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Old 11-Aug-2010, 4:52 AM   #1
Gillez
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Join Date: Mar 2010
Posts: 7
Outdoor antenna selection after attic installation results (CM2016,4221,4228?)

Hi everyone,

Here is the link to my TVfool situation: http://www.tvfool.com/?option=com_wr...9fbef9b65d88f0

The first antenna I built was the DIY bow-tie on youtube. The results weren't spectacular, but it worked so it encouraged me to learn more.

I then built a 4-bay McLapp bow-tie antenna. Since the materials I had on hand made the antenna neither pretty or weather-resistant, I installed it in the attic. I'm now receiving the US networks from 83 miles away with rarely an interruption. When there is a rainstorm and my satellite receiver cuts out, I switch to my OTA antenna which is always working fine.

After fiddling with a number of attic locations to find the best one for my antenna, I realized that my house's design was forcing me to compromise. There are 2 portions of the house where the outside brick wall goes all the way up to top of the roofline, forming a point. These 2 points happen to be pointing exactly towards the 2 areas where my stations are: at 230 degrees for the US networks and at 180 degrees for my local stations. If I move my antenna so I have a line towards one set of stations that goes only through plywood and shingles, the view towards the other stations is through brick. I set up my antenna so that the most distant stations have the least interference and the locals the most. This works OK for the distant signals, but I'm having problems with my locals. I'm thinking I might have to set up an outside antenna.

Ideally, my outside antenna would have to:

1) Be able to receive upper VHF local stations (20 miles away) because my market will still have such channels once Canada is finished converting to ATSC.
2) It must also have a wide enough reception pattern so I can get both locals and distant networks with a 60 degree spread without a rotor.
3) it must be a reasonable size.

These 3 criteria are almost (but barely not-quite) met by my 4-bay antenna in the attic, I figure simply moving it outside would probably do the trick.

Since I don't have access to quality materials to build an outdoor antenna, I was thinking that buying a Channel master 4221 and installing it outside would probably work, but I'm not sure about it's upper VHF reception.

From what I've read, the CM4228 has longer range and upper VHF reception, but a much narrower beam, so it might not be the best solution for me. Especially when a 4bay antenna might be enough.

Looking through the channel master brochure, I saw the CM-2016. It has upper VHF reception, a fairly wide beam width and a small enough size.

The catalog mentions it is good for distances of up to 35 miles. It's gain peaks around 9 db in the range I need. From what I've read, the 4 bay McLapp has a peak gain around 12dB, but aiming through plywood and asphalt shingles must cut down the signal considerably. Would a 9db gain outside be better than 12 in the attic? I'm tempted to think so but I'd really appreciate your help.

If the CM2016 isn't ideal, is there anything else out there that might be suitable? I know that antenna selection is always a compromise, and that I have many restrictions.

Thanks in advance for your help and advice.
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Old 12-Aug-2010, 5:20 AM   #2
mtownsend
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Join Date: Dec 2009
Posts: 632
I think a Winegard HD7695P or Antennacraft HBU-44 would be a better fit for you. These antennas are designed to deal with channels 7-69, so they are going to be smaller (narrower) than a full band antenna. These tend to perform better than the 7-69 antennas from Channel Master.

Unfortunately, you need to make a trade-off between having a "wide beam width" and having "high gain". If you choose to go with an antenna with a wide beam width, it will not have very high gain, and therefore you might lose some of the sensitivity you need to pull in the weaker stations. If you go with a high gain antenna, it will have a narrow beam width (by necessity) and you will have less sensitivity toward the "sides" of the antenna.

My initial instinct would be to go after more gain and a narrower beam width. I think that most of your local stations are so strong that it won't matter that they are going in through the "side" of the antenna. The extra antenna gain will help you pull in the more distant stations reliably.



Signal loss due to building penetration can vary a lot. Depending on the construction material, thickness, dampness, signal frequency, etc., the loss caused by the building is usually in the range of 5 to 15 dB. Wood and drywall will usually cause less signal loss than brick and concrete. Sometimes hidden objects (e.g., ducts, plumbing, foil-backed insulation, wire mesh inside of stucco, etc.) can cause a lot of signal loss.

It's almost always better to get the antenna outside. You have less signal loss due to the building, but you also get less multipath reflections and a cleaner signal to begin with. A stronger and cleaner signal means better reception all around. You just need to make sure your antenna is able to stand up to the elements and last a long time.
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