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Old Mar 16, 2010, 06:33 PM
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Martin - AKA mr.sneezy
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Joined May 2004
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Originally Posted by Iflyj3 View Post
If you disect any of the 2.4 GHz antennas, I think you will find a coaxial antenna hidden in the last 50 mm of the antenna case. The other length of the plastic has nothing to do with the antenna except make it appear longer.

Where the manufacturers get their gain numbers is beyond me. Antenna comparisons used to be made against a dipole antenna which was the standard to which the compare was made. A coaxial antenna is essentially the same as a dipole. 2 db gain as compared to what? Marketing??????
May as well go off topic for a bit as not much new FrSky stuff is happening right now...

Yes good info about the gains and the lengths above.
Physical length is as said above, irrelevant (as long as it's not being shrouded by the TX's metal handle).

More gain is a problem, if you don't understand the way they work.
Unlike many things where 'more' = 'better', RF antenna gain comes at a price, that being the radiating pattern. Low gain dipole antennas (like these) are fairly unidirectional in the way they emmit the signal, and that's good for RC aircraft where the model may be at various heights and angles from the TX. High gain antennas (stacked dipoles or similar) radiate unevenly so the signal is stronger in the horizontal plane (gain) and consequently has less signal in the vertical, that's not so good for model aircraft as the signal drops off a lot if the model flies over the tip of the antenna when the antenna is upright.

My own choice is to fly with the lowest gain types, typically the 2dBi standard types. I avoid the 'high gain' types for RC, but they are great for my WiFi Router :-)

Actually I have another idea about the way we should be using our 2.4Ghz antennas if anyone still interested in more OT chat ?
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