I picked up some asprin at the store today, and lo and behold, it had a
security sticker on it.  I thought of that old thread on these types of
devices, and took a closer look.  The device is a spiral foil antenna,
stuck face down on the box.  The outside dimension of the square is
37mm, the inside dim is 13mm, and the turns are 11.  Now, are there any
ambitious individuals out there that can model the RF loop in software,
and figure out what the frequency response of the loop is?  Just a
thought.

Chris Eddy, PE
Pioneer Microsystems, Inc.