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[195.171.43.25]) by mx.google.com with ESMTP id x6si9970920eew.167.2013.07.06.07.08.05 for ; Sat, 06 Jul 2013 07:08:05 -0700 (PDT) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org; dkim=pass header.i=@gmail.com Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UvSob-0004AB-UM for rs_out_1@blacksheep.org; Sat, 06 Jul 2013 14:46:17 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UvSob-0004A2-BC for rsgb_lf_group@blacksheep.org; Sat, 06 Jul 2013 14:46:17 +0100 Received: from mail-ob0-f178.google.com ([209.85.214.178]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1UvSoY-000737-OJ for rsgb_lf_group@blacksheep.org; Sat, 06 Jul 2013 14:46:16 +0100 Received: by mail-ob0-f178.google.com with SMTP id fb19so3901084obc.23 for ; Sat, 06 Jul 2013 06:46:12 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=YvygZLq1OhbtoQ/aNp8jmzUJ56jfCwu24F8FiW/ofoo=; b=WPq5uBNfKAfUoDm2EnenkzYQk5UISl4RQ1oQyOawidS5KHVso6xUUARdfhUZudcjiw XxFN99pTYK9K4SftFuoGuMIE5s4YAmRb+rDuPMBde3y+xoM3GnQyCRMz9Eae10r8g6AF tHnW4yxR3CJQnRQ+YFIw0RI+xaSzR+23XyV+LAUTP13yix++RXmI6+U8FgkOlRPfkPgK Qefa6XuULnl8Li4roQNmrW2RSlCzFWuGHbZ4MRRvewReCpCTSZgg25K9fACgliDfpe8m fDHEPz/LyJc7282bo24dgEjlet5HNkBpZHOF9b7BnH8Bbd/TSflUVOgVduwD4D0BaRmd G1wQ== MIME-Version: 1.0 X-Received: by 10.182.71.38 with SMTP id r6mr14911196obu.64.1373118372269; Sat, 06 Jul 2013 06:46:12 -0700 (PDT) Received: by 10.60.161.237 with HTTP; Sat, 6 Jul 2013 06:46:12 -0700 (PDT) In-Reply-To: <20130706131640.GG5246@cs.utwente.nl> References: <51D498BD.3050007@iup.uni-heidelberg.de> <005b01ce798a$b0476600$6d01a8c0@DELL4> <20130706131640.GG5246@cs.utwente.nl> Date: Sat, 6 Jul 2013 09:46:12 -0400 Message-ID: From: Warren Ziegler To: rsgb_lf_group 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: Pieter-Tjerk, The electrostatic field analogy was pointed out in the AMRAD active whip article: http://www.arrl.org/files/file/Technology/tis/info/pdf/0109031.pdf (see p. 36 "Siting and Installation" [...] 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 [209.85.214.178 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (wd2xgj[at]gmail.com) -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 X-Scan-Signature: 87525734ac0bb319fb3f44295fe6963b Subject: Re: LF: VK1OD's analysis of the MiniWhip antenna Content-Type: multipart/alternative; boundary=e89a8fb1f56cd0517504e0d8086c X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=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 Status: O X-Status: X-Keywords: X-UID: 3119 --e89a8fb1f56cd0517504e0d8086c Content-Type: text/plain; charset=ISO-8859-1 Pieter-Tjerk, The electrostatic field analogy was pointed out in the AMRAD active whip article: http://www.arrl.org/files/file/Technology/tis/info/pdf/0109031.pdf (see p. 36 "Siting and Installation" The author suggested a finite -element package to calculate the field potentials (Quickfield http://quickfield.com/ ) It would take a great deal of work to adequately model my property, and I have so far not made the effort. 73 Warren K2ORS On Sat, Jul 6, 2013 at 9:16 AM, Pieter-Tjerk de Boer wrote: > Hello all, > > I tend to think about the mini-whip on LF and MF in terms of an (almost) > static electric field. > Then it essentially measures the electric field's _potential difference_ > between a point somewhere up in the air, namely where the mini-whip's > metal plate is located, and ground. The ground reference is brought up > to the mini-whip's electronics either via the metal pole on which it is > mounted, or (the outside of) the coaxial cable. > > This explains Roelof's observation (see below) that it doesn't matter > whether he mounts the mini-whip on a vertical pole, or on a horizontal > pole out of a window (but in the same position). > In both cases, it measures the same potential difference, although in > the latter case the ground connection is longer, namely taking the detour > via the horizontal pole and whatever is inside the house. Presumably, > Roelof's house is small compared to the 399.5 kHz wavelength, so this > detour shouldn't matter. > > This view also at least approximately matches VK1OD's NEC4 calculation, > in the sense that he finds an output voltage which is of the order of > the field strength times the antenna height. > > A weak point in this reasoning is the fact that since the entire pole > (or outside of the coaxial cable) is at ground potential, it distorts > the electric field around it. So the mini-whip's plate is not at the > same potential as it would be without the ground connection reaching out > to it. I still intend to try to calculate how much this distortion is. > > Of course, this whole reasoning breaks down at higher frequencies, where > the height of the pole is not small compared to the wavelength; then one > cannot simply assume anymore that the entire pole is at ground potential. > > 73, Pieter-Tjerk, PA3FWM > > > On Fri, Jul 05, 2013 at 07:47:33PM +0200, Roelof Bakker wrote: > > Hello Jay, > > > > > > I don't think so. > > > > I have carried out a test with a vertical feed line and a horizontal > > feed line on a pole pushed out an upstairs windows. In both cases > > the antenna was in the same position and showed equal signal levels > > from the groundwave of ONO-399.5 at 59 km. > > > > 73, > > Roelof, pa0rdt > > > > -- 73 Warren K2ORS WD2XGJ WD2XSH/23 WE2XEB/2 WE2XGR/1 --e89a8fb1f56cd0517504e0d8086c Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Pieter-Tjerk,

