Fast-travel to Charlie Camp to the northwest of the island and head to the marked objective. The area is restricted so expect enemies to shoot you on sight even with the uniform on. Tag your targets and kill them stealthily if you want. If you're carrying a suprressed sniper rifle, take out the snipers on the towers first. The area has lots of foliage and open area to run; you can also use the bunker to move around in cover.
Once you've reached the entrance, blow the steel door open with explosives. The door will collapse behind you so dig in and clear the enemies inside. Make your way outside to reach the satellite dish. After clearing it and before planting the C-4 on the dish, make sure to plant some mines around the possible enemy entrances, especially around the dish.
As soon as you plant the C4, stay in cover and protect the explosive until Sam arrives. Once the Sam's chopper lands, board it to escape. Mission complete.