I want to use an OTA HD antenna...

Gmood1 - You stated that OTA HD is uncompressed. It is always compressed to fit into standard 6MHz bandwidth but cable companies compress it even more to save on cable bandwidth.

Same is for directionality - it is as directional as antenna is at given channel and being analog or digital has nothing to do with it.

Also sombody mentioned HD Antenna. There is no HD Antennas - they just call them HD or DIGITAL to promote sale. Frequencies are the same (VHF/UHF)and bandwidth is the same (6MHz). I got HDTV in 2001 and started using it with existing cheap antenna (15 year old Radio Shack) with good results.

I use now Winegard HD-7084P 68 element 131" long antenna (VHF/UHF). Directionality is pretty poor as stated by Winegard and tested by me on the roof. I live about 30 miles from transmitter. For example - beam width at half power is 69deg at channel 2 and 41deg at channel 32.

Actually I stated I wasn't sure if compression was the cause for the difference I see compared to cable . It probably has more to do with the miles of copper and equipment used by cable companies.
Yes this is true..UHF..is used for digital transmission. As far as directional goes, the analog channels are much easier to receive here without the extra fine tuning needed for the HD channels ..of course they don't look nearly as good either.

Thanks for the in depth explanation.

I'm too lazy to read all the posts, so this has probably already been mentioned, but any UHF/VHF antenna will pick up the new digital signals. You don't need to buy a gimmicky HD antenna. Of course, you'll need the converter box, or a new TV with a HD tuner.

For the past 3 or 4 years, we've been watching HD programming exclusively for free thanks to our standard roof antenna ($75-100 at any TV store), and our HD Sony CRT TV. Unlike cable, the signal is always crystal.

(TIVO plug) Instead of spending money on cable we also invested in a HD Tivo and we record the shows we want to watch or stream/download movies/programming. Other than ESPN and Discovery, we're not missing much.