US Power FLARM Antennas

[Andy[_1_]]

The data sheet for the PFBrick FLARM TX/RX and PCAS/ADS-B antennas
can be found here :

http://www.linxtechnologies.com/resources/data-guides/ant-916-mhw-xxx-x.pdf

One has to wonder if an antenna tuned for 915MHz is the best choice
for PCAS/ADS-B. Maybe that antenna would be best used as the FLARM RX
only antenna?

Andy

[Evan Ludeman[_4_]]

On Jun 12, 10:00*am, Andy > wrote:
> The data sheet for the PFBrick FLARM TX/RX and *PCAS/ADS-B antennas
> can be found here :
>
> http://www.linxtechnologies.com/resources/data-guides/ant-916-mhw-xxx...
>
> One has to wonder if an antenna tuned for 915MHz *is the best choice
> for PCAS/ADS-B. *Maybe that antenna would be best used as the FLARM RX
> only antenna?
>
> Andy

Picked up several PCAS hits this weekend with PF brick. The range
seems adequate, but not convincingly so. I think I'd like a little
more than what I am currently seeing. I'd like to be seeing pcas
targets at at least 3 miles, I don't think I'm getting that much
reliably. I don't know if this is a hardware limitation or the way
the software is set up.

Evan Ludeman / T8

[Eric Greenwell[_4_]]

On 6/12/2012 7:00 AM, Andy wrote:
> The data sheet for the PFBrick FLARM TX/RX and PCAS/ADS-B antennas
> can be found here :
>
> http://www.linxtechnologies.com/resources/data-guides/ant-916-mhw-xxx-x.pdf
>
> One has to wonder if an antenna tuned for 915MHz is the best choice
> for PCAS/ADS-B. Maybe that antenna would be best used as the FLARM RX
> only antenna?

I thought the dipole was only for the Flarm A antenna, not the PCAS
antenna, as PCAS already has acceptable range. Remember, PCAS is
receiving signals from 130 to 250 watt transmitters, while Flarm
transmitters are 20 milliwatts or so.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Andy[_1_]]

On Jun 12, 2:55*pm, Eric Greenwell > wrote:
> I thought the dipole was only for the Flarm A antenna, not the PCAS
> antenna, as PCAS already has acceptable range. Remember, PCAS is
> receiving signals from 130 to 250 watt transmitters, while Flarm
> transmitters are 20 milliwatts or so.


Ah yes, but the PFB comes with 2 dipoles according to someone that
recently received theirs. The difference only being that one has a
standard SMA and the other an RPSMA.

Anyone with a new brick like to confirm that?

Andy

[Evan Ludeman[_4_]]

On Jun 12, 6:42*pm, Andy > wrote:
> On Jun 12, 2:55*pm, Eric Greenwell > wrote:
>
> > I thought the dipole was only for the Flarm A antenna, not the PCAS
> > antenna, as PCAS already has acceptable range. Remember, PCAS is
> > receiving signals from 130 to 250 watt transmitters, while Flarm
> > transmitters are 20 milliwatts or so.
>
> Ah yes, but the PFB comes with 2 dipoles according to someone that
> recently received theirs. *The difference only being that one has a
> standard SMA and the other an RPSMA.
>
> Anyone with a new brick like to confirm that?
>
> Andy

That's correct.

T8

[noel.wade]

Wanted to follow-up on the Antenna(s) for the PowerFLARM "Brick": Got
mine today and the updated installation manual on the www.powerflarm.us
website is decent; though there's still room for improvement.

In the manual, they mention that the dipole antenna mounted on the
glareshield should be "at least 4 inches ahead" of the compass. From
the "Hall of Fame/Hall of Shame" photos, it would appear that this is
referring to the dipole being placed between the pilot's head and the
compass.

