Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Ground Plane

Matronics Email Lists Forum Index -> Europa-List

View previous topic :: View next topic

Author Message

astills(at)cox.net
Guest

Posted: Sun Dec 17, 2006 4:27 pm Post subject: Ground Plane

Hi all,

I've been having a little problem with ATC reading my transponder all the

time. I suspect a bit of shadowing.. I have the 2 1/2"-3" transponder

antenna mounted

upside down on a shelf on the rear corner of the baggage bay. I have a 6"

steel ground plane mounted to the antenna. What size ground plane have

others used

successfully and where is your antenna mounted.  ATC reads me better out of

KGEU with a feed from Luke AFB while KDVT (where I'm hangered) gets their

feed

from Phoenix Sky Harbor airport. By far KDVT is worse than KGEU. I know

there is difference in the feed from the different radars but need to get

rid of most of the

shadowing if possible. Sure would make me more presentable to the guys at

KDVT. (One of the busiest GA ariports in the nation)

Have about 8 hrs on the plane now and the grin is still in place. Gets even

bigger the more I fly!



Al Stills

N625AZ

grahamsingleton(at)btinte
Guest

Posted: Sun Dec 17, 2006 4:52 pm Post subject: Ground Plane

Al

the best place might be up on the roof, upside down. Nothing much to 

shadow it up there? Your ground plane sounds OK but a halfwave dipole is 

better, Bob Archer makes a heat one. Gives a flatter distribution pattern

Graham



AlStills wrote:



 	  Quote: 	
		  



Hi all,

I've been having a little problem with ATC reading my transponder all the

time. I suspect a bit of shadowing.. I have the 2 1/2"-3" transponder

antenna mounted

upside down on a shelf on the rear corner of the baggage bay. I have a 6"

steel ground plane mounted to the antenna. What size ground plane have

others used



Al Stills

N625AZ

SPurpura(at)aol.com
Guest

Posted: Sun Dec 17, 2006 5:50 pm Post subject: Ground Plane

TRY IT WITHOUT THE GROND PLANE,MY BOB ARCER HAS NONE. [quote][b]

M.Grass(at)comcast.net
Guest

Posted: Sun Dec 17, 2006 6:45 pm Post subject: Ground Plane

Very bad advise!!!

  

 The Bob Archer Antenna is a "dipole" antenna and is similar in design as  your Com antenna if built like suggested in the Europa manual. The 2 1/2 inch  antenna is a monopole antenna and needs a ground plane of either 51/2 inch  diameter or at least 27 inch or greater. Everything between or smaller is  bad.

  

 I would be concerned about all metal within the close proximity of the  antenna. I am thinking of fuel lines, flap actuator, hard point out of metal in  the fuselage etc.. You should be fine if you keep any metal pieces (could be  even a length of your AWG24 wire) of the size of 21/2 inches or greater at least  6 inches away. The ideal ground plane is any metal circular in shape with 5 1/2  inch diameter and the monopole antenna sticking through the hole and points  downwards. You have to have a very low resistance between the outer part of your  BNC connector and the ground plane.

  

 Hope that helps.

  

 Michael Grass

 A266 Trigear

 Detroit Michigan  

 [quote]   ---

jimpuglise(at)comcast.net
Guest

Posted: Sun Dec 17, 2006 7:39 pm Post subject: Ground Plane

Al-

  

 I have mine installed but have not used it yet.  I think you are going to be much better off with a vertical dipole in the Europa than a ground plane.  The Archer antenna the others spoke about is a vertical dipole.  Mine is fastened to a piece of balsa wood that is fitted to the contour of the fuselage on the port side as far aft as possible.  It is just about opposite the inspection port in the root of the rudder.  I'll let you know how it works in a year or so.

