Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-me06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 5DC95380000B3; Tue, 8 Jan 2013 20:12:31 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1TskCR-0004A9-Aq for rs_out_1@blacksheep.org; Wed, 09 Jan 2013 01:11:23 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1TskCQ-0004A0-NF for rsgb_lf_group@blacksheep.org; Wed, 09 Jan 2013 01:11:22 +0000 Received: from smtpout4.wanadoo.co.uk ([80.12.242.68] helo=smtpout.wanadoo.co.uk) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1TskCN-0004G2-IY for rsgb_lf_group@blacksheep.org; Wed, 09 Jan 2013 01:11:21 +0000 Received: from AGB ([2.26.16.164]) by mwinf5d55 with ME id ldAx1k0073YP8Wy03dAx6T; Wed, 09 Jan 2013 02:10:58 +0100 Message-ID: From: "Graham" To: References: <8EFF74C5288B4CC1B0776D52DBE13A77@gnat> In-Reply-To: <8EFF74C5288B4CC1B0776D52DBE13A77@gnat> Date: Wed, 9 Jan 2013 01:10:57 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 X-Spam-Score: 0.0 (/) 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: Could be on the grounds of part of a magnetic loop , where the circuiting current is bolstered by the 'diffused ' return path , I was thinking of the high level of circulating currant causing the radiation as opposed to a 'wave size' array [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [80.12.242.68 listed in list.dnswl.org] 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 29f1b43ee9e13e220716185d38bfb88c Subject: Re: LF: Re: Comparing earth-electrode v. Marconi antenna on 472kHz Content-Type: multipart/alternative; boundary="----=_NextPart_000_022C_01CDEE06.2E0BC470" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30,HTML_MESSAGE, MISSING_OUTLOOK_NAME 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-sid: 3039ac1d608e50ecc3ff6208 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_022C_01CDEE06.2E0BC470 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Could be on the grounds of part of a magnetic loop , where the = circuiting current is bolstered by the 'diffused ' return = path , I was thinking of the high level of circulating currant = causing the radiation as opposed to a 'wave size' array =20 G.. From: Alan Melia=20 Sent: Wednesday, January 09, 2013 12:10 AM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: Re: Comparing earth-electrode v. Marconi antenna on 472kHz There is nothing wrong with the "science" of doing simple experiments = Roger ......The bad science is if you try to read too much into = them......which you have not done. Your results do align with the books = in the subject though most are for ELF. It doesnt work this way for = everyone it depends on local ground conditions.....thats why there is = always so much discussion :-))=20 I cant remember the detail but the skin depth of your ground at 500k is = probablty quite shallow but it probably could still be several feet = giving a reasonable area loop, and the conductivity must be quite good. Graham's idea of a TWA is feasible but I think it is too short(normal = requirement 300 to 900 m) to have directionality, not terminated, and = too low ar this frequency. TWAs usually work best on receive over poor = ground and would very inefficient as transmitting aerials. But any bit = of wire will act as an aerial and there is no guarantee there is a = single mode of operation :-)) Alan G3NYK ----- Original Message -----=20 From: Roger Lapthorn=20 To: rsgb_lf_group@blacksheep.org ; rsgb_lf_group@yahoogroups.co.uk=20 Sent: Tuesday, January 08, 2013 9:06 PM Subject: LF: Comparing earth-electrode v. Marconi antenna on 472kHz This evening I've been noting my WSPR S/N reports from stations across = the country and nearer Europe using my 9m long Marconi antenna (an = average arrangement for a small garden plot like mine - but not the = best) and comparing these with the reports last night when I was using = just the 15m baseline earth-electrode "antenna". I crudely plotted the = "improvement factor" in dB on a polar plot. Each dot represents a = station reporting my signal with the dB improvement over the = earth-electrode antenna plotted on a 0-20dB scale out from the centre. = This is not good science, it is G3XBM science I'm afraid, but it give a = fair idea of the difference and how direction affects this (see attached = rough polar plot). Although in some directions the difference is very little, in other = directions the reports are up to 14dB better on the (omni-directional) = Marconi. My conclusion is that the earth electrode antenna is behaving somewhat = like a loop with some directionality along the line of the = earth-electrode baseline and a null off the sides. With stations = receiving me off the sides there is most improvement with the Marconi, = and less difference with stations end-on who were getting a reasonable = signal with the earth-electrode antenna. CONCLUSION: the simple, stealth, earth-electrode antenna is a VERY = useful antenna on 472kHz as long as one is prepared to accept a 2-14dB = loss compared with a "small garden" Marconi. In all honesty, I am = getting better reports on the Marconi but few new stations are copying = me: most could copy me on the earth electrode antenna.=20 I shall run WSPR overnight to see if any more distant stations copy = me, then probably put away the 472kHz gear and Marconi for a while to = find another interesting challenge - possibly something on 10m or VHF.=20 These last few days have been fun, and that is really what this hobby = is about. 73s Roger G3XBM --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk https://sites.google.com/site/sub9khz/ http://qss2.blogspot.com/ ------=_NextPart_000_022C_01CDEE06.2E0BC470 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Could  be  on the  grounds  of  part of = a =20 magnetic  loop  , where  the  circuiting  = current =20 is  bolstered  by the  'diffused '     =20 return  path ,  I was thinking of the  high  = level =20 of  circulating  currant   causing  the  = radiation=20 as  opposed to  a 'wave  size' =20 array    
 
