We also use Direct TV and have the Winegard RoadTrip Minimax 800S antenna roof mounted on our coach. It's an automatic stationary non-HD antenna and works great for us.
I just can't see paying more $$$ for the HD antenna, and DTV extra for an HD receiver as we're OK with our non-HD mode picture.
Here's a site where you can find a DTV HD antenna although a bit pricey:
http://www.winegard.com/travler/travler-directv-slimline.phpOn their website, I couldn't find any "Dome" type roof mount antenna that received HD signals from Direct TV but most did for Dishnet...Go Figure..:h
Good luck with your search & safe travels...:)