Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-de02.r1000.mx.aol.com (Internet Inbound) with ESMTP id E8D3F3800008B; Tue, 30 Aug 2011 06:34:55 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QyLdx-0004EX-E1 for rs_out_1@blacksheep.org; Tue, 30 Aug 2011 11:34:09 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QyLdx-0004EO-0j for rsgb_lf_group@blacksheep.org; Tue, 30 Aug 2011 11:34:09 +0100 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QyLdv-00010L-Jj for rsgb_lf_group@blacksheep.org; Tue, 30 Aug 2011 11:34:08 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p7UAY6RD032141 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 30 Aug 2011 12:34:06 +0200 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id p7UAY6WS016875 for ; Tue, 30 Aug 2011 12:34:06 +0200 Message-ID: <4E5CBC9A.5020900@iup.uni-heidelberg.de> Date: Tue, 30 Aug 2011 12:34:02 +0200 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <16BC8B3CA8672445BC2A29B4C14A26D4379ED2AAB4@exlnmb01.eur.nsroot.net> <4DF9EFD1.5010208@iup.uni-heidelberg.de> <1313780109.51443.YahooMailNeo@web111907.mail.gq1.yahoo.com> <9CD1E11E8BC9402CB4AECECAC4088443@JimPC> <1314394178.5030.YahooMailNeo@web111905.mail.gq1.yahoo.com> <1314641183.5605.YahooMailNeo@web111910.mail.gq1.yahoo.com> In-Reply-To: <1314641183.5605.YahooMailNeo@web111910.mail.gq1.yahoo.com> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Re: Ferrite wideband antennas? Content-Type: multipart/alternative; boundary="------------030203090504000302040807" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,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-SCORE: 0:2:379258272:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40ca4e5cbcce259a X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------030203090504000302040807 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi Daniele, > Could it be possible to tune a ferrite loop over a frequency range as > wide as 100-500KHz? Or at least over the EU NDB band (say 300-500KHz)? > Any practical suggestion (and/or references on the web) about how to > build it? I think it is no problem. A narrow band but adjustable antenna is a good choice. Just use a large variable cap, e.g. 2x500 pF. It may be helpful to use switched caps and a smaller variable cap like i did. If you have a high Q antenna, you can then easily fine tune the system. So maybe 5...100 pF +100 pF+180 pf+270 pF+560 pF or so, depending on your L. > About the ferrites, there are several sellers on eBay who offer a > russian MU400HH type. Would it be suitable for LF? Yes, very suitable. I have exactly these types in my LF ferrite antenna and got a Q of 480. Q will change over the frequency. So maybe it is even helpful to realise a switched L, for the higher frequencies. 73, Stefan --------------030203090504000302040807 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi Daniele,

Could it be possible to tune a ferrite loop over a frequency range as wide as 100-500KHz? Or at least over the EU NDB band (say 300-500KHz)?
Any practical suggestion (and/or references on the web) about how to build it?
I think it is no problem. A narrow band but adjustable antenna is a good choice. Just use a large variable cap, e.g. 2x500 pF. It may be helpful to use switched caps and a smaller variable cap like i did. If you have a high Q antenna, you can then easily fine tune the system.
So maybe 5...100 pF +100 pF+180 pf+270 pF+560 pF or so, depending on your L.
About the ferrites, there are several sellers on eBay who offer a russian MU400HH type. Would it be suitable for LF?
Yes, very suitable. I have exactly these types in my LF ferrite antenna and got a Q of 480. Q will change over the frequency. So maybe it is even helpful to realise a switched L, for the higher frequencies.

73, Stefan
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