  

 Jim Puglise - A-283 

  

 [quote]-------------- Original message -------------- 

From: "AlStills" <astills(at)cox.net> 



[quote] --> Europa-List message posted by: "AlStills" 

 

 Hi all, 

 I've been having a little problem with ATC reading my transponder all the 

 time. I suspect a bit of shadowing.. I have the 2 1/2"-3" transponder 

 antenna mounted 

 upside down on a shelf on the rear corner of the baggage bay. I have a 6" 

 steel ground plane mounted to the antenna. What size ground plane have 

 others used 

 successfully and where is your antenna mounted. ATC reads me better out of 

 KGEU with a feed from Luke AFB while KDVT (where I'm hangered) gets their 

 feed 

 from Phoenix Sky Harbor airport. By far KDVT is worse than KGEU. I know 

 there is difference in the feed from the different radars but n  eed to  R>>  [quote][b]

jodel(at)nildram.co.uk
Guest

Posted: Mon Dec 18, 2006 2:16 am Post subject: Ground Plane

I’ve got the Archer dipole in my Europa.  It is mounted about 6” forward of the inspection hole at the bottom of the fin.  It works fine.  

   

I would be concerned about flying with a transponder aerial  mounted in the baggage area.  The radiation is damaging to eyes etc and the aerial should be mounted as far away as possible from the crew.    

   

More info on exposure risk is available at http://www.pfa.org.uk/Consultation%20and%20Lobbying/Mode%20S/Non-ionising%20Radiation%20Risks%20and%20Mode%20S.pdf  

   

(The line might wrap so you may have to stitch)  

   

Simon  

         

  

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of jimpuglise(at)comcast.net

 Sent: 18 December 2006 03:39

 To: europa-list(at)matronics.com

 Subject: Re: Ground Plane  

  

     

Al-  

    

   

    

I have mine installed but have not used it yet.  I think you are going to be much better off with a vertical dipole in the Europa than a ground plane.  The Archer antenna the others spoke about is a vertical dipole.  Mine is fastened to a piece of balsa wood that is fitted to the contour of the fuselage on the port side as far aft as possible.  It is just about opposite the inspection port in the root of the rudder.  I'll let you know how it works in a year or so.  

    

   

    

Jim Puglise - A-283   

    

   

  [quote]  

-------------- Original message -------------- 

 From: "AlStills" <astills(at)cox.net> 

 

 > --> Europa-List message posted by: "AlStills" 

 > 

 > Hi all, 

 > I've been having a little problem with ATC reading my transponder all the 

 > time. I suspect a bit of shadowing.. I have the 2 1/2"-3" transponder 

 > antenna mounted 

 > upside down on a shelf on the rear corner of the baggage bay. I have a 6" 

 > steel ground plane mounted to the antenna. What size ground plane have 

 > others used 

 > successfully and where is your antenna mounted. ATC reads me better out of 

 > KGEU with a feed from Luke AFB while KDVT (where I'm hangered) gets their 

 > feed 

 > from Phoenix  Sky Harbor airport. By far KDVT is worse than KGEU. I know 

 > there is difference in the feed from the different radars but n eed to R>>    	  Quote: 	
		    www.aeroelectric.com 	
0 	  Quote: 	
		   	
1 	  Quote: 	
		   	
2 	  Quote: 	
		   	
3 	  Quote: 	
		   	
4 	  Quote: 	
		   	
5 	  Quote: 	
		   	
6 	  Quote: 	
		   	
7 	  Quote: 	
		   	
8 	  Quote: 	
		   	
9 	  Quote: 	
		  	
0 	  Quote: 	
		  	
1 	  Quote: 	
		  	
2 	  Quote: 	
		  	
3 	  Quote: 	
		  	
4 	  Quote: 	
		  	
5[b]

europa flugzeug fabrik

Joined: 13 Feb 2006
Posts: 65
Location: North Coast, USA

Posted: Mon Dec 18, 2006 6:29 am Post subject: Re: Ground Plane

Note that the linked PFA document does point out that transponder replies are very brief and occasional -- low average power, but no detailed studies done.  There is an RF exposure calculator on ARRLâ€™s web site which suggests, if one makes some plausible assumptions and fiddles with it, that a cell phone is more hazardous, and little evidence of a problem there so far.  Many of us yak on cells (continuous xmission) in a year longer than we might spend flying in a year (occasional bursts of a like a millisecond each but at higher power).  Distance from the body (a square in the formula) matters greatly re RF power.



Fred F.

astills(at)cox.net
Guest

Posted: Mon Dec 18, 2006 6:43 am Post subject: Ground plane

Thanks to all who replied. I'll trim my ground plane down and try that

first. If needed I've seen the Bob Archer  antenna's and may switch.

