X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 30 [X] Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 05 Mar 2007 21:49:00 -0500 Message-ID: X-Original-Return-Path: Received: from smtp113.sbc.mail.mud.yahoo.com ([68.142.198.212] verified) by logan.com (CommuniGate Pro SMTP 5.1.7) with SMTP id 1903437 for lml@lancaironline.net; Mon, 05 Mar 2007 18:17:34 -0500 Received-SPF: none receiver=logan.com; client-ip=68.142.198.212; envelope-from=elippse@sbcglobal.net Received: (qmail 15507 invoked from network); 5 Mar 2007 23:16:47 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=sbcglobal.net; h=Received:X-YMail-OSG:Message-ID:From:To:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=4SfLw+X7CH9QnmM4ofOlwQwlFrHYXPKD2D6wQsRxV8HCQ0Jrusne3R4gIoi9CqdfIPxFaDVHAV8zr9JEKfspS+nwD5VVJggQ/FmqQFWPabkFLUVetg3GmkJ7zRE2L8vgqgTR9EtDCOPzGURnANmaPaLTrxPtWHDPB8jZ+Qu3Mu4= ; Received: from unknown (HELO Computerroom) (elippse@sbcglobal.net@75.15.139.173 with login) by smtp113.sbc.mail.mud.yahoo.com with SMTP; 5 Mar 2007 23:16:47 -0000 X-YMail-OSG: d6smcigVM1mAhnDTrJ_AeHqDLEspm2QB5uA_s5KgL2XPQql2v9oRMVsMLw4F6CB.EqQAEjSMIWh3G18Rljkb.HYvxvu5FliyNOczTBD9EoPr1_o94wLxmP52NYnSUQPqgyYUtM9L7uEuTX8- X-Original-Message-ID: <000c01c75f7c$5aa27c50$ad8b0f4b@Computerroom> From: "Paul Lipps" X-Original-To: "Marv Kaye" Subject: Ground-plane X-Original-Date: Mon, 5 Mar 2007 15:16:46 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01C75F39.49E5F3D0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 This is a multi-part message in MIME format. ------=_NextPart_000_0006_01C75F39.49E5F3D0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable The so-called ground-plane, more accurately referred to as a = counterpoise, is an integral part of the antenna element, and as such, = must be of the very highest conductivity so as not to incur tx-rx = losses. Even a steel counterpoise will degrade an antenna's performance. = The counterpoise should be either aluminum, copper, or gold. It should = have its longest dimension in the direction to which you want the = greatest sensitivity. A curved counterpoise will affect the radiation = direction. An antenna on the bottom of a curved fuselage can benefit by = the counterpoise running up the sides of the fuselage. In this respect, = it will take on more of the length of a 1/4 wave section, basically = forming a 1/2 wave dipole. A short, flat counterpoise will have very = poor radiation characteristics. Since carbon fiber is more at one with a = carbon resistor, it makes a poor counterpoise, absorbing much power. As to GS antennas, I just installed one in a carbon fiber wingtip = extension. I cut off about an inch along the 18" trailing edge, attached = a foam wedge to form the new trailing edge, then folded two 1" wide by 8 = 1/2" long pieces of .01" sheet brass over the foam, then covered it = with fiberglass. The two brass pieces were separated by 1/4" in the = center, with coax attached to the separated ends. Several ferrite beads = were placed over the coax near the feed to serve as a balun. In the = opposite tip I installed a similar antenna, but this one had 1/16" wires = coming straight back 6" from the dipole ends, with 1" diameter loops = formed on the wire ends to act as capacitance to increase the radiation = resistance to 25 ohms. This serves for VOR and Localizer, and with the = wire ends, does not have a perceptible null in the direction of the = array. ------=_NextPart_000_0006_01C75F39.49E5F3D0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
The so-called ground-plane, more accurately = referred to as=20 a counterpoise, is an integral part of the antenna element, and as such, = must be=20 of the very highest conductivity so as not to incur tx-rx losses. Even a = steel=20 counterpoise will degrade an antenna's performance. The counterpoise = should be=20 either aluminum, copper, or gold. It should have its longest dimension = in the=20 direction to which you want the greatest sensitivity. A curved = counterpoise will=20 affect the radiation direction. An antenna on the bottom of a curved = fuselage=20 can benefit by the counterpoise running up the sides of the fuselage. In = this=20 respect, it will take on more of the length of a 1/4 wave section, = basically=20 forming a 1/2 wave dipole. A short, flat counterpoise will have very = poor=20 radiation characteristics. Since carbon fiber is more at one with a = carbon=20 resistor, it makes a poor counterpoise, absorbing much = power.
As to GS antennas, I just installed one in a = carbon=20 fiber wingtip extension. I cut off about an inch along the=20 18" trailing edge, attached a foam wedge to form the new trailing = edge,=20 then folded two 1" wide by 8 1/2" long pieces of  .01" sheet = brass=20 over the foam, then covered it with fiberglass. The two brass pieces = were=20 separated by 1/4" in the center, with coax attached to the separated = ends.=20 Several ferrite beads were placed over the coax near the feed to serve = as a=20 balun. In the opposite tip I installed a similar antenna, but this one = had 1/16"=20 wires coming straight back 6" from the dipole ends, with 1" diameter = loops=20 formed on the wire ends to act as capacitance to increase the radiation=20 resistance to 25 ohms. This serves for VOR and Localizer, and with the = wire=20 ends, does not have a perceptible null in the direction of the=20 array.
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