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[195.171.43.25]) by mx.google.com with ESMTP id l8si1988953wib.38.2013.10.25.15.28.38 for ; Fri, 25 Oct 2013 15:28:38 -0700 (PDT) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org; dkim=pass (test mode) header.i=@comcast.net Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1VZpPw-0007zg-Ql for rs_out_1@blacksheep.org; Fri, 25 Oct 2013 22:59:40 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1VZpPw-0007zX-0t for rsgb_lf_group@blacksheep.org; Fri, 25 Oct 2013 22:59:40 +0100 Received: from qmta03.emeryville.ca.mail.comcast.net ([76.96.30.32]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1VZpPs-0000wv-Kg for rsgb_lf_group@blacksheep.org; Fri, 25 Oct 2013 22:59:38 +0100 Received: from omta10.emeryville.ca.mail.comcast.net ([76.96.30.28]) by qmta03.emeryville.ca.mail.comcast.net with comcast id hZBP1m0010cQ2SLA3ZzaSc; Fri, 25 Oct 2013 21:59:34 +0000 Received: from Owner ([166.147.69.121]) by omta10.emeryville.ca.mail.comcast.net with comcast id hZzC1m00J2czTUe8WZzJFn; Fri, 25 Oct 2013 21:59:29 +0000 From: "hvanesce" To: References: <526ACC49.6030208@t-online.de> <29208E66335B49E08158AB7E38F57C7C@AGB> <526AD2A4.9060704@t-online.de> In-Reply-To: Date: Fri, 25 Oct 2013 16:58:59 -0500 Message-ID: <0a4101ced1cd$728cbd10$57a63730$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 thread-index: AQH8IOERziXMUXCj182tk4tOcBCiBwKeaDPnAJS7oCoB8sCPXZmCID/g Content-Language: en-us DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20121106; t=1382738374; bh=QGVc5FUmHZP8qsEVn4DGLH+3TKbVI5EKAEitwzq9uAs=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=ZjJZT0Crdt13YaIB6S6xou0NT1eMiw0qmjhXR8ZU9BDziMWMRQQwCy7WSprJWA0o3 /zE678ZD6G1HmIFW/zC67Dk0q2zMHXSMVPhHrEgiUhKOWwg6UENTGUCvwzK+cjn6ZM XYCd2a5sjhbuEIyldJd2iGeT8Ipmk1987DUBRb6hhqe3KVXCr1dtr7+gv7ypmhcxdq tAsqvVaDJ7zoCCjoxsyz/UK3sHt6f22+p/owAjTm++MczlQRdHfYiStB+cUZUYPA1l bGOsCmrL66QUE58sncWnE11NcTg65w8K8bgozbPEe0FeN/qSSuclPLquikc6u16Q+2 z31OVNR8rL1qQ== X-Spam-Score: -0.4 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Chris, I'll second Warren's motion.The radiation efficiency of a 100-turn, 1-meter diameter solenoid (of any reasonable length/diameter ratio) at 100kHz is in the hundreds of nano-ohms, i.e. a very difficult starting point with respect to dissipative losses directly and indirectly associated with wire resistance and coil inductance. Radiation resistance of a solenoid scales with turns squared, but with resistance scaling directly with turns, large numbers of turns is not a reasonable approach for practical wire diameters. [...] Content analysis details: (-0.4 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [76.96.30.32 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (hvanesce[at]comcast.net) -0.0 SPF_PASS SPF: sender matches SPF record -0.4 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 4007433f91838c822ced221546b88d5a Subject: RE: LF: air solenoids Content-Type: multipart/alternative; boundary="----=_NextPart_000_0A42_01CED1A3.89B79F70" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.2 required=5.0 tests=HTML_50_60,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 Status: O X-Status: X-Keywords: X-UID: 1734 This is a multipart message in MIME format. ------=_NextPart_000_0A42_01CED1A3.89B79F70 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Chris, I'll second Warren's motion.The radiation efficiency of a 100-turn, 1-meter diameter solenoid (of any reasonable length/diameter ratio) at 100kHz is in the hundreds of nano-ohms, i.e. a very difficult starting point with respect to dissipative losses directly and indirectly associated with wire resistance and coil inductance. Radiation resistance of a solenoid scales with turns squared, but with resistance scaling directly with turns, large numbers of turns is not a reasonable approach for practical wire diameters. The reactive field (induction field), which comprises most of the field (for a solenoid that is presumably a small fraction of a wavelength) does not suffer low efficiency, but reactive field strength falls by a factor of eight for (practically speaking) for every doubling of distance, starting near the aperture boundary. The reactive field strength 1km from a 1-meter diameter solenoid (properly oriented away from the null) would be 1E-9 that of the field strength near the aperture boundary. Regards, Jim AA5BW From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Warren Ziegler Sent: Friday, October 25, 2013 3:50 PM To: rsgb_lf_group Subject: Re: LF: air solenoids Christoph, A while back someone on the US longwave reflector posted the result of an experiment. They took a receiver to the site of a high power Tesla coil operating at LF, I believe it was being driven at 175kHz. they expected to hear it at some distance but were surprised to find out they could only hear the Tesla coil at very short distances. It seems that a coil by itself is an extremely poor radiator at LF! It is unknown to me if there was any earth connection to the Tesla coil, perhaps only through the mains connection. 73 Warren On Fri, Oct 25, 2013 at 4:20 PM, Christoph Schumacher wrote: no, cylindrical coils Am 25.10.2013 22:11, schrieb Graham: toroidal ? From: Christoph Schumacher Sent: Friday, October 25, 2013 8:53 PM To: rsgb_lf_group@blacksheep.org Subject: LF: air solenoids Dear all, is there anyone who was concerned sometime with the self radiating properties of single layer air solenoids without any piece of antenna wire? 73 dl7saq, Chris -- 73 Warren K2ORS WD2XGJ WD2XSH/23 WE2XEB/2 WE2XGR/1 ------=_NextPart_000_0A42_01CED1A3.89B79F70 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Chris,

