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<html> <head> <title>RFID-Bulletin Board: Re: RFID tag on a metal surface, Tam Hulusi at 9/09/2000 16:29</title> <!-- Anfang Header --><!-- Ende Header --> </head> <BODY BGCOLOR="#fffcf4"><!-- Anfang BeitragsseitenKopf --><!-- Ende BeitragsseitenKopf --><!-- AnfangBanner --><!-- EndeBanner --><blockquote> <center> <h1>Re: RFID tag on a metal surface</h1> </center><!-- Anfang BeitragsNavigationsLeisteOben --><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><center><P><B>[ <a href="../index.htm">RFID-Bulletin Board</a> ]</B></P></center><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><!-- Ende BeitragsNavigationsLeisteOben --><p>Written by <a href="mailto:tamh@newmarktechnology.com">Tam Hulusi</a> at 09 Sep 2000 16:29:03:<p>As an answer to: <a href="15.htm">Re: RFID tag on a metal surface</a> written by Klaus Finkenzeller at 27. May 1999 at 20:37:48:<p>Dear Klaus : I cannot connect to the RFID handbook - can you help??<p>Many thanks, Tam Hulusi<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><br><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><form method=POST action="http://f16.parsimony.net/forum26490/wwwforum.cgi?formular"><input type=hidden name="followup" value="12,15,158"><input type=hidden name="origname" value="Tam Hulusi"><input type=hidden name="origemail" value="tamh@newmarktechnology.com"><input type=hidden name="origsubject" value="Re: RFID tag on a metal surface"><input type=hidden name="origdate" value="09 Sep 2000 16:29:03"><input type=hidden name="subject" value="Re: RFID tag on a metal surface"><input type=hidden name="body" value=">Dear Klaus : I cannot connect to the RFID handbook - can you help??>Many thanks, Tam Hulusi>>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"><input type="submit" name="abschicken" value="Write an answer"> <br><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><p><a name="followups"><B>Answers:</B></a><br><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--><!-- Anfang BeitragsNavigationsLeisteUnten --><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><center><P><B>[ <a href="../index.htm">RFID-Bulletin Board</a> ]</B></P></center><!-- AnfangLinie --><center><p><HR></p></center><!-- EndeLinie --><!-- Ende BeitragsNavigationsLeisteUnten --></blockquote><!-- Anfang BeitragsseitenFuss --><!-- Ende BeitragsseitenFuss --></body></html>⌨️ 快捷键说明
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