Return-Path: Received: (qmail 15149 invoked from network); 27 Oct 2001 20:20:36 -0000 Received: from unknown (HELO murphys-inbound.services.quay.plus.net) (212.159.14.225) by excalibur-qfe1-smtp-plusnet.harl.plus.net with SMTP; 27 Oct 2001 20:20:36 -0000 Received: (qmail 5632 invoked from network); 27 Oct 2001 20:19:13 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys.services.quay.plus.net with SMTP; 27 Oct 2001 20:19:13 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 15xZrz-0001mc-00 for rsgb_lf_group-outgoing@blacksheep.org; Sat, 27 Oct 2001 21:15:51 +0100 Received: from latimer.mail.uk.easynet.net ([195.40.1.40]) by post.thorcom.com with esmtp (Exim 3.33 #2) id 15xZry-0001mX-00 for rsgb_lf_group@blacksheep.org; Sat, 27 Oct 2001 21:15:51 +0100 Received: from ericadodd (tnt-3-58.easynet.co.uk [195.40.202.58]) by latimer.mail.uk.easynet.net (Postfix) with SMTP id B5E2053A9D for ; Sat, 27 Oct 2001 21:15:07 +0100 (BST) Message-ID: <001f01c15f25$ee835e60$3aca28c3@ericadodd> From: "g3ldo" To: rsgb_lf_group@blacksheep.org References: Subject: LF: Re: Tiny coils Date: Sat, 27 Oct 2001 21:27:42 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Hi Bob > I noticed in RF DESIGN a note on 'antenna coils' designed for RFID > applications at 125 kHz, and made of ferrite laminated on to a ceramic base, > with values to 8.1 mH. They are very small, 12 x 4 x 3 mm, and may not be of > use for our purpose, but the "125 kHz" sort of jumped out at me, and I > thought I would mention it. The company has a website at www.coilcraft.com. These will be fine for receive applications but are no use for transmitting loading coils. The reason is that, with antennas so electrically small, the potential gradient across the coil is very high. LF transmitting coils have to be physically large for that reason. Regards, Peter, G3LDO e-mail Web