Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id w12HrPYH003725 for ; Fri, 2 Feb 2018 18:53:27 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ehfQ5-0002N1-CV for rs_out_1@blacksheep.org; Fri, 02 Feb 2018 17:46:37 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ehfQ3-0002Ms-HL for rsgb_lf_group@blacksheep.org; Fri, 02 Feb 2018 17:46:35 +0000 Received: from resqmta-ch2-07v.sys.comcast.net ([2001:558:fe21:29:69:252:207:39]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1ehfPz-0003ZB-3l for rsgb_lf_group@blacksheep.org; Fri, 02 Feb 2018 17:46:34 +0000 Received: from resomta-ch2-08v.sys.comcast.net ([69.252.207.104]) by resqmta-ch2-07v.sys.comcast.net with ESMTP id hfPHeRDCxTixQhfPuerjVg; Fri, 02 Feb 2018 17:46:26 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20161114; t=1517593586; bh=gJmZQwrhtD8QRMY1AX77TabTNFf1yGATNulAiyaeXh0=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=oa9E0zmHJ4xrEWIRfPENHRejKyv5+z//L08iMRA0Pjt5A+uk5L0hd+D8BD4xn2I0l kCOKJtJBCHO4vbLmvCqskVzqVKlDQox+IeL4kEICOUiThQaIa3re4nH1Eobp1OJ9yi 8uvvBKZU14hs0DfOsSkA7+oCOcRqvGV7KyMYwLTENKgHcq/9mVhxAWwzcf53DSj64h 5aLIJ6QV/wuCeqMLVZuBYAHGIfi1gIil8DwJUjcTCsXa2PaGQP5RUqFF7wU0MNKYsO lY+QD/CYBZvGTaJMrKhDzs3GGKL0BTFoIS4l6Qt1JePe+r6DiYj6H0s+v4H1ckGetS ZCE93MxKJYzGQ== Received: from Owner ([IPv6:2601:140:8500:7f9f:78f6:dd:b547:d008]) by resomta-ch2-08v.sys.comcast.net with SMTP id hfPrec7y5e3xXhfPreR0B4; Fri, 02 Feb 2018 17:46:24 +0000 From: To: References: <579355A36AEE9D4FA555C45D556003AB9AB485D3@servigilant.vigilant.local> <5A7377F7.4050802@posteo.de> <017101d39bab$2f0e3710$8d2aa530$@comcast.net> In-Reply-To: Date: Fri, 2 Feb 2018 12:46:20 -0500 Message-ID: <022801d39c4d$bc803510$35809f30$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQKIjaFcimWHhYva/6wQoj7d7es8IQKX8hVkAgTLYngBLbgExaH5Eohw Content-Language: en-us X-CMAE-Envelope: MS4wfD8+EOFH92JSqu4UHe7a676aDWyXkgMtEZbKb+ixzNRsECq4jmDvTOqYINfZhOSUKqi1jasO7rg8LaYz8LWV5UirlfLXPPM87HO6duCsxWYXnQxvJEA4 OTmhhKai7gYQyJdXLxf9HvKCA6vOhejLGMg= X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Roger, Thank you for your Ferrite Rod TX Antennas link, nicely written, and worth its e-weight in gold from my perspective. I am in decade 6 of increasing hope for theory that would assist intriguing experiments such as yours. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (hvanesce[at]comcast.net) 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: 57c46fc57df9e768804caa43485df2f4 Subject: RE: LF: VLF Small magnetic antenna for Tx Content-Type: multipart/alternative; boundary="----=_NextPart_000_0229_01D39C23.D3AC9E10" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_40_50,HTML_MESSAGE, NO_REAL_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 This is a multipart message in MIME format. ------=_NextPart_000_0229_01D39C23.D3AC9E10 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Roger, =20 Thank you for your Ferrite Rod TX Antennas link, nicely written, and = worth its e-weight in gold from my perspective. =20 I am in decade 6 of increasing hope for theory that would assist = intriguing experiments such as yours. Fascinating to realize that scientific theory doesn=E2=80=99t explain = air core solenoid inductance, much less ferrite core, much less solenoid = self-resonant frequency, and alas, ETA for useful scientific theory for = ferrite loop transmitters is probably past my metaphysical transition = date. Whence my appreciation for documentation such as yours. After they = resolve dark matter and quantum vacuum plasma, maybe they will figure = out solenoids and even magnetics. In the meantime, inspiring = electromagnetics and propagation electrophysics emanate, thank goodness, = from ham shacks and web reflectors et al. From one of these I would like = to borrow a valuable model for this subject area: =20 =E2=80=9CWhat happens in the far field goodness only knows=E2=80=9D =20 I intend to ask author=E2=80=99s permission to cite the above model, it = is the best I=E2=80=99ve seen. (Found on https://sites.google.com/site/g3xbmqrp3/antennas/ferrite_tx) =20 =20 73, =20 Jim AA5BW =20 =20 =20 =20 From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Roger Lapthorn Sent: Friday, February 2, 2018 5:15 AM To: rsgb_lf_group@blacksheep.org Subject: Re: LF: VLF Small magnetic antenna for Tx =20 I am definitely NOT a theory man! However, I have had success on HF with = ferrite rod antennas on TX and low power WSPR. Although inefficient, I = often wonder if such a structure might have some place on lower bands as = long as the ferrite rod does not saturate. Yes a decent BIG antenna will = be much better. =20 See https://sites.google.com/site/g3xbmqrp3/antennas/ferrite_tx =20 73s Roger G3XBM =20 On 1 February 2018 at 22:22, wrote: Luis, =20 Thank you for the underground mapping example; nice work by the speleo = team.