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<html> <head> <title>RFID-Bulletin Board: Re: RFID tag on a metal surface, Klaus Finkenzeller am 27.5.99</title> <!-- Anfang Header --><!-- Ende Header --></head><BODY BGCOLOR="#fffcf4"><!-- Anfang BeitragsseitenKopf --><!-- Ende BeitragsseitenKopf --> <center> <h1>Re: RFID tag on a metal surface</h1> </center><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><center>[ <a href="#followups">Answers</a> ] [ <a href="#postfp">Reply</a> ] [ <a href="../index.htm">RFID-Bulletin Board</a> ]</center><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><p><blockquote>Written by <a href="mailto:bm242372@fbmev.de">Klaus Finkenzeller</a> on 27. May 1999 at 20:37:48:<p>In Reply to: <a href="12.htm">RFID tag on a metal surface</a> written by Brian HooSang on 19. May 1999 at 21:43:48:<p>Dear Brian,<p>>Placing a tag on a metal surface will destroy the coupling effects if the tag is too close to the metal. What type of material would "block" the existence of the ground from the tag antenna's point of view? <br>>Any suggestions would be appreciated.<p>It is not possible to fit a magnetic antenna directly onto a metallic surface. The magnetic flux through the metal surface induces eddy currents within the metal, which oppose the field responsible for their creation, i.e. the reader's field (Lenz's law), thus damping the magnetic field in the surface of the metal to such a degree that communication between reader and transponder is no longer possible. It makes no difference here whether the magnetic field is generated by the coil mounted upon the metal surface (reader antenna) or the field approaches the metal surface from "outside" (transponder on metal surface).<br>By inserting highly permeable ferrite between the coil and metal surface it is possible to largely prevent the occurence of eddy currents. This makes it possible to mount the antenna on metal surfaces. When fitting antennae onto ferrite surfaces it is necessary to take into account the fact that the inductance of the conductor loop or coils may be significantly increased by the permeability of the ferrite material, and it may therefore be necessary to readjust the resonant frequency or even redimension the matching network (in readers) altogether.<p>(text taken out of the RFID-Handbook; see attatched link)<p>With best reards,<br>Klaus Finkenzeller<p><br><br><ul><li><a href="http://homepages.muenchen.org/bm693257/rfid-handbook.html">The RFID-Handbook</a></ul><br><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><p><a name="followups"><B>Answers:</B></a><br><ul><!--insert: 15--><!--top: 158--><li><a href="158.htm">Re: RFID tag on a metal surface</a> <b>Tam Hulusi</b> <i>9/09/2000 16:29</i>(<!--responses: 158-->1)<ul><!--insert: 158--><!--top: 160--><li><a href="160.htm">Re: RFID tag on a metal surface / New URL</a> <b>Klaus Finkenzeller</b> <i>9/12/2000 09:41</i>(<!--responses: 160-->0)<ul><!--insert: 160--></ul><!--end: 160--></ul><!--end: 158--><!--top: 17--><li><a href="17.htm">RFID-Preise</a> <b>Heiko Seif</b> <i>10.6.99</i>(<!--responses: 17-->0)<ul><!--insert: 17--></ul><!--end: 17--></ul><!--end: 15--><br><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><a name="postfp"><center><P><A HREF="http://www.eva-marbach.net"><IMG SRC="http://banner.parsimony.net/banner/button/marbach.gif" WIDTH=88 HEIGHT=31 BORDER=0 ALT="Eva Marbach" ></A></P></center><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><p><H3>Writing an Answer:</H3></a><p><form method=POST action="http://f16.parsimony.net/forum26490/wwwforum.cgi"><input type=hidden name="followup" value="12,15"><input type=hidden name="origname" value="Klaus Finkenzeller"><input type=hidden name="origemail" value="bm242372@fbmev.de"><input type=hidden name="origsubject" value="Re: RFID tag on a metal surface"><input type=hidden name="origdate" value="27. May 1999 at 20:37:48">Name:<br> <input type=text name="name" size=50 maxlength=50><br>E-Mail:<br> <input type=text name="email" size=50 maxlength=80><p>Subject:<br> <input type=text name="subject"value="Re: RFID tag on a metal surface" size=50 maxlength=80><p>Comment:<br><textarea name="body" COLS=100 ROWS=10>>Dear Brian,>>Placing a tag on a metal surface will destroy the coupling effects if the tag is too close to the metal. What type of material would "block" the existence of the ground from the tag antenna's point of view? >>Any suggestions would be appreciated.>It is not possible to fit a magnetic antenna directly onto a metallic surface. The magnetic flux through the metal surface induces eddy currents within the metal, which oppose the field responsible for their creation, i.e. the reader's field (Lenz's law), thus damping the magnetic field in the surface of the metal to such a degree that communication between reader and transponder is no longer possible. It makes no difference here whether the magnetic field is generated by the coil mounted upon the metal surface (reader antenna) or the field approaches the metal surface from "outside" (transponder on metal surface).>By inserting highly permeable ferrite between the coil and metal surface it is possible to largely prevent the occurence of eddy currents. This makes it possible to mount the antenna on metal surfaces. When fitting antennae onto ferrite surfaces it is necessary to take into account the fact that the inductance of the conductor loop or coils may be significantly increased by the permeability of the ferrite material, and it may therefore be necessary to readjust the resonant frequency or even redimension the matching network (in readers) altogether.>(text taken out of the RFID-Handbook; see attatched link)>With best reards,>Klaus Finkenzeller</textarea><p>Your Homepage-URL:<br> <input type=text name="url" size=50 maxlength=80><br>Title of Homepage:<br> <input type=text name="url_title" size=50 maxlength=80><br>URL of an image:<br> <input type=text name="img" size=50 maxlength=80><p><input type="submit" name="abschicken" value="Submit"> <input type="submit" name="vorschau" value="Preview"> <input type="reset" value="Cancel"> <b>Click only once!</b><p><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><center>[ <a href="#followups">Answers</a> ] [ <a href="#postfp">Reply</a> ] [ <a href="../index.htm">RFID-Bulletin Board</a> ]</center></blockquote><!-- Anfang BeitragsseitenFuss --><!-- Ende BeitragsseitenFuss --></body></html>⌨️ 快捷键说明
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