Where is the most appropriate RFD900X antenna's position on the fix-wing and vtol aircraft.?

ArduCopter
1

I very confuse about the correct position of rfd900x antenna which is set up on aircraft

which one is the most appropriate RFD900X ?

  1. set up both antenna on left/right side of fuselage. (one side vertical and other parallel)
  2. one vertical on top of the aircraft and other vertical from bottom of the aircraft.

IMG_2755-scaled
IMG_2755-scaled2048×936 39.1 KB