=20 =20 =E2=80=9CAs this is the near field it is supposed to work only at = magnetic field due to the small size of the antenna ? So only magnetic = field for underground signals at this distances ?=E2=80=9D =20 At 38kHz the impedance of the transmitting loop=E2=80=99s field at 100 = meters is ~ 25 ohms, which puts an optimized E-field (electric probe) = receiver at perhaps a 45dB disadvantage, but your near-field intensity = through 70 meters of average-conductivity rock and 30 meters of air may = be (based on your schematic and description) as much as 0.1 pT, so the = E-field (electric probe) receiver will work well at 100 meters. =20 =20 =E2=80=9CCan we expect to receive the signal with an electric probe = antenna in the near field or the only chance is to be further away ? = And then losing the signal due to the distance =E2=80=A6.=E2=80=9D =20 Based on your schematic and description: only in the near field.=20 At 1 km (and 38 kHz) and farther, any disadvantage of the E-field = (electric probe) receiver is small. At 1 km the near-field strength for the configuration that you described = could be as much as ~ 1fT, so the near field component of the signal at = 1 km would be detectable (with significant integration time and/or low = noise), using an electric probe receiving antenna or a loop receiving = antenna. But due primarily to the small aperture of the loop transmitting antenna = that you described, the radiated field component at 1 km is far below = the threshold of detectability (perhaps 0.01 attotesla at 1km), so at = distances greater than a kilometer, the near field component fades below = detectability, and the far-field component of the signal fades even = farther below the level of detectability. For most practical purposes, to be detected well into the far field, a = VLF loop transmitting antenna needs to be physically very large and = driven by more power than batteries can practically provide.=20 Note: the electric-probe antenna efficiently detects the radiated = component of the signal, and the radiated component of the signal = decreases from the transmitting antenna through the far field, so in = outdoor above-ground (=E2=80=9Copen field=E2=80=9D) VLF signal = reception, moving an electric-probe receiving antenna from a = magnetic-loop transmitter=E2=80=99s near field to its far field never = improves reception by a receiver with electric-probe antenna. =20 =20 =E2=80=9CWhat would be the radiated power of such antenna ?=E2=80=9D =20 Based on your schematic and description, probably less than 100 pW. =20 Portable ULF and VLF loop transmitters are great for hundreds of meters = through rock or air, but detection of ULF/VLF loop-transmitter signals = in the far field requires transmitting-antenna apertures that are = mechanically and electrically challenging in many independent ways =20 =20 Thank you for the underground mapping example; and best wishes to the = speleo team. I suppose it would be too complicated, but I wonder if they = could correct their maps for angle-effects of air/rock conductivity = variations, if they monitored phase in addition to angle of arrival. =20 73, =20 Jim AA5BW =20 =20 =20 From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of DK7FC Sent: Thursday, February 1, 2018 3:27 PM To: rsgb_lf_group@blacksheep.org Subject: Re: LF: VLF Small magnetic antenna for Tx =20 Hi Luis,=20 You seem to generate much activity on all bands in your Spanish region = :-) That is fine! Am 01.02.2018 19:58, schrieb VIGILANT Luis Fern=C3=A1ndez:=20 =20 As this is the =E2=80=9Cnear field=E2=80=9D it is supposed to work only = at magnetic field due to the small size of the antenna ? So only = magnetic field for underground signals at this distances ? The E field also works in the near field of course but through the = ground you will have no chance with an underground E field TX antenna = :-) Just try it on LF at home :-) Can we expect to receive the signal with an electric probe antenna in = the near field or the only chance is to be further away ? In the moment i can receive my 970 Hz signal radiated from the E field = antenna and received by the H field antenna. But it is not optimal. The = signal strength will be higher when using the same type of antenna as = long as you are in a range of < 0.7 * far field distance. =20 Which would be the radiated power of such antenna ?=20 There are formulas on Rik's websites for 136 kHz, = http://www.strobbe.eu/on7yd/136ant/#Loops 73, Stefan =20 ------=_NextPart_000_0229_01D39C23.D3AC9E10 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

Roger,

 

Thank you for your Ferrite Rod TX Antennas link, nicely written, and = worth its e-weight in gold from my perspective.

 

I am in decade 6 of increasing hope for theory that would assist = intriguing experiments such as yours.

Fascinating to realize that scientific theory doesn=E2=80=99t explain = air core solenoid inductance, much less ferrite core, much less solenoid = self-resonant frequency, and alas, ETA for useful scientific theory for = ferrite loop transmitters is probably past my metaphysical transition = date. Whence my appreciation for documentation such as yours. After they = resolve dark matter and quantum vacuum plasma, maybe they will figure = out solenoids and even magnetics. In the meantime, inspiring = electromagnetics and propagation electrophysics emanate, thank goodness, = from ham shacks and web reflectors et al. From one of these I would like = to borrow a valuable model for this subject = area:

 

=E2=80=9CWhat happens = in the far field goodness only knows=E2=80=9D

 

I intend to ask author=E2=80=99s permission to cite the above model, = it is the best I=E2=80=99ve seen.

(Found on = http= s://sites.google.com/site/g3xbmqrp3/antennas/ferrite_tx)

 

 

73,

 

Jim AA5BW =C2=A0=C2=A0

 

 

 

From:= = owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Roger = Lapthorn
Sent: Friday, February 2, 2018 5:15 AM
To: = rsgb_lf_group@blacksheep.org
Subject: Re: LF: VLF Small = magnetic antenna for Tx

 

I = am definitely NOT a theory man! However, I have had success on HF with = ferrite rod antennas on TX and low power WSPR. Although inefficient, I = often wonder if such a structure might have some place on lower = bands as long as the ferrite rod does not saturate. Yes a decent BIG = antenna will be much better.

 

 

73s

Roger G3XBM

 

On 1 = February 2018 at 22:22, <hvanesce@comcast.net> = wrote:

Luis,

 

Thank you for the underground mapping example; = nice work by the speleo team.

