FLARM antenna question (hindrance from metal)

I am going to wave my white "not a hardware guy" flag again here (while ducking).

If the (main) FLARM antenna is mounted on a tin or aluminum surface (specifically, a short length of 0.5 by 0.1 inch of what is tin, aluminum, or some other light metal), will it interfere with the antenna's performance?

Or should I go with the wood alternative ... ?

~ted/2NO

On Thursday, March 14, 2013 6:07:35 PM UTC-7, 2NO wrote:
I am going to wave my white "not a hardware guy" flag again here (while ducking). If the (main) FLARM antenna is mounted on a tin or aluminum surface (specifically, a short length of 0.5 by 0.1 inch of what is tin, aluminum, or some other light metal), will it interfere with the antenna's performance? Or should I go with the wood alternative ... ? ~ted/2NO

See for some antenna solutions.

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

Richard
www.craggyaero.com

At 01:07 15 March 2013, 2NO wrote:
I am going to wave my white "not a hardware guy" flag again
here (while
ducking).

If the (main) FLARM antenna is mounted on a tin or aluminum
surface
(specifically, a short length of 0.5 by 0.1 inch of what is tin,
aluminum,
or some other light metal), will it interfere with the antenna's
performance?

Or should I go with the wood alternative ... ?

~ted/2NO



Dunno if this helps, but for my European (Swiss) Flarm, I had to
mount the Flarm GPS antenna a long way from my Logger antenna
(in fact on my headrest, whereas logger is on the instrument panel
coaming) to get an adequate GPS signal into Flarm. Dunno about
material for mounting – I use non metallic for that; and the other
Flarm-Flarm antenna screws into the Swiss Flarm plastic case so it
was not an issue.

HTH.

Chris

Thanks Richard ... did you get the email I sent you this morning asking about LX7007 firmware upgrade?

2NO, if you are talking about the "rubber ducky" antennas that come on the portable PowerFlarm, they do not want to be mounted on metal (they don't need a ground plane).

For the center-fed dipole antennas that now come with the "core" (previously called brick). Again, no ground plane needed and they should be mounted as clear of metal (or conductive material like carbon fiber) as possible. Metal (or CF) is especially bad if nearby and in the same plane as the radials (not quite so bad if the metal is at right angles to the antenna radial, though it may still block RF if close. Also, be sure to keep the coaxial cable running straight away from the antenna for a few inches - - don't run it alongside the radial.

bumper

bumper,

I'm talking about the main bipole antenna (I have a core unit, not a portable).

Is that coaxial cable so poorly shielded that I have to create a special routing for it away from the radials? What kind of performance degradation are we talking about if the coax is, say, 1cm from the radial (and no metal is involved for the mounting)?

In PF's "Good Examples" section of their web page, the first example shows the coax lead running close to the lower radial. It also looks like a metal bracket, but I could be wrong about that.

2NO

That was he http://powerflarm.us/powerflarm-installation-notes/

On Friday, March 15, 2013 9:36:32 AM UTC-4, 2NO wrote:
I'm talking about the main bipole antenna (I have a core
unit, not a portable).

DIPOLE !

Is that coaxial cable so poorly shielded that I have
to create a special routing for it away from the radials?

No, the outside of the coax is a ground, which needs to be
away from the radiating portions of the dipole.
Mount it on wood, plastic, or glass, AWAY from other
antennas and metal. PLEASE read and follow the FLARM
recommendations from PowerFLARM.us and ignore uninformed
speculation on RAS !

Hope that helps,
Best Regards, Dave

On Friday, March 15, 2013 6:55:47 AM UTC-7, Dave Nadler wrote:


No, the outside of the coax is a ground, which needs to be

away from the radiating portions of the dipole.

Mount it on wood, plastic, or glass, AWAY from other

antennas and metal. PLEASE read and follow the FLARM

recommendations from PowerFLARM.us and ignore uninformed

speculation on RAS !



Hope that helps,

Best Regards, Dave

Dave,

Just to be clear, my reply to 2NO wasn't uninformed RAS speculation. I simply did not go into detail as to the reasons why, when I wrote, "Also, be sure to keep the coaxial cable running straight away from the antenna for a few inches - - don't run it alongside the radial.".

bumper

Ted et al:
Saw an interesting FLARM antenna installation in Pete Alexander's ASG29 which according to Pete works fine. This seems a good option for any glider with carbon in the nose. The dipole antennas were protruding through the glare shield either side of center, with just one pole of the antenna in the pilot's view. I didn't pull the canopy off to see where the left hand one was relative to the vent pushrod. Suppose this could be done in tandem too, but the vent door may block reception directly forward.
Jim