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GPS Antenna location
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coop85(at)bellsouth.net
Guest

Posted: Tue Apr 25, 2006 4:10 pm Post subject: GPS Antenna location

I know this has been addressed before, but I was wondering if any of you

that opted to put the GPS antenna under the cowling have any feedback, good

or bad, on the idea?  I suspect reception is okay, my biggest concern is the

heat in that area affecting the not so cheap antenna.



Thanks,

Marcus



Do not archive

ron.mcgann(at)baesystems.
Guest

Posted: Tue Apr 25, 2006 5:19 pm Post subject: GPS Antenna location

I have checked the -10 archive and there is some confusing info there.   

Both the Garmin and Comant antennas '. . . must be mounted on top of the aircraft . . . '[Comant ref and GNS430 Installation manual].  The Comant manual explicitly states a ground plane is NOT required.  The GNS 430 does not say that a ground plane is required. The Comant reference  http://www.comant.com/htmls/guide2.html even counsels against painting the antenna.  

Why wouldn't the best place for a GPS antenna be on top of the cabin cover (just aft of the windshield)?  The antenna cable could be fed down through the WD-1043 Centre Cabin Brace (which could also serve as a local ground point).   

I have heard (rumour only) that GPS satellite coverage is not the best in the southern parts of Australia.  Mounting the antenna under the cowl with airframe obscuration behind may further compromise performance.  Mounting the antenna with the best view of the sky is the least risk option for me.  

cheers,  

Ron  

187 fuse   

--

coop85(at)bellsouth.net
Guest

Posted: Tue Apr 25, 2006 6:21 pm Post subject: GPS Antenna location

Ron,  

   You make an excellent point about the antenna on top of the cabin.  In fact, I’ve been testing out my 480 by just having the antenna out in the yard, clearly no ground plane, and it works fine.  I think I’m going to at least try the “low drag” comm antenna from Van’s ($7, what could go wrong?) for my secondary radio so now I wonder if having the comm antenna near the GPS antenna could be an issue.  Perhaps I’m making this too hard, but that’s half the fun I guess.  

   

Marcus  

40286  

do not archive  

   

--

Tdawson(at)avidyne.com
Guest

Posted: Tue Apr 25, 2006 7:03 pm Post subject: GPS Antenna location

Can anyone explain why the "low drag" antenna shouldn't be called a "no drag" antenna?



TDT

40025

do not archive

--

Tim(at)MyRV10.com
Guest

Posted: Tue Apr 25, 2006 7:26 pm Post subject: GPS Antenna location

Now you should know that Tim....The thing probably weighs a few ounces,

and every ounce of weight in the plane will cause just that much more

drag as the angle of attack needs to compensate to lift it.  You'd

probably still lose at least .000000001 Kt of speed by adding that

antenna, don'tcha think?



Tim Olson - RV-10 N104CD - Flying

do not archive

Tim Dawson-Townsend wrote:

[quote] Can anyone explain why the "low drag" antenna shouldn't be called a "no drag" antenna?

 

 TDT

 40025

 do not archive

 

 

 --

Tdawson(at)avidyne.com
Guest

Posted: Tue Apr 25, 2006 7:31 pm Post subject: GPS Antenna location

Okay, how about the "no parasitic drag and only a tiny bit of induced drag antenna"??



TDT



--

jesse(at)itecusa.org
Guest

Posted: Tue Apr 25, 2006 7:32 pm Post subject: GPS Antenna location

Is there any really good reason that it couldn't go on the upper forward

fuse skin right in front of the windshield and aft of the firewall?  That

would not obstruct the pilot's view, and the cable would only need to be

about 18 inches or so.  N256H has it on the glareshield inside the cabin

(avoids any problems with water getting in through a bad seal), and it works

great.  Would it look terrible in front of the windshield?



Do not archive.



Jesse Saint

I-TEC, Inc.

jesse(at)itecusa.org

www.itecusa.org

352-465-4545



--

JSMcGrew(at)aol.com
Guest

Posted: Tue Apr 25, 2006 7:35 pm Post subject: GPS Antenna location

I'm just throwing this out because no one else has mentioned it - I'm  putting my GPS antennas on the glareshield. The antennas will certainly  have a great view of the sky up through the plexi-glass, the install is easy and  there is no concern about engine heat cooking them.

  

 Jim McGrew

 40134

  

 In a message dated 4/25/2006 6:12:03 P.M. Mountain Daylight Time,  coop85(at)bellsouth.net writes:

  	  Quote: 	
		  -->    RV10-List message posted by: "Marcus Cooper"    <coop85(at)bellsouth.net>



I know this has been addressed before, but    I was wondering if any of you

that opted to put the GPS antenna under the    cowling have any feedback, good

or bad, on the idea?  I suspect    reception is okay, my biggest concern is the

heat in that area affecting    the not so cheap antenna.