 

=E2=80=9CAs = this is the near field it is supposed to work only at magnetic field due = to the small size of the antenna ? So only magnetic field for = underground signals at this distances ?=E2=80=9D

 

At 38kHz the impedance of the transmitting = loop=E2=80=99s field at 100 meters is ~ 25 ohms, which puts an optimized = E-field (electric probe) receiver at perhaps a 45dB disadvantage, but = your near-field intensity through 70 meters of average-conductivity rock = and 30 meters of air may be (based on your schematic and description) as = much as 0.1 pT, so the E-field (electric probe) receiver will work well = at 100 meters.    

 <= /o:p>

=E2=80=9CCan= we expect to receive the signal with an electric probe antenna in the = near field or the only chance is to be further away ?  And then = losing the signal due to the distance = =E2=80=A6.=E2=80=9D

 <= /o:p>

Based on your schematic and description: only = in the near field.

At 1 km (and 38 kHz) and farther, any = disadvantage of the E-field (electric probe) receiver is = small.

At 1 km the near-field strength for the = configuration that you described could be as much as ~ 1fT, so the near = field component of the signal at 1 km would be detectable (with = significant integration time and/or low noise), using an electric probe = receiving antenna or a loop receiving antenna.

But due primarily to the small aperture of the = loop transmitting antenna that you described, the radiated field = component at 1 km is far below the threshold of detectability (perhaps = 0.01 attotesla at 1km), so at distances greater than a kilometer, the = near field component fades below detectability, and the far-field = component of the signal fades even farther below the level of = detectability.

For most practical purposes, to be detected = well into the far field, a VLF loop transmitting antenna needs to be = physically very large and driven by more power than batteries can = practically provide.

Note: the electric-probe antenna efficiently = detects the radiated component of the signal, and the radiated component = of the signal decreases from the transmitting antenna through the far = field, so in outdoor above-ground (=E2=80=9Copen field=E2=80=9D) VLF = signal reception, moving an electric-probe receiving antenna from a = magnetic-loop transmitter=E2=80=99s near field to its far field never = improves reception by a receiver with electric-probe = antenna.

         

 <= /o:p>

=E2=80=9CWha= t would be the radiated power of such antenna = ?=E2=80=9D

 <= /o:p>

Based on your schematic and description, = probably less than 100 pW.

 

Portable ULF and VLF loop transmitters are = great for hundreds of meters through rock or air, but detection of = ULF/VLF loop-transmitter signals in the far field requires = transmitting-antenna apertures that are mechanically and electrically = challenging in many independent ways

 

 <= /o:p>

Thank you for the underground mapping example; = and best wishes to the speleo team. I suppose it would be too = complicated, but I wonder if they could correct their maps for = angle-effects of air/rock conductivity variations, if they monitored = phase in addition to angle of arrival.

 

73,

 

Jim AA5BW

 <= /o:p>

 

 

From:= = owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf = Of DK7FC
Sent: Thursday, February 1, 2018 3:27 = PM
To: rsgb_lf_group@blacksheep.org
Subject: = Re: LF: VLF Small magnetic antenna for = Tx

 <= /o:p>

Hi Luis, =

You seem to generate much activity on all bands in your Spanish = region :-) That is fine!

Am 01.02.2018 19:58, schrieb VIGILANT = Luis Fern=C3=A1ndez:

 <= /o:p>

As this is = the =E2=80=9Cnear field=E2=80=9D it is supposed to work only at magnetic = field due to the small size of the antenna ? So only magnetic field = for

underground = signals at this distances ?

The E field also = works in the near field of course but through the ground you will have = no chance with an underground E field TX antenna :-) Just try it on LF = at home :-)

Can we = expect to receive the signal with an electric probe antenna in the near = field or the only chance is to be further away ?

In the moment i = can receive my 970 Hz signal radiated from the E field antenna and = received by the H field antenna. But it is not optimal. The signal = strength will be higher when using the same type of antenna as long as = you are in a range of  < 0.7 * far field = distance.

 <= /o:p>

Which would = be the radiated power of such antenna ?

There are = formulas on Rik's websites for 136 kHz, http://www.strobbe.eu/on7yd/136ant/#Loops

73= , Stefan

 

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