be warned about antennaweb.org, it has been trumped as the place to find out all your hd needs...while there is useful information, it is not entirely accurate...based on their website, it was recommended I purchased a 13' antenna, yes 13 FEET!!! I actually purchased the antenna, and then realized there was no way I was putting up something so ugly...it was only through the help of someone local that I found out that a RS double bowtie did the job even though I was about 55 miles away from the location...and my terrain is hilly not flat...
is this the case for everyone? probably not, but do your best to start with something smaller, something indoors before you go out and buy a bohemoth antenna to put on your roof