Dreaming of a BETTER PowerFLARM antenna

On Saturday, October 31, 2015 at 9:36:35 AM UTC-7, Ramy wrote:
As a strong advocate of power flarm I can't agree more. Every time I see those stock dipole antennas on a top of a glare shield it disturbs me. Our forward visibility is already restricted and those antennas are so awkward. Mine are in the nose of the glider since the early 27a do not have carbon on the nose. Works great. I recommended those with carbon nose to put the antennas below the glare shield with only the top sticking out. Looks much better and still working well enough. There are other solutions.

Ramy

If you don't put it on the glare shield, how are you going to cover it with a tin foil hat when those awful leachers are about?

Well, this is an old discussion.
I already published my home built bottom fed Flarm (and ADSB) dipole antennas 2 years ago.
https://sites.google.com/site/threeu...flarm-antennas
By now, my antennas are painted black.

I personally did not like the bulkiness of the standard center fed dipoles either.
That's why I build my own thin "whisker" ones.
However, it has been discussed here in the past also already that the fact that humans have stereoscopic vision, means that an object like a Flarm antenna at 2-3 ft distance does not limit / obstruct the human field of view.

I cannot subscribe to Ramy's recommendation to put the antenna under the glareshield without knowing what is under your glareshield.
On my carbon ship, there is metal tubing structure right under the glareshield. Putting the antennas down in between that structure would significantly impact the performance.
In general, placing an antenna close to metal structures, like frames or metal housing of electronics boxes (radios, transponders, varios, flarm boxes, etc.) is a bad idea.
I needed to raise the antennas as high as possible above the glareshield
See images in the link above.
On other ships like modern gliders with a panel attached to a glass composite bottom shelf, this might be a viable option.

With respect to placing antennas on the side rails, you have to keep in mind that while the Flarm systems have an option for 2 receive antenna, there is only 1 Flarm transmit (and receive) antenna. And then there is of course the single ADSB receive antenna.
So, if you would place the Flarm Tx/Rx antenna on one side and the ADSB receive antenna on the other side of the canopy frame, you would get a skewed range diagram.
Difficult to say how skewed. Would be worth while an experiment with the Flarm range evaluation tool.

3U

To be a bit clearer on the side rail mounting:
If you use both Flarm antennas (A and B) on either side of the canopy then your Flarm reception should be well balanced.
However, your Flarm transmission would be skewed to one side as only the Flarm A antenna transmits. The Flarm B antenna is receive only.

Mounting the ADSB/PCAS antenna on either side rail should not be an issue as the transponders are transmitting at very high power levels (150-250 Watts)
So, you will be receiving more than enough signal from a transponder equipped aircraft a few miles away.

On Saturday, October 31, 2015 at 1:56:57 PM UTC-7, wrote:
To be a bit clearer on the side rail mounting:
If you use both Flarm antennas (A and B) on either side of the canopy then your Flarm reception should be well balanced.
However, your Flarm transmission would be skewed to one side as only the Flarm A antenna transmits. The Flarm B antenna is receive only.

Mounting the ADSB/PCAS antenna on either side rail should not be an issue as the transponders are transmitting at very high power levels (150-250 Watts)
So, you will be receiving more than enough signal from a transponder equipped aircraft a few miles away.

I am getting 4 nm to 8 nm range with my antennas. 1/2 wave dipole on the panel and the standard T antenna in the nose.

Analysis on this page at the bottom.

http://www.craggyaero.com/cables_&_antennas.htm


Richard

I'm offering new covert, semi-low drag mounts.

https://upload.wikimedia.org/wikiped...e_110_1945.jpg

On Saturday, October 31, 2015 at 2:28:43 PM UTC-7, bumper wrote:
I'm offering new covert, semi-low drag mounts.

https://upload.wikimedia.org/wikiped...e_110_1945.jpg

And, with that on your glider, you probably won't have to worry about the leachers as they will be well in front!

Does one of those neat caps in the photo come with each unit?

