How would aluminum siding effect an outdoor antenna? - AVS Forum
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post #1 of 10 Old 07-09-2008, 07:09 PM - Thread Starter
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I have an outdoor CM 4228 on my back porch roof. The house has aluminum siding. Because the porch is small, the antenna ends up being about 3' away from the siding.

How would this alter performance? Would the siding act as a reflector, a radiator, an emitter of its own noise or would it just absorb everything?
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post #2 of 10 Old 07-09-2008, 07:17 PM
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How would aluminum siding affect an outdoor antenna? Adversely, but fortunately, the Channel Master bowties have high front-to-back ratios, and digital signals are less suseptible to degradation from weaker out of phase reflections, so it usually isn't fatal.
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post #3 of 10 Old 07-09-2008, 07:21 PM - Thread Starter
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Originally Posted by AntAltMike View Post

How would aluminum siding affect an outdoor antenna? Adversely, but fortunately, the Channel Master bowties have high front-to-back ratios, and digital signals are less suseptible to degradation from weaker out of phase reflections, so it usually isn't fatal.

It's not fatal in my case. I was just wondering what to expect in terms of improvement when I raise the antenna.

Slightly odd factor: if I rotate the antenna to face the siding, it works almost as well. That's what has me wondering if somehow the siding is acting as a reflector.

I guess I'll really know when I raise it to the roofline.
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post #4 of 10 Old 07-09-2008, 08:57 PM
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Quote:
Originally Posted by MeowMeow View Post

Slightly odd factor: if I rotate the antenna to face the siding, it works almost as well. That's what has me wondering if somehow the siding is acting as a reflector.

In this situation, the aluminum siding is definitely acting as a reflector. But the bow ties have good pickup to the rear in normal circumstances, so you may be getting a reflected signal or directly through the bowtie. Hard to tell so long as multipath does not cause breakups in the digital picture.
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post #5 of 10 Old 07-10-2008, 05:58 PM - Thread Starter
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Originally Posted by n4yqt View Post

Trial and error. If you are not having any problems right now, leave it alone. Otherwise, install the antenna as high as you can.

Problems are hard to define when you're in a fringe location.

There is actually only one channel that makes me think there is a problem. At my old house, with this same rig, I was able to get our nearest CBS affiliate WTAJ (40 mi) rock solid through major foliage and the wrong side of the hill. At the new house there is a lot less in the way and we're on the right side of the hill, and the channel is difficult to tune. We're talking a two degree range on the rotator to get it stable.

While the transmitter is not perfect, all of the antenna tools (TV Fool, AntennaWeb, etc.) say I should have no trouble with this channel.

I am planning at some point to get a wall mount kit and go higher with the antenna. Right now it is just sitting on top of the back porch. Considering this is western Pennsylvania (hills, trees, more hills, more trees), and some of my signals are 60 mi away, it actually performs incredibly well.
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post #6 of 10 Old 07-10-2008, 07:48 PM
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Originally Posted by MeowMeow View Post

While the transmitter is not perfect, all of the antenna tools (TV Fool, AntennaWeb, etc.) say I should have no trouble with this channel.

It looks like WTAJ may be operating temporarily on low power with a directional signal to the southeast; according to the FCC. The ERP is listed as 3.33kw
LL
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post #7 of 10 Old 07-10-2008, 09:19 PM - Thread Starter
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Originally Posted by Digital Rules View Post

It looks like WTAJ may be operating temporarily on low power with a directional signal to the southeast; according to the FCC. The ERP is listed as 3.33kw

You pulled the wrong polar plot. That's the DS permit, which, if the FCC weren't dreadfully lazy, should have been removed from the database years ago.

WTAJ's current polarization doesn't favor a particular direction. And they're now running at 800 or so kw. Since I'm easily 20 miles from the edge of their broadcast area, it's a channel I should receive well. It is the only channel for 60 miles with a good pattern that I have trouble receiving.
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post #8 of 10 Old 07-10-2008, 09:26 PM
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I have a giant tin roof with aluminized paint.

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post #9 of 10 Old 07-11-2008, 05:44 AM
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Quote:
Originally Posted by MeowMeow View Post

That's the DS permit, which, if the FCC weren't dreadfully lazy, should have been removed from the database years ago.

What exactly is a "DS permit"? The website describes it as a "Special Temporary Authority" permit. I've seen construction permits, but don't ever remember seeing this type.

Thanks!!
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post #10 of 10 Old 07-12-2008, 09:25 AM - Thread Starter
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Quote:
Originally Posted by Digital Rules View Post

What exactly is a "DS permit"? The website describes it as a "Special Temporary Authority" permit. I've seen construction permits, but don't ever remember seeing this type.

Thanks!!

The DS permits are issued when they're just starting a transmitter. 99.9% of the ones on file are leftovers from the earliest days of DTV. The special authority basically allows a station to begin transmission with under-powered transmitter.

The FCC doesn't seem to issue them anymore. Everything I've seen lately is either listed as a construction permit or just full authority.

Why the DS ones are still listed for stations that are transmitting at full power under full authority is beyond me. I'd imagine the FCC has spent so much time lately adding to the database that no one has had the opportunity to reconfigure the system to not display the old DS authority stuff.
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