Today's Message Index:
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1. 10:18 AM - Antenna doubler plates ()
2. 10:58 AM - Re: Antenna doubler plates (James Redmon)
3. 11:18 AM - Re: Antenna doubler plates (Ralph E. Capen)
Message 1
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Subject: | Antenna doubler plates |
--> Avionics-List message posted by: <bakerocb@cox.net>
Avionics-List message previously posted by: "Ralph E. Capen"
<recapen@earthlink.net>
> Fellow listers, I am starting the installation of my Comant CI122 com
> antenna on the underbelly
> of my RV6A. All I can find in the archives is Eric Newton's post on a 3" x
> 6" x .040 doubler
> along with a couple of others that indicate that one is required/has been
> used
> - check the 43.13. No mention of the basis for the dimensions used.
> Obviously, the AC 43.13 should have info on the determination of the
> appropriate
> dimensions - but I have not learned to read that mumbo jumbo well enough
> to
> get any usable information from it. If someone could point out the correct
> paragraph or how >they arrived at their specific numbers, I would greatly
> appreciate it. Ralph Capen RV6AQB N822AR
4/13/2005
Hello Ralph, Since you are putting this antenna on a relatively large metal
surface you are not concerned with providing a ground plane for electro
magnetic performance purposes, but just providing some additional strength
for structural purposes.
The dimensions are therefore not very critical assuming that the only holes
through the aircraft skin are for the center coax connection and the antenna
mounting screws. The trade off then becomes one of adding sufficient
additional strength to carry the bending forces on the skin from the
antenna,but not adding excessive unneeded weight.
You could go to Figure 4-16 of AC 43.13 and use those samples to crunch some
numbers if you wish, but that is not really necessary. Cut a doubler plate
in a square or rectangular shape (easier to make than a round doubler plate)
that is comfortably larger than the antenna base (at least two inches larger
all around should do it). Take into account the nearness of any bulkheads or
other structure that would interfere with drilling and riveting. Round off
the corners. Use a rivet spacing (no greater than that used in the
surrounding sturcture) that works out nicely for each side of the double
plate.
OC
Message 2
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Subject: | Re: Antenna doubler plates |
--> Avionics-List message posted by: "James Redmon" <james@berkut13.com>
Dunno about the mount, but the ground plane for the xponder antenna only
needs to be a 5.5" diameter circle.
http://www.berkut13.com/berkut30.htm#transponder
James Redmon
Berkut #013 N97TX
http://www.berkut13.com
----- Original Message -----
From: "Ralph E. Capen" <recapen@earthlink.net>
Subject: Avionics-List: Antenna doubler plates
> All I can find in the archives is Eric Newton's post on a 3" x 6" x .040
> doubler along with a couple of others that indicate that one is
> required/has been used - check the 43.13. No mention of the basis for the
> dimensions used.
Message 3
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Subject: | Re: Antenna doubler plates |
--> Avionics-List message posted by: "Ralph E. Capen" <recapen@earthlink.net>
Got the grounding plane covered.......aluminum skin.......I'm concerned about stiffening
the .025 skin....
I've seen the stuff you did - I'll be doing mine relatively the same way as I'll
have a couple of antennas mounted up under the engine cowling....
-----Original Message-----
From: James Redmon <james@berkut13.com>
Subject: Re: Avionics-List: Antenna doubler plates
--> Avionics-List message posted by: "James Redmon" <james@berkut13.com>
Dunno about the mount, but the ground plane for the xponder antenna only
needs to be a 5.5" diameter circle.
http://www.berkut13.com/berkut30.htm#transponder
James Redmon
Berkut #013 N97TX
http://www.berkut13.com
----- Original Message -----
From: "Ralph E. Capen" <recapen@earthlink.net>
Subject: Avionics-List: Antenna doubler plates
> All I can find in the archives is Eric Newton's post on a 3" x 6" x .040
> doubler along with a couple of others that indicate that one is
> required/has been used - check the 43.13. No mention of the basis for the
> dimensions used.
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