FLARM Fusion Range

Hi Darryl,

Here is a link to the pix. Sadly they are TIFFs: https://www.dropbox.com/sh/dhe9415hd...5VFoQ9eMa?dl=0
Yes, I am talking FLARM A, and B. ADS-B is dead center up high under the glare shield and seems to be working fine. you can find a recent FAA report there as well.

Matt



On Wednesday, April 21, 2021 at 3:20:17 PM UTC-7, Darryl Ramm wrote:
On Tuesday, April 20, 2021 at 10:28:54 AM UTC-7, Matt Herron Jr. wrote:
Hi guys,

I just installed a FLARM Fusion and am getting some very poor results. The antennas are installed symmetrically on either side of the canopy rail (see photographs) in an ASW27b. They clip into a plastic adaptor printed from ABS, and each antenna has a clear 180 degree view out the side of the canopy. This seems to me like a pretty ideal setup to avoid the carbon in the cockpit, etc. Can anyone help me understand why the range is not better, and in particular, why the range is better on one antenna vs the other? that makes no sense to me.

Thanks,

Matt Herron


PastedGraphic-4.tiff

PastedGraphic-1.tiff

PastedGraphic-2.tiff
You can't past images to Google groups, or USENET like this. Can you share the image somewhere, like Google Drive and provide a link to them (and in jpg not TIFF?).

And to be clear you are talking FLARM A and FLARM B antennas? Where is your 1090 MHz antenna?

On Thursday, April 22, 2021 at 12:25:49 AM UTC-5, Matt Herron Jr. wrote:
Hi Darryl,

Here is a link to the pix. Sadly they are TIFFs: https://www.dropbox.com/sh/dhe9415hd...5VFoQ9eMa?dl=0
Yes, I am talking FLARM A, and B. ADS-B is dead center up high under the glare shield and seems to be working fine. you can find a recent FAA report there as well.

Matt
On Wednesday, April 21, 2021 at 3:20:17 PM UTC-7, Darryl Ramm wrote:
On Tuesday, April 20, 2021 at 10:28:54 AM UTC-7, Matt Herron Jr. wrote:
Hi guys,

I just installed a FLARM Fusion and am getting some very poor results.. The antennas are installed symmetrically on either side of the canopy rail (see photographs) in an ASW27b. They clip into a plastic adaptor printed from ABS, and each antenna has a clear 180 degree view out the side of the canopy. This seems to me like a pretty ideal setup to avoid the carbon in the cockpit, etc. Can anyone help me understand why the range is not better, and in particular, why the range is better on one antenna vs the other? that makes no sense to me.

Thanks,

Matt Herron


PastedGraphic-4.tiff

PastedGraphic-1.tiff

PastedGraphic-2.tiff
You can't past images to Google groups, or USENET like this. Can you share the image somewhere, like Google Drive and provide a link to them (and in jpg not TIFF?).

And to be clear you are talking FLARM A and FLARM B antennas? Where is your 1090 MHz antenna?
Matt,

I'm looking at picture 2 and have a couple of concerns:
-The antenna is not shown in the mounting bracket, but from picture 3 it seems certain that the lower arm would be very close and probably touching the fiberglass frame of the canopy. The upper arm is very likely close or touching the canopy itself.
-If the canopy frame is carbon, mounting so close would definitely affect performance, probably severely.

Even though the plexiglass or polycarbonate canopy is not conducting, they both have a higher dielectric constant than air and will definitely affect the tuning of the antenna. Most likely tuning it to a lower frequency than intended. The suggestion to use a wood mounting block to space the antenna away from the mounting surface is a good idea. I'd suggest trying to move it somewhere where there is at least an inch or two air around the antenna (especially the ends of the arms, the mounting bracket is OK as long as it is only near the middle).

I can't say for sure this will fix your problem. The RF design of these systems assume a considerable amount of attenuation from things like this, but if there is too much attenuation you will definitely see unacceptable range. I would also check the cable for crimps and loose SMA connectors.

Rich L.

