Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dg05.r1000.mx.aol.com (Internet Inbound) with ESMTP id EE905380000B1; Wed, 9 Jan 2013 11:47:15 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Tsymr-0006Bj-9I for rs_out_1@blacksheep.org; Wed, 09 Jan 2013 16:45:57 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Tsymq-0006Ba-F3 for rsgb_lf_group@blacksheep.org; Wed, 09 Jan 2013 16:45:56 +0000 Received: from rhcavuit01.kulnet.kuleuven.be ([134.58.240.129] helo=cavuit01.kulnet.kuleuven.be) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1Tsymn-0007BN-QE for rsgb_lf_group@blacksheep.org; Wed, 09 Jan 2013 16:45:55 +0000 X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: 68A6B13809C.A7219 X-KULeuven-Information: Katholieke Universiteit Leuven Received: from icts-p-smtps-1.cc.kuleuven.be (icts-p-smtps-1e.kulnet.kuleuven.be [134.58.240.33]) by cavuit01.kulnet.kuleuven.be (Postfix) with ESMTP id 68A6B13809C; Wed, 9 Jan 2013 17:45:29 +0100 (CET) Received: from ICTS-S-HUB4.luna.kuleuven.be (icts-s-hub4.luna.kuleuven.be [10.112.9.18]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by icts-p-smtps-1.cc.kuleuven.be (Postfix) with ESMTPS id 6BBEF4042; Wed, 9 Jan 2013 17:45:29 +0100 (CET) Received: from ICTS-S-MBX5.luna.kuleuven.be ([fe80::312b:f3bc:9c4:4ebb]) by ICTS-S-HUB4.luna.kuleuven.be ([fe80::c11b:83f0:c46c:c366%26]) with mapi id 14.02.0309.002; Wed, 9 Jan 2013 17:45:28 +0100 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@yahoogroups.co.uk" , "rsgb_lf_group@blacksheep.org" Thread-Topic: [rsgb_lf_group] Earth electrode antenna with wire at zero height (WSPR 472kHz) Thread-Index: AQHN7nlDkugqmYvLkU+2+z74f//fVZhBKdZL Date: Wed, 9 Jan 2013 16:45:28 +0000 Message-ID: <7E7DFBB4D102A04DB5ADC88D66628A4A0FB68393@ICTS-S-MBX5.luna.kuleuven.be> References: <3401C753-302E-4621-9137-45B9A216D17F@gmail.com> In-Reply-To: <3401C753-302E-4621-9137-45B9A216D17F@gmail.com> Accept-Language: nl-BE, en-US Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.112.13.11] MIME-Version: 1.0 X-HELO-Warning: Remote host 134.58.240.129 (rhcavuit01.kulnet.kuleuven.be) used invalid HELO/EHLO cavuit01.kulnet.kuleuven.be - verification failed X-Spam-Score: -0.7 (/) 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: Hello Roger, assuming that the underground antenna behaves like a loop: For a classic loop area of the loop and the current flow are well defined (the current goes through the wire = circumference of the loop). [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [134.58.240.129 listed in list.dnswl.org] 0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: a3fd3ca670e1dd908c2723cee298dee8 Subject: LF: RE: [rsgb_lf_group] Earth electrode antenna with wire at zero height (WSPR 472kHz) Content-Type: multipart/alternative; boundary="_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FB68393ICTSSMBX5lunaku_" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=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 x-aol-global-disposition: G x-aol-sid: 3039ac1d410d50ed9f137907 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FB68393ICTSSMBX5lunaku_ Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Hello Roger, assuming that the underground antenna behaves like a loop: For a classic loop area of the loop and the current flow are well defined (= the current goes through the wire =3D circumference of the loop). This is not the case for the underground antenna, there will be a current f= low through an area or even a volume. But one could define the virtual area of the underground antenna as the are= a of a classic loop that procudes the same ERP (with the same antenna curre= nt) as the underground antenna. But how to determine this virtual loop area? Suggestion: You can measure the relative ERP of your underground loop (at a given anten= na current) using daytime WSPR and some local RX station (daytime and local= will rule out any propagation changes). Let's define the virtual area of the underground antenna as A1 (m^2) and th= e relative ERP as P1 (=3D dB values from WSPR). Next you could raise the wire, increasing the loop area by a know value A2)= . Again measure the relative ERP P2 (as before, using the same WSPR RX stat= ions at daytime). Now the total loop area is A1+A2, where we know A2 (the above ground part) = but not A1 (the virtual underground part). A1 can be calculated: At a constant antenna current the ERP will be proportional to the square of= the loop area. So P1 is proportional to A1^2 and P2 is proportional to (A1+A2)^2. Or: P2/P1 =3D (A1+A2)^2/A1^2 =3D (A1^2+2*A1*A2+A2^2)/A1^2 And after some more math: A1 =3D ((1+sqrt(P2/P1))/((P2/P1)-1))*A2. So based on the ERP increase (P2/P1) and the above ground area (A2) of the = loop the virtual area (A1) of the "submerged" part can be calculated. If this is done for some different heights of the wire (=3D different value= s of A2) one would have an indication if this theory is valid (the outcome = of the virual area should be more or less the same). 73, Rik ON7YD - OR7T ________________________________ Van: rsgb_lf_group@yahoogroups.co.uk [rsgb_lf_group@yahoogroups.co.uk] name= ns Roger Lapthorn [rogerlapthorn@gmail.com] Verzonden: woensdag 9 januari 2013 15:54 To: rsgb_lf_group@blacksheep.org; rsgb_lf_group@yahoogroups.co.uk Onderwerp: [rsgb_lf_group] Earth electrode antenna with wire at zero height= (WSPR 472kHz) Ok, so as the final instalment of this test I have now got the wires from t= he earth rods coming to the transverter just resting on the wet grass (what= was elevated by 1.5m is now zero). It seems to work best just feeding the = transverter straight into the rods without matching suggesting low reactanc= e and near 50 ohms. I'm still getting decent reports! So, it confirms the "loop in the ground" = theory, or it is acting as some bizarre E field antenna. Will again leave it running overnight to get a decent number of spots but a= lready I think we have an answer. What I can try next - is this ever going to end!? - is elevate the loop par= t "in the air" to much greater height (about 9m to match the top of the Mar= coni I just took down) and see how much improvement I get. More in the air = implies greater loop area so more signal. Just how much will indicate how m= uch of the loop's effective area is in the soil/rock. WSPR spots please folks. 73s Roger G3XBM __._,_.___ Reply to sender= | Reply to group | Reply via web post | Start a new topic Messages in this topic (1) Recent Activity: * New Members 8 * New Photos 1 * New Links 1 Visit Your Group [Yahoo! Groups] Switch to: Text-Only, Daily Digest = =95 Unsubscribe =95 Terms of Use . __,_._,___ --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FB68393ICTSSMBX5lunaku_ Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

