Path: utzoo!utgpu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!ists!sparrms!sparatd!mb
From: mb@sparrms.ists.ca (Mike Bell)
Newsgroups: sci.electronics
Subject: Anti-theft tag: how does this one work?
Keywords: crime theft shoplifting
Message-ID: <1991Feb14.211239.890@sparrms.ists.ca>
Date: 14 Feb 91 21:12:39 GMT
Organization: Spar Aerospace Ltd, Toronto, Canada
Lines: 19

I have this hobby of dismembering store anti-theft tags. 
This one is unusual and I'm stuck on how it works.

It consists of a plastic self-adhesive package, about
40mm x 13mm x 2mm. Inside are two mettalic strips. One is a
rectangle 38mm x 12.2 mm. The other is a parallelogram:

        __________________ 
       /                 /     ^
      /                 /      |12.2mm
     /_________________/       |

    <    29mm         >

The angle is 45 degrees. All dimensions are +/- 0.25mm

The two strips are separated by a plastic membrane. 

Anybody able to explain the principle of operation?