Choosing the Correct Attic Antenna

[afbbb]

Hey all,

I've been lurking here for a little while. I've been without ANY TV for about 4 months now - I don't miss it TOO much! But I'm to the point where I'd like to get the major networks...

Here is my report - http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d3cf41051f666ca

The house is a single story, with a standard gabled roof. The surrounding terrain is flat with no obstructions between the signal and me. I would prefer to pull in the Chicago channels that are listed at 311*, I don't care at all about the stronger local signals (channels 24, 17, and 49).

I'm currently renting the house, so I can't install anything on the roof. I put the elevation at 15' on my report. I would like to choose an antenna that I can stick up in the attic (plenty of room up there) and run some RG6 straight to my TV (only 1 set). I'm probably going to be adding a Home Theater PC in the near future, so I don't know if that will influence any of the hardware setup.

I hope that I can get this to work! Thanks in advance for your help...

Eric

[Dave Loudin]

Thanks to WBBM using RF channel 12, you need a high-VHF/UHF antenna. As to what model, let's step through calculating the requirements:

TVFool's predictions suggest that you have about 20dB margin to the good in signal strengths for the Chicago stations. To protect against local interference and the more unusual reception conditions not accounted for in the prediction, we like to keep a 10 dB or so margin in the system. That's still ok, you're now 10 dB to the good.

However, the model shows that the path from the transmitters to you is 2-edge, meaning the signals have to bend over two terrain features to get to you. In practice, this adds more variability to signals than predicted, so factoring in another 6 dB or so is good practice. No worries, yet, as you are still 4 dB to the good.

The killer is mounting in the attic. It's hard to say exactly how much loss you will encounter, but it's safe to say it will be at least 10 dB and could be 20dB. Now you are between 4 and 14 dB below decodable signal levels. You will need that much antenna gain (not pre-amp gain) to have watchable signals. Thus, larger antennas (with more gain) will give you better reception reliability.

The minimum antennas I would recommend are the Winegard HD7696P or the AntennaCraft HBU-44. I would also recommend avoiding using a pre-amplifier due to the strength of the local LPTVs.

[Tower Guy]

I would prefer to pull in the Chicago channels that are listed at 311*, I don't care at all about the stronger local signals (channels 24, 17, and 49).

Eric

You're on the right track;

You need a medium-high gain 7-69 antenna with a preamp to make up for the attic looses.

Options are:
HBU-44 or HBU-55
HD 7696P or HD 7698P

Preamps: HDP-269, AP 8700, or 7778 are popular.

The highly rated 7777 has too much gain for your location.

[afbbb]

Thanks for the quick, detailed replies!

I appreciate you getting into the calcs - it helps me understand this wizardry that I don't know a lot about!

[John Candle]

The 'reference point' for Tv reception is 0 NM (dB) , + 10 NM (dB) gives some elbow room , and more then +10 is better and better. . Negative - 10 is about the cut off point for a 'reliable' receivable signal.