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Old 6-Aug-2013, 1:59 AM   #1
pointer
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fluctuating multipath; need solution

I installed a new Winegard HD-7084P antenna months ago. Now I have frequent dropouts ("no signal" on the TV), which I'm pretty sure are due to fluctuating multipath.

I had to add a rotator, and now I have to nudge the pointing angle as much as 30 degrees to find a strong spot. Sometimes the signal fluctuates in a few seconds from strong to weak while I'm watching the signal strength monitor on the converter box. Sometimes it varies slowly, over a few days, then I have to move it. Often drop outs correlate with the weather. There are times when I have to point it 70 degrees North of Mt. Wilson, which is line of sight East by SouthEast of here. I can see it from the antenna. But there are mountains running from NorthEast of here across the North to the West.

When I get it pointed right, almost all the signals are good, with a few working at medium. Then the signal moves; I get some dropouts and have to move the antenna.

Apparently the antenna beam is narrow enough to capture the strong point. There are also a few other points spread over 90 degrees where the strong stations come in but not the weaker ones. I think these are multipaths, not sidelobes, because these signals are fairly strong. (In a highly directional antenna the sidelobes are small.)


Is there a way to at least minimize the frequent need to move the antenna? Or do I have to accept Mother Nature as is?
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Old 6-Aug-2013, 11:59 AM   #2
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How close is the airport between you & Mt. Wilson? Signal reflections from low flying aircraft may be causing the strong to weak signal fluctuations that you are describing.
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Old 6-Aug-2013, 6:09 PM   #3
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Airport is 30 miles South of here, completely out of the way.
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Old 6-Aug-2013, 6:39 PM   #4
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The image you attached in your first post shows an airport just a few miles away in the same direction as Mt Wilson. Am I missing something??
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Old 6-Aug-2013, 6:45 PM   #5
pointer
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What picture? There was none in the first posting of this question:


pointer
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fluctuating multipath; need solution
I installed a new Winegard HD-7084P antenna months ago. Now I have frequent dropouts ("no signal" on the TV), which I'm pretty sure are due to fluctuating multipath.

etc.
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Old 6-Aug-2013, 6:47 PM   #6
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This one.

http://forum.tvfool.com/attachment.p...2&d=1333417863
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Old 6-Aug-2013, 8:36 PM   #7
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Oh. If you mean Whiteman airport, it's negligible. It's tiny, servicing light planes, South of the beamwidth of the antenna. Traffic seems unrelated to the timing of the fluctuations I see, especially the seasonal ones.
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Old 7-Aug-2013, 11:29 AM   #8
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OK, I thought that airport and/or Bob Hope Airport may have been part of the problem. Those wild fluctuations are synonymous with airplane induced multipath.
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Old 7-Aug-2013, 6:57 PM   #9
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This may well be multipath... But have you turned the power off in your home to everything except the TV? The goal is to try to rule out interference sources such as motors, electronic devises, lighting systems, etc.
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If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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Old 7-Aug-2013, 11:58 PM   #10
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Yes.

The question is: Can anything done to combat the multipath, which varies slowly with seasons, weather, and time of day?
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