XM and GPS hidden under glare shield

[bigginsking]

Hey guys:
I just got a Garmin 396 and installed the antennas under the glare shield such that they are invisible from the top. I made holes in my glareshield with a standard 2.25" instrument hole punch tool, put clear packing tape on top and bottom for the antenna to push up against from underneath and then used a single 0.032, 1 inch wide strap to pull the antennas up against the hole. The strap is riveted to the glareshied with (4) 3/32 flush rivets and the antennas are attached to the strap with the standard garmin screws. I then have my glare shield covered with black fabric.


Putting a mark on the center of the packing tape and the antenna helps align the antenna to the hole when you are drilling up through the glare shield for the rivet holes.

I have flown 10 hrs and not had any signal issues: the 2.25 hole is plenty big enough to let the RF pass through. I've been using the "under the cowl antenna shelf" for quite some time but I didn't think the XM antenna would do very well in the heat under the cowl besides its a pain to pull the wire with a connector through the firewall especially in an RV-8.

I'm an RF engineer and I know the wavelength is much larger than that hole but I'm not seeing any appreciable degradation of signal from this setup.

Bill Judge
N84WJ RV-8, 220 hrs
rv-8.blogspot.com

[Norman CYYJ]

Sounds like a great idea. It would look tidier than placing them on top. I have put them under the cowling and never had a problem and also behind the roll bar on the tip up. Just at the intersection of the roll bar brace.