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Author Topic: Delta loop (multiband) polarization question  (Read 1209 times)
W1CEW
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« on: May 24, 2012, 01:10:00 PM »

Hey all,

I've got a 40 meter full wave delta loop in the backyard strung up about 50 feet between two trees via slingshot/fishing line technology.  It is situated with the apex down, and I'm feeding it with balanced line at the bottom apex (no matching stub).  From what I've read, this should be horizontally polarized on 40.  I'm curious though whether it would retain that same polarization on the higher bands.  I checked with a local station on 10 meters who could switch back/forth between his vertical and yagi, and he indicated I was significantly stronger on the vertical.  Just curious.  Thanks!

Thanks!

Chuck
W1CEW
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WB6BYU
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« Reply #1 on: May 24, 2012, 01:18:06 PM »

The polarization depends on the direction, among other things.  It tends to be
horizontal off the face of the loop and vertical off the sides.

Generally such a vertical loop is NOT a particularly good antenna when used on higher
bands because the major radiation lobes tend to be at high angles.  You end up losing
a lot of radiation in angles that aren't particularly useful.

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W1CEW
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« Reply #2 on: May 24, 2012, 01:28:29 PM »

In other words, your thinking is that I might be better off just pulling up that bottom apex into the other tree and making it a skywire, right?  So far results are pretty good, though I have to admit I'm hearing almost nothing on 6 meters, though that might be conditions as well.  I've previously had an 80 meter skywire and actually worked really well on 6 meters.

73,

Chuck
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WA4FNG
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« Reply #3 on: May 24, 2012, 02:59:45 PM »

Yes, if you plan to use it on the higher bands. The vertically oriented delta loop is a great single band antenna, not so much on the higher bands. As a horizontal loop you may find it much better on the higher bands, and 40m may also be different with the change in orientation. Strong lobes as well as nulls on the higher bands. Many write that if you want to use the sky wire for DX on 40m you should cut it for 80m. The TOA is lower on the 2WL band and above. YMMV, experiment and see what works best for your location.
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WB6BYU
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« Reply #4 on: May 24, 2012, 03:47:22 PM »

Here is the article from the late W4RNL that discusses the radiation patterns of a 40m
delta loop on different bands:

http://www.cebik.com/content/a10/scv/vdelt.html

Unfortunately he doesn't mention polarization, and only shows the radiation pattern in
one plane.

Here is one of his articles on horizontal loops:

http://www.cebik.com/content/a10/wire/horloop.html

That will give you some ideas on shapes, sizes, radiation patterns, etc.  Generally, as
a loop gets longer in terms of wavelengths, the radiation is primarily in the plane of
the loop, and the number of lobes and nulls increases.  An individual lobe may have
useful gain over a dipole, but there will be more directions where the loop doesn't
work as well because of the nulls in the pattern.
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W1CEW
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« Reply #5 on: May 24, 2012, 05:14:10 PM »

Thanks this is perfect, thanks for the info, just registered on this site.
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