On Saturday, October 31, 2015 at 4:21:12 PM UTC-4, wrote:
Well, this is an old discussion.
I already published my home built bottom fed Flarm (and ADSB) dipole antennas 2 years ago.
https://sites.google.com/site/threeu...flarm-antennas
By now, my antennas are painted black.

Thanks 3U for contributing. Yes I'm familiar with your work and website. I wish you would expand your article to include "how to" details so DIY guys like me could fabricate their own antennas.

Regarding PowerFLARM antenna A, what amount of signal degradation would be experienced if there were two "A" antennas by means of some sort of splitter?

On Sat, 31 Oct 2015 15:28:07 -0700, bensoaring wrote:

On Saturday, October 31, 2015 at 4:21:12 PM UTC-4,
wrote:
Well, this is an old discussion.
I already published my home built bottom fed Flarm (and ADSB) dipole
antennas 2 years ago.
https://sites.google.com/site/threeu...rm/powerflarm-
antennas
By now, my antennas are painted black.

Thanks 3U for contributing. Yes I'm familiar with your work and
website. I wish you would expand your article to include "how to"
details so DIY guys like me could fabricate their own antennas.

Regarding PowerFLARM antenna A, what amount of signal degradation would
be experienced if there were two "A" antennas by means of some sort of
splitter?

A thought: you can pick up nylon-covered steel trace (1.3mm OD, the steel
trace is 1.0mm diameter from eBay (10m for $8.95) and good fishing shops
also stock it. Crimp the end over and add a blob of epoxy for eye
protection and there's a very thin antenna. On a glare shield one of
these would be almost invisible. The older Swiss FLARMs, used antennae
which were just a 1/4 wave length of what looked like 0.8mm (1/32") music
wire mounted at the centre of a circular 80mm diameter metal ground
plane.

The fox-hunting crowd, i.e. orienteers who run XC in search of a hidden
radio beacon) make Yagi DF antennae from steel tape-measures and plastic
plumbing pipe which seem to work pretty well, so would this nylon-coated
steel trace be any good for making up PowerFLARM dipoles or bottom-fed
antennae?

I'd be interested to hear what somebody who understands antennae thinks
about using this stuff or even thinner trace material: it is available
down to 20 lb breaking strain.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Saturday, October 31, 2015 at 6:56:02 PM UTC-4, Martin Gregorie wrote:
On Sat, 31 Oct 2015 15:28:07 -0700, bensoaring wrote:

On Saturday, October 31, 2015 at 4:21:12 PM UTC-4,
wrote:
Well, this is an old discussion.
I already published my home built bottom fed Flarm (and ADSB) dipole
antennas 2 years ago.
https://sites.google.com/site/threeu...rm/powerflarm-
antennas
By now, my antennas are painted black.

Thanks 3U for contributing. Yes I'm familiar with your work and
website. I wish you would expand your article to include "how to"
details so DIY guys like me could fabricate their own antennas.

Regarding PowerFLARM antenna A, what amount of signal degradation would
be experienced if there were two "A" antennas by means of some sort of
splitter?

A thought: you can pick up nylon-covered steel trace (1.3mm OD, the steel
trace is 1.0mm diameter from eBay (10m for $8.95) and good fishing shops
also stock it. Crimp the end over and add a blob of epoxy for eye
protection and there's a very thin antenna. On a glare shield one of
these would be almost invisible. The older Swiss FLARMs, used antennae
which were just a 1/4 wave length of what looked like 0.8mm (1/32") music
wire mounted at the centre of a circular 80mm diameter metal ground
plane.

The fox-hunting crowd, i.e. orienteers who run XC in search of a hidden
radio beacon) make Yagi DF antennae from steel tape-measures and plastic
plumbing pipe which seem to work pretty well, so would this nylon-coated
steel trace be any good for making up PowerFLARM dipoles or bottom-fed
antennae?

I'd be interested to hear what somebody who understands antennae thinks
about using this stuff or even thinner trace material: it is available
down to 20 lb breaking strain.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Smiling...us redneck bass fisherman know this as nylon coated stainless steel fishing leader.