Return-Path: Received: (qmail 7608 invoked from network); 22 Oct 2002 11:55:37 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 22 Oct 2002 11:55:37 -0000 X-Priority: 3 Received: (qmail 5867 invoked from network); 22 Oct 2002 11:54:58 -0000 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 22 Oct 2002 11:54:58 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from majordom by post.thorcom.com with local (Exim 4.10) id 183xaJ-0007An-00 for rsgb_lf_group-outgoing@blacksheep.org; Tue, 22 Oct 2002 12:52:31 +0100 Received: from [134.58.10.57] (helo=mail3.cc.kuleuven.ac.be) by post.thorcom.com with esmtp (Exim 4.10) id 183xaJ-0007Ae-00 for rsgb_lf_group@blacksheep.org; Tue, 22 Oct 2002 12:52:31 +0100 Received: from dell-rik.fys.kuleuven.ac.be ([10.33.165.177]) by mail3.cc.kuleuven.ac.be (8.12.1/8.12.1) with ESMTP id g9MBq05l063526 for ; Tue, 22 Oct 2002 13:52:00 +0200 Message-ID: <5.1.0.14.0.20021022135524.02a4a4f0@pb623250.kuleuven.be> X-Sender: pb623250@pb623250.kuleuven.be X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Tue, 22 Oct 2002 13:57:35 +0200 To: rsgb_lf_group@blacksheep.org From: "Rik Strobbe" In-reply-to: <5.1.0.14.0.20021022114543.009ed1c0@POP3.freeler.nl> References: <000001c2793a$fcd867a0$276336d2@xtr743187> MIME-Version: 1.0 Subject: Re: LF: Re: Drooping top loading Content-Type: text/html; charset=windows-1252 X-Spam-Status: No, hits=0.3 required=5.0tests=BIG_FONT,IN_REP_TO,SPAM_PHRASE_00_01version=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Content-transfer-encoding: 8bit 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