Return-Path: Received: (qmail 19917 invoked from network); 2 Apr 2002 13:15:30 -0000 Content-Transfer-Encoding: 8bit Received: from unknown (HELO warrior.services.quay.plus.net) (212.159.14.227) by excalibur-qfe1-smtp-plusnet.harl.plus.net with SMTP; 2 Apr 2002 13:15:30 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 22191 invoked from network); 2 Apr 2002 13:15:39 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior.services.quay.plus.net with SMTP; 2 Apr 2002 13:15:39 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 16sPb8-0003jo-00 for rsgb_lf_group-outgoing@blacksheep.org; Tue, 02 Apr 2002 15:49:22 +0100 Received: from mail2.cc.kuleuven.ac.be ([134.58.10.50]) by post.thorcom.com with esmtp (Exim 3.33 #2) id 16sPb6-0003jj-00 for rsgb_lf_group@blacksheep.org; Tue, 02 Apr 2002 15:49:21 +0100 Received: from LCBD15.fys.kuleuven.ac.be (LCBD15.fys.kuleuven.ac.be [134.58.80.15]) by mail2.cc.kuleuven.ac.be (8.12.1/8.12.1) with SMTP id g32DAkJ5078808 for ; Tue, 2 Apr 2002 15:10:46 +0200 Message-ID: <3.0.1.16.20020402140550.30cf29da@pb623250.kuleuven.be> X-Sender: pb623250@pb623250.kuleuven.be X-Mailer: Windows Eudora Pro Version 3.0.1 (16) Date: Tue, 02 Apr 2002 14:05:50 To: rsgb_lf_group@blacksheep.org From: "Rik Strobbe" Subject: LF: loop inductance In-reply-to: <19519.020329@dx.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Hello group, thanks to all who replied to my request, either direct or via the reflector. The result is a nice collection of formulas, both for round as for square single turn loops (3 formulas for round loops and 3 for square loops). Apart from the very simple formula that was given by RA9MB all other formulas were based on the natural logaritm of the loop circumreference vs. wire diameter ratio, but all with other dimensions. And surprisingly (or not so surprisingly ?) ... after converting everything to a circumreference in meter and wire diameter in mm all 3 formulas were very similar (only few % difference). So either several people came to the same result independently from each other or all formulas were derived from the same 'mother of all formulas" for loop inductance. Anyway, for those interested : Round loop : L = 0.2*W*(ln(W/d)+5.85) Square loop : L = 0.2*W*(ln(W/d)+5.5) L = loop inductance in uH W = loop circumreference (perimeter) in m d = wire diamter in mm ln = natural logaritm Further I found : Octagonal loop : L = 0.2W*(ln(W/d)+5.73) Hexagonal loop : L = 0.2W*(ln(W/d)+5.66) Pentagonal loop : L = 0.2W*(ln(W/d)+5.59) Triangular loop : L = 0.2W*(ln(W/d)+5.1) (all the above for equilaterally shapes) Rectangular triangle loop : L = 0.2W*(ln(W/d)+4.96) Interesting constatation : A. Round loop with 10m diameter (circumref.= 31.4m, area = 78.5m^2) = 48uH B. differently shaped loops with same circumreference : square = 46uH rect. triangle = 43uH B. diffently shaped loops with same area : square = 53uH rect. triangle = 61uH So at first sight the loop inductance is more determined by the circumreference than by the area. So far I haven' found any formula for rectangular loops, unfortunately this is the most common shape for big transmitting loops. 73, Rik ON7YD