Which end of roof tv antenna toward station

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snipped-for-privacy@mucks.net wrote:

Hi, Line loss on what? Hard coax, nitrogen charged waveguide have very low loss and SWR is near 1 to 1. Explain then why signal disappears when height is lowered. Noise level is more important than signal level when dealing with terrestrial signal.(-90db range)
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Standard TV coax is on subject. It does have losses that should be considered.

In theory (doesn't exist in this case) e fields can cancel or be additive at different heights.

Maybe you forgot that the subject is a TV antenna. No nitrogen charged wave guide. No hard coax. This is a TV antenna. A TV antenna is a multiple frequency antenna unlike the ones you seem to be referring to. A TV antenna does not have radial ground wires buried in the ground like broadcast antennas to enhance signal gain.
No sweet spot exist for multiple frequency antennas like TV antennas over normal ground. A TV antenna can not take advantage of ground reflections because there are no buried radials, and even if it had buried radials how can you find a sweet spot for the entire frequency range of the antenna? Raise and lower it when you change channels?
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snipped-for-privacy@mucks.net wrote:

Hi, One more and I am out. Is there a theory for TV antenna and another for microwave? On theory we use isopole or dipole in free space usinf reference dbi or dbd.
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wrote:


Theory and reality are very different. In reality microwaves compared to vhf/uhf waves behave differently when hitting earth ground. In reality microwaves react differently when it comes to traveling around the curvature of the earth. In reality microwaves dissipate differently in air. In reality microwaves use different feed lines. In reality microwaves are a single frequency. In reality attributing theory or microwaves to explain a TV antennas behavior is not reality.
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On May 2, 12:46�pm, snipped-for-privacy@mucks.net wrote:

not necessarily true. radio waves (tv waves) are like waves on a pond, in places they add to make larger waves......... in other places they cancel one another.
So you can go higher and get worse results
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wrote:

This in ONLy true when the antenna is only a few wavelength from the ground. At best with a perfectly reflecting ground plane, that doesn't exist, you may expect a 6db maximum gain at these additive reflection distances, however this perfect ground planer does not exist and height can easily give greater gains than 6db.
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snipped-for-privacy@mucks.net wrote:

Height is not the case with satellite TV. Lower is better.
Up/down has no effect on reception, but having the dish at shoulder height makes aiming easier and removal of snow, leaves, and bird nests a cinch. For these reasons, lower is better.
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cshenk wrote:

Around here, I'd need about 3 different antennas, or a rotator. Several of the neighbors have those 'flying saucer' omni antennas, with built-in amps, but I'm not sure how well they work, and I'd have to rewire the coax a tad (move the splitters inside) so as to not put any DC into the satt receiver, which they do not like. I suppose I should try to catch one of said neighbors out working in their yard, and ask what stations they get. The web sites say I'm too far away from the xmitters for an omni, but they always are conservative in their estimates. To put up a real fringe antenna with a rotator, I'd either have to kill a tree, or move the pole to other end of house.
-- aem sends...
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I tried that once. I put up an antenna and took the tv up on the roof to see where I got the best reception. For a moment I lost my footing, and my $3800 sixty inch plasma tv went crashing to the ground, never to work again. I tried to grab it as it slid down the shingles, and I too went off the edge of the roof, falling some 30 feet to the concrete pavement below. Besides losing my $3800 tv, I spent 9 weeks in the hospital, which cost me over $220,000 in medical bills, and I have been in a wheelchair ever since, watching a $29 portable black and white Walmart closeout tv set, in the basement of a rented apartment, paid for by uncle Sam, because I had to sell my home to pay the medical bills.
Fred
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Real method? Hardly. Get an antenna rotator, a small motor that mounts on the mast. The control is near the TV so you can move the antenna from inside.
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"Bob M." wrote

Um, Bob, if he had that sort of fancy setup, he wouldnt be asking with direction to point it in ;-)
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Um, cshenk, Bob didn't say he had that sort of fancy setup. He said "*get* an antenna rotator".
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"1D10T" wrote

LOL, ok, ya got me. Should have read better. I wonder what such run now in cost? Not relevant me but curiousity. We never had one as a kid.
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I haven't looked into a rotator yet; not even sure if they're even available anymore. I just built this one: http://www.flickr.com/photos/joearnold/3399193845 / from instructions in a youtube video:
http://www.youtube.com/watch?v=EWQhlmJTMzw

It does work quite well, but seems very directional. I made a second one and paralleled them; facing 45 apart. Much better, but I think I now need to mess with different heights. I'm in a remote area, with transmitters averaging 40 miles away. Getting 13 digital channels, but still need to get a consistent PBS feed.
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On 5/2/2009 7:00 AM cshenk spake thus:

>

I just did exactly this for one of my clients a couple days ago: I climbed on roof, grabbed antenna and moved it while she went inside and checked TV, came out and said "Better!" or "Worse!" until it was optimal. (Fortunately, she only watches one TV station for the most part, making it easy to adjust.)
I hate climbing on roofs, by the way.
--
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Kill Yourself
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Jimw wrote:

www.dishnetwork.com
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Steve Barker wrote:

Not everyone can spare that kind of money every month, especially these days. And even if you can, a roof antenna as a backup is still a good idea. (not to mention Dish still doesn't offer local channels in all markets.)
-- aem sends...
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It's called a Yagi antenna, very common in ham radio. The narrow end points toward the TV station's antenna; the wide end is the "back" of the antenna, the reflector.
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Jimw wrote:

use the end that brings in the most channels.
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