Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id v8NDJvfE001518 for ; Sat, 23 Sep 2017 15:19:58 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dvkFf-0005M0-D4 for rs_out_1@blacksheep.org; Sat, 23 Sep 2017 14:13:47 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dvkFe-0005Lr-NS for rsgb_lf_group@blacksheep.org; Sat, 23 Sep 2017 14:13:46 +0100 Received: from emout04.email.it ([212.97.34.71]) by relay1.thorcom.net with esmtp (Exim 4.89) (envelope-from ) id 1dvkFZ-0002G7-Vh for rsgb_lf_group@blacksheep.org; Sat, 23 Sep 2017 14:13:45 +0100 Received: from emout04.email.it (localhost [127.0.0.1]) by emout04.email.it (Postfix) with ESMTP id 3DE2C961EE for ; Sat, 23 Sep 2017 15:13:39 +0200 (CEST) Received: from x220.localnet (94-36-116-96.adsl-ull.clienti.tiscali.it [94.36.116.96]) by emout04.email.it (Postfix) with ESMTPA id C826B961ED for ; Sat, 23 Sep 2017 15:13:38 +0200 (CEST) From: Claudio Pozzi To: rsgb_lf_group@blacksheep.org Date: Sat, 23 Sep 2017 15:11:14 +0200 Message-ID: <2512261.QPMy9ZKvPq@x220> User-Agent: KMail/4.14.1 (Linux/3.16.0-4-amd64; KDE/4.14.2; x86_64; ; ) In-Reply-To: <59C634ED.8252.27CCAAE3@mike.dennison.ntlworld.com> References: <59C634ED.8252.27CCAAE3@mike.dennison.ntlworld.com> MIME-Version: 1.0 X-Spam-Score: 0.3 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: On Saturday 23 September 2017 11:18:21 you wrote: > Knowing the effective height of a Marconi antenna is essential in the > calculation of radiated power /antenna efficiency at LF/MF. The > formula for this includes figures for the capacitance to ground of > the vertical and horizontal wires. The result being somewhere between > 50% and 100% of the actual height. > > As long as I have been interested in LF - over 20 years - I have seen > (and used) a figure of 5pF/m for the capacitance of the horizontal > wire and 6pF/m for the vertical wire. However, I have recently been > asked how this figure originated, and must admit that I don't > remember. Was it amateur experimentation, or a professional source > such as the Admiralty Handbook? The very first amateur UK LF book, a > slim spiral bound volume by Peter Dodd, may have the answer but I > don't have a copy. Peter's bigger follow-up book, The Low Frequency > Experiemnter's Handbook, published in 2000, already takes these > figures as understood. > > Can anyone help, please? > > Mike, G3XDV > ========== [...] Content analysis details: (0.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (smtp01[at]email.it) -0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.2 FREEMAIL_ENVFROM_END_DIGIT Envelope-from freemail username ends in digit (smtp01[at]email.it) 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 5934134de2d93cab1d5fc440b67de82f Subject: Re: LF: Effective antenna height? Content-Type: multipart/alternative; boundary="nextPart1648063.cSWhE0t1RL" Content-Transfer-Encoding: 7Bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=1.0 required=5.0 tests=FROM_ENDS_IN_NUMS,HTML_60_70, HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false This is a multi-part message in MIME format. --nextPart1648063.cSWhE0t1RL Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" On Saturday 23 September 2017 11:18:21 you wrote: > Knowing the effective height of a Marconi antenna is essential in the > calculation of radiated power /antenna efficiency at LF/MF. The > formula for this includes figures for the capacitance to ground of > the vertical and horizontal wires. The result being somewhere between > 50% and 100% of the actual height. > > As long as I have been interested in LF - over 20 years - I have seen > (and used) a figure of 5pF/m for the capacitance of the horizontal > wire and 6pF/m for the vertical wire. However, I have recently been > asked how this figure originated, and must admit that I don't > remember. Was it amateur experimentation, or a professional source > such as the Admiralty Handbook? The very first amateur UK LF book, a > slim spiral bound volume by Peter Dodd, may have the answer but I > don't have a copy. Peter's bigger follow-up book, The Low Frequency > Experiemnter's Handbook, published in 2000, already takes these > figures as understood. > > Can anyone help, please? > > Mike, G3XDV > ========== The navy VLF books are downloadable from this link: http://www.navy-radio.com/manuals/shore-vlf.htm[1] But the VLF bible in my opinion is this book, with wires capacity formulas and tables: Arthur D. Watt, VLF Radio Engineering, Pegamon Press 1967 Also the capacity of 2 or more parallel top loading wires are here. 73 de Claudio, IK2PII -------- [1] http://www.navy-radio.com/manuals/shore-vlf.htm -- ZE-Light e ZE-Pro: servizi zimbra per caselle con dominio email.it, per tutti i dettagli Clicca qui http://posta.email.it/caselle-di-posta-z-email-it.php?utm_campaign=email_Zimbra_102014=main_footer/f Sponsor: Registra i domini che desideri ed inizia a creare il tuo sito web Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=13323&d=23-9 --nextPart1648063.cSWhE0t1RL Content-Transfer-Encoding: 7Bit Content-Type: text/html; charset="us-ascii"

On Saturday 23 September 2017 11:18:21 you wrote:

> Knowing the effective height of a Marconi antenna is essential in the

> calculation of radiated power /antenna efficiency at LF/MF. The

> formula for this includes figures for the capacitance to ground of

> the vertical and horizontal wires. The result being somewhere between

> 50% and 100% of the actual height.

>

> As long as I have been interested in LF - over 20 years - I have seen

> (and used) a figure of 5pF/m for the capacitance of the horizontal

> wire and 6pF/m for the vertical wire. However, I have recently been

> asked how this figure originated, and must admit that I don't

> remember. Was it amateur experimentation, or a professional source

> such as the Admiralty Handbook? The very first amateur UK LF book, a

> slim spiral bound volume by Peter Dodd, may have the answer but I

> don't have a copy. Peter's bigger follow-up book, The Low Frequency

> Experiemnter's Handbook, published in 2000, already takes these

> figures as understood.

>

> Can anyone help, please?

>

> Mike, G3XDV

> ==========

 

The navy VLF books are downloadable from this link:

 

http://www.navy-radio.com/manuals/shore-vlf.htm

 

But the VLF bible in my opinion is this book, with wires capacity formulas and tables:

 

Arthur D. Watt, VLF Radio Engineering, Pegamon Press 1967

 

Also the capacity of 2 or more parallel top loading wires are here.

 

73 de Claudio, IK2PII

 

 




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