Thanks,

Marcus



Do not  ==========================     es  Day                                                     

  -->  ==================================================              - NEW MATRONICS LIST WIKI -

_-=  sp;                           ->  =========================p;               - List Contribution Web Site                               ==================================================



	


 



  

 Jim "Scooter"  McGrew

jsmcgrew(at)aol.com

Tdawson(at)avidyne.com
Guest

Posted: Tue Apr 25, 2006 7:39 pm Post subject: GPS Antenna location

Where do you put your coffee cup, then?   :  )



TDT

40025, firewall forward

do not archive

--

jjessen

Joined: 22 Apr 2006
Posts: 285
Location: OR

Posted: Tue Apr 25, 2006 9:57 pm Post subject: GPS Antenna location

In the Audi cup holder, which unfolds from the dash with a slight push of

the index finger.   



--

dav1111(at)cox.net
Guest

Posted: Wed Apr 26, 2006 1:19 am Post subject: GPS Antenna location

I cut out two openings in the upper forward fuse skin. One on the left and 

one on the right side of the center line.   I then took some left over 

fiberglass from cutting out the door windows and riveted it underneath the 

skin holes and fiberglassed over the holes to create two openings of 

fiberglass.  Next, I installed a tray underneath each fiberglassed cut out 

to mount the GPS antennas.



They look up directly through the fiberglass cutouts just as they would if 

underneath the cowl or on top of the canopy.   I hope to fly in the next 

month so I will keep you posted on performance.



Russ Daves

#40044



---

rvbuilder(at)sausen.net
Guest

Posted: Wed Apr 26, 2006 3:17 am Post subject: GPS Antenna location

  The reality is  that GPS signals are basically immune to any type of fiberglass or plastic as  long as it isn't covered with a metallic paint or anything else electrically  conductive.  Carbon fiber and metal will block most of the frequencies we deal  with.  Sure you will get some tiny amount of degradation  from mounting it under glass but nothing worth mentioning  usually.  Lot's of people have made a little shelf just forward of the  firewall to mount it on under the cowl and probably just as many have mounted it  under their canopy.  Both are as good of spots as mounting it on the  exterior.  If you do decide to mount on the exterior the drag will not  amount to much, probably less than a knot depending on where you put it.   It's more of a "clean look" type of decision.  But if you are worried about  it and on the fence, just mount it on the exterior as you can't go  wrong.

  

   As far as the  engine cooking the antenna, most GPS (and XM/Sirius) antennas are amplified  so there are some electronics in the antenna head.  As with any other piece  of electronic gear performance can suffer if it becomes too hot, just make sure  it isn't mounted next to anything that radiates a bunch of heat like the exhaust  headers.

  

   Lastly GPS, and  most satellite antennas we consumers deal with for that  matter, are circularly polarized and do not require ground  planes.

  

  

   Hope that helps.  I'm not an expert but I slept at a Holiday Inn Express last night. 

  

Michael Sausen 

RV-10 #352 Working on  Fuselage 

Recent RV-10 Build Activity

  



   From: owner-rv10-list-server(at)matronics.com  [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of  JSMcGrew(at)aol.com

Sent: Tuesday, April 25, 2006 10:35  PM

To: rv10-list(at)matronics.com

Subject: Re: GPS  Antenna location

 

   I'm just throwing this out because no one else has mentioned it - I'm  putting my GPS antennas on the glareshield. The antennas will certainly  have a great view of the sky up through the plexi-glass, the install is easy and  there is no concern about engine heat cooking them.

  

 Jim McGrew

 40134

  

 In a message dated 4/25/2006 6:12:03 P.M. Mountain Daylight Time,  coop85(at)bellsouth.net writes:

  	  Quote: 	
		  -->    RV10-List message posted by: "Marcus Cooper"    <coop85(at)bellsouth.net>



I know this has been addressed before, but    I was wondering if any of you

that opted to put the GPS antenna under the    cowling have any feedback, good

or bad, on the idea?  I suspect    reception is okay, my biggest concern is the

heat in that area affecting    the not so cheap antenna.



Thanks,

Marcus



Do not    ==========================  es Day                                                   

--> ==================================================                                   ->    =========================p;            - List    Contribution Web Site                               ==================================================



	


 



  

 Jim "Scooter"  McGrew

jsmcgrew(at)aol.com

rvbuilder(at)sausen.net
Guest

Posted: Wed Apr 26, 2006 3:17 am Post subject: GPS Antenna location

My 'puter has a coffee cup holder when I press a button on the front, bet that there could work in da airplane.  

