Agree, the Dish 500 is not completely round, I think it's 20x22.Dish 300 is designed to be used with one lnb.
Other larger Dish Network dishes are detuned horizonally to cover 2 or 3 lnb's so they give you a false sense of better signal to be.
Another way is to buy a 30" single lnb designed dish like the Winegard DS2177.