Return-Path: Received: from mtain-mg11.r1000.mx.aol.com (mtain-mg11.r1000.mx.aol.com [172.29.96.211]) by air-me02.mail.aol.com (v129.4) with ESMTP id MAILINME024-8ba74c1bee61297; Fri, 18 Jun 2010 18:08:33 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mg11.r1000.mx.aol.com (Internet Inbound) with ESMTP id 6D4DB380002E1; Fri, 18 Jun 2010 18:08:31 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OPjiP-0001Cj-2g for rs_out_1@blacksheep.org; Fri, 18 Jun 2010 23:07:09 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OPjiO-0001Ca-Bg for rsgb_lf_group@blacksheep.org; Fri, 18 Jun 2010 23:07:08 +0100 Received: from mail-bw0-f43.google.com ([209.85.214.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OPjiL-0003Rb-Re for rsgb_lf_group@blacksheep.org; Fri, 18 Jun 2010 23:07:08 +0100 Received: by bwz19 with SMTP id 19so539212bwz.16 for ; Fri, 18 Jun 2010 15:07:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=dwG2Y7RzPmoL+fBYwG4te4xs+QgRAP2xhsTcco+WCqU=; b=Xfg8tsF6+P1Tco2fzx/VX+Hj/namMA+SykeaSZGvyscoJuLpHVCfiSrnlSv14Hrvy1 U8bxOjmLOQvjaQtDRNYZYOjxrtbV5XZ+UOTbpTYccZEcIc0vDRufhyVWGQ6Q1Uqg7LRT D1MPJyGS2bDFx+caYHuuRjdviTJH+7QAOsvIg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=GS+0zZNLChvmyNz2omCc+SsS4Wakrb1s07D/PVOnVwHkQe9ZD/QfhUT3PJ309buWTU 7jeGxp0WZohi9EmVNy4qsD6XaXKPolhKmsUJHnZgdTAe7J2FlSeSYzbLG7PaU9pICPP9 G2SDkmsritCxfM7uzW7WdTDrTd4Ks4EY+629s= MIME-Version: 1.0 Received: by 10.204.73.194 with SMTP id r2mr1298906bkj.153.1276898823808; Fri, 18 Jun 2010 15:07:03 -0700 (PDT) Received: by 10.204.100.69 with HTTP; Fri, 18 Jun 2010 15:07:03 -0700 (PDT) In-Reply-To: <001101cb0f30$62e6f0a0$0202a8c0@laptopcore2> References: <001101cb0f30$62e6f0a0$0202a8c0@laptopcore2> Date: Fri, 18 Jun 2010 23:07:03 +0100 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: AW: RE: Earth electrode loop area - I'm struggling Content-Type: multipart/alternative; boundary=0016e6dd8c41cea7910489552cfc X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.0 required=5.0 tests=HTML_30_40, HTML_FONTCOLOR_UNKNOWN,HTML_FONTCOLOR_UNSAFE,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-AUTHENTICATION: mail_rly_antispam_dkim-m205.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d60d34c1bee5f7aa3 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0016e6dd8c41cea7910489552cfc Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Thanks Eddie. Yes I saw your reports on the database along with those from M0BMU, G0KTN and G3XIZ tonight. I will take Rik's suggestion to better match the loop and see if I can squeeze a few more dBs of ERP out of it. Then I think the experiment is done, apart from repeating it on 137kHz at a future date. PA0A has been a very strong signal on 500kHz WSPR here tonight via the ear= th electrode set-up. Last night I also copied G4JNT, G7NKS, G0NBD and PE1GRL= . 73s and thanks again to everyone for the few days of fun. Roger G3XBM On 18 June 2010 22:51, g3zjo wrote: > Hi Roger > > > > I did spot you 3 times tonight -28dB, -29dB and -30dB, using my inverted= L, > normal TX antenna. Nothing on the Doublet, the spots are on the database= now > although they didn=92t get uploaded at the time. > > > > *Eddie* > > > > -----Original Message----- > *From:* owner-rsgb_lf_group@blacksheep.org [mailto: > owner-rsgb_lf_group@blacksheep.org] *On Behalf Of *Roger Lapthorn > *Sent:* 18 June 2010 22:42 > *To:* rsgb_lf_group@blacksheep.org > *Subject:* Re: LF: AW: RE: Earth electrode loop area - I'm struggling > > > > 137kHz is a project for later this year Stefan. > > 73s > Roger G3XBM > > 2010/6/18 Stefan Sch=E4fer > > Interesting! > I wish i would know my ERP during the 9 kHz test where i reached 2km. Bu= t > the grabber is still not calibrated :-( > > Roger, when will you try 137 kHz? > > 73 es gl > > Stefan/DK7FC > > ________________________________ > > Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Rik Strobbe > Gesendet: Fr 18.06.2010 23:10 > An: rsgb_lf_group@blacksheep.org > Betreff: LF: RE: Earth electrode loop area - I'm struggling > > > Hello Roger, > > my pennyworth: > > assuming > - 50uW ERP > - antenna is traded as a loop (gain =3D -0.4dBd) > > Due to the negative gain (-0.4dB versus dipole) a loop antenna must > "radiate" 55uW to get 50uW ERP. > Since the antenna feeding current is 0.15A the radiation resistance is= 2.44 > milliOhm (R=3D P/I^2) > The radiation resistance of a small loop is : Ra =3D 320xPi^4*A^2/L^4 > where A =3D loop area (m^2) and L =3D wavelength (m) > For 500kHz Ra =3D 5*10^(-7)*A^2 or A =3D 1416*sqrt(Ra) > If Ra =3D 0.00244 Ohm then effective the loop area is 70m^2 > > 73, Rik ON7YD - OR7T > > > ________________________________ > > Van: owner-rsgb_lf_group@blacksheep.org [ > owner-rsgb_lf_group@blacksheep.org] namens Roger Lapthorn [ > rogerlapthorn@gmail.com] > Verzonden: vrijdag 18 juni 2010 22:29 > Aan: rsgb_lf_group@blacksheep.org > Onderwerp: LF: Earth electrode loop area - I'm struggling > > > Please can someone help me with the maths? I've been trying to work out= my > effective loop area and I cannot get sensible answers. These are the > measured or estimated numbers I have: > > Voltage across "loop" =3D 24.48V rms - measured > Current flowing in "loop" =3D 0.15A - measured > ERP (from far field levels) =3D 50-100uW (may be less) based on -18dB S/= N > with M0BMU > > From these figures I should be able to work out the loop area, but eithe= r > my calculations are wrong or the figure is correct and the effective loo= p > area is very very small. > > Help! > > 73s > Roger G3XBM > > -- > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > http://www.youtube.com/user/g3xbm > G3XBM GQRP 1678 ISWL G11088 > > > > > -- > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > http://www.youtube.com/user/g3xbm > G3XBM GQRP 1678 ISWL G11088 > --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --0016e6dd8c41cea7910489552cfc Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Thanks Eddie.

