At 07:55 12 June 2012, Bert TW wrote:
On Jun 11, 9:13=A0pm, Kimmo Hytoenen wrote:
At 13:44 10 June 2012, Bert TW wrote:









On Jun 10, 1:16=3DA0am, Chris Nicholas =A0wrote:
I think that if Flarm were installed with 2 antennae, one
high
in the
cockpit or on top of the fuselage, and the other below,
there
would be
no Flarm blind spot and it would be as near perfect as
possible. We
don=3D92t do that because it is too much trouble and/or
too
expensive. It
is hard enough to persuade many pilots to have Flarm
even
in its most
basic available form.

Chris N.

That's what I decided on last winter., because the Flarm
range
analysis on my carbon fuselage Flarm installation (Ventius
cM)
showed
that there were some blind spot (ranges antenna
splitter, the original Flarm antenna outside the fuselage
near
the
gear doors, and a stripe antenna behind my head inside
the
canopy.
"Blind spot" now means a range of 4 km ( a bit more than
2
nautical
miles for the colonials).
Investment was $200. My ass is worth more than that.

Bert,

This kind of information is exactly what I would like to hear.
FLARM is an excellent idea, and I hope everyone installs one
in
their ship. Also I hope that everyone make sure that his/her
FLARM system operates well. My problem is, that I have no
idea
how to improve FLARM operation. I have changed the
position of
antennas, and got mixed results, according to the range
analysis.

I believe that system of two antennas would be good. Can
you
Bert please share with us your knowledge of antenna
splitters
and antennas used, so that we can make similar
installations.
Possibly we could add necessary components
intowww.soartronic.comas DIY
k=
its, so that everyone can have one
on minimum cost.

Kimmo,

I am not a specialist at all. By chance I discovered
www.dolba.de
where you can see the antenna mounted as strips into the
canopy. I
talked to the guy (Bernd Dolba, I'm pretty sure that he speaks
English
as well), and he talked me into installing two antennas. He
obviously
sold be the stuff he makes for that :-) but I'm happy with it.
The
splitter is a small passive box which receives the input of the
two
antenna, and feeds them into the antenna input of the Flarm. I
did
measure the required cable lengths first, and he send me the
antenna,
the splitter and the three cables (the lower antenna outside the
fuselage is the original Flarm antenna, he just provided me the
socket).
Improvement was great - I had tried various
positions/antennas in the
previous year, but the combination of a carbon fuselage, a
relatively
solid instrument panel (it's GRP, but behind its crammed with
metal
boxes...) and my requirement that I don't want any antenna
blocking
any of my view is more or less hopeless for not having blind
spots.
With the present configuration, I cover the whole space around
me.


I got reply from a specialist today. Unfortunately he explained in
detail how a system of two antennas cause loss of the signal where the
waves block each others (interference). The
PowerFLARM solution with two receivers seems to be the only
working solution for two (or more) antennas.