Attic Installations: Signal Reduction - AVS Forum
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post #1 of 23 Old 06-18-2009, 01:39 PM - Thread Starter
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For those who are considering attic installations, especially in weak signal reception areas:

Per Winegard: http://www.winegard.com/kbase/antenna_results.php
Quote:


Please be aware that attic installations will reduce signal by 50% and roofing made of cement tile, clay tiles or metal will reduce signal by 90%.


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post #2 of 23 Old 06-18-2009, 01:59 PM
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But... a two-splitter reduces your signal by 50% on each leg also.

So, if I'm correct, with an "optimal" attic installation you get a -3dB loss of signal.

With that, keep in mind that signal strength meters (that are typically built into STB's) do not really measure "strength", but reflect signal-to-noise ratio.

Two different measurements and may not be a need for "panic". FWIW... an attic antenna is the better compromise than using an indoor antenna when the roof (outdoors) is not an option.

I do agree that when aiming through cement/stucco/metal from the attic is generally not feasible. If you're fortunate enough to have plywood, asphalt shingles and vinyl... it's worth a shot to test.

As always, all situations are different and require a lot of testing with finding a "sweet spot".
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post #3 of 23 Old 06-18-2009, 02:22 PM
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you need to buy at least twice the antenna for your actual distance for 1 set is a good rule of thumb. times 2 again for every split. likely that unless you are 'in town' with the station you would need a distribution amp and not splitters.
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post #4 of 23 Old 06-18-2009, 02:38 PM
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Quote:
Originally Posted by johnpost View Post

... you would need a distribution amp and not splitters.

Or perhaps better, a pre-amp at the antenna to boost the signal to multiple TV's if splitters are used to compensate for a long distance (~50-75'?)
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post #5 of 23 Old 06-18-2009, 02:41 PM
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Quote:
Originally Posted by ota.dt.man View Post

For those who are considering attic installations, especially in weak signal reception areas:

Per Winegard: http://www.winegard.com/kbase/antenna_results.php

There is no doubt that an attic installation reduces signal compared to an outside antenna, I question the 50% reduction figure.

I have tile roof with an attic antenna and get excellent reception at 40 miles in flat Florida, I use a 5 element channel 13 Yagi for channels 12 and 13 and a Radio Shack UHF Yagi for UHF stations.

If your signal is good enough to receive desired stations, the fact that you could get X% more is unimportant. An antenna protected from the elements can be a big advantage.
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post #6 of 23 Old 06-18-2009, 02:42 PM
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Quote:
Originally Posted by Ratman View Post

But... a two-splitter reduces your signal by 50% on each leg also.

True, but if you're in a weak signal area you shouldn't be using a non amplified splitter anyway. Also note a attic installation can introduce multipath problems that wouldn't be their with a similar rooftop installation.
While a attic installation may look nicer(it's what I use) I do have multipath problems with one channel and with digital, multipath can = no picture at times
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post #7 of 23 Old 06-18-2009, 02:53 PM
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Look... there's no reason to "scare" people away from trying an attic installation. It can/does work with some testing, effort and perhaps frustration. As I stated previously, all situations are different.

Yes... multipathing can be a problem. Even outdoors on a roof.

There is no "optimal" solution unless you personally are the installer/contractor for a particular area with a good background/experience with DTV.

And... I went through the same exercise in 2002 to get stable reception trying 4 or 5 indoor antennas and then two outdoor antennas mounted in the attic. There is no magic bullet, but it can work.
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post #8 of 23 Old 06-18-2009, 02:57 PM
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Look at this from Winegard's perspective.

If every one of their new OTA customers mounted their antennas outside, think how many less support calls they would get for low signal?
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post #9 of 23 Old 06-18-2009, 03:18 PM
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Winegard could care less... they sell the antenna. It's up to the individual/installer to perform their due diligence.