 

I’ll second Warren’s motion.The radiation efficiency of a = 100-turn, 1-meter diameter solenoid (of any reasonable length/diameter = ratio) at 100kHz is in the hundreds of nano-ohms, i.e. a very difficult = starting point with respect to dissipative losses directly and = indirectly associated with wire resistance and coil inductance. = Radiation resistance of a solenoid scales with turns squared, but with = resistance scaling directly with turns, large numbers of turns is not a = reasonable approach for practical wire diameters. =

 

The reactive field (induction field), which comprises most of the = field (for a solenoid that is presumably a small fraction of a = wavelength) does not suffer low efficiency, but reactive field strength = falls by a factor of eight for (practically speaking) for every doubling = of distance, starting near the aperture boundary. The reactive field = strength 1km from a 1-meter diameter solenoid (properly oriented away = from the null) would be 1E-9 that of the field strength near the = aperture boundary.

 

Regards,

 

Jim AA5BW

 

From:= = owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Warren = Ziegler
Sent: Friday, October 25, 2013 3:50 PM
To: = rsgb_lf_group
Subject: Re: LF: air = solenoids

 

Christoph,

    A while back someone on the US longwave = reflector posted the result of an experiment. They took a receiver to = the site of a high power Tesla coil operating at LF, I believe it was = being driven at 175kHz. they expected to hear it at some distance but = were surprised to find out they could only hear the Tesla coil at very = short distances. It seems that a coil by itself is an extremely poor = radiator at LF!  It is unknown to me if there was any earth = connection to the Tesla coil, perhaps only through the mains = connection.

 

73 Warren

 

 

 

On Fri, Oct 25, 2013 at 4:20 PM, Christoph Schumacher = <chris-schum@t-online.de> = wrote:

no, cylindrical = coils

Am 25.10.2013 22:11, schrieb Graham: =

toroidal ?

 <= /o:p>

Sent:= = Friday, October 25, 2013 8:53 PM

Subject: LF: air = solenoids

 

Dear all,
is there anyone who was concerned sometime = with the self radiating properties of single layer air solenoids without = any piece of antenna wire?

73 dl7saq, = Chris

 



 

-- =
73 Warren K2ORS
              =   WD2XGJ
              =   WD2XSH/23
              =   WE2XEB/2
              =   WE2XGR/1

 

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