[sci.electronics] Anti-theft tag: how does this one work?

mb@sparrms.ists.ca (Mike Bell) (02/15/91)

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?