In my DG-300 my compass is not in quite the extreme-forward position
as shown in some of those photos. So I may be able to mount the FLARM
dipole 4-6 inches forward of the compass (between the compass and the
nose of the glider). Any PowerFLARM insiders care to comment on
whether this is a bad idea/location?

Also: Between my 2 loggers' GPS antennae and the PowerFLARM antennae,
I'm running out of places to stick them all, while maintaining good
separation. Any comments on whether the ADS-B antenna would work OK
if I stick it to the inside the "roof" of the turtledeck? The ship is
all fiberglass, but I wonder about the landing-gear metal below, the
nearby speaker in the turtledeck, the proximity to the wing-spars
(8-12 inches away), etc. Thoughts/comments/ideas?

Thanks!

--Noel

[FLARM]

Mounting the FLARM antenna in front of the compass is by far the best location unless you have metal or carbon vent outlets forward of it at the same height.

We will publish an 'Antenna Installation' application note this week.
Don't worry too much about the ADS-B antenna, the signals it receives are pretty strong.

FLARM

[John Cochrane[_2_]]

On Jun 20, 2:27*pm, FLARM > wrote:
> Mounting the FLARM antenna in front of the compass is by far the best location unless you have metal or carbon vent outlets forward of it at the same height.
>
> We will publish an 'Antenna Installation' application note this week.
> Don't worry too much about the ADS-B antenna, the signals it receives are pretty strong.
>
> FLARM

"FLARM" You're listening! Please please please find a better antenna
than this ugly center-fed dipole with plastic attachment that goes
right in our field of vision. The RAS thread found lots of bottom-fed
and bottom-mounted dipoles. Please check that one of them works and
send an antenna that even plausibly is suited for a bottom-fed
installation on a glider glareshield!
John Cochrane

[noel.wade]

On Jun 20, 4:07*pm, John Cochrane >
wrote:

> and bottom-mounted dipoles. Please check that one of them works and
> send an antenna that even plausibly is suited for a bottom-fed
> installation on a glider glareshield!
> John Cochrane

While I don't disagree with John's desire for a "nicer" dipole, I am
barely going to see the dipole that came with my FLARM as I'm mounting
it beyond the compass and run the wire straight back and down (so the
compass body will hide it from my sensitive pilot's eyes).

The current dipole is *tiny*. The posted photos don't give you a
proper scale - the "center body" of the thing is barely larger than my
thumbnail! Here's a datasheet for what appears to be the same antenna
that came with my device. Less than 4" in total length -
http://www.linxtechnologies.com/resources/data-guides/ant-916-mhw-xxx-x.pdf

If they want to stick with the same supplier, this dipole (also from
Linx) may be a simple substitute: http://www.linxtechnologies.com/resources/data-guides/ant-db1-vdp-xxx.pdf
(although I'm no electrical engineer!)

So in the end - it could be nicer but its not a huge issue IMHO.

--Noel

[Andy[_1_]]

On Jun 20, 12:27*pm, FLARM > wrote:
> We will publish an 'Antenna Installation' application note this week.
> Don't worry too much about the ADS-B antenna, the signals it receives are pretty >strong.

Hope the antenna installation guide considers that most pilots like to
clean the inside of the canopy before every flight. On many modern
gliders the glareshield is attached to the canopy leaving little space
for a hand and cloth even when no antenna is present.

It's a bit surprising that people think the PCAS antenna positioning
is not important. I understand that the signal is stronger that the
FLARM signal, but ZAON is quite emphatic about the need for proper
positioning of the MRX PCAS antenna.

Hope FLARM will also explain the status of FCC certification and the
impact, if any, on sales of the brick.