G..

From: Alan Melia
Sent: Wednesday, January 09, 2013 12:10 AM
To: rsgb_lf_group@blacksheep.org= =20
Subject: LF: Re: Comparing earth-electrode v. Marconi = antenna on=20 472kHz

There is nothing wrong with the = "science" of doing=20 simple experiments Roger ......The bad science is if you try to read too = much=20 into them......which you have not done. Your results do align with the = books in=20 the subject though most are for ELF. It doesnt work this way for = everyone it=20 depends on local ground conditions.....thats why there is always so much = discussion :-))
 
I cant remember the detail but the skin = depth of=20 your ground at 500k is probablty quite shallow but it probably could = still be=20 several feet  giving a reasonable area loop, and the conductivity = must be=20 quite good.
 
Graham's idea of a TWA is feasible but = I think it=20 is too short(normal requirement 300 to 900 m) to have directionality, = not =20 terminated, and too low ar this frequency. TWAs usually work best on = receive=20 over poor ground and would very inefficient as transmitting = aerials. But=20 any bit of wire will act as an aerial and there is no guarantee there is = a=20 single mode of operation :-))
 
 
Alan
G3NYK
----- Original Message -----
From:=20 Roger=20 Lapthorn
Sent: Tuesday, January 08, 2013 = 9:06=20 PM
Subject: LF: Comparing = earth-electrode v.=20 Marconi antenna on 472kHz

This evening I've been noting my WSPR S/N reports from stations = across=20 the country and nearer Europe using my 9m long Marconi antenna (an = average=20 arrangement for a small garden plot like mine - but not the best) and=20 comparing these with the reports last night when I was using just the = 15m=20 baseline earth-electrode "antenna". I crudely plotted the "improvement = factor"=20 in dB on a polar plot. Each dot represents a station reporting my = signal with=20 the dB improvement over the earth-electrode antenna plotted on a = 0-20dB scale=20 out from the centre. This is not good science, it is G3XBM science I'm = afraid,=20 but it give a fair idea of the difference and how direction affects = this (see=20 attached rough polar plot).

Although in some directions the = difference=20 is very little, in other directions the reports are up to 14dB better = on the=20 (omni-directional) Marconi.

My conclusion is that the earth = electrode=20 antenna is behaving somewhat like a loop with some = directionality along=20 the line of the earth-electrode baseline and a null off the sides. = With=20 stations receiving me off the sides there is most improvement with the = Marconi, and less difference with stations end-on who were getting a=20 reasonable signal with the earth-electrode = antenna.

CONCLUSION: the=20 simple, stealth, earth-electrode antenna is a VERY useful antenna on = 472kHz as=20 long as one is prepared to accept a 2-14dB loss compared with a "small = garden"=20 Marconi. In all honesty, I am getting better reports on the = Marconi but=20 few new stations are copying me: most could copy me on the earth = electrode=20 antenna.

I shall run WSPR overnight to see if any more = distant=20 stations copy me, then probably put away the 472kHz gear and Marconi = for a=20 while to find another interesting challenge - possibly something on = 10m or=20 VHF.

These last few days have been fun, and that is really = what this=20 hobby is about.

73s
Roger G3XBM
--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
https://sites.google.com/= site/sub9khz/
http://qss2.blogspot.com/

<= /DIV>
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