X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 05 Nov 2013 13:16:23 -0500 Message-ID: X-Original-Return-Path: Received: from moutng.kundenserver.de ([212.227.126.186] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTPS id 6577673 for lml@lancaironline.net; Tue, 05 Nov 2013 13:11:18 -0500 Received-SPF: none receiver=logan.com; client-ip=212.227.126.186; envelope-from=nick@beaglepup.info Received: from Asus8 (74-173.58.158.serverdedicati.seflow.it [158.58.173.74]) by mrelayeu.kundenserver.de (node=mrbap3) with ESMTP (Nemesis) id 0M0RJt-1VuC4s1gk9-00v4Kd; Tue, 05 Nov 2013 19:10:43 +0100 X-Original-Message-ID: <85C9951CDFF24630B722DA0BF7F84CC9@Asus8> Reply-To: "Nick Long" From: "Nick Long" X-Original-To: "Lancair Mailing List" References: In-Reply-To: Subject: Re: [LML] Re: TXPDR antenna X-Original-Date: Tue, 5 Nov 2013 18:00:25 -0000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_006E_01CEDA50.E73E1F10" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 16.4.3508.205 X-MimeOLE: Produced By Microsoft MimeOLE V16.4.3508.205 X-Antivirus: avast! (VPS 131105-0, 05/11/2013), Outbound message X-Antivirus-Status: Clean X-Provags-ID: V02:K0:VTuEpeFh+l39xaw5bZDB55h828YRLxg9yFhoOs8BH49 h5D1f/QorjWKwXdNpjoRv0ipMTeplzN0WkWhwbvspWnmv1rT9T VBc2Dc/IivsGq/GGzhCScpjsY+vZtaP2EJl6PKGNMq2/gvwlmh l3Q/tYmqwDyzF48+wTmIGP0hfJpfXw0A7S8Ih5hV9i6zla+r27 PZ6GgohNCYG1aHd090pvfMjdmcYLQIntKECxqQgHYLbWmggvJO LdX8fBNhZnQj79dIcRDrbWvMwZGs3feg2hI1ompYy3SC4Ndqrz 5LS/29bQo02Nx9ZsoOtV4xx4KxIHHAvk1SzUGjgCTCi7aXvsXW wenNzaHtx5xHUKse7cNM= This is a multi-part message in MIME format. ------=_NextPart_000_006E_01CEDA50.E73E1F10 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hello, Obviously I don=E2=80=99t know the installation in question, but let me = offer my 2cents. My day job is as an RF engineer. A metal ground plane is much better than paint. But it doesn=E2=80=99t = have to be any significant thickness. Foil, or sticky back foil or tape = is ok. The reason for needing a ground plane is because the structure is non = conducting. Effectively the structure is not there as far as the radio = signal is concerned, so it=E2=80=99s just as good to put the ground = plane on the inside, which is a bit easier. Follow that logic through and you come to the idea that the whole = antenna can be inside, providing you can set up a suitable ground plane = or equivalent. The difficulty comes if the aircraft structure is partly conducting, = rather than insulating, and therefore absorbs radio energy instead of = being transparent to it. This is where there=E2=80=99s a gap in my = knowledge =E2=80=93 I don=E2=80=99t know the electrical characteristics = of carbon fibre. I suspect it can be treated as an insulator, but maybe = someone can confirm that. Nick Long From: Colyn Case=20 Sent: Tuesday, November 5, 2013 1:36 PM To: Lancair Mailing List=20 Subject: [LML] Re: TXPDR antenna John, I'm trying to figure out how a xponder antenna would be between = the rudder pedals and the firewall. Paint works at first but can fracture.=20 A physically robust connection to the ground plane is best. If it were me I would take the antenna off (assuming it's outdoors like = it should be), grind through all the filler down to the carbon, install = a small sheet metal ground plane, provide a good strong contact area, = reassemble, and then bodywork over the remaining visible ground plane. Colyn On Nov 5, 2013, at 7:46 AM, John Barrett wrote: Hello all, Behind the rudder pedal the antenna for the transponder can be ID'd by = the brown Rg cable. ATC sometimes loses my squawk and I am thinking I need to add a ground = plane. Question for the group is if I can paint conductive paint around = the antenna and under neath the hydraulic lines as much as possible. = Will the Jeffco tank sealer interfere with effecitveness? Do I need to = remove the antenna or can the hub be painted to provide continuity? Any suggestions welcome. Thanks, John Sent from my iPad=20 Begin forwarded message: From: John Barrett <2thman1@gmail.com> Date: November 4, 2013 at 12:47:56 PM PST To: John Barrett Sent from my iPhone ------=_NextPart_000_006E_01CEDA50.E73E1F10 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
Hello,
 
Obviously I don=E2=80=99t know the installation in question, but = let me offer my=20 2cents. My day job is as an RF engineer.
 
A metal ground plane is much better than paint. But it = doesn=E2=80=99t have to be=20 any significant thickness. Foil, or sticky back foil or tape is = ok.
 
The reason for needing a ground plane is because the structure is = non=20 conducting. Effectively the structure is not there as far as the radio = signal is=20 concerned, so it=E2=80=99s just as good to put the ground plane on the = inside, which is=20 a bit easier.
 
Follow that logic through and you come to the idea that the whole = antenna=20 can be inside, providing you can set up a suitable ground plane or=20 equivalent.
 
The difficulty comes if the aircraft structure is partly = conducting, rather=20 than insulating, and therefore absorbs radio energy instead of being = transparent=20 to it. This is where there=E2=80=99s a gap in my knowledge =E2=80=93 I = don=E2=80=99t know the electrical=20 characteristics of carbon fibre. I suspect it can be treated as an = insulator,=20 but maybe someone can confirm that.
 
Nick Long
 
 
From: Colyn Case
Sent: Tuesday, November 5, 2013 1:36 PM
Subject: [LML] Re: TXPDR antenna
 
John,  I'm trying to figure out how a xponder antenna would be = between=20 the rudder pedals and the firewall.
Paint works at first but can = fracture.=20
A physically robust connection to the ground plane is best.
If it were me I would take the antenna off (assuming it's outdoors = like it=20 should be), grind through all the filler down to the carbon, install a = small=20 sheet metal ground plane, provide a good strong contact area, = reassemble, and=20 then bodywork over the remaining visible ground plane.
 
Colyn
 
On Nov 5, 2013, at 7:46 AM, John Barrett wrote:
 
Hello all,
 
Behind the rudder pedal the antenna for the transponder can be ID'd = by the=20 brown Rg cable.
 
ATC sometimes loses my squawk and I am thinking I need to add a = ground=20 plane.  Question for the group is if I can paint conductive paint = around=20 the antenna and under neath the hydraulic lines as much as = possible.  Will=20 the Jeffco tank sealer interfere with effecitveness?  Do I need to = remove=20 the antenna or can the hub be painted to provide continuity?
 
Any suggestions welcome.
 
Thanks,
John

Sent from my iPad=20
 

Begin forwarded message:

From: John Barrett <2thman1@gmail.com>
Date:=20 November 4, 2013 at 12:47:56 PM PST
To: John Barrett <jbarrett@carbinge.com>


<photo.JPG>



Sent = from my=20 iPhone
 
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