Again thanks for the answers

Al Stills

N625AZ

air.guerner(at)wanadoo.fr
Guest

Posted: Mon Dec 18, 2006 11:06 am Post subject: ground plane

Hi Al,<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> 

  

I have been looking at the antennas on composites airplanes (Lancairs, Glasairs, etcâ€¦) for years and the fact is that most builders install all antennas  inside the airframe for obvious drag reduction, except for XPDR and DME antennas. Of course I am talking about glass, not carbon fiber airframes. XPDR and DME works in the 1030- 1090 MHz frequency range and are therefore more sensitive to shadowing and any less than perfect installation. Best practice is  to install the antenna outside, pointing downwards, on the belly of the aircraft,  with the appropriate ground plane.  Minimum size of the ground plane is 4 wave length in diameter. <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />10 inch diameter, .025 inch thick aluminum is suggested in the litterature. Another thing is to make sure your BNC connectors (both center wire and shielding) are soldered not just crimped, as this warrants a better contact in the long term and a better reliability. 

  

Good flights 

  

Remi 

  

  

  

Time: 04:27:46 PM PST US

From: "AlStills" <astills(at)cox.net (astills(at)cox.net)>

Subject: Ground Plane

Hi all,

I've been having a little problem with ATC reading my transponder all the

time. I suspect a bit of shadowing.. I have the 2 1/2"-3" transponder

antenna mounted

upside down on a shelf on the rear corner of the baggage bay. I have a 6"

steel ground plane mounted to the antenna. What size ground plane have

others used

successfully and where is your antenna mounted.  ATC reads me better out of

KGEU with a feed from Luke AFB while KDVT (where I'm hangered) gets their

feed

from Phoenix Sky Harbor airport. By far KDVT is worse than KGEU. I know

there is difference in the feed from the different radars but need to get

rid of most of the

shadowing if possible. Sure would make me more presentable to the guys at

KDVT. (One of the busiest GA ariports in the nation)

Have about 8 hrs on the plane now and the grin is still in place. Gets even

bigger the more I fly!



Al Stills

N625AZ  [quote][b]

astills(at)cox.net
Guest

Posted: Mon Dec 18, 2006 3:41 pm Post subject: ground plane

Remi,

Thanks for the info. I think I have the solution. Probably a couple of things and not just one.

Al Stills

N725AZ

--

justin(at)systemwise.co.u
Guest

Posted: Tue Dec 19, 2006 4:19 am Post subject: Ground Plane

I like to think I saved weight in constructing a backplane for my transponder aerial by using tin foil. I constructed a flat 12” by 14”  backplane using two layers of bid, On a glass surface I put one layer down and then some drinking straws across for stiffening and then a second layer. This produced a flat surface which I then covered with cooking tinfoil. The aerial was mounted in the middle and the whole lot stuck to the inside wall of the fuselage as far back as was practical. It needed two legs made from rolled up paper with scraps of bid wound round them to support it inboard. This has worked well, needs no maintenance and is not too heavy. I suspect the weight saving is minimal but the backplane is huge and works well.  

   

Merry Christmas and safe flying to all.  

Justin Kennedy  

G-ZTED  

       [quote][b]

grahamsingleton(at)btinte
Guest

Posted: Tue Dec 19, 2006 6:26 am Post subject: Ground Plane

Justin

only downside is possible corrosion of the connection to the cable 

braid. Might be worth finding a silver loaded resin to add long term 

reliability

Graham

btw I think your wing roots are the nicest I've seen. I bet the wind 

sighs when it flows over them 



Justin Kennedy wrote:



 	  Quote: 	
		   I like to think I saved weight in constructing a backplane for my 

 transponder aerial by using tin foil. I constructed a flat 12” by 14” 

 backplane using two layers of bid, On a glass surface I put one layer 

 down and then some drinking straws across for stiffening and then a 

 second layer. This produced a flat surface which I then covered with 

 cooking tinfoil. The aerial was mounted in the middle and the whole 

 lot stuck to the inside wall of the fuselage as far back as was 

 practical. It needed two legs made from rolled up paper with scraps of 

 bid wound round them to support it inboard. This has worked well, 

 needs no maintenance and is not too heavy. I suspect the weight saving 

 is minimal but the backplane is huge and works well.



 Merry Christmas and safe flying to all.



 Justin Kennedy



 G-ZTED

Display posts from previous:

	Matronics Email Lists Forum Index -> Europa-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum