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Spray-able Antenna Ground Plane?

9GT

Well Known Member
Patron
My buddy finally received his Garmin GDL 82 and we are trying to figure out a spot for the GPS antenna and a ground plane. About the only available location at this point would be the top of the engine cowling where we could get a ground plane underneath the top cowling. Its not an RV and is all composite COZY MKIV. Pretty sure I read about a spray-able metallic conductive material for this purpose here on the forum a couple years ago, but no joy finding it now. May be of interest for me also on the RV-9A build, as I am trying to keep as much drag to minimum in my build. I remember a spray-able conductive material sold by AS&S for this purpose, but can not seem to find it on their website now. It may have been something like this? https://www.amazon.com/MG-Chemicals-Conductive-Coating-Improved/dp/B01N3AWGNX/ref=dp_ob_title_def
Any help greatly appreciated here. Dave
 
I used thin copper foil from a local hobby store, with high temperature contact adhesive. Worked fine on my composite structure for a ground plane. Make sure you clean the surface real well first.
 
Spraylat 599 is one that is often recommended. I've never used it so can't comment on its effectiveness.

Another is Super Shield - available in liquid and spray forms:
mgchemicals.com/downloads/tds/tds-841-a.pdf
mgchemicals.com/downloads/tds/tds-841-l.pdf
It seems to take several coats of this stuff to get down to a reasonable surface resistance, and even at that it isn't a true zero ohm conductor - two coats of spray got the DC resistance down to about 1.5 ohms per foot. (So says a fellow builder who experimented with it.)
 
If you're using the relatively inexpensive patch/puck antenna, the ground plane does not have to be that big ... 70mm x 70 mm (2.7" square) is more than enough (no particular benefit to larger).

+1 on the copper foil (or thin aluminium); I wouldn't trust any spray-on "conductive" coating to do anything useful at 1.575 GHz.
 
We used AL foil all the time when I did 2/4/6GHz microwave combiner work in the '80s. Same stuff you get a Lowes for your favorite HVAC system. Dont over think or complicate this.

Or go to your wifes kitchen drawer and get out the AL foil she has.......works just the same.
 
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I still have a decent size piece of the self stick aluminum foil heat shielding I used on the cowling of my RV-10. I?ll cut a 16? circle and use that then. Thanks everyone. 👍
 
David,

My co-workers at Garmin call my Long-EZ the "wonder-woman plane" because it is so transparent to GPS and SXM signals.

I have the SXM antenna for the GDL 52R, the GA 26C GPS antenna for the G3X Touch PFD display, the GA 26C GPS antenna for the G5 flight display, and the GA 36 GPS antenna for the GTX 345R w/GPS all mounted on a small aluminum plate underneath the removable fiberglass cover in the nose, and all work great.

I get 100% passing numbers on the ADS-B compliance reports, so I know the GPS receiver inside the GTX 345R is pretty happy with the GA 36 antenna mounted inside the aircraft.

I even have the UAT monopole antenna for the GDL 52R mounted inside the nose pointed down with no ground plane, and at 9,500', I often see strong signals on ground stations over 100 nm away.

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Invisible_plane.jpg


You might try mounting your GDL 82 GPS antennas inside the nose of the Cozy, and see if you get similar performance.

Steve
 
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