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[195.171.43.25]) by mx.google.com with ESMTP id da8si22809711wib.3.2014.06.24.10.27.29 for ; Tue, 24 Jun 2014 10:27:29 -0700 (PDT) Received-SPF: none (google.com: owner-rsgb_lf_group@blacksheep.org does not designate permitted sender hosts) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: owner-rsgb_lf_group@blacksheep.org does not designate permitted sender hosts) smtp.mail=owner-rsgb_lf_group@blacksheep.org; dkim=pass header.i=@mx.aol.com; dmarc=pass (p=REJECT dis=NONE) header.from=aol.com Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1WzU7u-0004DJ-VU for rs_out_1@blacksheep.org; Tue, 24 Jun 2014 18:03:22 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1WzU7u-0004DA-Db for rsgb_lf_group@blacksheep.org; Tue, 24 Jun 2014 18:03:22 +0100 Received: from omr-d01.mx.aol.com ([205.188.252.208]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.82) (envelope-from ) id 1WzU7r-0003VW-D7 for rsgb_lf_group@blacksheep.org; Tue, 24 Jun 2014 18:03:21 +0100 Received: from mtaomg-mba02.mx.aol.com (mtaomg-mba02.mx.aol.com [172.26.133.112]) by omr-d01.mx.aol.com (Outbound Mail Relay) with ESMTP id 39B24700A8C4E for ; Tue, 24 Jun 2014 13:03:17 -0400 (EDT) Received: from core-afa03a.mail.aol.com (core-afa03.mail.aol.com [172.27.24.3]) by mtaomg-mba02.mx.aol.com (OMAG/Core Interface) with ESMTP id A46E638000081 for ; Tue, 24 Jun 2014 13:03:16 -0400 (EDT) References: <53A97738.2070501@gmail.com> To: rsgb_lf_group@blacksheep.org In-Reply-To: <53A97738.2070501@gmail.com> X-MB-Message-Source: WebUI MIME-Version: 1.0 From: Markus Vester X-MB-Message-Type: User X-Mailer: AOL Webmail BASIC Received: from 194.138.39.60 by webmail-m293.sysops.aol.com (64.12.152.47) with HTTP (WebMailUI); Tue, 24 Jun 2014 13:03:16 -0400 Message-Id: <8D15DE5531A8822-27BC-8EBC@webmail-m293.sysops.aol.com> X-Originating-IP: [194.138.39.60] Date: Tue, 24 Jun 2014 13:03:16 -0400 (EDT) x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1403629397; bh=Hq60x2DdUdLnXgxgUq6blH/Ge20P/wkq0UtbUCbCNjU=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=ghkNSTCMBvENIktFdgbFiyXCdR7PR03fF0qZcofQ3RCcWeiU66sc7LQqPfWAuehWO erBY5VJxX+nD2fSqh4a90qPfWAyMUzES4htWZVQ7yTsmZ8tyF8hiCdJy/jT1Fg5g9u torX6o9d98y4sncR2Z0cl/y3WeXgK2daxlc2llis= x-aol-sid: 3039ac1a857053a9af5450a1 X-Spam-Score: 1.0 (+) 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: Stefan, Joe  > I think that 8m above ground should be fine for any tests :-) well (apart from practical reasons like people tripping over it), you might just as well lay the (insulated) wire on the ground.  From receive measurements with your earlier and shorter earth antenna, we deduced a depth of return current of 29 meters at 23.4 kHz, which would scale to about 48 m at 8.3 kHz. Thus a two kilometer long earth antenna would have the same radiation resistance (0.35 milliohm) as a 17 m high top-loaded vertical. But skin depth and efficiency might be greater for very low ground conductance.  Best 73, Markus  -----Ursprüngliche Mitteilung----- Von: Markus Vester <markusvester@aol.com> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org> Verschickt: Mi, 21 Jul 2010 9:07 pm Betreff: VLF: RE: DLF passive received with earth antenna ...  Thus the effective height of the 280 m long earth antenna was  heff = U/E = 3.97 m at 23.4 kHz, giving a ground loop area  A = heff * lambda/2pi = 8090 m^2, and an effective return current depth  d = heff /length = 29 m.  This depth appears to be much less than half of the baseline length, so it is probably indeed skin effect limited. Scaling the 23.4 kHz results to 9 kHz would give 1.6 times more skin depth, but 1.6 times less effective height (ie. 2.5 m) due to the larger wavelength to loop length ratio. Thus the transmit efficiency at 9 kHz would be about 26 dB less than that of a 100 m kite antenna with similar loss resistance. ... [...] Content analysis details: (1.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [205.188.252.208 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid 1.0 FREEMAIL_REPLY From and body contain different freemails X-Scan-Signature: 882bdeb3d60c37e569eb1f790f5c4a0f Subject: Re: LF: VLF in Canada - earth loop Content-Type: multipart/alternative; boundary="--------MB_8D15DE553586E86_27BC_1E21D_webmail-m293.sysops.aol.com" 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=FORGED_AOL_TAGS,HTML_20_30, HTML_FONTCOLOR_UNKNOWN,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 This is a multi-part message in MIME format. ----------MB_8D15DE553586E86_27BC_1E21D_webmail-m293.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Stefan, Joe =C2=A0 >=C2=A0I think that 8m above ground should be fine for any tests :-) well (apart from practical reasons like people tripping over it), you might= just as well lay the (insulated) wire on the ground. =C2=A0 From=C2=A0receive measurements with your earlier=C2=A0and shorter earth ant= enna, we deduced a depth of=C2=A0return current=C2=A0of 29 meters at 23.4 k= Hz,=C2=A0which would=C2=A0scale to about 48 m at 8.3 kHz.