View Single Post
Old May 21, 2009, 03:12 AM
thomasscherrer is offline
Find More Posts by thomasscherrer
Registered User
thomasscherrer's Avatar
Danmark, Hovedstaden, Ballerup
Joined May 2007
3,260 Posts
About Video diversity:

wavelangth in coax cables is not interesting in this case.
diversity antenna distance is the thing that is important
some use different frequencies so the wavelength will be different.
300 / 900MHz = 0.33 meters for one wavelength
300 / 1300MHz = 0.23 meters for one wavelength
300 / 2400MHz = 0.125 meters for one wavelength

you need antenne centre to antenne centre distance of
, 1, 2, 3, 4, and so on is the optimal distance in wavelength,
say you use 2.4 and 3 is easy for you
0.125 x 3.5 = 0.437 meters same as 43.7cm


and reflections from ground :

if both your antennas have exactly the same height to the ground
and they are both pointing to the plane,
then most likely the reflections from ground will hit both antennas
with same phase and same amplityde, then you get short noise pulses
or even black outs, have you seen this ?

I think you can try to angle your setup so they are like 45 deg
and still pointing to plane, now see any better ?


about RX battery voltage, I suggest you use a 4 cell pack,
use eneloop cells with low internal resistance and higher output voltage,
the voltages you mention for your packs sounds to me like old and dead packs :-)
I often see people use normal hi capacity cells for RC, they are cool for kids toys
but not for your RC ! you need hi current cells, they have lower capacity
and weight more.
thomasscherrer is offline Find More Posts by thomasscherrer
Last edited by thomasscherrer; May 21, 2009 at 03:20 AM.
Reply With Quote