 

 

 Michael Sausen

 RV-10 #352 Working on Fuselage

 Do Not Archive

 Recent RV-10 Build Activity

 

 

 --

Tim(at)MyRV10.com
Guest

Posted: Wed Apr 26, 2006 3:49 am Post subject: GPS Antenna location

One thing that turns me off about mounting it under a panel

somewhere (less of an issues perhaps than mounting it under

the cabin top, is that it could be harder to get a total

clear view of the sky in all directions.   Imagine yourself

digging a 6' deep square hole in your yard, 8' x 8' wide.

Sure, you'll see some satellites, because a few of them are

high above the horizon.   Will you see those that are low

on the horizon....well, at a certain point, no.



I'm not saying that it's crazy to mount the antenna elsewhere.

Certainly under the cowl will be better than under the

aluminum of the forward fuselage from the above scenario.

Everyone has their choice.  The part that I find hard to

swallow when I think about doing this myself is that I

for the life of me can't figure out why anyone would

accept even the slightest degradation from mounting

location in a system that's designed to keep them locked

into a system that supposedly is to help them stay alive

by navigating to the runway through a cloud.   If it

was a VFR install, I'd have much less concern.



Is "pretty good", or "fairly well", or "most of the time"

reliable enough for you?



Tim Olson - RV-10 N104CD - Flying

do not archive

RV Builder (Michael Sausen) wrote:

 	  Quote: 	
		     The reality is that GPS signals are basically immune to any type of 

 fiberglass or plastic as long as it isn't covered with a metallic paint 

 or anything else electrically conductive.  Carbon fiber and metal will 

 block most of the frequencies we deal with.  Sure you will get some tiny 

 amount of degradation from mounting it under glass but nothing worth 

 mentioning usually.  Lot's of people have made a little shelf just 

 forward of the firewall to mount it on under the cowl and probably just 

 as many have mounted it under their canopy.  Both are as good of spots 

 as mounting it on the exterior.  If you do decide to mount on the 

 exterior the drag will not amount to much, probably less than a knot 

 depending on where you put it.  It's more of a "clean look" type of 

 decision.  But if you are worried about it and on the fence, just mount 

 it on the exterior as you can't go wrong.

  

   As far as the engine cooking the antenna, most GPS (and 

 XM/Sirius) antennas are amplified so there are some electronics in the 

 antenna head.  As with any other piece of electronic gear performance 

 can suffer if it becomes too hot, just make sure it isn't mounted next 

 to anything that radiates a bunch of heat like the exhaust headers.

  

   Lastly GPS, and most satellite antennas we consumers deal with for 

 that matter, are circularly polarized and do not require ground planes.

  

 

   Hope that helps.  I'm not an expert but I slept at a Holiday Inn 

 Express last night.

 

  

 

 Michael Sausen

 

 RV-10 #352 Working on Fuselage

 

 Recent RV-10 Build Activity 

 <http://www.mykitlog.com/display_project.php?project_id=22>

 

  

 

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

 *From:* owner-rv10-list-server(at)matronics.com 

 [mailto:owner-rv10-list-server(at)matronics.com] *On Behalf Of 

 *JSMcGrew(at)aol.com

 *Sent:* Tuesday, April 25, 2006 10:35 PM

 *To:* rv10-list(at)matronics.com

 *Subject:* Re: GPS Antenna location

 

 I'm just throwing this out because no one else has mentioned it - I'm 

 putting my GPS antennas on the glareshield. The antennas will certainly 

 have a great view of the sky up through the plexi-glass, the install is 

 easy and there is no concern about engine heat cooking them.

  

 Jim McGrew

 40134

  

 In a message dated 4/25/2006 6:12:03 P.M. Mountain Daylight Time, 

 coop85(at)bellsouth.net writes:

 

     

 

     I know this has been addressed before, but I was wondering if any of you

     that opted to put the GPS antenna under the cowling have any

     feedback, good

     or bad, on the idea?  I suspect reception is okay, my biggest

     concern is the

     heat in that area affecting the not so cheap antenna.

 

     Thanks,

     Marcus

 

     Do not ==========================  es Day                          

                      

     --> ==================================================              

                 -> =========================p;            - List

     Contribution Web Site                        

     ==================================================

 

 

 

 

 

 

 

 

 

  

 Jim "Scooter" McGrew

 jsmcgrew(at)aol.com

Jerry Grimmonpre'

Joined: 09 Jan 2006
Posts: 144
Location: Huntley, Illinois 60142

Posted: Wed Apr 26, 2006 4:33 am Post subject: GPS Antenna location

Gents ...

 Check out Dan Checkoway's site on how he created removable glass  panels between windshield and cowling area.  

