摘要 |
A glass-coated article having substantially rectangular cross-section is excited using a tickler magnetic field. Harmonics of the a.c. magnetic field that are thusly caused to emanate from said article are detected by either magnetic field sensing coils or by mixing with a propagating radio frequency field. A portal design ensures the detection of the glass-coated article having substantially rectangular cross-section, no matter its spatial orientation. Teachings of the instant invention are critical for the use of glass-coated articles having substantially rectangular cross-section in a number of applications that include but are not limited to anti-theft systems; monitoring of tamper-proof packages; tracking, tracing and identification of currency, secure documents, drivers licenses, and passports; tracking of personnel, labels and paper products, merchandising items, and composites; monitoring movement of textiles including clothing and garments and materials used to make said textiles containing the invention; authentication and brand theft protection, credit card verification and protection against fraud; biometrics and other medical applications. |