Hi Rich,

You are correct in that the lower portion of the antenna gets very close to the canopy frame. The upper portion does as well. This was done to get as much forward and rearward view for the antenna as possible. I believe moving the antennas inboard 1-2 inches would really hurt my front range, which is important of course. The fact that one antenna is performing much better in range than the other can't be ignored, and leads me to suspect some other root cause than placement. BTW, the system performs better than average in transmission (according to OGN). Is there a way to measure attenuation?

Cable crimps are good, and SMA connections are tight.

Matt,

I'm looking at picture 2 and have a couple of concerns:
-The antenna is not shown in the mounting bracket, but from picture 3 it seems certain that the lower arm would be very close and probably touching the fiberglass frame of the canopy. The upper arm is very likely close or touching the canopy itself.
-If the canopy frame is carbon, mounting so close would definitely affect performance, probably severely.

Even though the plexiglass or polycarbonate canopy is not conducting, they both have a higher dielectric constant than air and will definitely affect the tuning of the antenna. Most likely tuning it to a lower frequency than intended. The suggestion to use a wood mounting block to space the antenna away from the mounting surface is a good idea. I'd suggest trying to move it somewhere where there is at least an inch or two air around the antenna (especially the ends of the arms, the mounting bracket is OK as long as it is only near the middle).

I can't say for sure this will fix your problem. The RF design of these systems assume a considerable amount of attenuation from things like this, but if there is too much attenuation you will definitely see unacceptable range. I would also check the cable for crimps and loose SMA connectors.

Rich L.

Matt,

Are you sure the that the Black Mount ABS does not have carbon for a colorant?

Richard
www.craggyaero.com

On Thursday, April 22, 2021 at 8:29:43 AM UTC-7, Richard Pfiffner wrote:
Matt,

Are you sure the that the Black Mount ABS does not have carbon for a colorant?

Richard
www.craggyaero.com

Matt,

I suspect that the colorant in ABS is carbon black.
Make sure there is little to no carbon content, which would seriously alter antenna and system performance. BLACK anything -- including plastics -- is usually the worst, as they often have high carbon content. Think of applying black paint with carbon in it as applying very thin, black tin foil. Would you do that? Of course not. It would be both a shield and reflector, both of which are bad for the antenna (shield), the system connected to it (reflected power, VSWR, etc.), not to mention system performance.

Matt

I suspect that the colorant in ABS is carbon black.

Make sure there is little to no carbon content, which would seriously alter antenna and system performance. BLACK anything -- including plastics -- is usually the worst, as they often have high carbon content. Think of applying black paint with carbon in it as applying very thin, black tin foil. Would you do that? Of course not. It would be both a shield and reflector, both of which are bad for the antenna (shield), the system connected to it (reflected power, VSWR, etc.), not to mention system performance.

Richard
www.craggyaero.com

Have you tried swapping the two antennas? If the bad performance moves, you have a bad antenna or a bad mount. I have seen two antenna failures in my club; one a club glider, one a privately-owned glider. If you have an OGN receiver nearby, you can use "Glidertracker" to see your received power at the antennna (this is how I diagnose bad FLARMs, and also use a known good antenna to test the antennas); (click on your glider icon, a window pops up showing info including received signal strength at the receiver. In each failure, the power at our OGN station was 20 db lower on the bad antennas (OEM), about 50m away). I have saved shipping two FLARMs for unnecessary diagnosis by discovering bad antennas. Antennas are cheap, and they sometimes arrive dead, or break, particularly if they are often touched/handled/'twanged'. Link for Glidertracker is https://glidertracker.org/#lat=1105585&lon=6428048&z=5 . You can zoom it to your area. OGN stations are inexpensive and very useful for crew wondering how their pilot is doing.

I use long antennas ($20 each) on foam blocks:

https://photos.app.goo.gl/tg8GHbnkDu3Lj7t78

Range:

https://drive.google.com/file/d/12rM...w?usp=drivesdk

Installing a short antenna next to a conductive item about the size of the antenna can interfere with the antenna performance. I attached a short antenna diagonally on a steel tube in a towplane and got abysmal performance.

