Return-Path: Received: (qmail 25112 invoked from network); 16 Jul 2001 09:05:44 -0000 Received: from unknown (HELO warrior-inbound.servers.plus.net) (212.159.14.227) by excalibur-qfe1-smtp-plusnet.harl.plus.net with SMTP; 16 Jul 2001 09:05:44 -0000 Received: (qmail 6261 invoked from network); 16 Jul 2001 09:04:46 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 16 Jul 2001 09:04:46 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 15M48t-0002zK-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 16 Jul 2001 09:54:15 +0100 Received: from relay.dera.gov.uk ([192.5.29.49]) by post.thorcom.com with smtp (Exim 3.16 #2) id 15M48o-0002zF-00 for rsgb_lf_group@blacksheep.org; Mon, 16 Jul 2001 09:54:11 +0100 Received: (qmail 2938 invoked from network); 16 Jul 2001 09:51:48 +0100 Received: from trtnmail.dera.gov.uk (146.80.9.56) by relay.dera.gov.uk with SMTP; 16 Jul 2001 09:51:48 +0100 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 6007 invoked from network); 16 Jul 2001 09:55:26 +0100 Received: (ofmipd 192.5.29.90); 16 Jul 2001 08:55:04 -0000 Received: by bob.dera.gov.uk; (8.8.8/1.3/10May95) id JAA10769; Mon, 16 Jul 2001 09:59:01 +0100 (BST) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: (qmail 19623 invoked from network); 16 Jul 2001 09:45:29 -0000 Received: from gauntlet.mail.dera.gov.uk (172.16.9.10) by baton.dera.gov.uk with SMTP; 16 Jul 2001 09:45:29 -0000 Received: by gauntlet.mail.dera.gov.uk; id JAA17021; Mon, 16 Jul 2001 09:34:24 GMT Received: from unknown(10.71.64.31) by gauntlet.mail.dera.gov.uk via smap (3.2) id xma016973; Mon, 16 Jul 01 09:33:50 GMT Received: from mailex.dera.gov.uk (unverified) by mailguard.dera.gov.uk (Content Technologies SMTPRS 4.1.5) with SMTP id for ; Mon, 16 Jul 2001 09:52:09 +0100 Received: (qmail 31539 invoked from network); 16 Jul 2001 08:42:03 +0100 Received: from softdnserror (HELO cchecker.dstl.gov.uk) (192.168.248.52) by mailex.dstl.gov.uk with SMTP; 16 Jul 2001 07:42:03 -0000 Received: from FRN-MAIL-R3 (unverified) by cchecker.dstl.gov.uk (Content Technologies SMTPRS 4.1.2) with ESMTP id for ; Mon, 16 Jul 2001 08:42:03 +0100 Received: by FRN-MAIL-R3 with Internet Mail Service (5.5.2650.21) id <356X2K9P>; Mon, 16 Jul 2001 09:51:42 +0100 Date: 16 Jul 2001 09:43:42 +0100 Message-ID: <7D653C9C42F5D411A27C00508BF8803D55C555@pdw-mail-r1.dstl.gov.uk> From: "Andrew Talbot" To: rsgb_lf_group@blacksheep.org Subject: LF: Re: Near field of 9kHz antenna IV MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/html; charset=windows-1252 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Content-transfer-encoding: 8bit

For our garden sized antennas I think that resonating a wire is completely impractical at these frequencies. What I intend looking at, (if a 9kHz NoV ever happens :-( is something like a ground loop. I'm basing the idea on the US Submarine comms experience at ELF / ULF. (Have a look on the web at Project Sanguine I think its called) If a really long wire is laid out at low elevation - just lying on the ground even - then fed against a real earth connection then a ground loop will be set up. There will probably not even be a need to ground the far end. With a skin depth, particularly in low conductivity ground, measured in 10s or 100s of metres then quite a large loop will result.

I know ground loops were tried on 73kHz, with only moderate sucess, but the much lower frequency ought to improve the efficacy of the system. Even in my urban plot, it will be possible to lay out several hundred metres of wire by just trailing it over the garden wall and along a grass verge by the road. I'll be limited in wire length only by roundabouts where the verge stops.

Andy G4JNT

The corrected figures are even more dramatic than for the loop.

To feed 1kW into the 180m high 15mm copper pipe the current must be 154A and the voltage on the antenne becomes 2.5MV! Perhaps the pipe would survive the current but the voltage makes the system completely unrealistic (corona).

And what would the required 286mH loading coil for that voltage and current look like ...





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