X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 03 Jan 2012 15:03:08 -0500 Message-ID: X-Original-Return-Path: Received: from qmta12.westchester.pa.mail.comcast.net ([76.96.59.227] verified) by logan.com (CommuniGate Pro SMTP 5.4.3) with ESMTP id 5335658 for lml@lancaironline.net; Tue, 03 Jan 2012 12:51:08 -0500 Received-SPF: pass receiver=logan.com; client-ip=76.96.59.227; envelope-from=jmorgan1023@comcast.net Received: from omta17.westchester.pa.mail.comcast.net ([76.96.62.89]) by qmta12.westchester.pa.mail.comcast.net with comcast id H1641i0071vXlb85C5qZlm; Tue, 03 Jan 2012 17:50:33 +0000 Received: from [192.168.1.100] ([24.11.157.176]) by omta17.westchester.pa.mail.comcast.net with comcast id H5qY1i00v3odyL83d5qZry; Tue, 03 Jan 2012 17:50:33 +0000 From: Jack Morgan Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-30--586519821 Subject: Nav/Com Antennas X-Original-Date: Tue, 3 Jan 2012 12:50:30 -0500 In-Reply-To: X-Original-To: Lancair Mailing List References: X-Original-Message-Id: <04B60D98-4A42-40F0-AFBD-4EDE73021EC7@comcast.net> X-Mailer: Apple Mail (2.1084) --Apple-Mail-30--586519821 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Dean: I used Bob Archer antennas on my IV P with excellent results. The = vertical tail unit is COM 1. I placed the wingtip version in each tip. = The right tip (also containing the magnetic heading sensor) feeds the = G900 nav/gs 4 way splitter recommended by Garmin while the left tip is = the COM 2 antenna. Tuning a distant ATIS shows both com antennas have = the same sensitivity. You may hear that com antennas should be = vertically polarized which is correct in theory. In actual practice the = scatter experienced by both the XMIT and received signals makes the = polarization effect negligible. I also placed the GPS/XM antennas below the eglass turtledeck. The xpdr = antenna is the only external antenna which is on the bottom using the = carbon fiber as a ground plane with excellent results. Jack Morgan On Jan 3, 2012, at 6:00 AM, Lancair Mailing List wrote: > I was looking for some advice about communication antennas. The = legacy is setup to have one com antenna. We want a capable IFR airplane = and I am hesitant to have one antenna with a diplexer (or is it = duplexer, I've seen it both ways) as a possible single point of failure. = Is this the method that most people are using? If you mounted a 2nd = com antenna, where did you place it? I searched the archives and found = someone else who asked the same question but I couldn't find the answer. = Any other input or advice on the subject would be appreciated. >=20 > Dean Whiting --Apple-Mail-30--586519821 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii