PowerFLARM antenna mounts

On 7/5/2012 5:35 AM, John Godfrey (QT) wrote:

Thanks,
Best Regards, Dave "YO electric"

PS: If you're interested in a mount for a flat-top
glare-shield (SH, etc) - send Rex a note.

End fed dipole could also be very thin.

"Fat" antennas are used to broaden the frequency range of the antenna,
but I don't know if that is the reason for the PowerFlarm antenna width.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz

On Wednesday, July 4, 2012 11:50:53 AM UTC-4, Dave Nadler wrote:
Rex is looking into making glare-shield antenna mounts
for the PowerFLARM dipole antenna, especially for
gliders with glare-shields that jettison with the
canopy (Schleicher, LS). The mount will featu
- mast sticks up above glare-shield
- base mounts underneath glare-shield with velcro
- anti-glare flat-black finish
This arrangement permits safe canopy jettison
and easy canopy removal.

You'll cut a ~ 3-4" round hole in the glare-shield,
afix the velcro, then stick on the antenna so it
is vertical in flight attitude (with coax at
about 45 degrees away from the antenna).

Cost guestimated at $75 including shipping.

Please send Rex an email if you're interested as
he needs to gauge interest; contact info he
http://www.williamssoaring.com

Thanks,
Best Regards, Dave "YO electric"

PS: If you're interested in a mount for a flat-top
glare-shield (SH, etc) - send Rex a note.

Sloped groundplane (like base station antennas) should ensure propagation down to canopy rail angle. Need GHz antenna geek.

On Jul 4, 10:50*am, Dave Nadler wrote:

Rex is looking into making glare-shield antenna mounts
for the PowerFLARM dipole antenna, especially for
gliders with glare-shields that jettison with the
canopy (Schleicher, LS).

If the proposed alternative glare screen antenna mount comes to
fruition, doesn't the coax between the unit and the antenna cause an
impediment to the jettisoning of the canopy? Or is there a breakaway
connection of some sort?

You'll cut a ~ 3-4" round hole in the glare-shield,
afix the velcro, then stick on the antenna so it
is vertical in flight attitude (with coax at
about 45 degrees away from the antenna).

Out of curiosity, why such a large 3-4" hole? Is that so both
antennas can stick through a single hole? Could you not drill two
smaller holes at the correct spacing? Or do the pictures of the
PowerFlarm I find at your site (which shows two small diameter
antennas) differ from reality and we are now only have one antenna?
Just don't want someone to needlessly emasculate their glare screen!

Thanks, John

Googling "PowerFlarm antenna" I see both two antenna (thin or thick)
and single antenna installations.
But I still don't get the 3-4" hole. Expiring minds want to know.

And then this rather interesting picture of a PowerFlarm "Perfect"
antenna location as mentioned by Craggy Aero. ;-)

http://www.google.com/imgres?hl=en&b... r:0,s:0,i:73

Thanks, John

On Jul 5, 8:49*am, JohnDeRosa wrote:
Googling "PowerFlarm antenna" I see both two antenna (thin or thick)
and single antenna installations.
But I still don't get the 3-4" hole. *Expiring minds want to know.

And then this rather interesting picture of a PowerFlarm "Perfect"
antenna location as mentioned by Craggy Aero. *;-)

http://www.google.com/imgres?hl=en&b...=isch&tbnid=UD...

Thanks, John

Because the glareshield jettsons with the canopy, and the whole mess
has to stay with the glider, not the canopy. If you feed it through
two holes, you've just permanently attached the canopy to the glider.
This is a BIG no-no. If you can't jettison the canopy, you can't get
out of the glider. This has happened, with pda cables holding the
canopy to the glider.

I understand from Dave Nadler that Flarm has tried lots of the
interesting antenna suggestions from this forum, including the rather
obvious idea of bottom-fed and bottom-mounted dipoles, and found they
don't work well enough. Given that fact, roll your own without
extensive testing is probably not a good idea. (Dave: A list of "here
are the antennas we tried that don't work" might be useful here.) That
also suggests that we not hold our breaths for more aesthetically
pleasing antennas any time soon, but perhaps Dave would rather comment
on that possibility.

John Cochrane

The original post describes how the antenna assembly is attached to the glare shield with velcro. Presumably from underneath with just enough velcro to get the job done, but not impede the jettison process. Knowing the quality of fabrication that Rex and the team does at Williams, I suspect this will be a nice solution for those of us with Schleichers. I'll be ordering one.


On Thursday, July 5, 2012 6:40:47 AM UTC-7, JohnDeRosa wrote:
On Jul 4, 10:50*am, Dave Nadler wrote:

Rex is looking into making glare-shield antenna mounts
for the PowerFLARM dipole antenna, especially for
gliders with glare-shields that jettison with the
canopy (Schleicher, LS).

If the proposed alternative glare screen antenna mount comes to
fruition, doesn't the coax between the unit and the antenna cause an
impediment to the jettisoning of the canopy? Or is there a breakaway
connection of some sort?

You'll cut a ~ 3-4" round hole in the glare-shield,
afix the velcro, then stick on the antenna so it
is vertical in flight attitude (with coax at
about 45 degrees away from the antenna).

Out of curiosity, why such a large 3-4" hole? Is that so both
antennas can stick through a single hole? Could you not drill two
smaller holes at the correct spacing? Or do the pictures of the
PowerFlarm I find at your site (which shows two small diameter
antennas) differ from reality and we are now only have one antenna?
Just don't want someone to needlessly emasculate their glare screen!

Thanks, John

As Dave Nadler says, a vertical antenna "disappears". when focused at infinity - as long as you have two eyeballs and the antenna is dark colored, the brain doesn't pay any attention to it.

As to making the antenna out of very thin wire; from my Nave ET days, a thin antenna element has a more narrow bandwidth. Since flarm uses a frequency hopping protocol (I think from 885 to 915 Mhz), thin may not work very well.

Like Rex Mayes (Williams Soaring), I made the mount for my PF as a shelf that sits just aft and slightly below the glareshield. Power lead goes through a small hole in the top of the glareshield, then through a male to female in-line coaxial plug connector (Amazon - 5.5mm X 2.1mm, commonly used for CCTV) to allow clean canopy jettison. If the canopy goes away it takes the PF with it.

bumper

On Jul 5, 9:10*am, bumper wrote:

As to making the antenna out of very thin wire; from my Nave ET days, a thin antenna element has a more narrow bandwidth. Since flarm uses a frequency hopping protocol (I think from 885 to 915 Mhz), thin may not work very well.


lower freq 902.20000000 upper freq 927.80000000

Source - FCC application for PFP (no application, or other
certification data, published for PFB).

We are all faced with fitting these things to legacy gliders of varying geometry and materials. The carbon fibre fuselage seems to pose most problems.

I hope glider designers in future make installation of transponders, Flarm and PowerFlarm etc. easier, without dead spots or vision impairment.

Chris N

We have published an Application note for the FLARM antenna installation:
http://powerflarm.us/manuals-softwar...release-notes/

Deep link:
http://powerflarm.us/wp-content/uplo...e_ANTENNAS.pdf

Still a bit raw, but we will update it with more pictures and examples.