Yes I saw your reports on the database along with th= ose from M0BMU, G0KTN and G3XIZ tonight.=A0 I will take Rik's suggesti= on to better match the loop and see if I can=20 squeeze a few more dBs of ERP out of it. Then I think the experiment is=20 done, apart from repeating it on 137kHz at a future date.

PA0A has= been a very strong signal on 500kHz WSPR here tonight via the earth elect= rode set-up.=A0 Last night I also copied G4JNT, G7NKS, G0NBD and PE1GRL.
73s and thanks again to everyone for the few days of fun.

Roger= G3XBM


On 18 June 2010 22:51, g3zjo= <g3zjo@npton= .plus.com> wrote:

Hi Roger

=A0

I did spot= you 3 times tonight -28dB, -29dB and -30dB, using my inverted L, normal TX antenna. Nothing on the Doublet, the spots are on the database now although they didn=92t get uploaded at the time.

=A0

Eddie

=A0

-----Original Message-----
From: ow= ner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.= org] On Behalf Of Rog= er Lapthorn
Sent: 18 June 2010 22:42<= br> To: rsgb_lf_group@blacksheep.org<= /a>
Subject: Re: LF: AW: RE:= Earth electrode loop area - I'm struggling

=A0

137kHz is a project for later this year Stefan.

73s
Roger G3XBM

2010/6/18 Stefan Sch= =E4fer <scha= efer@hst.tu-darmstadt.de>

Interesting!
I wish i would know my ERP during the 9 kHz test where i reached 2km. But= the grabber is still not calibrated :-(

Roger, when will you try 137 kHz?

73 es gl

Stefan/DK7FC

________________________________

Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Rik Strobbe
Gesendet: Fr 18.06.2010 23:10
An: rsgb= _lf_group@blacksheep.org
Betreff: LF: RE: Earth electrode loop area - I'm struggling


Hello Roger,

my pennyworth:

assuming
- 50uW ERP
- antenna is traded as a loop (gain =3D -0.4dBd)

Due to the negative gain (-0.4dB versus dipole) a loop antenna must "radiate" 55uW to get 50uW ERP.
Since the antenna feeding current is 0.15A the radiation resistance is 2.4= 4 milliOhm (R=3D P/I^2)
The radiation resistance of a small loop is : Ra =3D 320xPi^4*A^2/L^4
where A =3D loop area (m^2) and L =3D wavelength (m)
For 500kHz Ra =3D 5*10^(-7)*A^2 or A =3D 1416*sqrt(Ra)
If Ra =3D 0.00244 Ohm then effective the loop area is 70m^2

73, Rik =A0ON7YD - OR7T


________________________________

Van: owner-rsgb_lf_group@blacksheep.org [o= wner-rsgb_lf_group@blacksheep.org] namens Roger Lapthorn [rogerlapthorn@gmail.com]
Verzonden: vrijdag 18 juni 2010 22:29
Aan: rsg= b_lf_group@blacksheep.org
Onderwerp: LF: Earth electrode loop area - I'm struggling


Please can someone help me with the maths? I've been trying to work ou= t my effective loop area and I cannot get sensible answers. These are the measu= red or estimated numbers I have:

Voltage across "loop" =A0=3D 24.48V rms =A0- measured
Current flowing in "loop" =3D 0.15A - measured
ERP (from far field levels) =3D 50-100uW (may be less) based on -18dB S/N= with M0BMU

>From these figures I should be able to work out the loop area, but either= my calculations are wrong or the figure is correct and the effective loop are= a is very very small.

Help!

73s
Roger G3XBM

--
http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.u= k <http://www.g3xbm= .co.uk/>
http://www= .youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088<= /p>




--
http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.u= k
http://www= .youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088




--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--0016e6dd8c41cea7910489552cfc--