  

 http://www.rvproject.com/hidden_antennas.html

  

 Refer your questions to Dan  ...  dan(at)rvproject.com (dan(at)rvproject.com)   ..   

  

 Jerry Grimmonpre'

 RV8A  Electrical

rvbuilder(at)sausen.net
Guest

Posted: Wed Apr 26, 2006 6:52 am Post subject: GPS Antenna location

  One trick to determine your field of view is to tape a long piece of string to the center of the antenna and hold it a various angles.  If at any point one of those angles intersect something that blocks that view of the sky you have your answer on if it's a good spot.  Short of mounting the antenna at the absolute highest point of your airframe, you will have some of the sky view blocked.  In most cases it's almost nothing but in some locations it can be substantial.

 

   Another thing to remember is those big sacs of water in the cabin (us) do a much better job at blocking many types of signals than the fiberglass or plastic.  Keep that in mind as you decide where to put your antennas.  In the same respect traveling below or around massive buildups (not someplace I would want to be anyway) would be much more effective at blocking your GPS than the fiberglass cabin lid.  Either way if you are getting any amount of regular RAIM messages with modern GPS receivers you have a major installation problem in either the equipment or location.  You can effectively block half of the sky view and you should still maintain a positive 3D lock almost the entire time with the possible exception of when sats are setting or rising over the horizon.

 

 Michael

 

 --

gorejr(at)bellsouth.net
Guest

Posted: Wed Apr 26, 2006 8:43 am Post subject: GPS Antenna location

That was slick.  I thought the XM and GPS receivers could not be enclosed in metal.  Thought they had to have a clear view of the sky.  Thanks

Jim Gore RV-10

Georgia

 	  Quote: 	
		   

 From: "Jerry Grimmonpre" <jerry(at)mc.net>

 Date: 2006/04/26 Wed AM 08:30:37 EDT

 To: <rv10-list(at)matronics.com>

 Subject: Re: GPS Antenna location

 

 Gents ...

 Check out Dan Checkoway's site on how he created removable glass panels between windshield and cowling area.  

 

 http://www.rvproject.com/hidden_antennas.html

 

 Refer your questions to Dan  ...  dan(at)rvproject.com   ...  

 

 Jerry Grimmonpre'

 RV8A  Electrical

glastar(at)gmx.net
Guest

Posted: Wed Apr 26, 2006 9:04 am Post subject: GPS Antenna location

My Garmin 196 with Antenna under the windshield had no issue in the 

south of NSW, Victoria and South Australia.



Werner



do not archive



McGANN, Ron wrote:



[quote] I have checked the -10 archive and there is some confusing info there.



 Both the Garmin and Comant antennas '. . . must be mounted on top of 

 the aircraft . . . '[Comant ref and GNS430 Installation manual].  The 

 Comant manual explicitly states a ground plane is NOT required.  The 

 GNS 430 does not say that a ground plane is required. The Comant 

 reference  http://www.comant.com/htmls/guide2.html even counsels 

 against painting the antenna.



 Why wouldn't the best place for a GPS antenna be on top of the cabin 

 cover (just aft of the windshield)?  The antenna cable could be fed 

 down through the WD-1043 Centre Cabin Brace (which could also serve as 

 a local ground point).



 I have heard (rumour only) that GPS satellite coverage is not the best 

 in the southern parts of Australia.  Mounting the antenna under the 

 cowl with airframe obscuration behind may further compromise 

 performance.  Mounting the antenna with the best view of the sky is 

 the least risk option for me.



 cheers,

 Ron

 187 fuse



 --

rvbuilder(at)sausen.net
Guest

Posted: Wed Apr 26, 2006 9:59 am Post subject: GPS Antenna location

They actually aren't.  The top cover is fiberglass so their sky view is unimpeded for the most part.

 

 Do not archive

 

 --

dmasys(at)cox.net
Guest

Posted: Wed Apr 26, 2006 3:50 pm Post subject: GPS Antenna location

---- Marcus Cooper <coop85(at)bellsouth.net> wrote: 

 	  Quote: 	
		   

 

 I know this has been addressed before, but I was wondering if any of you

 that opted to put the GPS antenna under the cowling have any feedback, good

 or bad, on the idea?  I suspect reception is okay, my biggest concern is the

 heat in that area affecting the not so cheap antenna.


	


I have my GPS antenna under the cowl on my -7A, and connected to a GX-60.  In 200 flight hours the GPS has never been anything but rock stable and available.  It may be that whatever signal attenuation accrues to being beneath the cowl is offset by the fact that the cable run to the back of the GPS unit is only about 18 inches.  In the SoCal RV group, there are at least 8 or 10 RVs configured this way and to my knowledge no one has ever reported and problems with the arrangement.  Will do the same for the -10.



-Dan Masys

#40448

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