But... if one desires, Winegard (Channel Master, AntennasDirect, and others) would be happy to sell more hardware to you!
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post #10 of 23 Old 06-18-2009, 03:39 PM
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At my location, my attic antennas (CM4228 for UHF and and Winegard YA-1713 for VHF, no amplifiers or splitters) have a current range (through wood siding and/or plywood roof with asphalt shingles about equally) of around 50-55 miles in mid-day conditions. I'm in an average suburban neighborhood with fairly flat terrain, homes spaced fairly well apart, some decent-sized trees around, but not a forest, and with no multipath problems at all. I'm right on the fringe for a 54-mile UHF station with this setup, and cannot reliably get stations at 60-65 miles with either antenna in the daytime, although they do tend to come in later at night. I would imagine that, absent hills or mountains, dense forests or lots of nearby tall buildings, many people might have similar conditions to mine and would therefore experience similar reception results from their attic. I plan to do some outside antenna testing shortly to check on improvement of the 60-65 mile stations and see if an outside installation is worthwhile for me.
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post #11 of 23 Old 06-19-2009, 12:07 AM
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Quote:
Originally Posted by Joel Graffman View Post

........I have tile roof with an attic antenna and get excellent reception at 40 miles in flat Florida, ......If your signal is good enough to receive desired stations, the fact that you could get X% more is unimportant. An antenna protected from the elements can be a big advantage.

yesssss! i agree 100%...i have had very good results with attic tv antennas....and many people here on AVSFORUM have said the same thing at distances of 50 miles or more.....

always try an attic antenna location first....and experiment with different orientations/locations/positions of the antenna in the attic, if possible...

the very poorly made 'consumer grade' junk tv antennas we are all forced to buy will last forever in an attic ....plus lightning issues are 99% eliminated....these 'consumer grade' junk antennas age very quickly when exposed to the weather....you're lucky to get more than a couple of years of good performance before corrosion, wind damage, birds, etc etc start taking their toll on an outdoor tv antenna....

sometimes an attic location wont work....every house/location/situation can be different....but if it does work u'll have a long lasting and very dependable 'zero maintenance' antenna system and u'll never have to climb ladders or risk any kind of roof/shingle/chimney damage!

*** its high time to go back to OTA antennas and CANCEL our cable/satellite pay tv services! their greed is totally & insanely out of control! ***
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post #12 of 23 Old 06-19-2009, 08:23 PM - Thread Starter
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Hello pm3839,

I couldn't agree with you more about the advantages of an attic antenna system. We've had a zero-maintenance attic antenna that has worked well for us for many years. No need for lightening protection and it doesn't detract from a home's "curb appeal"

However, all that changed on 6/12/09. Judging by the significant fluctuations on our CM-7000's signal meter, multi-path is causing DTV audio &/or video dropouts. Additionally, in the presence of multi-path, our two weakest stations fall victim to the DTV "cliff effect".

"Experiment with different orientations/locations/positions of the antenna in the attic ..." is rather cumbersome with a larger antenna. The size of our CM-1162 (Length 139", width 106", turning radius - 84") severely limits the amount it can be turned inside an attic before one end of it hits a roof truss. Its size and the limited attic space obviously prohibit the use of a rotor. If all your stations are UHF, a high gain UHF may work in an attic due to its smaller size especially if you wish to use a rotor.

In the digital era with a much more crowed TV band in the major metro areas & lower x-mitter power, the advantages of an attic antenna have to be balanced against: restricted height above ground, reduced signal strength, and a greater likelihood of multi-path interference.

(If interested, see this thread for more detail.)

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post #13 of 23 Old 06-20-2009, 03:24 AM
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Quote:
Originally Posted by Joel Graffman View Post

I question the 50% reduction figure

Me too, especially the 90% figure for cement tile roofs.

I'm 25-35 miles from our local broadcast antennas.
We have a very old VHF/UHF antenna that's like 90 long in the attic, under a cement tile roof.
We do use an antenna pre-amp (Aver. Gain Specs: 16db VHF / 23db UHF)
It's a 300 ohm antenna with a 300 to 75 ohm transformer used.
The coax is then split; sending half to a digital 1080p TV and the other half to a CECB.

So far, at least, we receive all seven San Diego stations. Six of the seven display reception strength of 5 out of 5 bars on the TV and are way into the Good Range on the CECB. The seventh isn't that strong but has very good PQ. We also get a lot of channels from Mexico (maybe another 30 miles away), several with very good reception.


We do have a high, almost completely unobstructed, view to the broadcast antennas.
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post #14 of 23 Old 06-20-2009, 07:23 AM
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Quote:
Originally Posted by ota.dt.man View Post

Hello pm3839,

I couldn't agree with you more about the advantages of an attic antenna system. We've had a zero-maintenance attic antenna that has worked well for us for many years. No need for lightening protection and it doesn't detract from a home's "curb appeal"

However, all that changed on 6/12/09. Judging by the significant fluctuations on our CM-7000's signal meter, multi-path is causing DTV audio &/or video dropouts. Additionally, in the presence of multi-path, our two weakest stations fall victim to the DTV "cliff effect".

