I currently don't have a SAT dish, but these things are designed to be out in the weather all year. I would assume that a mild soap and soft cloth should not harm the finish. A mild spray on cleaner like Simple Green should also work. As they typically say, test in a small hidden area if unsure.
Something to think about while cleaning the dish is this new hydrophobic coating from Rust-Oleum called NeverWet to help keep the SAT dish clean. Liquids just roll off. Check it out, just Google NeverWet.
Redick & Peggy + 1 dog & 1 cat
2007 DSDP 4035
99 Yamaha Royal Star & 13 F150 SCAB