Antennae

I have a new glider on order and naturally I want to build-in all the
things it will need over the next ten years at least, rather than adding
things later piecemeal. In the non-carbon part of the fin I plan to have a
radio aerial, a transponder aerial and a Flarm aerial. However it seems
that ADS-B (In & Out) is the coming thing and so presumably another
built-in aerial would be a good idea, rather than something above the
instrument panel. Have anyone fitted four aerials in the fin and do they
co-exist happily with each other? I don't know if differences between
European standards and US standards would make a difference to the type of
aerial fitted.

On 7/19/19 9:38 AM, John McCullagh wrote:
I have a new glider on order and naturally I want to build-in all the
things it will need over the next ten years at least, rather than adding
things later piecemeal. In the non-carbon part of the fin I plan to have a
radio aerial, a transponder aerial and a Flarm aerial. However it seems
that ADS-B (In & Out) is the coming thing and so presumably another
built-in aerial would be a good idea, rather than something above the
instrument panel. Have anyone fitted four aerials in the fin and do they
co-exist happily with each other? I don't know if differences between
European standards and US standards would make a difference to the type of
aerial fitted.


European and U.S. radios only differ in channel spacing, so they would
use the same type of aerial. I would prefer to put the transponder
antenna down low near the main gear, since it's very high power and
could interfere with receivers. ADS-B out is usually the same output as
the the transponder, so no need for separate antenna. ADS-B in is a
small antenna, receiving very high power signals, so placement is not
critical.

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

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

While they are building it, it would be neat if they could put some non-carbon antenna windows in the belly and top for these?

Assuming a carbon fiber fuselage, I'd put the transponder and PowerFLARM A antennae in the fin. The COM antenna is in the rear of the fin. There should be one foot separation among the antennae.

You will need something like LMR-300 cable to the Flarm, and perhaps transponder, antenna in the fin to limit loss to acceptable values. Get a Flarm Antenna with a short lead.

Consider an access port in the fin.

It would be really nice if glider manufacturers included a conduit to accommodate future cables between the instrument panel and the fin.

The PowerFLARM ADS-B antenna will do just fine ahead of the instrument panel. Transponder signals are considerably stronger than Flarm signals.

It won't hurt to have a Flarm B antenna ahead of the instrument panel. The Core 1.1 can transmit on both antennae if you purchase the RFB option.

If installing ADS-B Out, you may be facing extra requirements for the GPS antenna. Plus the vario and Flarm have their own GPS antennae. A splitter may help.

On Friday, July 19, 2019 at 4:19:15 PM UTC-4, wrote:
While they are building it, it would be neat if they could put some non-carbon antenna windows in the belly and top for these?

While we are talking about building it right in the first place: There are many issues with long air tubes connecting a TE probe (typically back in the tail) and the vario(s). How come I havn't seen a vario design that puts the pressure sensor near the probe, and connects that to the panel part of the vario via electrical wires instead of air tubes? You'd want to build that with a way to access the pressure sensing unit for future maintenance or replacement. The sensor does not need to be immediately adjacent to the probe, could be down near the tailwheel, or somewhat more forward in the tailcone, wherever access can be arranged.

On Friday, July 19, 2019 at 6:19:07 PM UTC-4, George Haeh wrote:

It won't hurt to have a Flarm B antenna ahead of the instrument panel. The Core 1.1 can transmit on both antennae if you purchase the RFB option.

Hi George. I believe the dual-transmit is not yet for us in North America; from the release notes for firmware 6.40:

"PowerFLARM: Fully symmetric antenna diversity, dynamic receive and transmit on both antennas (except USA and Canada)"

I'd love to be wrong on this one. I have read (somewhere) that it's an FCC/ISEDC (Industry, Science, Economic Development Canada - replaced IC) approval problem. I have re-read the release notes up to the current fw 6.67 and North American approval isn't mentioned.

Dan

On Friday, July 19, 2019 at 6:19:07 PM UTC-4, George Haeh wrote:
Assuming a carbon fiber fuselage, I'd put the transponder and
PowerFLARM A antennae in the fin. The COM antenna is in the rear of the fin.
There should be one foot separation among the antennae.

Except, it's impossible to achieve required spacing for all 3 in the fin,
(COM, transponder/ADS-b, FLARM) even very large gliders.
If you put the FLARM antenna in the fin, you'll need to put the
transponder antenna on the fuselage in the vicinity of the gear.
If you put the transponder antenna near the FLARM antenna (as in
both in the fin), you will fry the FLARM receiver.
Details of required spacing are in the FLARM manual.

Also, if you put the FLARM antenna in the fin, you will need to
specify the country it where will be used, as the different frequencies
required by different countries will require different antennas.

Some manufacturers have been happy to put all the antennas in the
fin when requested by the customer. The customer may not have been
too happy with the outcome.

Hope that helps,
Best Regards, Dave

On Fri, 19 Jul 2019 15:54:57 -0700, moshe.braner wrote:

On Friday, July 19, 2019 at 4:19:15 PM UTC-4, wrote:
While they are building it, it would be neat if they could put some
non-carbon antenna windows in the belly and top for these?

While we are talking about building it right in the first place: There
are many issues with long air tubes connecting a TE probe (typically
back in the tail) and the vario(s). How come I havn't seen a vario
design that puts the pressure sensor near the probe, and connects that
to the panel part of the vario via electrical wires instead of air
tubes? You'd want to build that with a way to access the pressure
sensing unit for future maintenance or replacement. The sensor does not
need to be immediately adjacent to the probe, could be down near the
tailwheel, or somewhat more forward in the tailcone, wherever access can
be arranged.

I don't think that's relevant with modern pressure sensing varios though
it was with the older flow sensors. This is because a pressure change can
propagate along a relatively small tube a lot faster than air can flow
through the same tube.


--
Martin | martin at
Gregorie | gregorie dot org