Return-Path: Received: (qmail 19959 invoked from network); 22 Oct 2002 14:05:58 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 22 Oct 2002 14:05:58 -0000 Content-Transfer-Encoding: 8bit Received: (qmail 3332 invoked from network); 22 Oct 2002 14:05:17 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 22 Oct 2002 14:05:17 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 4.10) id 183zcy-0007Uz-00 for rsgb_lf_group-outgoing@blacksheep.org; Tue, 22 Oct 2002 15:03:24 +0100 Received: from [212.125.75.12] (helo=mail4.messagelabs.com) by post.thorcom.com with smtp (Exim 4.10) id 183zcw-0007UH-00 for rsgb_lf_group@blacksheep.org; Tue, 22 Oct 2002 15:03:23 +0100 X-VirusChecked: Checked Received: (qmail 12910 invoked from network); 22 Oct 2002 14:02:24 -0000 Received: from unknown (HELO ukfw1.ge.boc.com) (193.131.2.157) by server-9.tower-4.messagelabs.com with SMTP; 22 Oct 2002 14:02:24 -0000 Received: from z-160-100-160-136.est.ibm.com ([160.100.160.136]) by ukfw1.ge.boc.com; Tue, 22 Oct 2002 15:02:17 +0100 (BST) Received: from exc_wil04.edwards.boc.com ([162.118.144.226]) by exc_cra03.edwards.boc.com with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) id TP3FKX1M; Tue, 22 Oct 2002 15:05:21 +0100 Received: by EXC_WIL04 with Internet Mail Service (5.5.2653.19) id ; Tue, 22 Oct 2002 10:02:00 -0400 Message-ID: From: "Ashlock,William" To: rsgb_lf_group@blacksheep.org Date: Tue, 22 Oct 2002 10:02:00 -0400 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Subject: RE: LF: Re: Drooping top loading Content-Type: text/plain; charset=iso-8859-1; format=flowed X-Spam-Status: No, hits=-0.6 required=5.0tests=EMAIL_ATTRIBUTION,EXCHANGE_SERVER,INVALID_MSGID, SPAM_PHRASE_03_05version=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Hi Rik, Thank you for collecting and posting this information. The conclusion, therefore, (and for those not having the time to study this) is that at least a moderate loss of signal signal occurs when a typical set of radials are drooped more than 20deg from the horizontal, right? I'm not sure I buy the "shielding effect" that the drooping radials impose, but I suppose the 'canceling effect' due to the reversal in current is one way to look at how a shield works. Bill A -----Original Message----- From: Rik Strobbe [mailto:rik.strobbe@fys.kuleuven.ac.be] Sent: Tuesday, October 22, 2002 7:58 AM To: rsgb_lf_group@blacksheep.org Subject: Re: LF: Re: Drooping top loading John, G4CNN, did some extensive calculations on drooping toploads (umbrella antennas). A summary of his work and a link to the webpage with all info can be found at : http://www.qsl.net/on7yd/136ant.htm#Umbrella 73, Rik ON7YD At 12:16 22/10/2002 +0200, you wrote: To All from PA0SE In order to find the effect of drooping top load wires upon the radiation resistance I modelled an umbrella antenna using K6STI's antenna simulation program Antenna Optimizer. The antenna modelled consists of a vertical wire of 10 m with at the top four wires of 10 m each in the directions N, E, S and W. The wires include an angle of alpha degrees with the horizontal. All wires have a diameter of 1.5 millimetres. The antenna is erected over perfect ground. Alpha Rrad Capacitance (degrees) (mohm) (pF) 0 26 256 (horizontal top wires) 20 18 254 40 12 250 60 8 237 80 8 175 73, Dick, PA0SE JO22GD _____________________________________________________________________ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com _____________________________________________________________________ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com