= Hello Roger,

 

= assuming that the undergr= ound antenna behaves like a loop:

For a classic loop area of the = loop and the current flow are&nb= sp;well defined (the current goes through the wire =3D circumference of the loop).

This is = not the case for the underground antenna, there will be a current flow through<= /a> an area or<= /a> even a volume.

But one could define the v= irtual area of the underground antenna as the area of a classic loo= p that procudes the same<= a> ERP (with the same antenna current<= a>) as the underground antenna.

But how to determine this virtu= al loop area?

Suggestion:=

You can measure the relative ERP of your underground loop (at a given= antenna current) using daytime WSPR and some local=  RX station (daytime and&nbs= p;local will rule out any propagation changes).

Let's define<= a> the virtual area of the underground antenna as A1 (m^2) and the rel= ative ERP as P1 (=3D dB values=  from WSPR).

Next you could raise the wire, increasing the loop area by a know value<= a> A2). Again measure the relative ERP P2 (as before<= /a>, using the same WSPR RX = stations at daytime).

Now the = total loop area is A1+A2= , where we know A2 (the above=  ground part) but not=  A1 (the virtual underground p= art).

A1 can=  be calculated:

At a constant antenna current<= a> the ERP will be pr= oportional to the square of the loop area.

So P1<= a> is proportional to A1^2 and P2 is proportional to (A1= +A2)^2.

Or: P2/P1 =3D (A1+A2)^2/A1^2 =3D (A1^2+2*A1= *A2+A2^2)/A1^2

And after s= ome more math:

A1 =3D ((1= 3;sqrt(P2/P1))/((P2/P1)-1))*A2.

So based on the ERP increase (P2/P1) and the above ground&= nbsp;area (A2) of the loop the virtual<= /a> area (A1) of the "submerged" part can be calculated= .

If this is done for some= different heights of the wire (=3D d= ifferent values of A2) one<= /a> would have an indication<= /a> if this theory= is valid (the outcome of the virual area=  should be more or=  less the same).

 

73, Rik  ON7YD<= /a> - OR7T 

 

 

Van: rsgb_lf_group@yahoogroups.co.uk [rsgb= _lf_group@yahoogroups.co.uk] namens Roger Lapthorn [rogerlapthorn@gmail.com= ]
Verzonden: woensdag 9 januari 2013 15:54
To: rsgb_lf_group@blacksheep.org; rsgb_lf_group@yahoogroups.co.uk Onderwerp: [rsgb_lf_group] Earth electrode antenna with wire at zero= height (WSPR 472kHz)

 

Ok, so as the final instalment of this test I have now got the wires fro= m the earth rods coming to the transverter just resting on the wet grass (w= hat was elevated by 1.5m is now zero). It seems to work best just feeding t= he transverter straight into the rods without matching suggesting low reactance and near 50 ohms.

I'm still getting decent reports! So, it confirms the "loop in the gro= und" theory, or it is acting as some bizarre E field antenna.

Will again leave it running overnight to get a decent number of spots but a= lready I think we have an answer.

What I can try next - is this ever going to end!? - is elevate the loop par= t "in the air" to much greater height (about 9m to match the top = of the Marconi I just took down) and see how much improvement I get. More i= n the air implies greater loop area so more signal. Just how much will indicate how much of the loop's effective area = is in the soil/rock.

WSPR spots please folks.

73s
Roger G3XBM

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