=A0 The electrostatic field analogy was pointed out in the AMRAD active w= hip article:
(see p. 36 "Siting and Installation"

=A0 The author suggested a finite -element= package to calculate the field potentials (Quickfield =A0http://quickfield.com/=A0)
It would take a great deal of work to adequately model my proper= ty, and I have so far not made the effort.

73 Warren K2ORS



On Sat, Jul 6, 2013 at 9:16 AM, Pieter-Tjerk de = Boer <ptdeboer@cs.utwente.nl> wrote:
Hello all,

I tend to think about the mini-whip on LF and MF in terms of an (almost) static electric field.
Then it essentially measures the electric field's _potential difference= _
between a point somewhere up in the air, namely where the mini-whip's metal plate is located, and ground. The ground reference is brought up
to the mini-whip's electronics either via the metal pole on which it is=
mounted, or (the outside of) the coaxial cable.

This explains Roelof's observation (see below) that it doesn't matt= er
whether he mounts the mini-whip on a vertical pole, or on a horizontal
pole out of a window (but in the same position).
In both cases, it measures the same potential difference, although in
the latter case the ground connection is longer, namely taking the detour via the horizontal pole and whatever is inside the house. Presumably,
Roelof's house is small compared to the 399.5 kHz wavelength, so this detour shouldn't matter.

This view also at least approximately matches VK1OD's NEC4 calculation,=
in the sense that he finds an output voltage which is of the order of
the field strength times the antenna height.

A weak point in this reasoning is the fact that since the entire pole
(or outside of the coaxial cable) is at ground potential, it distorts
the electric field around it. So the mini-whip's plate is not at the same potential as it would be without the ground connection reaching out to it. I still intend to try to calculate how much this distortion is.

Of course, this whole reasoning breaks down at higher frequencies, where the height of the pole is not small compared to the wavelength; then one cannot simply assume anymore that the entire pole is at ground potential.
73, Pieter-Tjerk, PA3FWM


On Fri, Jul 05, 2013 at 07:47:33PM +0200, Roelof Bakker wrote:
> Hello Jay,
>
>
> I don't think so.
>
> I have carried out a test with a vertical feed line and a horizontal > feed line on a pole pushed out an upstairs windows. In both cases
> the antenna was in the same position and showed equal signal levels > from the groundwave of ONO-399.5 at 59 km.
>
> 73,
> Roelof, pa0rdt
>




--
= 73 Warren K2ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1

=A0
--e89a8fb1f56cd0517504e0d8086c--