=C2=A0Thus=C2=A0a = two kilometer long earth=C2=A0antenna would have the same radiation resista= nce=C2=A0(0.35 milliohm) as a 17 m high top-loaded vertical. But=C2=A0skin = depth and efficiency might be greater for very low ground conductance. =C2=A0 Best 73, Markus =C2=A0 -----Urspr=C3=BCngliche Mitteilung-----=20 Von: Markus Vester <markusvester@aol.com> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org> Verschickt: Mi, 21 Jul 2010 9:07 pm Betreff: VLF: RE: DLF passive received with earth antenna ... =C2=A0 Thus the effective height of the 280 m long earth antenna was=20 =C2=A0heff =3D U/E =3D 3.97 m at 23.4 kHz, giving a=C2=A0ground loop area=20 =C2=A0A =3D heff * lambda/2pi =3D 8090 m^2, and an effective return current depth =C2=A0d =3D heff /length =3D 29 m. =C2=A0 This depth appears to be much less than half of the baseline length, so it = is probably indeed skin effect limited. Scaling the 23.4 kHz results to 9 k= Hz would give 1.6 times more skin depth, but 1.6 times less effective heigh= t (ie. 2.5 m) due to the larger wavelength to loop length ratio. Thus the t= ransmit efficiency at 9 kHz would be about 26 dB less than that of a 100 m = kite antenna with similar loss resistance. ... -----Urspr=C3=BCngliche Mitteilung-----=20 Von: DK7FC <73dk7fc@googlemail.com> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org> Verschickt: Di, 24 Jun 2014 3:05 pm Betreff: Re: LF: VLF in Canada Oh yes, Joe, if you have plenty of forest where you can play VLF games, i w= ould also play with a dipole antenna. That's what i said to Laurence a few = months ago. Just install a dipole with say 10 km length, adding 100m each d= ay and see how the performance increases. This will be an interesting proje= ct :-) Maybe you remember my 700m long earth antenna which allowed me to be copied= in 45 km distance in 4.5 mHz FFT BW, back in 2011 :-) Someone removed the = antenna completely but if you have more space, just give it a try. I think = that 8m above ground should be fine for any tests :-) Nice to think about it :-) 73, GL, Stefan Am 24.06.2014 12:55, schrieb Markus Vester:=20 Joe, good to read this!=20 =C2=A0 Regarding the loading coil, I would agree with Stefan that a large multitur= n air coil is the best option. A laminated iron core would suffer from exce= ssive eddy current losses, and the effect of ferrites is limited by saturat= ion and hysteresis losses. =C2=A0 My 1.3 henry coil consumed 2.3 km of 0.4 mm enameled wire, using 7 buckets = with 480 turns on each: df6nm.bplaced.net/VLF/VLF_110304-06/coil_legospacers.jpg. The advantage is that due to magnetic coupling between layers, you will nee= d less wire for a given inductance. And the inductance is adjustable across= a wide range, using spacers. Disadvantages are the high electric field bet= ween layers limiting voltage capability, and less effective heat removal fr= om the inner buckets. Stuffing the buckets too tightly into one another is = surely not a good idea: df6nm.bplaced.net/VLF/pictures/arced_coil_140601.jpg =C2=A0 An nonresonant earth antenna across high resistivity rock could also radiat= e moderately well, avoiding coil making and high voltage issues altogether.= But to compete with your vertical in terms of radiation resistance, it wou= ld need to be really long, on the order of a couple of miles. It will have = magnetic loop directional pattern which may be a disadvantage. =C2=A0 For a transatlantic detection eg. by Paul Nicholson, a Rubidium or GPS lock= ed signal source would be very beneficial. Using SpecLab with 1pps phase lo= ck to eliminate soundcard output glitches has worked well for DJ8WX, PA1SDB= , and myself. =C2=A0 Best of luck, Markus (DF6NM) -----Urspr=C3=BCngliche Mitteilung-----=20 Von: DK7FC <73dk7fc@googlemail.com> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org> Verschickt: Di, 24 Jun 2014 12:48 am Betreff: Re: LF: VLF in Canada Hi Joe, Fine to hear that you're give it a try. Please, don't ask Indu= stry Canada if the 10mW is RF power of ERP! To get out a real signa= l on VLF, there is no alternative to a real large coil without ferrites!= Think about the high voltages... But 100m of antenna wire is a good sta= rt. I remember 550 mH for my 100m kite antenna. For me it was 2000m of 0= .4mm diameter wire :-) Nice work is that. Takes long but is a funny game= :-) 73, GL, Stefan Am 23.06.2014 21:33, schrieb jcraig@mun.ca: = Dear Group, I tried again to get an LOA for VLF. This time, the respon= se from Industry Canada was favourable: 10 mW 8.0-8.3 kHz. Yesterday, a= fter a few slight rf burns, and thanks to PA0RDT's miniwhip design and = DL4YHF's Spectrum Lab and advice, VLF sigs on 8.277 kHz were heard at = 200m from the 100m wire aerial. This was a reception outside my back ya= rd! 10 watts from an 1970's keyboard amp (volume control set on 3) were= stepped up with an xfmr to a lossy 500 ohm tuning coil peaked with a fe= rrite rod for maximum squeal at L=3D0.35 H. Is it possible for someone wh= o is not especially enthralled by winding a mile of 0.7mm wire to use an = iron core to make a VLF tuning coil? 73 Joe VO1NA =20 ----------MB_8D15DE553586E86_27BC_1E21D_webmail-m293.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8"
Stefan, Jo= e
 
