Return-Path: Received: (qmail 84403 invoked from network); 27 Dec 2003 21:50:52 -0000 Received: from unknown (HELO ptb-mxscan02.plus.net) (212.159.14.236) by ptb-mailstore01.plus.net with SMTP; 27 Dec 2003 21:50:52 -0000 Received: (qmail 62520 invoked from network); 27 Dec 2003 21:50:52 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 Received: from ptb-mxcore02.plus.net (212.159.14.216) by ptb-mxscan02.plus.net with SMTP; 27 Dec 2003 21:50:50 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1AaMKg-000G2g-Ii for dave@picks.force9.co.uk; Sat, 27 Dec 2003 21:50:50 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1AaMKS-0005Kj-RQ for rs_out@blacksheep.org; Sat, 27 Dec 2003 21:50:36 +0000 Received: from [210.86.15.58] (helo=standby2.xtra.co.nz) by post.thorcom.com with esmtp (Exim 4.14) id 1AaMKR-0005Jk-Cz for rsgb_lf_group@blacksheep.org; Sat, 27 Dec 2003 21:50:35 +0000 Received: from web2-rme.xtra.co.nz ([210.86.15.141]) by standby2.xtra.co.nz with ESMTP id <20031227215002.IHVA3427.standby2.xtra.co.nz@web2-rme.xtra.co.nz> for ; Sun, 28 Dec 2003 10:50:02 +1300 X-Fake-Domain: quaycustomer Received: from quaycustomer ([219.89.180.146]) by web2-rme.xtra.co.nz with SMTP id <20031227215002.UWXU9867.web2-rme.xtra.co.nz@quaycustomer> for ; Sun, 28 Dec 2003 10:50:02 +1300 X-Bad-Message-ID: no DNS (quaycustomer) Message-ID: <009301c3ccc5$3a153d80$c401a8c0@quaycustomer> From: "Vernall" To: rsgb_lf_group@blacksheep.org References: <6.0.1.1.2.20031227144750.035a8d70@POP3.freeler.nl> Date: Sun, 28 Dec 2003 11:03:09 +1300 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Re: "T" versus "L"aerial Content-Type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on post.thorcom.com X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,HTML_FONT_BIG,HTML_MESSAGE autolearn=no version=2.60 X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SPAMFiltered: yes X-Spam-Rating: 2 Content-transfer-encoding: 8bit
Dick PA0SE,
 
Fine on the test result.  As you stated, the tested T has twice the amount of top loading wire (2x 20 metres) than the L (1x 20 metres).
 
It would be interesting to know if a T is better than an L for constant length top loading i.e. what the difference is if the upwire joins at the end or the middle of the horizontal top wire (theory suggests the T is better as there is minimal horizontally polarised component).
 
73, Bob ZL2CA 
----- Original Message -----
Sent: Sunday, December 28, 2003 3:09 AM
Subject: LF: "T" versus "L"aerial

To All from PA0SE

Further to my e-mail of 26 December I measured the field strength as radiated by the aerial in
Inverted L-configuration. From this I found EMRP = 57 milliwatt.

This confirms the benificial effect of top loading. The T-aerial radiated 140 milliwatt.

So going from a single 20m top load wire for the "L" to 2 x 20m for the "T" resulted in an improvement by a factor 2.46 (3.9dB) in radiated power.

The vertical part of the "T" consisted of an open wire feedline of 11m with the two wires connected in parallel in the attic shack. For the "L" one of the feedline wires was removed. I assume this did not appreciably affect the EMRP.

73, Dick, PA0SE