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Ground Plane on Carbon

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Dennis Johnson

Joined: 10 Jan 2006
Posts: 89
Location: N. Calif.

Posted: Thu Sep 27, 2007 9:20 am Post subject: Ground Plane on Carbon

Hi Dan,

  

 I installed antenna ground planes on the outside of my carbon fiber  Legacy.  Bob is right that there are big advantages of doing it inside the  fuselage, but for the comm antenna on the Legacy, it is difficult because of the  many obstructions inside.  Putting the ground plane on the outside was way  easier.

  

 I made the comm antenna ground plane out of 1/4" wide adhesive backed  copper foil strips available from stained glass supply stores, making them the  length that Bob advises.  I made eight "spokes" or radials equally spaced  around the antenna mounting location.  I soldered the foil radials to each  other where they met at the center in a way that it would make good contact with  the antenna base.  Then I covered each foil radial with deck cloth  saturated with epoxy to keep the radials permanently attached to the carbon  fiber belly.  The foil is so thin that with a little body work, it makes  a nearly imperceptible bump.  Besides, it's on the belly where  nobody can see it anyway. 

  

 I've been flying since March.  I have no way of quantifying it, but my  experience with the type of long distance cross country flights that the  Legacy is suited for, I'm happy with the performance of my radio.  Bob has  often observed that these unquantified testimonials aren't all that valuable,  but it's all I've got and I think it may be better than nothing.

  

 The interesting thing is that there are Legacy builders who've done  just about every ground plane variation possible, including no ground plane at  all, and they all seem satisfied with their antenna's performance.  It  could be we're worrying over nothing?

  

 Dennis      

    [quote][b]

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echristley(at)nc.rr.com
Guest

Posted: Thu Sep 27, 2007 10:08 am Post subject: Ground Plane on Carbon

Dennis Johnson wrote:

 	  Quote: 	
		   I made the comm antenna ground plane out of 1/4" wide adhesive backed copper foil strips available from stained glass supply stores, making them the length that Bob advises.  


	


RST-Engineering sells a kit with a roll of the copper foil tape and a 

handful of the ferrite torroids for something like $30.  The big bonus 

is the manual that describes all sorts of options and guidelines for how 

to use them.  The education is worth the price of admission.  The 

materials that enable you to go out and use what you learned is a bonus.



http://www.rst-engr.com/

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Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Thu Sep 27, 2007 2:07 pm Post subject: Ground Plane on Carbon

I once saw an antenna installation using a single loop of wire which was glued inside the hull as a full circle and which acted like a toroid, no ground plane fitted. The operator claimed he was happy with the performance. I would like to find out some more about the design length if anyone knows.  

Peter H        

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Dennis Johnson

 Sent: Friday, 28 September 2007 3:20 AM

 To: aeroelectric-list(at)matronics.com

 Subject: Ground Plane on Carbon  

  

     

Hi Dan,  

    

   

    

I installed antenna ground planes on the outside of my carbon fiber Legacy.  Bob is right that there are big advantages of doing it inside the fuselage, but for the comm antenna on the Legacy, it is difficult because of the many obstructions inside.  Putting the ground plane on the outside was way easier.  

    

   

    

I made the comm antenna ground plane out of 1/4" wide adhesive backed copper foil strips available from stained glass supply stores, making them the length that Bob advises.  I made eight "spokes" or radials equally spaced around the antenna mounting location.  I soldered the foil radials to each other where they met at the center in a way that it would make good contact with the antenna base.  Then I covered each foil radial with deck cloth saturated with epoxy to keep the radials permanently attached to the carbon fiber belly.  The foil is so thin that with a little body work, it makes a nearly imperceptible bump.  Besides, it's on the belly where nobody can see it anyway.   

    

   

    

I've been flying since March.  I have no way of quantifying it, but my experience with the type of long distance cross country flights that the Legacy is suited for, I'm happy with the performance of my radio.  Bob has often observed that these unquantified testimonials aren't all that valuable, but it's all I've got and I think it may be better than nothing.  