> = I think that 8m above ground should be fine for any tests :-)
well (apar= t from practical reasons like people tripping over it), you might just as w= ell lay the (insulated) wire on the ground.
 
From = receive measurements with your earlier and shorter earth antenna, we d= educed a depth of return current of 29 meters at 23.4 kHz, w= hich would scale to about 48 m at 8.3 kHz. Thus a two kilome= ter long earth antenna would have the same radiation resistance (= 0.35 milliohm) as a 17 m high top-loaded vertical. But skin depth and = efficiency might be greater for very low ground conductance.
 
Best 73,
Markus
 
-----Urspr= =C3=BCngliche Mitteilung-----
Von: Markus Vester <markusvester@aol.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Mi, 21 Jul 2010 9:07 pm
Betreff: VLF: RE: DLF passive received with earth antenna
...
 
Thus the effective height of the 280 m long earth antenna was
 heff =3D U/E =3D 3.97 m at 23.4 kHz,
giving a ground loop area
 A =3D heff * lambda/2pi =3D 8090 m^2,
and an effective return current depth
 d =3D heff /length =3D 29 m.
 
This depth appears to be much less than half of the baseline length, s= o it is probably indeed skin effect limited. Scaling the 23.4 kHz results t= o 9 kHz would give 1.6 times more skin depth, but 1.6 times less effective = height (ie. 2.5 m) due to the larger wavelength to loop length ratio. Thus = the transmit efficiency at 9 kHz would be about 26 dB less than that of a 1= 00 m kite antenna with similar loss resistance.
...

