Antenna for a combination EAS/RFID tag with a detacher

1. A security device for detaching a combination electronic article surveillance (EAS) and radio frequency identification (RFID) tag (EAS/RFID tag), said security device comprising:

a detacher configured to selectively disengage a clutch release disposed in a first portion of the combination EAS/RFID tag; and

a near field substantially circular microstrip antenna configured to electronically read information stored in a second portion of the combination EAS/RFID tag, said near field antenna configured to substantially encircle said detacher and configured to read information from said second portion of the combination EAS/RFID tag at a position relative to said detacher when said second portion of said tag is disposed at any angle relative to said detacher.

2. A security device according to claim 1 , wherein the near field antenna is configured to read information only when said detacher is positioned to disengage the clutch release in the first portion of the combination EAS/RFID tag.

3. A security device according to claim 1 , wherein the detacher magnetically disengages the clutch release.

4. A security device according to claim 3 , wherein the near field antenna is configured to only read information when said detacher is positioned to disengage the clutch release in the first portion of the combination EAS/RFID tag.

5. A security device according to claim 1 , wherein the security device further comprises:

a substrate, the substrate having a first surface and a second surface;

a feed port mounted on the substrate;

a terminating resistor mounted on the substrate; and

a ground plane,

wherein the circular antenna microstrip is mounted on the first surface of the substrate and the second surface of the substrate is mounted on the ground plane, and

wherein the feed port is coupled to a first portion of the antenna and the terminating resistor is coupled to a second portion of the antenna and to the ground plane.

6. A security device according to claim 5 wherein the substantially circular microstrip has a diameter ranging from about c/{2πf(∈ r ) 1/2 } to about c/{πf(∈ r ) 1/2 }, where c is the speed of light (3×10 8 meters/second), f is the operating frequency (cycles/second), and ∈ r is the relative permittivity of the substrate.

7. A security device according to claim 6 , wherein the feed port is excited by one of a monopole and a dipole feed excitation signal.

8. A security device according to claim 1 , wherein the second portion of the combination EAS/RFID tag includes an RFID element and the RFID element resides substantially outside of the perimeter of the circular microstrip antenna.

9. A security device for detaching combination electronic article surveillance (EAS) and radio frequency identification (RFID) tags (EAS/RFID tags), said security device comprising:

a detacher having an axis defined therethrough, said detacher configured to selectively disengage a clutch release disposed in a first portion of the combination EAS/RFID tag;

a substantially circular-shaped monopole microstrip near field antenna configured to electronically read information stored in a second portion of the combination EAS/RFID tag, said near field antenna configured to substantially encircle said detacher and configured to read information from said second portion of the combination EAS/RFID tag when said combination EAS/RFID tag is positioned at any angle relative to said axis.

10. A security device according to claim 9 , wherein the near field antenna is configured to only read information when said detacher is positioned to disengage the clutch release in the first portion of the combination EAS/RFID tag.

11. A security device according to claim 9 , wherein the detacher magnetically disengages the clutch release.

12. A security device according to claim 11 , wherein the near field antenna is configured to read information only when said detacher is positioned to disengage the clutch release in the first portion of the combination EAS/RFID tag.

13. A security device according to claim 9 , wherein the security device further comprises:

a substrate, the substrate having a first surface and a second surface;

a feed port mounted on the substrate;

a terminating resistor mounted on the substrate; and

a ground plane,

wherein

the circular antenna microstrip is mounted on the first surface of the substrate and the second surface of the substrate is mounted on the ground plane, and

the feed port is coupled to a first portion of the antenna and the terminating resistor is coupled to a second portion of the antenna and to the ground plane.

14. An antenna for use with a combination electronic article surveillance (EAS) and radiofrequency identification (RFID) tag, the tag being removable from an article by a detacher, the antenna comprising

a substrate;

a substantially circular microstrip mounted on the substrate; and

the antenna configured to electronically read information stored in an RFID portion of the combination EAS/RFID tag, said antenna configured to substantially encircle said detacher and configured to read information from said RFID portion of the combination EAS/RFID tag at a position relative to said detacher when said RFID portion of said tag is disposed at any angle relative to said detacher.

15. A security device according to claim 9 , the detacher further comprising:

a detacher magnet having a substantially circular perimeter, the substantially circular microstrip being mounted on the substrate around the perimeter of the detacher magnet.

16. A security device according to claim 9 , further comprising a substrate, the substrate comprises first and second surfaces, the substantially circular microstrip being mounted on the first surface of the substrate, and wherein the antenna further comprises a detacher magnet having a substantially circular perimeter, the detacher magnet being disposed in proximity to the second surface of the substrate such that the substantially circular microstrip is disposed outside the perimeter of the detacher magnet.

17. An antenna according to claim 14 , wherein the antenna further comprises:

a feed port mounted on the substrate; and

a terminating resistor mounted on the substrate, wherein

the feed port is coupled to a first portion of the antenna and the terminating resistor is coupled to a second portion of the antenna.

18. An antenna according to claim 17 , wherein the substrate comprises first and second surfaces, wherein the antenna further comprises:

a ground plane, and

wherein the circular antenna microstrip is mounted on the first surface of the substrate and the second surface of the substrate is mounted on the ground plane, and

the feed port is coupled to a first portion of the antenna and the terminating resistor is coupled to a second portion of the antenna and to the ground plane.

19. An antenna according to claim 17 , wherein the feed port is excited by one of a monopole and dipole feed excitation signal.

20. An antenna according to claim 14 , wherein the substantially circular microstrip has a diameter ranging from about c/{2πf(∈ r ) 1/2 } to about c/{πf(∈ r ) 1/2 }, where c is the speed of light (3×10 8 meters/second), f is the operating frequency (cycles/second), and ∈ r is the relative permittivity of the substrate.