    

   

    

The interesting thing is that there are Legacy builders who've done just about every ground plane variation possible, including no ground plane at all, and they all seem satisfied with their antenna's performance.  It could be we're worrying over nothing?  

    

   

    

Dennis        

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        [quote][b]

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peter(at)sportingaero.com
Guest

Posted: Fri Sep 28, 2007 7:50 am Post subject: Ground Plane on Carbon

Could I observe that antennae inside carbon structures often don’t perform very well. On sailplanes the comm antenna is often moulded into the fin; however on sailplanes with a carbon fuselage the antenna is often installed in the rudder (skinned with glass) for much improved transmit & receive performance.   

   

Peter  

   

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nuckolls.bob(at)cox.net
Guest

Posted: Fri Sep 28, 2007 9:22 am Post subject: Ground Plane on Carbon

Peter, you're correct that while carbon fiber is not as

conductive as aluminum (1000x the sheet resistance) it

IS conductive enough to degrade antenna performance for

devices mounted inside the structure. The loop antenna

you were recalling is cited in this posting from the past:



Bob  . . .



-----------------------------------------




If your tailcone has a diameter of around 31 inches, you can try the Morris 

Com Loop antenna, which does not require a ground plane and is a better 

antenna than the typical quarter wave whip.



http:www.DaveMorris.com/MorrisComLoop

Dave Morris

-----------------------------------------



At 04:48 PM 9/28/2007 +0100, you wrote:



[quote]Could I observe that antennae inside carbon structures often don t perform 

very well. On sailplanes the comm antenna is often moulded into the fin; 

however on sailplanes with a carbon fuselage the antenna is often 

installed in the rudder (skinned with glass) for much improved transmit & 

receive performance.



Peter



--

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nuckolls.bob(at)cox.net
Guest

Posted: Fri Sep 28, 2007 10:16 am Post subject: Ground Plane on Carbon

I thought I had uploaded Dave's article to my website

waaaayyy back when and when I went to look for it, it wasn't

there. This is a pretty slick antenna solution for certain

situations so I've taken the liberty of adding Dave's work

to the archives of the best we know how to do at:



http://aeroelectric.com/articles/Morris_Com_Loop_Antenna.pdf



Bob . . .

At 12:18 PM 9/28/2007 -0600, you wrote:



[quote]

<nuckolls.bob(at)cox.net>



Peter, you're correct that while carbon fiber is not as

conductive as aluminum (1000x the sheet resistance) it

IS conductive enough to degrade antenna performance for

devices mounted inside the structure. The loop antenna

you were recalling is cited in this posting from the past:



Bob  . . .



-----------------------------------------




If your tailcone has a diameter of around 31 inches, you can try the 

Morris Com Loop antenna, which does not require a ground plane and is a 

better antenna than the typical quarter wave whip.



http:www.DaveMorris.com/MorrisComLoop

Dave Morris

-----------------------------------------



At 04:48 PM 9/28/2007 +0100, you wrote:



>Could I observe that antennae inside carbon structures often don t 

>perform very well. On sailplanes the comm antenna is often moulded into 

>the fin; however on sailplanes with a carbon fuselage the antenna is 

>often installed in the rudder (skinned with glass) for much improved 

>transmit & receive performance.

>

>Peter

>

>--

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Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Fri Sep 28, 2007 2:08 pm Post subject: Ground Plane on Carbon

Peter   

The application was a glass plane and mine is also. I would like to get design details ie length, diameter ,gain factor and how to match it, to compare with the external bent whip. Probably something in the Google will tell.,  

Peter H  

         

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Peter Pengilly

 Sent: Saturday, 29 September 2007 1:49 AM

 To: aeroelectric-list(at)matronics.com

 Subject: RE: AeroElectric-List: Ground Plane on Carbon  

  

   

Could I observe that antennae inside carbon structures often don’t perform very well. On sailplanes the comm antenna is often moulded into the fin; however on sailplanes with a carbon fuselage the antenna is often installed in the rudder (skinned with glass) for much improved transmit & receive performance.   

   

Peter  

   

--

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Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Fri Sep 28, 2007 2:15 pm Post subject: Ground Plane on Carbon

THANKS yet again Bob.



Peter H



--

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