Antennae

On 7/19/19 7:39 PM, Dave Nadler wrote:
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


Here's a note that says don't use small diameter coax like RG174 for
long runs, use something like RG58 or RG400 (pg 16)

https://flarm.com/wp-content/uploads...stallation.pdf

Wonder how many glider mfgs are doing quality installations when the
customer asks for multiple antennas in the tail? Probably not many.

Since it's apparently ok to install a transponder antenna under a carbon glider, which requires drilling a hole, why not drill a small hole and feed a cable through to an external flarm antenna?

I'm considering that, though access to the bottom can be a problem.

On 7/22/2019 7:48 AM, wrote:
Since it's apparently ok to install a transponder antenna under a carbon glider, which requires drilling a hole, why not drill a small hole and feed a cable through to an external flarm antenna?

--
Dan, 5J

On 7/22/19 7:48 AM, wrote:
Since it's apparently ok to install a transponder antenna under a carbon glider, which requires drilling a hole, why not drill a small hole and feed a cable through to an external flarm antenna?


That's a fine solution, particularly for a B antenna on the belly. But
I think people are trying to be super cool and eliminate external
antennas on carbon ships by putting them all in a fiberglass tail.

Another possibility is putting the Trig remote box and PowerFLARM Core in the fin with possibly a LiFePO4 battery. Perhaps less coax to run, but the transponder harness would have a long way to run.

As for distance between Flarm and transponder antennae, you can check with Flarm and Trig.

As for distance between Flarm and transponder antennae,
you can check with Flarm and Trig.

Apparently I was not clear enough above.
Do NOT put both transponder antenna and a FLARM antenna in the vertical fin.

"Apparently I was not clear enough above.
Do NOT put both transponder antenna and a FLARM antenna in the vertical fin."

Could you share the reasons and data supporting this statement?

On Monday, July 22, 2019 at 5:30:12 PM UTC-4, George Haeh wrote:
"Apparently I was not clear enough above.
Do NOT put both transponder antenna and a FLARM antenna in the vertical fin."

Could you share the reasons and data supporting this statement?

I'll give you 3 reasons not to put the PowerFLARM antenna in the vertical fin.
1- It is a very low power device and antenna losses matter.
2- The elevator push rod will do no good things for performance.
3- There is no reason to do so. There are many well functioning systems with the A antenna up front as suggested. The higher the better.
Reason for not putting the transponder antenna in the fin? The suppliers of the devices say best performance is on the bottom of the aircraft.

FWIW
UH

On Monday, July 22, 2019 at 2:30:12 PM UTC-7, George Haeh wrote:
"Apparently I was not clear enough above.
Do NOT put both transponder antenna and a FLARM antenna in the vertical fin."

Could you share the reasons and data supporting this statement?

How about it won't work.

Richard

On Monday, July 22, 2019 at 6:54:33 PM UTC-4, wrote:
On Monday, July 22, 2019 at 5:30:12 PM UTC-4, George Haeh wrote:
"Apparently I was not clear enough above.
Do NOT put both transponder antenna and a FLARM antenna in the vertical fin."

Could you share the reasons and data supporting this statement?

I'll give you 3 reasons not to put the PowerFLARM antenna in the vertical fin.
1- It is a very low power device and antenna losses matter.
2- The elevator push rod will do no good things for performance.
3- There is no reason to do so. There are many well functioning systems with the A antenna up front as suggested. The higher the better.
Reason for not putting the transponder antenna in the fin? The suppliers of the devices say best performance is on the bottom of the aircraft.

FWIW
UH

All good points. But I think Dave emphasized the word "both". As in: you can put either one of those antennas in the fin, but not both. As he wrote in his first posting in this thread: "If you put the transponder antenna near the FLARM antenna (as in both in the fin), you will fry the FLARM receiver." The transponder transmits at about 200 watts!

FLARM A antenna in front is good, but where to put the B antenna, that's what I'm pondering. If the A antenna is in front of the pilot, I suspect there will be a gap in reception from the direction behind (and somewhat below) the pilot. It's not too hard in my case, given no carbon (and no transponder) in the glider, so even if the B antenna is mounted high (under the turtledeck) it should have a "view" of that direction. Aluminum control rods nearby won't help, but perhaps won't hurt too much.

Anybody know where I can get adhesive pads with small non-metallic rings attached? That would help with experimenting with antenna locations. There is one such in my glider holding some electrical cables tidy, but when searching for such on Amazon I got the strangest irrelevant search results.