Antennae

On Friday, July 19, 2019 at 1:21:32 PM UTC-4, kinsell wrote:

PowerFlarm uses very small cables with high loss, don't think they
belong in the tail. Do the best you can with them near the glare
shield. Maybe you run a Flarm B cable all the way to the tail, but I'm
dubious of the benefit. Definitely wouldn't put a Flarm antenna
anywhere close to transponder output.

Dave

I'm trying to fit two FLARM antennas and a goTenna, plus GPS reception by cellphone for IGCdroid (besides the GPS reception within the FLARM) into my cockpit, and that's enough to give me a headache. Existing glider, with VHF radio antenna in the tail, but probably won't add anything to the tail. Would like to keep the goTenna far away from the FLARM antennas, since it's relatively high power (1 watt - nothing like a transponder) on a very similar frequency. Also would like to mount the FLARM antennas one forward of the pilot and one aft, to maximize the coverage by minimizing the impact of the pilot's body blocking the signals. And of course want to keep the antennas away from metal objects such as control cables and electrical wires. It's a puzzle. At least my glider is all glass, no carbon.

On Fri, 19 Jul 2019 10:38:53 -0700, moshe.braner wrote:

On Friday, July 19, 2019 at 1:21:32 PM UTC-4, kinsell wrote:

PowerFlarm uses very small cables with high loss, don't think they
belong in the tail. Do the best you can with them near the glare
shield. Maybe you run a Flarm B cable all the way to the tail, but I'm
dubious of the benefit. Definitely wouldn't put a Flarm antenna
anywhere close to transponder output.

Dave

I'm trying to fit two FLARM antennas and a goTenna, plus GPS reception
by cellphone for IGCdroid (besides the GPS reception within the FLARM)
into my cockpit, and that's enough to give me a headache. Existing
glider, with VHF radio antenna in the tail, but probably won't add
anything to the tail. Would like to keep the goTenna far away from the
FLARM antennas, since it's relatively high power (1 watt - nothing like
a transponder) on a very similar frequency. Also would like to mount
the FLARM antennas one forward of the pilot and one aft, to maximize the
coverage by minimizing the impact of the pilot's body blocking the
signals. And of course want to keep the antennas away from metal
objects such as control cables and electrical wires. It's a puzzle. At
least my glider is all glass, no carbon.

Depending on what there is to attach the FLARM antennae to, they should
be fine on either side of the fuselage somewhat in front of the panel and
instruments, which would mean the Gotenna antenna should be OK behind the
cockpit.

I fly a 2021 Libelle with a standard FLARM, i.e. not PF. Its antenna is
mounted centrally on the front of the instrument tray at an adjustable
potition:

https://www.gregorie.org/gliding/lib...RM_install.jpg


This puts the antenna just below the top of the fuselage and about half-
way between the instruments and the rudder pedals. The position is quite
critical, I think this is due to RF reflections off pedals and
instruments, but when placed in the right fore/aft poisition it shows
good range forward and to the sides and acceptable range behind.



--
Martin | martin at
Gregorie | gregorie dot org