rbreak, let's give you a bit more information, so you'll understand why you can't have an automatic dome-type antenna for DirectTV HD.
Unlike DISH, which only requires 3 satellites on 1 frequency band for their HD service, Direct uses 5 satellites over 2 frequency bands for its HD. There isn't a way of putting 2 different frequency banded LNB horns in a dome, to operate on the same motor.
The Winegard Traveler DirectTV automatically pointed rooftop open-dish model has space to mount all 5 LNB horns with a wider parabola dish to focus the signals. So do the portable manually pointed dishes.
So, if you want an automatically pointed antenna and it has to be a dome, then you have to choose between DISH service or DirectTV SD only.