Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-df05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 455EA38000091; Wed, 4 Jan 2012 06:10:10 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RiOiH-00021a-Rd for rs_out_1@blacksheep.org; Wed, 04 Jan 2012 11:08:57 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RiOiH-00021R-8u for rsgb_lf_group@blacksheep.org; Wed, 04 Jan 2012 11:08:57 +0000 Received: from mailout-de.gmx.net ([213.165.64.22]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1RiOiF-0001lT-RH for rsgb_lf_group@blacksheep.org; Wed, 04 Jan 2012 11:08:57 +0000 Received: (qmail invoked by alias); 04 Jan 2012 11:08:49 -0000 Received: from p4FD0A220.dip.t-dialin.net (EHLO Clemens04) [79.208.162.32] by mail.gmx.net (mp068) with SMTP; 04 Jan 2012 12:08:49 +0100 X-Authenticated: #17214767 X-Provags-ID: V01U2FsdGVkX19dMdIa1CBdIUmsurBeInisJaffTsBbSi89aVIAIy crn+WyH+EUQ52d Message-ID: <024c01cccad1$3c099ba0$1502a8c0@Clemens04> From: "Clemens Paul" To: References: <008301ccc97c$51d9fcf0$0401a8c0@xphd97xgq27nyf>, ,<003501ccca06$6bdef490$0401a8c0@xphd97xgq27nyf> <4F02F9EA.1090101@iup.uni-heidelberg.de> <004601ccca20$8aa7d1c0$0401a8c0@xphd97xgq27nyf> <00fc01ccca65$47277e60$1502a8c0@Clemens04> <00d901ccca69$1f897260$0401a8c0@xphd97xgq27nyf> Date: Wed, 4 Jan 2012 12:08:43 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3664 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3664 X-Y-GMX-Trusted: 0 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Antennas Content-Type: multipart/alternative; boundary="----=_NextPart_000_0248_01CCCAD9.9A63FDA0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,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 x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:473143200:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40d94f0433924323 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_0248_01CCCAD9.9A63FDA0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8bit >A tuned loop on a Battleship could be tricky with all the metal about. Agreed. OTOH I know from a retired Marconi antenna engineer that tuned loops (first shielded later unshielded) in general have been used by the marine for DF. >From experience I also know that a Wellbrook *untuned* broadband receiving loop like the ALA1530 (diameter 1m) has a hard time when it is compared to a tuned dipole of only 2x15m on 160m or 80m. On 500kHz according to CCIR curves external noise is around 13dB stronger than on 1,6Mhz, i.e. about 63dB *at extremely quiet locations*, on 137kHz it's somewhere between 75dB and 80dB. So a receiving antenna could 'afford' an efficiency of say 70dB less than a fullsize dipole/monopole without degrading the SNR on a decent MW/LW receiver having a reasonable noise figure. Therefore it's obvious that a well made *tuned loop* with reasonable dimensions would compare favourably against any fullsize or near fullsize antenna (not talking of arrays). Don't forget that the Wellbrook loop version you've tested against your wire antennas was a broadband untuned design *and* not optimized for MW/LF. 73 Clemens DL4RAJ ----- Original Message ----- From: mal hamilton To: rsgb_lf_group@blacksheep.org Sent: Tuesday, January 03, 2012 11:43 PM Subject: Re: LF: Antennas Merchant ships used inv L antennas slung between two masts and in some cases additional long whips for MF/HF. Aircraft also used inv L and long wire antennas strung between the cockpit and the top of the tail fin for MF/HF plus a trailing antenna that could be wound in/out as required. No pocket micro or ferrite sticks used. Some early aircraft also had a small loop antenna for DF purposes. I know why fixed services used large wire arrays, for directivity and gain and switchable in direction in some cases but not so sure others did. A tuned loop on a Battleship could be tricky with all the metal about. mal/g3kev ----- Original Message ----- From: Clemens Paul To: rsgb_lf_group@blacksheep.org Sent: Tuesday, January 03, 2012 10:15 PM Subject: Re: LF: Antennas Mal, >Why do commercial receiving stations use large antenna farms out in the countryside ?? The reason is to get as much *directivity* gain as possible. BTW british military vessels since decades used to use tuned loops with a preamp for VFL/LW/MW operation. And they operated also in CW in those days... 73 Clemens DL4RAJ ----- Original Message ----- From: mal hamilton To: rsgb_lf_group@blacksheep.org Sent: Tuesday, January 03, 2012 3:03 PM Subject: Re: LF: Antennas 4120 - Ausgabedatum: 03.01.2012 ------------------------------------------------------------------------------ eMail ist virenfrei. Von AVG überprüft - www.avg.de Version: 10.0.1416 / Virendatenbank: 2109/4120 - Ausgabedatum: 03.01.2012 ------=_NextPart_000_0248_01CCCAD9.9A63FDA0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
>A tuned loop on a Battleship could be tricky = with all=20 the metal about.
 