Andy

[Andrzej Kobus]

On Jun 20, 7:07*pm, John Cochrane >
wrote:
> On Jun 20, 2:27*pm, FLARM > wrote:
>
> > Mounting the FLARM antenna in front of the compass is by far the best location unless you have metal or carbon vent outlets forward of it at the same height.
>
> > We will publish an 'Antenna Installation' application note this week.
> > Don't worry too much about the ADS-B antenna, the signals it receives are pretty strong.
>
> > FLARM
>
> "FLARM" You're listening! *Please please please find a better antenna
> than this ugly center-fed dipole with plastic attachment that goes
> right in our field of vision. The RAS thread found lots of bottom-fed
> and bottom-mounted dipoles. Please check that one of them works and
> send an antenna that even plausibly is suited for a bottom-fed
> installation on a glider glareshield!
> John Cochrane

I agree with John. I would like a bottom-fed installation as well.

[kirk.stant]

I'm wondering if an external solution would be the best way to go.

The Butterfly PF site has some interesting external antennas, but they look kinda hi-drag to my uneducated eye:

http://www.butterfly-store.de/en/Collision+Avoidance/PowerFLARM/Antennas/

Seems to me that a streamlined bottom-fed dipole mounted on top of fuselage just behind the canopy would provide the best coverage (nothing in front or back of it) and minimal drag (less than the TE probe), without cluttering up the cockpit. For gliders with carbon fiber fuselages, might need to add a bottom antenna. What we need is an antenna that can be removed easily from it's socket, so it will not interfere with the top of the trailer when the glider is derigged.

Make the socket a pass-through, plug in the antenna (held in place with an O-ring?), connect the co-ax in the fuselage, done.

Nothing in the field of view in the cockpit (whiskey compasses on the glareshield? really? when was the last time you ACTUALLY used that relic), easier to clean the inside of the canopy, etc. After all the point is to make it EASIER to see traffic!

Anybody know someone who makes custom antennas? How about an SSA non-profit initiative? Or better yet, Bumper, you reading this?

Kirk
66

[Eric Greenwell[_4_]]

On 6/20/2012 5:29 PM, Andy wrote:

> Hope the antenna installation guide considers that most pilots like
> to clean the inside of the canopy before every flight. On many
> modern gliders the glareshield is attached to the canopy leaving
> little space for a hand and cloth even when no antenna is present.

"Most"? I'm really curious about what is making the inside of your
canopy so dirty it requires such frequent cleaning? Do you tow from a
dirt airstrip?

I clean mine once a year, and I usually can't tell the difference;
however, if I cleaned it before every flight, I'd worry the
inside would be covered with fine scratches after 17 years and 100's of
flights.

Just to be clear, I'd like the antennas to be smaller or placed
somewhere else, so I'm not looking or taking pictures through them. But,
I'm getting use to them.

> It's a bit surprising that people think the PCAS antenna
> positioning is not important. I understand that the signal is
> stronger that the FLARM signal, but ZAON is quite emphatic about the
> need for proper positioning of the MRX PCAS antenna.

The signal is about 150watts/0.020watts = 7500 times stronger -
transponder signals are a lot stronger! My MRX manual isn't as emphatic
as yours, apparently, saying only:

"The preferred placement for MRX is on the glare shield of your aircraft
with the antenna angled vertically. This configuration affords MRX the
best possible sensitivity and accuracy. Position MRX at least 2” away
from any magnetic compass to avoid potential magnetic interference."

It also has a shorter antenna, and perhaps that makes it's positioning
more important than the PowerFlarm PCAS antenna.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Craig R.]

I spent the day installing my FLARM brick today. The antennas were added to the side of the glare shield (Discus 2b) VIA a $1 door stop and Velcro to give it a reasonable vertical orientation without banging on my canopy. I was leaning to balsa wood, but in my small town I couldn't find any. I will spruce up the installation a bit by painting the door stops with textured black paint. Since independent analysis shows the antenna orientation only marginally affects reception and rotating the antenna in the same location does more damage than moving it off of vertical, this should be good enough. It isn't blocking my forward view like some of the "recommended" installations have shown. Of course, it is a work in progress like all other folks out there. If things go to pot, I'll make changes and let you know the results.

Craig