Thank you, guys.

What I ended up doing is put the dish about 4' from a gable edge of the roof. I ran the cables to the edge, down about 3' to the grounding block (with a drip loop) then into a hole (after another drip loop) which I sealed with sylicon around the cables. A heavy guage aluminum wire runs from the grounding block down to an 8' length of rebar that was sunk 7' into the ground. The utilities are on the opposite side of the house, with no realistic way to get this ground to a water pipe or electrical box pipe.

Using a multimeter I found the metal dish to have continuity with the cable casing so I did not run a second ground from it. Inside the house the cable runs through a small box that has plugged into an outlet and grounds the cable casing to the house electrical ground.

If I get hit with lightening, I'll let you know.

Dave