"Experiment with different orientations/locations/positions of the antenna in the attic ..." is rather cumbersome with a larger antenna. The size of our CM-1162 (Length 139", width 106", turning radius - 84") severely limits the amount it can be turned inside an attic before one end of it hits a roof truss. Its size and the limited attic space obviously prohibit the use of a rotor. If all your stations are UHF, a high gain UHF may work in an attic due to its smaller size especially if you wish to use a rotor.

In the digital era with a much more crowed TV band in the major metro areas & lower x-mitter power, the advantages of an attic antenna have to be balanced against: restricted height above ground, reduced signal strength, and a greater likelihood of multi-path interference.

(If interested, see this thread for more detail.)

I agree with your remarks, but a 139" antenna is probably not well suited for an attic installation. If you need VHF, you might consider a single channel or a hi-band VHF Yagi both of which are comparitively small. Couple this to a small UHF antenna and you are in business.

As a related matter when I first installed my UHF antenna, I had severe multi-path problems from nearby stations that I was receiving on the beam (90 degrees off the pointy end). I found that careful exact vertical antenna alignment made a big difference and solved the problem.
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post #15 of 23 Old 08-31-2009, 01:45 PM
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Hi All:

As a follow-up to my previous post, I finally got the chance to test my Winegard YA-1713 and Antennas Direct 91XG outside for comparing reception against my attic location. In the attic, these antennas, as well as my CM4228, see signals through wood siding and/or plywood roof with asphalt shingles and receive stations up to around 50-55 miles in mid-day conditions. My area is an average suburban neighborhood with fairly flat terrain, homes spaced fairly well apart, some decent-sized trees around, but not a forest, and with no multipath problems at all.

The reason for my testing was that I'm right on the fringe for a 54-mile UHF station with my attic setup, and cannot reliably get stations at 60-65 miles in the daytime, although they do tend to come in later at night. My tv tuner will sense a signal starting at about 33 on the signal stength meter, and will reliably lock over about 37 or so.

I temporarily hoisted the two antennas (individually) outside up to about the height of the top of my chimney. I have four distant VHF stations of interest, one of which I've never gotten (71 miles), another which I've never gotten since they switched back to VHF (62 miles), and two that only occasionally came in late at night (each 65 miles). With the YA-1713, the one station that I've never gotten still didn't come in (perhaps they are not yet up to full power), the one which I've never gotten since they switched back to VHF barely came in at a 35, and the two that only occasionally came in late at night both came in solid at a 64. These last two channels even locked in around 40 when the YA-1713 was only 6 feet above my deck (much lower than the top of the chimney).

For UHF with the 91 XG, I tested a number of distant stations, several of which were in the 60-65 mile range. Some still did not come in at all. For one of my stations (at 68 miles) that only comes in late at night, it registered about a 40 and was stronger than from the attic. Another station at about 45 miles registered around a 60 on the meter, higher than the 48 or so it usually is from the attic. Another station (at 65 miles, and not very powerful) that I've only received once before (late at night) barely registered at a 35 on the meter.

From this, it seems that moving the antennas outside would indeed improve reception somewhat, bumping up my reception range by perhaps 10-15 miles. However, the improvement appeared much more pronounced for VHF than UHF. This also seems to confirm that the reception problems many people are experiencing with stations switching back to VHF are especially true where people are using indoor antennas.

Hope this is helpful to others planning their antenna setups these days...
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post #16 of 23 Old 09-01-2009, 07:24 AM
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Good morning,

Quote:


Winegard could care less... they sell the antenna. It's up to the individual/installer to perform their due diligence.

Let me assure you this is not the case. Not only is it important for our company to have good relations with our consumers by helping them receive the best reception possible, but it also economically makes sense for us to get it right the first time and not create a return or warranty issue on the antenna.

Please understand we are not trying to scare folks away from attic installations. If you read through our forums you will see one anti-attic poster that we constantly have to correct and show that attic installations do work.

However, Winegard does error on the side of caution when suggesting which antenna or installation to use. While the materials in your attic may cause a 10-20% reduction in signal the worst case scenario for those materials is around 50% and we feel it is important to let consumers know that BEFORE they purchase.

