For about $4 in parts you can build a helical antenna that provides a huge amount of gain and significantly increases the range of any 5.8GHz FPV system in a drone or RC plane. This DIY video shows you how to do it and I'll be posting more tests of the 5-turn and 3-turn versions shortly.

If you want to see the real-world tests just jump to 00:26:00 in the video.