Loop Antennas
 

See this link for some more info
http://lists.contesting.com/archives.../msg00393.html

"Cecil Moore" wrote in message
. com...
Michael wrote:

I had never hear of a loop antenna back in the 50s.

Loops started to come into their own with the invention
by C. C. Moore of the Cubical Quad circa 1939.
--
73, Cecil http://www.qsl.net/w5dxp

Loop Antennas
 

I appreciate all the comments very much. A folded dipole would be easier for
me. I will discuss this with my neighbor W0BBN. He has been using a loop for
20 years. It sounds like it is hard to go wrong if you are willing to put
out the work for a loop antenna. I have been away from low band work since
I started college. That has been very very long ago. I had never hear of a
loop antenna back in the 50s. There was no internet and other hams were few
and far between where I lived in the country.

Loop Antennas
 

The loop is a DC short and is very quiet. You can also feed it with a
quarter wave section of 75 ohm coax using (quarter wave length x Velocity of
coax) as the length of the matching section.

Good luck,

Bill, W4WNT
"Michael" wrote in message
...
I get a lot of noise from my random wire antenna. It transmits very well
but is very noisy in receive. My neighbor put up a 280 foot loop antenna
which he feeds with ladder line. He feeds the ladder line from a 4 to 1
balun to coax. The coax comes from a tuner. His setup performs very well on
all bands down to 75 meters. I went over to his shack last night and
listened to his receiver on 75. I was really impressed with the lack of
noise. I can safely say the difference in noise was profound. He has this
loop surrounding his house at a 30 ft. height. It is arranged in a square.

Has anybody else had this experience with loops? It looks like I have room
to put up a triangular loop. Will this work as well?

Can I use the same tuner I have now and just feed a coax into a balun. Or,
should I put the balun in the tuner and come straight out with ladder
line? There is a lot of room in this tuner. It is an old remote controlled
tuner surplused from a ship.

Loop Antennas
 

"Michael" wrote in
:

I get a lot of noise from my random wire antenna. It transmits very
well but is very noisy in receive. My neighbor put up a 280 foot loop
antenna which he feeds with ladder line. He feeds the ladder line from
a 4 to 1 balun to coax. The coax comes from a tuner. His setup
performs very well on all bands down to 75 meters. I went over to his
shack last night and listened to his receiver on 75. I was really
impressed with the lack of noise. I can safely say the difference in
noise was profound. He has this loop surrounding his house at a 30
ft. height. It is arranged in a square.

Has anybody else had this experience with loops? It looks like I have
room to put up a triangular loop. Will this work as well?

Can I use the same tuner I have now and just feed a coax into a balun.
Or, should I put the balun in the tuner and come straight out with
ladder line? There is a lot of room in this tuner. It is an old remote
controlled tuner surplused from a ship.

Michael, a horizontal full-wave loop is actually quite a good choice for
LOCAL networking on 75m. The feedpoint impedance will depend somewhat on
the distance above ground and on the quality of the ground but should
range between about 200 ohms down to as low as about 50 (or even lower if
your ground is good). The shape of the loop is not all that important
and, if it's symmetric, the feedpoint can be anywhere. The ideal height
would be about 65 feet, but lower will still work well.

The radiation characteristic of an antenna like this is horizontal
polarization but with the main lobe directly skyward (which is actually a
good thing on 75m for LOCAL work). It does this, of course, at the
expense of radiation at low angles, so it is not a useful DX antenna
(though it may outperform a dipole at the same height). Being a loop, it
is also somewhat immune to near-field electrostatic interference such as
from nearby power lines (which may account for the lower noise pickup).


--
Dave Oldridge+
ICQ 1800667

Loop Antennas
 

Sound like your discribing my station setup. I also use a Delta loop in the
shape of a diamond with the highest point at approximately 70 feet and the
lowest opposite corner is about 40 feet, both above ground. Now it gets
interesting as this set up is likely about 5 feet lower than the closest
neighbouring amateur's basement floor is and I still out perform his
inverted V. But the my loop is a full wave on 80 meters and I have a rather
uneak piece of property. My soil is very good conductively and my ground
happens to be a creek bed with a 8 inch water pipe submerged in the creek
which runs all year round with about a foot of water over the pipe.
Also when I was looking for property I drove my van in to the property as
far as I could and call CQ on my mobile hf. Made a contact in Glasglow,
Moscow and Japan. I bought the property that afternoon. And I haven't
stopped enjoying the bands even when we are at the low side of a cycle. I've
also played with a number of antennas and always came back to the delta loop
or a four square. I'm planning on putting up a full wave delta loop for 160
meters this spring. My present loop is hooted up to a homebrew 4:1 balun
with 300 ohm foam then a 10 foot piece of 9913 coax to a At-180 Icom tuner
to a IC-706MKIIG. On a bad night I can make contacts about the Mississippe
to Hawai, on a good night Europe and the Globe. If you have the room they
are one of the best antennas for the money invested. But you still have to
have a good location and a good ground, if your missing either there isn't
an antenna in the world that will help you. By the way I'm 147 feet above
sea level and my closest neighbouring amateur is 177 feet and his antenna is
30 feet above that, but I still out preform him hands down on any and all
bands.

