Signal levels drop off rapidly east of the middle of Cuba, resulting in little or no reception in the Caribbean without considering monstrous antennas. Areas to the West and Southwest may find reception requiring 1.2 meter and larger antennas. Reports from users all over the continental USA show more than adequate reception using the standard 24 inch dish. Lower 48, but a 24 inch model is recommended for most of the United States Lower 48 mainland, increasing to 75 to 90 cm in South Texas near the Rio Grande Valley, and possibly 75 cm in extreme southern Florida. 90 cm to 120 cm antennas can extend the ability to receive this signal several hundred miles into Mexico.
Same sizes allow reception into the north and western Caribbean.
South and East of Puerto Rico, requirements start at 120 cm are larger. Please check locally beyond that point to see what is successfully being used. Again, reports from users as far south as Florida report perfect reception using the standard 18 inch dish. Global Communications offers this comparison from a US point of view, and throws in their 2 cents on the legalities. Starchoice uses the brand new Anik F1 satellite, with a footprint that enables signal reception as far south now as Mexico.