try this, with the phantom on the ground, ready to take off, turn your back to it and see what happens. You lose connection. simple as that. I lose connection when there are tree branches between myself and the phantom. its line of sight. these are not like other radio waves... TV, FM or AM radio. Its line of site. and the tip of the antenna is the weakest part of it. it is the long sides of the antenna. so it the copter is away from you, the antenna should be straight up. If it is above you, it should be level.