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Old 7-Mar-2010, 12:30 AM   #1
mrraffer
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Join Date: Dec 2009
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UHF Ground Wave Antenna Recommendation

For a number of the distant stations at my location, the TVFool program suggests that the signal strength increases as the antenna height is reduced and in fact, is strongest at ground level. I thought this must have been a program bug, so a few months back, before you had the forum, I wrote to you and asked about it. Someone there sent me a very clear and detailed explanation, complete with graphics of how in certain fringe locations, the ground wave, although weak, is actually stronger than the signal that arrives at the antenna through the air. I was amazed not only at the phenomenon but that someone would take so much time to explain it to me!

Unfortunately, I have somehow lost that email. However, for the one distant VHF station I had asked about (a two edge signal from 85 miles away), I verified that the signal does indeed come in significantly better the closer I move the antenna to the ground, something that simply amazed me. (And recently, after losing that signal after heavy snow, I was able to regain it after I shoveled the three feet of accumulated snow out from UNDER the 10 element Yagi. Another confirmation of where the signal is actually coming from!)

I would like to receive three weak 2 edge UHF signals from a completely different direction about 55 miles out. Once again, TVFool predicts that the signal closest to the ground will be the strongest and I have verified this using an old 25 element UHF Yagi. With that antenna at ground level, one station comes in very well, a second fair, and the third one is not strong enough to lock. I would like to buy another antenna specifically to receive these signals. My question is, what type would you suggest to receive ground signals...a yagi such as the XG 91 or would an 8 bay bowtie give the similar or perhaps better results? Again, both would be mounted near the ground.

My intuition tells me that the long boom of the Yagi parallel to the ground would pick up more signal than an 8 bay. However, my intuition was wrong before, so I figured I would write and ask!

Thank you again for your help a few months back and in advance for any assistance on the UHF antenna selection.
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Old 7-Mar-2010, 11:12 AM   #2
mrraffer
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Join Date: Dec 2009
Posts: 4
UHF Ground Wave Antenna Recommendation

For a number of the distant stations at my location, the TVFool program indicates that the signal strength increases as the antenna height is reduced and in fact, is strongest at ground level. I thought this must have been a program bug, so a few months back, before you had the forum, I wrote to you and asked about it. Someone there sent me a very clear and detailed explanation, complete with graphics of how in certain fringe locations, the ground wave, although weak, is actually stronger than the signal that arrives at the antenna through the air. I was amazed not only at the phenomenon but that someone would take so much time to explain it to me!

Unfortunately, I have somehow lost that email. However, for the one distant VHF station I had asked about (a two edge signal from 85 miles away), I verified that the signal does indeed come in significantly better the closer I move the antenna to the ground, something that simply amazed me. (And recently, after losing that signal after heavy snow, I was able to regain it after I shoveled the three feet of accumulated snow out from UNDER the 10 element Yagi. Another confirmation of where the signal is actually coming from!)

I would like to receive three weak 2 edge UHF signals from a completely different direction about 55 miles out. Once again, TVFool predicts that the signal closest to the ground will be the strongest and I have verified this using an old 25 element UHF Yagi. With that antenna at ground level, one station comes in very well, a second fair, and the third one is not strong enough to lock. I would like to buy another antenna specifically to receive these signals. My question is, what type might be better to receive ground signals...a yagi such as the XG 91 or would an 8 bay bowtie give the similar or perhaps better results? Again, both would be mounted near the ground.

My intuition tells me that the long boom of the Yagi parallel to the ground would pick up more ground signal than an 8 bay. However, my intuition was wrong before, so I figured I would write and ask!

Thank you again for your help a few months back and in advance for any assistance on the UHF antenna selection.
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Old 7-Mar-2010, 6:32 PM   #3
mtownsend
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I actually do not expect there to be any difference in the antenna style when it comes to ground-wave reception. Gain is gain, and any antenna that can achieve high gain will do well. Gain is a "farfield" effect, so you don't really care about the close-in behavior of the antenna as long as you aren't doing anything to ruin the RF characteristics of the antenna (i.e., placing the antenna too close to other objects).

If you have specific channels that you need to pick up, you might want to check the gain specs on the specific channels you need. For example, most Yagi designs have their peak gain on higher frequencies that then tapers off as you go to lower frequencies. The 91XG has very high gain at channel 68, but it's not quite so good at channel 15. Bowtie antennas might have their peak gain in a different area, depending on design. So you'll find that Yagi antennas perform better at some frequencies, and bowties will perform better at others.

If you are able to determine that one make/model of antenna has the best gain on the specific channels that matter to you, then that is the one I would use. If you cannot tell, then look for antennas with high gain specs (and a reputation for accurate gain reporting).
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Old 8-Mar-2010, 8:17 PM   #4
mrraffer
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Join Date: Dec 2009
Posts: 4
Quote:
Originally Posted by mtownsend View Post
I actually do not expect there to be any difference in the antenna style when it comes to ground-wave reception. Gain is gain, and any antenna that can achieve high gain will do well. Gain is a "farfield" effect, so you don't really care about the close-in behavior of the antenna as long as you aren't doing anything to ruin the RF characteristics of the antenna (i.e., placing the antenna too close to other objects).

If you have specific channels that you need to pick up, you might want to check the gain specs on the specific channels you need. For example, most Yagi designs have their peak gain on higher frequencies that then tapers off as you go to lower frequencies. The 91XG has very high gain at channel 68, but it's not quite so good at channel 15. Bowtie antennas might have their peak gain in a different area, depending on design. So you'll find that Yagi antennas perform better at some frequencies, and bowties will perform better at others.

If you are able to determine that one make/model of antenna has the best gain on the specific channels that matter to you, then that is the one I would use. If you cannot tell, then look for antennas with high gain specs (and a reputation for accurate gain reporting).
Thanks for your reply. I will consider this advice when making my selection.
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Old 13-Mar-2010, 9:21 PM   #5
teleview
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Ground wave

Television signals tend to shift up and down in height at long distance. For ground wave reception at UHF , I suggest an 8 bay bow. As with all long distance Tv reception , move the Tv antenna around looking for a hot spot that is hot all the time.
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Old 15-Mar-2010, 11:05 PM   #6
mrraffer
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Join Date: Dec 2009
Posts: 4
Quote:
Originally Posted by teleview View Post
Television signals tend to shift up and down in height at long distance. For ground wave reception at UHF , I suggest an 8 bay bow. As with all long distance Tv reception , move the Tv antenna around looking for a hot spot that is hot all the time.
Might try a Winegard PR-8800 then. The channels in that direction are 27, 29, and 30. That particular antenna seems to have about the best gain in that range of channels.

Thanks for the advice.
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