Anyway this is what it's all about, haveing fun and making new friends.
73...de ve7agw, Al
Vancovuer Island, BC


"Michael" wrote in message
...
I get a lot of noise from my random wire antenna. It transmits very well
but is very noisy in receive. My neighbor put up a 280 foot loop antenna
which he feeds with ladder line. He feeds the ladder line from a 4 to 1
balun to coax. The coax comes from a tuner. His setup performs very well on
all bands down to 75 meters. I went over to his shack last night and
listened to his receiver on 75. I was really impressed with the lack of
noise. I can safely say the difference in noise was profound. He has this
loop surrounding his house at a 30 ft. height. It is arranged in a square.

Has anybody else had this experience with loops? It looks like I have room
to put up a triangular loop. Will this work as well?

Can I use the same tuner I have now and just feed a coax into a balun. Or,
should I put the balun in the tuner and come straight out with ladder
line? There is a lot of room in this tuner. It is an old remote controlled
tuner surplused from a ship.

Loop Antennas
 

What I find amazing is that "Michael" leaves the impression that he is in ND
when his neighbor W0BBM is in north central Kansas with two whole states in
between. It gives a whole new meaning to "neighbor."
Hard to compare antennas when the neighboring antennas are so far apart.
73, Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:

"Michael" wrote in message
...
I appreciate all the comments very much. A folded dipole would be easier
for
me. I will discuss this with my neighbor W0BBN. He has been using a loop
for
20 years. It sounds like it is hard to go wrong if you are willing to put
out the work for a loop antenna. I have been away from low band work since
I started college. That has been very very long ago. I had never hear of a
loop antenna back in the 50s. There was no internet and other hams were
few
and far between where I lived in the country.

Loop Antennas
 

Being a loop, it
is also somewhat immune to near-field electrostatic interference such as
from nearby power lines (which may account for the lower noise pickup)

Dunno...I consider this to be fictional content...
They may be slightly quieter as far as corona buildup, or
charge on the antenna itself, but not any noise in the far or
near field. If a loop picks up less noise in a certain direction
vs another antenna, it's the inferior antenna in that direction.
Noise is rf, and a signal, the same as any other signal.
If you get rid of noise, you get rid of *any* signal in that
direction and angle. I also consider the magic noise reducing
qualities of the "shielded" loops to be a fairy tale also.
I've done a good bit of testing, and can see no indication that
a shielded loop is any "quieter" than a regular unshielded loop.
The shielded loop design promotes good balance. But good
balance can be had with any loop.
I guess loops are ok, and they are efficient when fed with coax,
same as a dipole, but I usually prefer dipoles on 80m.
If you run a loop for NVIS, you want it all high up in the air,
with no parts dragging towards ground. Many stick loops
in the yard, and some parts will be high, some parts low.
The current distribution is "fairly" constant around the loop,
vs max on the dipole being at the feed point. So you have
more chances of increased ground and clutter loss with the
loops in many cases. I prefer the dipoles and inv vees because
the maximum current point is up high at the apex, and the
ends of the wires, which may droop lower, are voltage nodes.
I'd rather have the bulk of my radiation high up in the air,
rather than spread helter skelter around the yard area.
Often the dipole will outperform such a draggy loop...
But if all the loop is high and well supported, they can
be worthwhile. But still more work for little if any real
increase in performance vs the dipole.
MK

Loop Antennas
 

wrote:
They (loops) may be slightly quieter as far as ...
charge on the antenna itself, ...

When I lived in AZ, where the wind blew almost all the time
and the humidity was very low, particles in the wind would
deposit their charges on my dipole causing an extreme amount
of noise and sometimes even arcing. I hear dry snow can do
the same thing. I was trying out a 4:1 voltage balun one day
and noticed that particular noise source had gone away since
the balun was a DC short and bled off the charges. A later
loop also didn't have the problem. An RF choke or high-ohm
resistor across the dipole feedpoint will also cure the
problem.
--
73, Cecil http://www.qsl.net/w5dxp

Loop Antennas
 

Cec, in this little country we don't seem to suffer from static from
dust or other dry storms. Rather rarely, when a thunderstorm is in the
vicinity, I have experienced rain-static which occurs only during a
heavy 'tropical' downpour. At such times I am inclined to disconnect
the antenna, anyway, to avoid damage due to a direct lightning strike
on the antenna or house. The S-meter may rise to S-10 or S-11 for a
few minutes but this extreme occurs only once every few years. I have
never experienced static due to dry snow. I have only once experienced
static on a nice warm day with a completely blue sky and this lasted
only for half an hour. Never figured out why.

Using a high value resistor or choke to ground the antenna doesn't
have any effect on S-meter noise level. I would not expect it to.

I cannot see how loop antennas are less susceptible to static except
that their smaller size may have a smaller catchment area for
particles or raindrops.

Could you briefly describe what happens to the S-meter on the 160, 80
and 40 meter bands when severe static occurs in Texas, or any other
States, and how frequently static weather conditions occur strong
enough to temporally put one off the air?
----
Reg.

Loop Antennas
 

Reg Edwards wrote:
Could you briefly describe what happens to the S-meter on the 160, 80
and 40 meter bands when severe static occurs in Texas, or any other
States, and how frequently static weather conditions occur strong
enough to temporally put one off the air?

On my IC-745 in AZ, the coax connector would arc many
times at the transceiver about once a month during late
summer. It pinned the S-meter but didn't seem to
damage the IC-745. It arced whether the IC-745 was
on or off. A 4:1 voltage balun cured that particular
arcing problem although it generated other problems.
The PL-239 coax connectors must arc around 300 volts
or so.
--
73, Cecil http://www.qsl.net/w5dxp