using 14 gauge conduit solid wire down to 18 gauge stranded wire on
shorter ones. Our NVIS dipoles for 40m and 80m have multiple short canes
supporting it, thus has worked well with paralleled strands of telephone
wire, (cross connect pair wire).
Stuart Rohre
K5KVH
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