Haha. Okay. I'm learning this stuff too, I'm no antenna expert.
I think the first thing you need to ask yourself is what do you want out of your set up? Super long distance? Or just general good range.
If it's super long distance, is it going to be over farm land or over water?
If it's over land, then I think you'd want to lean towards a CP helix. A long CP antenna will shoot that signal out like a laser. But you have to be willing to aim it and steer your craft in one direct line. I would look at google maps and line it out perfectly so that while you're flying FPV you can steer the craft towards your goal... which might be the corner of a corn field or a small pond or whatever which you have mapped out in advance and which is a mile or two or three or four away. That way you know it is going in a perfect straight line. Then of course, you want to aim your CP sniper rifle antenna in that exact line and don't you dare move it. You might even set it on a table or a tripod or something.
And of course you'd want to have receiving antennas on your craft that match the polarization of the transmitted wave.
For FPV, you could do the same thing. The same idea applies, but you'd want the signal to spin the opposite way so they'd have a less chance of interering with each other. So one way to set it up is control might be LH and the FPV might be RH. Or vice versa. That way they won't interfere with each other because they will be blind to each other, since a RHCP receiving antenna can't see a LH circulating wave.
But if you plan on going long range over water, maybe you'd prefer a linear signal. Because you can get the advantage of the skip or bounce over the water which would not work with CP because the CP signal will bounce and then spin the wrong way after hitting the water - like a mirror.
On the other hand if you just want a nice general but still powerful set up, you might think in terms of a shorter CP (which would have a broader transmitting beam) such as a half sphere or even a linear antenna.
Or best of all, have antennas for every situation.
So that's my weak understanding of it all............
