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Old December 13th 05, 05:03 AM posted to rec.radio.shortwave
Dale Parfitt
 
Posts: n/a
Default To RHF, et al. Re Loops


"Telamon" wrote in message
...
In article Fnrnf.16004$hB6.15653@trnddc05,
"Dale Parfitt" wrote:

"Telamon" wrote in message
...
In article ,
"Robert11" wrote:

Hello:

Lots of good info on loops from posts. Thanks all.

Just want to be sure re this:

When you talk about a Horiz Loop, you mean a true loop where the end
is
connected back to the beginning.

Right ?

(not just a folded random length config with a free end)

Any possible advantages in not connecting it back ?
(Interested in broadband, omni coverage)

The answer to the first question is no. If you connect the ends
together
you short the loop. The loop is a circular, triangular or square shape
with one opening in it. At this opening in the loop you can directly
connect coax cable lead-in to the radio so the coax is connected across
the loop gap.

The answer to the second question is no. If you do not connect the
other
end to something then the loop is open and will behave as a random
length of wire or a wire antenna. This will pick up signals and a lot
of
local noise. The loop connected across the coax will have lower signal
levels and in general will pick up less local noise.

The loop wire routed horizontally will be fairly omnidirectional.

--
Telamon
Ventura, California


As in my above post, an omni horizontal loop is a rarity and occurs only
over a very narrow BW. Don't confuse the fact that the wire runs in 4
directions with making an omni. The resultant far field pattern is a
function of the vector currents in each wire- they add and cancel
resulting
in patterns with a number of lobes and a number of nulls, but not omni.


If the loop is electrically small then it will receive in the plane of
the loop, which in this case is horizontal and so will receive
omnidirectional.

--
Telamon
Ventura, California


The discussion I see is about running a wire loop with further questions
about whether the far end is connected or left open-direct coax feed. Maybe
I missed something- these would appear to be simple wire loops- not
electrically small loops I would associate with a capacity tuned loop and/or
loop preamps.
Electrically small loops are traditionally mounted vertically so the user
can take advantage of the nulling properties to reduce a local noise source.
Dale W4OP