Return-Path: Received: from wind.imbris.com ([216.18.130.7]) by ns1.olsusa.com (Post.Office MTA v3.5.3 release 223 ID# 0-64832U3500L350S0V35) with ESMTP id com for ; Mon, 5 Jun 2000 11:00:59 -0400 Received: from regandesigns.com (tnt149-49.imbris.com [216.18.149.49]) by wind.imbris.com (8.9.3/8.9.3) with ESMTP id IAA92700 for ; Mon, 5 Jun 2000 08:05:51 -0700 (PDT) Message-ID: <393BA5F1.6793DC61@regandesigns.com> Date: Mon, 05 Jun 2000 08:06:57 -0500 From: Brent Regan To: Lancair List Subject: RE: ELT antennas X-Mailing-List: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Walter is quite correct. Part 91 requires an ELT and the TSO specifies that whatever antenna is used meets the TSO's VSWR requirements. So get those VSWR meters out and test your system or Janet Reno's ELT Task force will bust down your door at 4:00 AM. The ugly piece of s**t that comes with the ELT (the antenna, not Janet) does meet the TSO but it can be "legally" replaced with another that one meets it as well. It also requires a 36" diameter ground plane if installed on a non conductive surface. Regarding the issue of horizontal verses vertical mounting and polarization, it is true that ground based stations have vertical antennas and therefore are strongly vertically polarized. If you plan to crash within the line of site of Center's or Tower's antenna then you want a vertical whip. If you plan to crash in a remote area, then you will likely (hopefully) be found by another aircraft. Most aircraft antennas are not strictly vertical. Most aircraft antennas are mounted at an angle or are bent, with part of the antenna horizontal, just go out an the ramp and look. In the real world, aircraft antennas are insensitive to polarization. They are not, however, insensitive to field strength and a vertical antenna's field strength is lowest directly above it, where the search plane is. I would rather be wrong and found than right and frozen. Regards Brent Regan >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://www.olsusa.com/Users/Mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>