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Author Topic: Radial Pattern  (Read 837 times)
KC2TRX
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« on: November 03, 2010, 10:59:11 AM »


  Because of the configuration of my roof, I have quarter-wave elevated radials in a pattern of 080 to 190 degrees around my ground plane vertical; no other options.  I've noticed that most of my contacts come from the south: southern US/Carribean/S. America.  To what degree can this be a result of the radial shape?  Thanks, Dan O'Connell/KC2TRX.
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K0BG
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« Reply #1 on: November 03, 2010, 11:04:41 AM »

You can always plot it with EZNEC, but I suspect propagation has more to do with your odd reception than the off-center radials.
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WB2WIK
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« Reply #2 on: November 03, 2010, 11:54:48 AM »

One of my antennas is a roof-mounted HF vertical (6BTV) with radials in "all directions," 360 degrees around its base.  When the radials need to go where there isn't enough roof, or no roof at all, the radials go off the edge of the roof and tie on to stuff in the yard, like tree branches or "anything" that will hold a rope with a few pounds of tension on it.

This isn't a big deal.
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KF6ABU
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« Reply #3 on: November 03, 2010, 12:21:50 PM »

with 1 radial going west-ish on my elevated 40m vertical (southern california)i worked kh6, vk,zl and zd8, hp1, ja, ra, pj5, j39 etc etc etc. those are pretty opposit directions around the globe. Surely it is better in one direction, but by how much i dont know. it worked ok in all directions. I now have 3 elevated radials spaced properly. I think your antenna works fine and its just propogation or characteristics not dependant on your radials.

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N3OX
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« Reply #4 on: November 03, 2010, 12:26:11 PM »

If you're talking 10m operation only, and I think you are (based on QRZ.com page), 10m is JUST starting to occasionally open up decently to other locations other than Carribean, Central and South America from our neck of the woods.  It's not your radials, it's ABSOLUTELY propagation.  Go ahead and listen on other bands.. you'll find you'll hear many different locations.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N2CJ
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Posts: 197


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« Reply #5 on: November 03, 2010, 01:11:32 PM »

You can always plot it with EZNEC, but I suspect propagation has more to do with your odd reception than the off-center radials.

I am inclined to agree. My elevated 6BTV vertical presently only has one radial each for 80 & 40, and 2-4 radials on all other bands. They are arranged in a semi-circle, perhaps no more than 200 degrees and there is no indication of directionality with the antenna. I have worked 175+ countries with this arrangement.

My 160M inv ell is also over a 180 deg. semicircle of buried radials and I similarly have not noticed any directionality.

I believe the cause is transequitorial propagation, which favors propagation between North America and S. America/Carribean, even when the bands are dead to other areas.
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KC2TRX
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« Reply #6 on: November 03, 2010, 07:36:16 PM »


  Thanks to all who replied.  It seems that the consensus is that it is not radial pattern, but rather propogation.  That's encouraging.  looking forward to better conditions on 10M. 
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G3TXQ
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« Reply #7 on: November 04, 2010, 04:48:50 AM »

It may well be a propagation issue. However, if you model an elevated quarter-wave vertical over radials which are constrained to one quadrant, you see azimuth responses which are as much as 12dB down in the direction opposite the radial field.

Steve G3TXQ
« Last Edit: November 04, 2010, 04:50:36 AM by Steve Hunt » Logged
N2CJ
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« Reply #8 on: November 04, 2010, 07:34:18 AM »

It may well be a propagation issue. However, if you model an elevated quarter-wave vertical over radials which are constrained to one quadrant, you see azimuth responses which are as much as 12dB down in the direction opposite the radial field.

Steve G3TXQ

When you say "quadrant" I'm assuming you mean a 90° arc. How does the pattern look when the radials fan out over 180° ?
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G3TXQ
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« Reply #9 on: November 04, 2010, 08:16:36 AM »

When you say "quadrant" I'm assuming you mean a 90° arc. How does the pattern look when the radials fan out over 180° ?
Same trend, but less exaggerated - about 6dB down in the "non-radial" direction.

Steve G3TXQ
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N3OX
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« Reply #10 on: November 04, 2010, 10:30:24 AM »

It may well be a propagation issue. However, if you model an elevated quarter-wave vertical over radials which are constrained to one quadrant, you see azimuth responses which are as much as 12dB down in the direction opposite the radial field.

At medium high elevation angles, I guess?   I've got a 20dB null on a single radial that slopes down at 25 degrees from the horizontal but it's up at 37 degrees elevation or so. 
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
G3TXQ
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Posts: 1524




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« Reply #11 on: November 04, 2010, 12:20:51 PM »

At medium high elevation angles, I guess?   I've got a 20dB null on a single radial that slopes down at 25 degrees from the horizontal but it's up at 37 degrees elevation or so. 
Dan,

Yes, it's elevation-angle-dependent. As you've found, a single radial can produce a very deep notch in the reverse direction at some elevation angles.

Steve G3TXQ
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