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Originally Posted by Thinkup
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At first, I want to scream "Are you kidding me?", because the answer is obvious, at least to me. I realize that you're asking because you are not familiar with this stuff at all, and that's OK.
The bottom line: I think your friend could use an indoor antenna, the Terk HDTVi in particular, to get at least 11 stations (and their sub-channels). Why can he do that and you not? Two items to compare between the two reports: Noise Margin and Path
The Noise Margin (NM), specified in dB, tells how much signal is present with respect to the noise level. Zero means the signal can be locked and decoded by almost all receivers. To protect against all kinds of fading, we like to design for an NM of +10.
I would expect you to point out that your top three stations have NMs of over 50 and 30! Why can't you use a small antenna? It's the second factor - Path. For your friend's case, the top stations are all "LOS," or line-of-sight, meaning that there are no terrain obstructions between his house and the transmitters. In your case, most of your stations are "2-edge," meaning that signals have to bend over two obstructions to get to you. As you might imagine, such signals will be more unreliable, so more margin for fade protection is needed. Designing to +20 NM is not unreasonable.
Now, after subtracting for fade margins, we are left with noise margins of 13 to 15 for most of what you want (and still 30 for WRGB). One more thing to consider: losses from putting the antenna inside. Measurements comparing attic to rooftop installations put the loss at 15 to 20 dB in most cases, with a best case of 10. Using the mid-point, we're now down to virtually zero NM. You need the gain provided by the antennas Tigerbangs recommended to get the NM back up for reliable reception.
You can follow this logic for your friend's case to see he can get by with an antenna that has zero to 2 dB gain.
Good luck!