DIY build and simulation of the Moxon antenna with 4nec2 software. Not a bad choice for long range FPV work on 433Mhz. Also it is simple and cheap to build.

Moxon design software.

http://www.moxonantennaproject.com/design.htm

Simulation software.

http://www.qsl.net/4nec2/

Interesting articles by VE2AZX

http://ve2azx.net/

My designs files on github.

https://github.com/rchacker/antennas