-----Urspr=C3=BCngliche Mitteilung-----
Von: DK7FC <73dk7fc@googlemail.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Di, 24 Jun 2014 3:05 pm
Betreff: Re: LF: VLF in Canada

Oh yes, J= oe, if you have plenty of forest where you can play VLF games, i would also= play with a dipole antenna. That's what i said to Laurence a few months ag= o. Just install a dipole with say 10 km length, adding 100m each day and se= e how the performance increases. This will be an interesting project :-)
Maybe you= remember my 700m long earth antenna which allowed me to be copied in 45 km= distance in 4.5 mHz FFT BW, back in 2011 :-) Someone removed the antenna c= ompletely but if you have more space, just give it a try. I think that 8m a= bove ground should be fine for any tests :-)

Nice to think about it :-)

73, GL, Stefan

Am 24.06.2014 12:55, schrieb Markus Vester:
Joe, good = to read this!
 
Regarding = the loading coil, I would agree with Stefan that a large multiturn air coil= is the best option. A laminated iron core would suffer from excessive eddy= current losses, and the effect of ferrites is limited by saturation and hy= steresis losses.
 
My 1.3 hen= ry coil consumed 2.3 km of 0.4 mm enameled wire, using 7 buckets with 480 t= urns on each:
df6nm.bplaced.net/VLF/VLF_110304-06/coil_legospacers.jpg.
The advantage is that due to magnetic coupling between layers, you will nee= d less wire for a given inductance. And the inductance is adjustable across= a wide range, using spacers. Disadvantages are the high electric field bet= ween layers limiting voltage capability, and less effective heat removal fr= om the inner buckets. Stuffing the buckets too tightly into one another is = surely not a good idea:
df6nm.bplaced.net/VLF/pictures/arced_coil_140601.jpg
 
An nonreso= nant earth antenna across high resistivity rock could also radiate moderate= ly well, avoiding coil making and high voltage issues altogether. But to co= mpete with your vertical in terms of radiation resistance, it would need to= be really long, on the order of a couple of miles. It will have magnetic l= oop directional pattern which may be a disadvantage.
 
For a tran= satlantic detection eg. by Paul Nicholson, a Rubidium or GPS locked signal = source would be very beneficial. Using SpecLab with 1pps phase lock to elim= inate soundcard output glitches has worked well for DJ8WX, PA1SDB, and myse= lf.
 
Best of lu= ck,
Markus (DF6NM)


-----Urspr=C3=BCngliche Mitteilung-----
Von: DK7FC <73dk7fc@googlemail.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Di, 24 Jun 2014 12:48 am
Betreff: Re: LF: VLF in Canada


Hi Joe,      Fine to hear that you're giv=
e it a try. Please, don't ask Industry    Canada if the 10mW is RF power of=
 ERP!      To get out a real signal on VLF, there is no alternative to a re=
al large    coil without ferrites! Think about the high voltages... But 100=
m of    antenna wire is a good start. I remember 550 mH for my 100m kite   =
 antenna. For me it was 2000m of 0.4mm diameter wire :-) Nice work is    th=
at. Takes long but is a funny game :-)      73, GL, Stefan      Am 23.06.20=
14 21:33, schrieb jcraig@mun.ca:   Dea=
r Group,   
I tried again to ge=
t an LOA  for VLF.  This time, the response from    Industry Canada was fav=
ourable: 10 mW 8.0-8.3 kHz.  Yesterday, after a    few slight rf burns, and=
  thanks to PA0RDT's miniwhip design and    DL4YHF's Spectrum Lab and advic=
e, VLF sigs on 8.277 kHz were heard at    200m from the 100m wire aerial. T=
his was a reception outside my back    yard!  10 watts from an 1970's keybo=
ard amp (volume control set on 3)    were stepped up with an xfmr to a loss=
y 500 ohm tuning coil peaked    with a ferrite rod for maximum squeal at L=
=3D0.35 H.   
Is it possible fo=
r someone who is not especially enthralled by winding   a mile of 0.7mm wir=
e to use an iron core to make a VLF tuning coil?   
73   Joe VO1NA
----------MB_8D15DE553586E86_27BC_1E21D_webmail-m293.sysops.aol.com--