Universal tracking assembly

1. An electronic article surveillance tag, said tag comprising:

a circuit having a capacitance;

a magnet which increases said capacitance; and

wherein said tag may be read by both an RF tag reader and an acousto-magnetic (AM) tag reader.

2. The electronic article surveillance tag of claim 1 , wherein said circuit further comprises:

an induction coil;

a capacitor formed over a portion of said induction coil; and

wherein said magnet overlaps a portion of said capacitor thereby affecting a total capacitance of the circuit.

3. The electronic article surveillance tag of claim 2 , wherein said induction coil and said capacitor are diecut from a single piece of foil and said capacitor is a plate capacitor.

4. The electronic article surveillance tag of claim 2 wherein a portion of said capacitor is secured to said induction coil with a dielectric glue.

5. The electronic article surveillance tag of claim 2 wherein said magnet and induction coil are separated by a layer of dielectric material.

6. The electronic article surveillance tag of claim 1 , wherein said tag further comprises:

a plurality of resonator strips, said strips being in operative communication with said magnet.

7. The electronic article surveillance tag of claim 6 , wherein said plurality of resonator strips include a first pair of strips having a first length and a second pair of strips having a second length, said second length being different from said first length.

8. The electronic article surveillance tag of claim 1 , wherein said magnet is a permanent bias magnet.

9. The electronic article surveillance tag of claim 1 wherein said tag has an adhesive backing to facilitate secure attachment of said tag to an item.

10. A hybrid tracking tag, said tag comprising:

a substrate;

an induction coil located on said substrate;

a plate capacitor overlapping a portion of said induction coil, said plate capacitor having a capacitance;

a bias magnet, said bias magnet overlapping a portion of said capacitor;

a plurality of resonator strips in communication with said bias magnet; and

wherein said bias magnet increases said capacitance of said plate capacitor such that said hybrid tracking tag may by used as both an RF tag and an acousto-magnetic (AM) tag.

11. The hybrid tracking tag of claim 10 , wherein said bias magnet is a permanent magnet that is about 38 mm in length.

12. The hybrid tracking tag of claim 10 , wherein said induction coil and said plate capacitor are formed from a single piece of diecut foil.

13. The hybrid tracking tag of claim 10 , wherein said substrate includes an adhesive backing.

14. The hybrid tracking tag of claim 10 , wherein said plurality of resonator strips include a first pair of strips having a first length and a second pair of strips having a second length, said second length being different from said first length.

15. The hybrid tracking tag of claim 10 , wherein said resonator strips are housed within a plastic enclosure.

16. A method of forming a hybrid electronic article surveillance tag, said method comprising the steps of:

defining acousto-magnetic (AM) circuitry on a substrate, said acousto-magnetic (AM) circuitry including a bias magnet;

defining RF circuitry on said substrate, said RF circuitry including an inductor; and

fixing a first portion of said bias magnet to lie in superposition over a second portion of said inductor, thereby affecting a capacitance of said RF circuitry.

17. The method of forming a hybrid electronic article surveillance tag in accordance with claim 16 , further comprising the steps of:

tuning an operational response of said hybrid tag by selectively varying an extent of said superposition between said first portion and said second portion.

18. The method of forming a hybrid electronic article surveillance tag in accordance with claim 16 , further comprising the steps of:

tuning an operational response of said hybrid tag by selectively varying a length of said bias magnet.

19. The method of forming a hybrid electronic article surveillance tag in accordance with claim 16 , further comprising the steps of:

selectively deactivating said AM circuitry by demagnetizing said bias magnet; and

selectively deactivating said RF circuitry by directing a high energy RF signal at said RF circuitry.