X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 24 Sep 2010 13:32:07 -0400 Message-ID: X-Original-Return-Path: Received: from [69.84.129.240] (HELO asp.reflexion.net) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTPS id 4478711 for lml@lancaironline.net; Thu, 23 Sep 2010 18:33:15 -0400 Received-SPF: none receiver=logan.com; client-ip=69.84.129.240; envelope-from=cberland@systems3.net Received: (qmail 14843 invoked from network); 23 Sep 2010 22:32:39 -0000 Received: from unknown (HELO mail-cs-01.app.dcb.reflexion.net) (10.84.19.1) by 0 (rfx-qmail) with SMTP; 23 Sep 2010 22:32:39 -0000 Received: by mail-cs-01.app.dcb.reflexion.net (Reflexion email security v6.20.4) with SMTP; Thu, 23 Sep 2010 18:32:39 -0400 (EDT) Received: (qmail 17679 invoked from network); 23 Sep 2010 22:32:39 -0000 Received: from unknown (HELO remote.systems3.net) (98.172.79.178) by 0 (rfx-qmail) with (AES128-SHA encrypted) SMTP; 23 Sep 2010 22:32:39 -0000 Received: from S3SBS08SERVER.Systems3.local ([fe80::6077:364b:fa39:c71b]) by S3SBS08SERVER.Systems3.local ([fe80::6077:364b:fa39:c71b%10]) with mapi; Thu, 23 Sep 2010 15:32:14 -0700 From: Craig Berland. X-Original-To: Lancair Mailing List X-Original-Date: Thu, 23 Sep 2010 15:32:12 -0700 Subject: [LML] Transponder ground plane Thread-Topic: [LML] Transponder ground plane Thread-Index: ActbZa77DLcVbAsVSG2Xte6GM1IMDAABWjow X-Original-Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: yes X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/related; boundary="_004_D7A6B5700A0803448C27264F1F538736490D9E5A3CS3SBS08SERVER_"; type="multipart/alternative" MIME-Version: 1.0 --_004_D7A6B5700A0803448C27264F1F538736490D9E5A3CS3SBS08SERVER_ Content-Type: multipart/alternative; boundary="_000_D7A6B5700A0803448C27264F1F538736490D9E5A3CS3SBS08SERVER_" --_000_D7A6B5700A0803448C27264F1F538736490D9E5A3CS3SBS08SERVER_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable We want to mount a transponder antenna in the belly of our LIV. Does the ca= rbon fiber provide an adaquate ground plane? Good question and I'm not sure of the long term answer. The carbon is very= conductive but you MUST be in contact with the "carbon". The epoxy is a v= ery good insulator. I used conductive paint from Lancair as ground planes = on my IV-P. I scuffed the carbon skins real good before painting on the gr= ound planes. As you can see from the results below, the carbon is as condu= ctive as the ground plane paint. The ground planes do not touch each other = and are only connected via the carbon. Biddle DLRO Meter (Digital Low Resistance Ohmmeter) Full scale of lowest setting is 6000 micro ohms (setting for this test was = 6 ohm full scale) Probes at Center of antenna mounting area Transponder =3D .040 ohm Com1 =3D .035 ohm TCAD =3D .045 ohm Com 2 =3D .037 ohm At far extreme of circle Transponder =3D .106 ohm Com1 =3D .134 ohm TCAD =3D .118 ohm Com 2 =3D .096 ohm From one ground plane to another (this shows conductivity of the carbon) Transponder to Com1 =3D .130 ohm Com1 to TCAD =3D .063 ohm TCAD to Com2 =3D .112 ohm Craig Berland N7VG --_000_D7A6B5700A0803448C27264F1F538736490D9E5A3CS3SBS08SERVER_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Blank

We want to mount a transponder antenna in the belly of our LIV. Does the carbon fiber provide = an adaquate ground plane?

 G= ood question and I’m not sure of the long term answer. T= he carbon is very conductive but you MUST be in contact with the “carbon= ”.  The epoxy is a very good insulator.  I used conductive paint from Lanc= air as ground planes on my IV-P.  I scuffed the carbon skins real good bef= ore painting on the ground planes.  As you can see from the results below,= the carbon is as conductive as the ground plane paint. The ground planes do not touch each other and are only connected via the carbon.

Biddle DLRO Meter (Digital Low Resistance Ohmmeter)

Full scale of lowest setting is 6000 micro ohms (setting for this test was 6 ohm full scale)

 

Probes at Center of antenna mounting area

Transponder  =3D  .040 ohm

Com1           =3D  .035 ohm

TCAD           =3D  .045 ohm

Com 2          =3D  .037 ohm<= o:p>

 

At far extreme of circle

Transponder  =3D  .106 ohm

Com1           =3D  .134 ohm

TCAD           =3D  .118 ohm

Com 2          =3D  .096 ohm<= o:p>

 

From one ground plane to another (this shows conductivity of the carbon)

Transponder to Com1  =3D  .130 ohm

Com1 to TCAD           =3D&nbs= p; .063 ohm

TCAD to Com2           =3D  = .112 ohm

 

Craig Berland

N7VG

 

 

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