Andy, you are right, the antenna is not necessary the dipole
version.
I think that dipole antenna is omnidirectional, since it radiates
equally in all directions in plane. The radiation pattern should be
donut shape.
If antenna is 1/4 wave stick on ground plate, isn't the pattern a half
sphere?

At 18:00 01 October 2012, Andy wrote:
On Oct 1, 9:30=A0am, Kimmo Hytoenen wrote:
The antennas delivered with
FLARM are omni-directional, so the range analysis is spherical in
optimum case.


A dipole is not omni-directional. The pattern of an ideal dipole in
free space is not sherical. Why do you believe that the antennas
delivered with FLARM are omni-directional?


Andy