I've tried many OTA antennas over the years, and the best, by FAR, I've used for OTA HD is the Radio Shack model U-75R, catalog number 15-2160.
I would post a link on their site, but this forum won't let me until I've got 15 posts. You can search and find it at radioshack.com.
I have this antenna on a short mast on my chimney, and I get 100% signal on all local HD channels on my VIP622 and 722, with no boosters, and the signal is split three ways! (Two VIP's, and my TV.) The station antenna's are about 25 miles away.
Just an amazing antenna if you need a uni-directional, outdoor, and it's only $29. (Was $17 when I bought mine two years ago.)
It's a no-gimmick antenna, doesn't say "HDTV" on it, which typically doubles the price, lol.
The OP said he lives in the country, 50 miles from Houston (I live in Austin, hey neighbor), so I think this would work excellent for him. Point it at Houston, and there you go.