Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dl06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 6131D38000098; Wed, 4 Jan 2012 06:42:14 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RiPDg-0002TC-EO for rs_out_1@blacksheep.org; Wed, 04 Jan 2012 11:41:24 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RiPDf-0002T3-NC for rsgb_lf_group@blacksheep.org; Wed, 04 Jan 2012 11:41:23 +0000 Received: from out1.ip07ir2.opaltelecom.net ([62.24.128.243]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1RiPDd-00027s-Gg for rsgb_lf_group@blacksheep.org; Wed, 04 Jan 2012 11:41:23 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AkEFADU6BE9cF/sE/2dsb2JhbABDggWWDZRUgQaBbQUBAQUIAQEDPA0CFAoOAQEDBQIBAxEEAQEKJRQBBBoGFggGEwoBAgIBAYdrtWaMDwSCW4UqhSwBmgY X-IronPort-AV: E=Sophos;i="4.71,455,1320624000"; d="scan'208,217";a="20110483" Received: from host-92-23-251-4.as13285.net (HELO xphd97xgq27nyf) ([92.23.251.4]) by out1.ip07ir2.opaltelecom.net with SMTP; 04 Jan 2012 11:41:15 +0000 Message-ID: <001901cccad5$bff43840$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" 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> <024c01cccad1$3c099ba0$1502a8c0@Clemens04> Date: Wed, 4 Jan 2012 11:41:07 -0000 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 V6.00.2600.0000 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_0016_01CCCAD5.BFB162E0" 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: 0:2:483485472:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d4ad44f043b165aa9 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_0016_01CCCAD5.BFB162E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Clemens It depends what you mean by a reasonable sized loop. A reasonable size = might be say 3 metres x 3 metres or more and probably a good enough = performer for size and optimised for the frequency of interest. But the = most used and talked about small antennas by the LF fraternity are small = untuned loops, uProbes and ferrite sticks that hardly produce enough = signal capture to enable AUDIO copy of DX long haul weak amateur = stations. I emphasize Audible as opposed to visual QRSS screen displays. 73 de mal/g3kev =20 ----- Original Message -----=20 From: Clemens Paul=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Wednesday, January 04, 2012 11:08 AM Subject: Re: LF: Antennas >A tuned loop on a Battleship could be tricky with all the metal = about.=20 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.=20 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 =20 ----- Original Message -----=20 From: mal hamilton=20 To: rsgb_lf_group@blacksheep.org=20 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.=20 A tuned loop on a Battleship could be tricky with all the metal = about.=20 mal/g3kev ----- Original Message -----=20 From: Clemens Paul=20 To: rsgb_lf_group@blacksheep.org=20 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 ??=20 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 -----=20 From: mal hamilton=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, January 03, 2012 3:03 PM Subject: Re: LF: Antennas 4120 - Ausgabedatum: 03.01.2012=20 -------------------------------------------------------------------------= --- eMail ist virenfrei. Von AVG =FCberpr=FCft - www.avg.de Version: 10.0.1416 / Virendatenbank: 2109/4120 - Ausgabedatum: = 03.01.2012=20 ------=_NextPart_000_0016_01CCCAD5.BFB162E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Clemens
It depends what you mean by a reasonable sized = loop. A=20 reasonable size might be say 3 metres x 3 metres or more and probably a = good=20 enough performer for size and optimised for the frequency of interest. =  But=20 the most used and talked about small antennas by the LF fraternity = are=20 small untuned loops, uProbes and ferrite sticks that = hardly=20 produce enough signal capture to enable AUDIO copy of=20 DX long haul weak amateur stations. I emphasize Audible as = opposed to=20 visual QRSS screen displays.
73 de mal/g3kev
   
----- Original Message -----
From:=20 Clemens = Paul
Sent: Wednesday, January 04, = 2012 11:08=20 AM
Subject: Re: LF: Antennas

>A tuned loop on a Battleship could be = tricky with=20 all 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=20 *untuned* broadband receiving loop like the ALA1530
(diameter 1m) has a hard time when it is compared to a tuned = dipole of=20 only 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=20 a 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
To: rsgb_lf_group@blacksheep.org= =20
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=20 arrays,   for directivity and gain and switchable in=20 direction in some cases but not so sure others=20 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=20 3:03 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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