Envelope-to: dave@picks.force9.co.uk Delivery-date: Thu, 20 Oct 2005 22:31:00 +0100 Received: by ptb-mxcore13.plus.net with spam-scanned (PlusNet MXCore v2.00) id 1ESi03-000805-Fe for dave@picks.force9.co.uk; Thu, 20 Oct 2005 22:31:00 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore13.plus.net with esmtp (PlusNet MXCore v2.00) id 1ESi03-0007ze-A9 for dave@picks.force9.co.uk; Thu, 20 Oct 2005 22:30:59 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1EShzL-0004iT-CS for rs_out_1@blacksheep.org; Thu, 20 Oct 2005 22:30:15 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1EShzK-0004iK-OU for rsgb_lf_group@blacksheep.org; Thu, 20 Oct 2005 22:30:14 +0100 Received: from imo-m23.mx.aol.com ([64.12.137.4] helo=imo-m23.mail.aol.com) by relay1.thorcom.net with esmtp (Exim 4.51) id 1ESigK-00022z-G2 for rsgb_lf_group@blacksheep.org; Thu, 20 Oct 2005 23:14:41 +0100 Received: from MarkusVester@aol.com by imo-m23.mx.aol.com (mail_out_v38_r5.5.) id l.196.498f41ee (3850) for ; Thu, 20 Oct 2005 17:30:04 -0400 (EDT) From: MarkusVester@aol.com Message-ID: <196.498f41ee.3089665b@aol.com> Date: Thu, 20 Oct 2005 17:30:03 EDT To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 X-Mailer: 8.0 for Windows sub 6104 Subject: LF: Transatlantic, NPG on Colour DF Content-Type: text/html; charset=windows-1252 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-PN-SpamFiltered: by PlusNet MXCore (v2.00) Content-transfer-encoding: 8bit ... this posting was sent last Monday but apparently hadn't made it through the reflector - hopefully still interesting.

Regards
Markus, DF6NM

Thema: TA and NPG on Colour DF
Datum: 17.10.2005 19:36:59 Westeuropäische Sommerzeit
Von: Markus Vester
An: rsgb_lf_group@blacksheep.org

Dear LF Group,

last night, I found a strong and isolated peak from XKO around 3:20, and more traces from XGJ, XES, XKO and NA around 5:30. The grabber snapshot is at
http://members.aol.com/df6nm2/TA_17Oct05.gif (273kB).

A screenshot of the NPG pair during its "good nights" on Oct. 15 and 16th is on
http://members.aol.com/df6nm2/NPG_15-16Oct05.gif (52kB).

Besides their sheer strength, one remarkable thing about these traces is the fairly uniform colour on the direction finder over the night. Quite unlike medium-range traces like SXV or the unid carrier near 137689.5 which sometimes show up to 360° colour changes around the fading minima. I believe these directional errors are probably produced by two mechanisms:

- in a fade caused by two ore more azimutally oblique paths, the angle of the resulting magnetic field vector can be offset from that of either path by a large degree;

- for steep incidence, the horizontal conductors of the loops receive field components with apparent directions depending on the polarization rather than actual azimuth, and which may have been altered by Faraday rotation in the ionosphere. I noted in the past that some European stations tend to display more variation than others, and have attributed this to either more pronounced skywave radiation by relatively large horizontal TX antenna current components, or to groundwave blocking by mountainous terrain. A low-angle DX signal would naturally suffer less from this effect.

73 from Nuernberg
Markus, DF6NM