Hello psychoflyy, Below Radar was never intended to work for handhelds, it was a bug and got fixed with the latest patch.
Ilga & Stinger are handheld anti-air weapons, Gustav Halling himself said that this was mainly made to counter Air Vehicles above the enemy base.
Personally, I almost never get locked by infantry carried missles, and if you are your simply sitting still for too long or your teammates aren't pushing at all. Unless your hovering over their base, there is no way an enemy should have enough time to sit in the open and acquire that lock.