Oh yes,

Looking at your antenna in the bracket, the lead runs parallel to the antenna when it should run at a 90° angle directly away from the dipole.

You really need to carefully read: FTD-041Â*Application Note FLARM Antenna Installation

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

Matt

Well since there is a PAPR report sitting there I'll bite.

Not that this will cause any FLARM antenna performance issues, but you need to get that ADS-B Out system performing correctly. Seems to be set up for 2020 (aka 14 CFR §91.227) compliance. Is this a TN72 GPS and a Trig TT22? It is not reporting altitudes correctly. It is totally useless as is, the FAA system is ignoring you, not making the glider a TIS-B client for example. And this system would not give you any ADS-B Out airspace privileges.. You are a candidate for a friendly FAA "she not be working, please explain" letter.

Start with what is the firmware version of this transponder and control head. Shown briefly on the LCD screen as the TT22 powers on... take a photo.

The minimal firmware version to support 14 CFR §91.227 compliance is transponder version 2.12 and TC20 Control Head version 1.14. The system must be at least at these levels. Older versions absolutely will not work. There is no advantage at being on transponder software version 2.13, ugt it's fine if you are. Oh and these are simple counting numbers after the decimal point, so say 2.4 is not 2.40 and is not later than 2.12 (this has confused at least two folks recently).

Is the ships static correctly connected to the TC20 control head? Had the transponder passed its biannual tests, including static/alt encoder checks? (and sure as heck, don't normally mess with the alt calibrations in the TT22 ADS-B setup menus). You can email me offline if stuck, there may be another local glider showing similar issues I am helping look at.

---

As for the FLARM antennas, touching the canopy/static concerns are extremely unlikely to be relevant. regardless of what the manual says. As folks have pointed out... get that coax away from the dipole arms, that is a bad setup. If plastic is RF opaque aslo as pointed out that will not be good. I would try just tapping the antennas (and coax lead) on the inside of the canopy and testing.

This may not be a very good location, You are close to metal components, rods, handles in the canopy mechanisms, wishing the RF near field which can significantly affect RF patterns. May be close to carbon in the fuselage canopy edge, even if the canopy frame has itself is RF opaque etc. There are likely no great choices for location, up on the instrument cover area is a conflict between ADS-B GPS antenna sky view, FLARM A and 1090ES so may not be much better. But you are really messing this up now with the coax running close parallel to the antenna. Lets see what the pattern looks like when you undo that.

On Wednesday, April 21, 2021 at 10:25:49 PM UTC-7, Matt Herron Jr. wrote:
Hi Darryl,

Here is a link to the pix. Sadly they are TIFFs: https://www.dropbox.com/sh/dhe9415hd...5VFoQ9eMa?dl=0
Yes, I am talking FLARM A, and B. ADS-B is dead center up high under the glare shield and seems to be working fine. you can find a recent FAA report there as well.

Matt
On Wednesday, April 21, 2021 at 3:20:17 PM UTC-7, Darryl Ramm wrote:
On Tuesday, April 20, 2021 at 10:28:54 AM UTC-7, Matt Herron Jr. wrote:
Hi guys,

I just installed a FLARM Fusion and am getting some very poor results.. The antennas are installed symmetrically on either side of the canopy rail (see photographs) in an ASW27b. They clip into a plastic adaptor printed from ABS, and each antenna has a clear 180 degree view out the side of the canopy. This seems to me like a pretty ideal setup to avoid the carbon in the cockpit, etc. Can anyone help me understand why the range is not better, and in particular, why the range is better on one antenna vs the other? that makes no sense to me.

Thanks,

Matt Herron


PastedGraphic-4.tiff

PastedGraphic-1.tiff

PastedGraphic-2.tiff
You can't past images to Google groups, or USENET like this. Can you share the image somewhere, like Google Drive and provide a link to them (and in jpg not TIFF?).

And to be clear you are talking FLARM A and FLARM B antennas? Where is your 1090 MHz antenna?