Wide bandwidth hybrid antenna for combination EAS and RFID label or tag
View Patent ↗A radio frequency identification (RFID) antenna exhibiting a multiple resonance is disclosed. In one exemplary embodiment, a dipole antenna and a loop antenna are disposed upon a substrate and have dimensions and orientation to exhibit the multiple resonance. The dipole antenna may exhibit a first dipole section having a first length and second dipole section having a second length. The loop antenna may be disposed in a region of the dipole antenna. The ratio of the perimeter of the loop antenna to the sum of the lengths of the dipole sections may be selected to exhibit the multiple resonance.
1. A Radio Frequency Identification (RFID) antenna, comprising:
a dipole antenna including a first dipole section having a first length and a second dipole section having a second length;
a plurality of feed tabs; and
a loop antenna having a perimeter, the loop antenna being electrically coupled to the first dipole section by at least one feed tab and electrically coupled to the second dipole section by a plurality of feed tabs, the length of the first and second dipole sections, the position of the loop antenna, and the number and positions of the plurality of feed tabs being selected to achieve a multiple resonance in a predetermined frequency band.
2. The RFID antenna of claim 1 , wherein the electrical coupling is achieved by direct connection of conductors forming the dipole antenna and the loop antenna.
3. The RFID antenna of claim 1 , wherein the loop antenna has a width and wherein the feed tab locations are no further than substantially a midpoint of the loop antenna width.
4. The RFID antenna of claim 1 , wherein the loop antenna is substantially rectangular and is oriented at an acute angle with respect to the first dipole section of the dipole antenna.
5. The RFID antenna of claim 1 , wherein the predetermined frequency band is from substantially 850 Megahertz (MHz) to substantially 960 MHz.
6. The RFID antenna of claim 1 , wherein a ratio of the loop antenna perimeter to the sum of the lengths of the first and second dipole sections is between about 0.22 to about 0.35.
7. The RFID antenna of claim 1 , wherein the loop antenna perimeter is substantially between 15 millimeters to 50 millimeters.
8. The RFID antenna of claim 7 , wherein the sum of the lengths of the first and second dipole sections is substantially between 40 millimeters and 230 millimeters.
9. The RFID antenna of claim 1 , further including a substrate, wherein the dipole antenna and the loop antenna are disposed upon the substrate.
10. The RFID antenna of claim 1 , wherein the first dipole section is a clockwise spiral and the second dipole section is a counterclockwise spiral.
11. The RFID antenna of claim 1 , wherein the loop antenna is interposed between the first and second dipole sections such that a distance between the first and second dipole sections is determined at least in part by a size of the loop antenna.
12. A combination Electronic Article Surveillance (EAS)/Radio Frequency Identification (RFID) security tag, comprising:
an EAS component;
an RFID component, comprising:
a dipole antenna having a first section having a first length and a second section having a second length;
a plurality of feed tabs; and
a loop antenna in electrical communication with the dipole antenna by the plurality of feed tabs, the loop antenna having a perimeter, the first length and the second length of the dipole antenna, a position of the loop antenna and the numbers and positions of the plurality of feed tabs being selected to exhibit a multiple resonance in a predetermined frequency band.
13. The security tag of claim 12 , further comprising an RFID integrated circuit coupled to the loop antenna.