Antennae

"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 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.

Today's analysis from 2 OGN receivers of my PowerFLARM with a single antenna, Craggy part number 500107, mounted to the glare shield.
Looks like about 270 degrees of 20km range better than 10dB.
Jim

https://www.dropbox.com/sh/nidqq8s4s...KIQg2dCta?dl=0

Actually, putting the Flarm antenna in the vertical stabilizer works well. Of course, how well I "see" another glider depends on their Flarm installation. For example, I "see" K4 and DZ consistently at 8-10 miles. DL and 4AF at not more than one mile. 5E and L6 at 4-5 miles.

The SZD 55-1 has a battery box at the base of the vertical stabilizer. I took the battery out, and put the Flarm in the battery box. The Flarm and ADS-B antenna are mounted in the gap between the rudder and the vertical fin.. The Flarm antenna is located as high as possible but below the metal components of the horizontal stabilizer. The ADS-B antenna is located as low as possible, but above the mass balance weight. This gives a very short distance between the Flarm and the antennas. The trick was running the data cable forward to the Butterfly display.

The comm antenna is located in the vertical fin, the transponder antenna is bonded to the inside of the fuselage aft of the main gear.

P9

The trick was running the data cable forward to the Butterfly display.


I guess you're not going to tell us your trick?

It is interesting how a thread diverges from the original question. I
posted this new thread because I had been talking to a former world
champion who has just taken delivery of a Ventus 3M. Schempp-Hirth put
three aerials in the fin: radio, transponder and PowerFlarm apparently
without problems, and they should know. Many of the replies in this thread
have been why this wouldn't work. I originally asked whether it was also
possible to put in an ADS-B aerial. I will be asking Schempps but I thought
I would ask around first.

At 06:38 23 July 2019, wrote:
Actually, putting the Flarm antenna in the vertical stabilizer works
well.
=
Of course, how well I "see" another glider depends on their Flarm
installa=
tion. For example, I "see" K4 and DZ consistently at 8-10 miles. DL and
4A=
F at not more than one mile. 5E and L6 at 4-5 miles.=20

The SZD 55-1 has a battery box at the base of the vertical stabilizer. I
t=
ook the battery out, and put the Flarm in the battery box. The Flarm and
A=
DS-B antenna are mounted in the gap between the rudder and the vertical
fin=
.. The Flarm antenna is located as high as possible but below the metal
com=
ponents of the horizontal stabilizer. The ADS-B antenna is located as
low
=
as possible, but above the mass balance weight. This gives a very short
di=
stance between the Flarm and the antennas. The trick was running the
data
=
cable forward to the Butterfly display. =20

The comm antenna is located in the vertical fin, the transponder antenna
is=
bonded to the inside of the fuselage aft of the main gear. =20

P9

On Tuesday, July 23, 2019 at 5:15:07 PM UTC+1, John McCullagh wrote:
It is interesting how a thread diverges from the original question. I
posted this new thread because I had been talking to a former world
champion who has just taken delivery of a Ventus 3M. Schempp-Hirth put
three aerials in the fin: radio, transponder and PowerFlarm apparently
without problems, and they should know. Many of the replies in this thread
have been why this wouldn't work. I originally asked whether it was also
possible to put in an ADS-B aerial. I will be asking Schempps but I thought
I would ask around first.



I have a V3M due soon with a transponder and 9070 + PF/ADSB/Dual antenna options. The primary Flarm BD12, transponder, and radio antennae are going in the fin . As John M says, SH report that the various fin antennae work OK together.

John Galloway

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