Thank you,

Andy Crowner
Winegard Company

For more information including Product Manuals, Engineering Specifications and questions answered by Winegard technicians please visit www.winegard.com.
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post #17 of 23 Old 09-01-2009, 09:41 AM
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Quote:
Originally Posted by winegard View Post

Good morning,



Let me assure you this is not the case. Not only is it important for our company to have good relations with our consumers by helping them receive the best reception possible, but it also economically makes sense for us to get it right the first time and not create a return or warranty issue on the antenna.

Please understand we are not trying to scare folks away from attic installations. If you read through our forums you will see one anti-attic poster that we constantly have to correct and show that attic installations do work.

However, Winegard does error on the side of caution when suggesting which antenna or installation to use. While the materials in your attic may cause a 10-20% reduction in signal the worst case scenario for those materials is around 50% and we feel it is important to let consumers know that BEFORE they purchase.

Thank you,

Agree 100%

'Better Living Through Modern, Expensive, Electronic Devices'

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post #18 of 23 Old 09-02-2009, 10:50 AM
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Well I have done it both ways. I recently moved but the move was only two miles so the conditions were similar. I am 35 miles from the Los Angeles transmitters on Mt Wilson. However there is a 2714' peak 3 miles from me directly between my location and the transmitters. In my old house the peak was not as solidly blocking which caused multi path due to the direct signal and the path around the peak.

In my old location's one story house I used a chimney mounted Winegard 8200 VHF/UHF antenna with a Winegard 8275 VHF/UHF preamp. Got all LA channels except one (13 then UHF) with only 2 others that were subject to occasional breakups. Only split it 2 ways and used 75' of RG11.

In my new location I use an attic installed Winegard 7015 VHF/UHF antenna with a Winegard 8275 VHF/UHF preamp. Get all channels. When I split it 6 ways I get all channels except PBS 28 is not reliable. My new house has a concrete tile roof but the house is higher up and it is a two story that gives the attic a good shot at the transmitters. The house wiring uses RG6Q but has maybe a total of 150' run for the downstairs TVs. I plan on adding a distribution amplifier.

I have Dish Network for the main TVs but use the antennas to get an extra tuner for them. The antenna also is to get HD for a couple of HD channels that Dish Network does not transmit in HD. Also use the antenna only for the guest room TV.

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post #19 of 23 Old 09-02-2009, 11:52 AM
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I'd say go with outdoor if feasible rather than try attic first, but that's partly because I'd rather climb a roof than work in my attic. I tried an antenna in my attic, and even though I got much higher signal levels (judging from analog station appearance) than my outdoor antenna (because my attic is higher, probably), multipath was awful and resulted in lousy digital reception. But that's my attic, your attic may vary.
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post #20 of 23 Old 09-02-2009, 12:00 PM
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Quote:
Originally Posted by nybbler View Post

(because my attic is higher, probably)

How is your attic "higher" than your roof?
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post #21 of 23 Old 09-02-2009, 05:33 PM
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I was attic mounted for about 2 years. In the attic, I was not LOS. I live on the west side of a hill...the towers are east of me 38 miles. I also have a 2nd DMA 62 miles northwest of me. All stations are 2 edge in the attic. Audio dropouts and digital audio noises were normal, although the pictures only dropped out during mid afternoons.

I now have 4 antennas mounted to a tower. These range from 43' AGL to 29' AGL. I also have a pair of antennas in my attic. The tower allows LOS over the hill (although through some very tall pine trees on the hill), and my attic antennas face a station 62 miles away and another weaker station 28 miles away. I now get perfect reception.

Outdoors is better in many situations. However, attic mounts can work wonderfully in LOS situations within perhaps 30-35 miles of the towers.

Also, there is a difference between wet or snowy roofs and dry roofs. In my circumstances, a wet or snow covered roof reduced the signal by quite a bit.

Just my two cents...

Bill
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post #22 of 23 Old 09-02-2009, 06:26 PM
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Bob Chase did some comparisons of various antennas and he used some of the antennas both outside mounted and attic mounted. IIRC, there was a fair amount of loss for the attic mount. He used a modern spectrum analyzer to do the test.

FWIW, if Winegard is referring to signal loss in dBmv then 50% would be a loss of 6 dB, not 3 dB. Example, if the first was reading was 1000 µv then 50% of that would be 500 µv or -6 dB.
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post #23 of 23 Old 09-02-2009, 06:33 PM
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Quote:
Originally Posted by Ratman View Post

How is your attic "higher" than your roof?

I can't mount on the roof (condo, the roof is a common element not subject to OTARD), so the outdoor antenna is on the deck (exclusive use area).
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