Agreed.
OTOH I know from a retired Marconi antenna engineer that tuned = loops=20 (first shielded
later unshielded) in general have been used by the marine for=20 DF.
From experience I also know that a Wellbrook = *untuned* broadband=20 receiving loop like the ALA1530
(diameter 1m) has a hard time when it is compared to a tuned dipole = of only=20 2x15m on 160m
or 80m.
On 500kHz according to CCIR curves  external noise is around = 13dB=20 stronger than on 1,6Mhz,
i.e. about 63dB *at extremely quiet locations*, on 137kHz it's = somewhere=20 between 75dB and 80dB. 
So a receiving antenna could 'afford' an efficiency of say 70dB = less than a=20 fullsize dipole/monopole
without degrading the SNR on a decent MW/LW receiver having a=20 reasonable noise figure.
Therefore it's obvious that a well made *tuned = loop*  with=20 reasonable dimensions would compare
favourably against any fullsize or near fullsize antenna (not = talking of=20 arrays).
Don't forget that the Wellbrook loop version you've tested against = your=20 wire antennas was a broadband
untuned design *and* not optimized for MW/LF.
 
73
Clemens
DL4RAJ   
 
 
----- Original Message -----
From:=20 mal=20 hamilton
Sent: Tuesday, January 03, 2012 = 11:43=20 PM
Subject: Re: LF: Antennas

Merchant ships used inv L antennas slung = between two=20 masts and in some cases additional long whips for MF/HF. Aircraft also = used=20 inv L and long wire antennas strung between the cockpit and the = top of=20 the tail fin for MF/HF plus a trailing antenna that could be wound = in/out as=20 required.
No pocket micro or ferrite sticks used. Some = early=20 aircraft also had a small loop antenna for DF purposes.
I know why fixed services used large wire = arrays, =20  for directivity and gain and switchable in direction in = some=20 cases but not so sure others did. 
A tuned loop on a Battleship could be tricky = with all=20 the metal about.
 
mal/g3kev
 
----- Original Message -----
From:=20 Clemens = Paul
To: rsgb_lf_group@blacksheep.org= =20
Sent: Tuesday, January 03, = 2012 10:15=20 PM
Subject: Re: LF: = Antennas

Mal,
 
>Why do commercial receiving stations use = large=20 antenna farms out in the countryside ??
 
The reason is to get as much *directivity* = gain as=20 possible.
BTW british military vessels since = decades used=20 to use tuned loops with a preamp
for VFL/LW/MW operation.
And they operated also in CW in those=20 days...
 
73
Clemens
DL4RAJ
----- Original Message ----- =
From:=20 mal=20 hamilton
To: rsgb_lf_group@blacksheep.org= =20
Sent: Tuesday, January 03, = 2012 3:03=20 PM
Subject: Re: LF: = Antennas

4120 - Ausgabedatum: 03.01.2012 =

eMail ist = virenfrei.
Von AVG=20 =FCberpr=FCft - www.avg.de
Version: 10.0.1416 /=20 Virendatenbank: 2109/4120 - Ausgabedatum: 03.01.2012=20

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