X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 22 Jul 2006 03:01:19 -0400 Message-ID: X-Original-Return-Path: Received: from smtp106.sbc.mail.mud.yahoo.com ([68.142.198.205] verified) by logan.com (CommuniGate Pro SMTP 5.1c.2) with SMTP id 1311337 for lml@lancaironline.net; Fri, 21 Jul 2006 22:50:19 -0400 Received-SPF: none receiver=logan.com; client-ip=68.142.198.205; envelope-from=elippse@sbcglobal.net Received: (qmail 7747 invoked from network); 22 Jul 2006 02:49:34 -0000 Received: from unknown (HELO Computerroom) (elippse@sbcglobal.net@75.15.118.103 with login) by smtp106.sbc.mail.mud.yahoo.com with SMTP; 22 Jul 2006 02:49:34 -0000 X-Original-Message-ID: <001101c6ad39$8490c8a0$67760f4b@Computerroom> From: "Paul Lipps" X-Original-To: "Marv Kaye" Subject: Antennas X-Original-Date: Fri, 21 Jul 2006 19:49:54 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000E_01C6ACFE.D6C78B30" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2869 This is a multi-part message in MIME format. ------=_NextPart_000_000E_01C6ACFE.D6C78B30 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Counterpoise (ground-plane) antenna performance drops off in the = direction where the ground-plane is shortest. They perform especially = poorly when the ground-plane is below the stub, as in a top-mounted = antenna, since most of the radiation is directed upward. I made all = half-wave dipoles for my radios, since they have exceptional radiation = in the horizontal direction, unmatched by 1/4 wave stubs over a = ground-plane with abbreviated length. The glide-slope and VOR are = bow-ties made from 0.010 aluminum flashing with bazooka baluns. The VOR = is in the left wing stub, and the GS is in the right wing stub. My comm = is brass sheet imbedded in the back of the rudder spar, with a ferrite = balun. My transponder antenna is a slot-fed dipole as shown in Fig. = 8-5a, p 246, of the Rad Lab series vol. 12, Microwave Antenna Theory and = Design. I had a little trouble with it initially since it pulled the = Xponder frequency off beyond spec. I added short BNC components in the = line, such as barrels, right-angles, etc until I got the reactive = component of the reflected wave to pass through zero at the transponder. = The KT76 output stage appears to be the oscillator, so it is sensitve to = VSWR. I used only Andrews 1/4" FSJ1-50 coax throughout for minimum loss = and no shield reception/radiation to put nulls in the pattern. It's = expensive, but why scrimp with thou$and$ spent on avionics. Perhaps = someone could figure out how to cut slots in the wings and fuselage of = carbon planes, backed by fiberglass, and feed the hoizontal slots to get = vertically-polarized radiation, and vertical slots to get horizontal = radiation. I proposed to some biplane builders who didn't want the comm = antenna to show that they conceal it in a wing strut! Where there's a = will, there's a way! ------=_NextPart_000_000E_01C6ACFE.D6C78B30 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

Counterpoise (ground-plane) = antenna=20 performance drops off in the direction where the ground-plane is = shortest. They=20 perform especially poorly when the ground-plane is below the stub, as in = a top-mounted antenna, since most of the radiation is directed=20 upward. I made all half-wave dipoles for my radios, since they have = exceptional radiation in the horizontal direction, unmatched by 1/4 wave = stubs=20 over a ground-plane with abbreviated length. = The glide-slope and=20 VOR are bow-ties made from 0.010 aluminum flashing with bazooka = baluns. The=20 VOR is in the left wing stub, and the GS is in the right wing stub. My = comm is=20 brass sheet imbedded in the back of the rudder spar, with a ferrite = balun. My=20 transponder antenna is a slot-fed dipole as shown in Fig. 8-5a, p 246, = of the=20 Rad Lab series vol. 12, Microwave Antenna Theory and Design. I had = a little=20 trouble with it initially since it pulled the Xponder frequency off = beyond spec.=20 I added short BNC components in the line, such as barrels, right-angles, = etc=20 until I got the reactive component of the reflected wave to pass through = zero at=20 the transponder. The KT76 output stage appears to be the oscillator, so = it is=20 sensitve to VSWR. I used only Andrews 1/4" FSJ1-50 coax throughout for = minimum=20 loss and no shield reception/radiation to put nulls in the pattern. = It's=20 expensive, but why scrimp with thou$and$ spent on avionics. Perhaps = someone=20 could figure out how to cut slots in the wings and fuselage of carbon = planes,=20 backed by fiberglass, and feed the hoizontal slots to get = vertically-polarized=20 radiation, and vertical slots to get horizontal radiation. I proposed to = some=20 biplane builders who didn't want the comm antenna to show that they = conceal it=20 in a wing strut! Where there's a will, there's a=20 way!

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