RHCP and LHCP antennas
RHCP (right hand circular polarized) LHCP (left hand circular polarized) antennas are omni directional that use circular polarization. I primarily use these type of antennas for transmitting downlink video feed from my plane to my ground station to control the plane when going out pass LOS (line of sight).
I have read online that LHCP and RHCP antennas don't really like working with each other meaning if your tx antenna is RHCP your receiver antenna should be RHCP as well, mixing the 2 will not provide good results. I did not really paid attention to this too much since the antennas that I buy are all RHCP whether its for 5.8 or 1.3 GHz. Not until a few days ago when I was trying to fly my Phantom FX-61 and for whatever reason I can't go farther than 1.5 kilometers on a 5.8 GHz 600mw vtx with a cloverleaf antenna on the plane and a 8-turn helical on the receiver without getting intermittent video blackouts. I can't figure out why this is happening, I have flown with the same antenna combo pass 4 kms in the past before I start to see video degradation so this is not really making any sense. Out of curiosity I went back to the site where I bought the cloverleaf and skew planar antenna combo and checked the specs (I got the helical from a different online vendor)long and behold the combo antennas were LHCP and my helical antenna is RHCP!
Pay close attention to the polarization when buying circular polarized Omni or directional antennas for your FPV rig.