Return-Path: Received: from mtain-md05.r1000.mx.aol.com (mtain-md05.r1000.mx.aol.com [172.29.96.89]) by air-ma10.mail.aol.com (v129.4) with ESMTP id MAILINMA103-b5424d2584252e5; Thu, 06 Jan 2011 03:58:13 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-md05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 4FBC4380000F7; Thu, 6 Jan 2011 03:58:11 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Palej-0004R3-T7 for rs_out_1@blacksheep.org; Thu, 06 Jan 2011 08:57:13 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Palej-0004Qu-BD for rsgb_lf_group@blacksheep.org; Thu, 06 Jan 2011 08:57:13 +0000 Received: from mail-iy0-f171.google.com ([209.85.210.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Paleg-0001cP-RM for rsgb_lf_group@blacksheep.org; Thu, 06 Jan 2011 08:57:13 +0000 Received: by iyj21 with SMTP id 21so15120644iyj.16 for ; Thu, 06 Jan 2011 00:57:04 -0800 (PST) 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=swDmTP1pr9RlIlkR6RoNv/5qBo/hIxZPBaOAj+VpRiI=; b=nb8fQSm7TTgl72wQaukx6R2VvNhj71Aijd5OzVRlCyzru0aMDjYqF+KwpAhF8AZVrA jZOGtn4qDVL+kaVYZqDWN2VlocJTPkzPhsjqFcbbuy0Iob3Sfzas9nWjmwGYmB3WC2YN A2pqBp2MTp2THkRuayuS3vQOYq/RXUqLYsgSU= 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=vRl8izGId8ScqhSYdTD9O9SGzcEHBuSRmZqaq1mn3+fVWnxy62S3okgagoDoyQWkdw Novau65tmV3cDIc2KMdc4gUbHREhQ/yMok5VxSFjYPxmkAJwfFPhFZJ5XbrcWdSWoL3S WKyI534nvs/xGy1n1fhlT0c3yaez6t0qNQnKQ= MIME-Version: 1.0 Received: by 10.231.13.137 with SMTP id c9mr24008970iba.37.1294304223916; Thu, 06 Jan 2011 00:57:03 -0800 (PST) Received: by 10.231.200.211 with HTTP; Thu, 6 Jan 2011 00:57:03 -0800 (PST) In-Reply-To: <001c01cbad30$5ad3da60$4001a8c0@lark> References: <001c01cbad30$5ad3da60$4001a8c0@lark> Date: Thu, 6 Jan 2011 08:57:03 +0000 Message-ID: From: Andy Talbot 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: G8IMR - stronger? ...and G3XBM on 136kHz WSPR this evening Content-Type: multipart/alternative; boundary=0022150467ef7f7234049929afca 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 x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m012.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d60594d258423612a X-AOL-IP: 195.171.43.25 X-Mailer: Unknown (No Version) --0022150467ef7f7234049929afca Content-Type: text/plain; charset=ISO-8859-1 We put it down to an increase in lossy paralle resistance. In dry conditions, the reactive (out of phase) near field current terminates on ground radials without passing through too much (relatively speaking) lossy ground material. When everything is covered in water, the reactive field is conducted away into lossy ground material before entering the radials. Being resistive, the current moves into phase with the E-field and ,starts to introduce added I^2R loss. Most significantly here, walls and roof tiles the top-hat passes close to become more conductive, extracting noticably in-phase currents from the E field. The result is a *decreased* resistance in *parallel *with the antenna capacitance, and when you plug decreased parallel R into the equation for parallel-to-serial transform, voila, an *increased series* term. The tuning shifts marginally, but it was far worse when the effect was first discovered on 73kHz. Was that really well over a decade ago - time flies! Andy www.g4jnt.com On 5 January 2011 23:28, Alan Melia wrote: > Yes that is what my aerial measurements said as well in rain....increased > loss resistance.....not sure though whether it is a ground effect or the > film of water on the wire. > > Alan G3NYK > > ----- Original Message ----- > From: "Andy Talbot" > To: > Sent: Wednesday, January 05, 2011 3:33 PM > Subject: Re: LF: G8IMR - stronger? ...and G3XBM on 136kHz WSPR this evening > > > > No - no changes at all. > > > > The only difference is that it is raining now.which - by the way these > > things work - has *increased* the antenna resistance and reduced power > > output by a dB or two. > > > > Andy > > 'JNT / 'IMR > > > > > > > > On 5 January 2011 14:53, Roger Lapthorn wrote: > > > > > Hi Andy, > > > > > > Your 136kHz WSPR beacon is coming in very well today at around -6/-7dB > S/N > > > at 188km. Have you made some further ERP improvements? PA0A is also a > very > > > good signal too. > > > > > > I hope to be TXing on 136kHz WSPR this evening ....but with a rather > weaker > > > signal than these two. Any reports (at all) would be very much > appreciated. > > > > > > 73s > > > Roger G3XBM > > > -- > > > g3xbm-qrp.blogspot.com/ > > > www.g3xbm.co.uk > > > www.youtube.com/user/g3xbm > > > G3XBM GQRP 1678 ISWL G11088 > > > > > > > > --0022150467ef7f7234049929afca Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
We put it down to an increase in lossy paralle resistance.
In dry conditions, the reactive (out of phase) near field current ter= minates on ground radials without passing through too much (relatively spe= aking) lossy ground material.
=A0
When everything is covered in water, the reactive field is conducted= away into lossy ground material before entering the radials.=A0 Being res= istive, the current moves into phase with the E-field and ,starts to intro= duce added I^2R loss.=A0 Most=A0significantly here, walls and roof tiles= the top-hat passes close to become more conductive, extracting noticably= in-phase currents from the E field.
=A0
The result is a decreased resistance in para= llel with the antenna capacitance, and when you plug decreased pa= rallel R into the equation for parallel-to-serial transform, voila, an increased series term.
=A0
The tuning shifts marginally, but it was far worse when the effect wa= s first discovered on 73kHz.
Was that really well over a decade ago - time flies!
=A0
Andy
=A0
=A0
=A0
On 5 January 2011 23:28, Alan Melia <alan.melia@btint= ernet.com> wrote:
Yes that is what my aerial mea= surements said as well in rain....increased
loss resistance.....not sur= e though whether it is a ground effect or the
film of water on the wire.

Alan G3NYK

----- Original Message= -----
From: "Andy Talbot" <andy.g4jnt@gmail.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, January 05, 2011 3:33 PM
Subject: Re: LF: G8IMR - stro= nger? ...and G3XBM on 136kHz WSPR this evening


> No - no cha= nges at all.
>
> The only difference is that it is raining now= .which - by the way these
> things work - has *increased* the antenna resistance and reduced powe= r
> output by a dB or two.
>
> Andy
> 'JNT /= 'IMR
>
>
>
> On 5 January 2011 14:53, Roger= Lapthorn <rogerlapthorn@gma= il.com> wrote:
>
> > Hi Andy,
> >
> > Your 136kHz WSPR beac= on is coming in very well today at around -6/-7dB
S/N
> > at= 188km. Have you made some further ERP improvements? =A0PA0A is also a
= very
> > good signal too.
> >
> > I hope to be TXing on= 136kHz WSPR this evening ....but with a rather
weaker
> > sig= nal than these two. Any reports (at all) would be very much
appreciated= .
> >
> > 73s
> > Roger G3XBM
> > --
>= ; > g3xbm-= qrp.blogspot.com/
> > www.g3xbm.co.uk
> > = www.youtube.com/user/g3xbm
> > <http://vlf_grabber/>G3XBM =A0 GQRP 1678 =A0= =A0ISWL G11088
> >
>



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