Loop antenna and RFID tag

Abstract

A loop antenna 1 for an RFID tag 100 includes an annular line member 10 that includes meandering parts 13 and 14 disposed on a dielectric substrate 2, and power feeding parts 11 that are provided on the line member 10. The annular line member 10 includes the meandering parts 13 and 14 at portions except for the vicinity of positions corresponding to loops of a standing wave occurring in the loop antenna 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing the configuration of an RFID tag according to a first embodiment of the invention.

FIG. 2 is a schematic view showing the configuration of the RFID tag according to the first embodiment of the invention.

FIG. 3 is a view showing a relationship between a loop antenna and a standing wave.

FIG. 4 is a view showing current distribution of the loop antenna.

FIG. 5 is a view showing results of a simulation.

FIG. 6 is a view showing the results of the simulation.

FIG. 7 is a view showing a modification of the RFID tag.

FIG. 8 is a view showing another modification of the RFID tag.

FIG. 9 is a view showing another modification of the RFID tag.

FIG. 10 is a view showing another modification of the RFID tag.,

Claims

1. A loop antenna for an RFID tag, comprising: an annular line member that includes one or more meandering parts; anda power feeding part provided on the line member,wherein the annular line member includes the meandering parts at portions except for the vicinity of positions corresponding to loops of a standing wave occurring in the loop antenna.

2. The loop antenna according to claim 1, wherein the annular line member includes at least one of the meandering parts at positions corresponding to nodes of the standing wave occurring in the loop antenna.

3. A loop antenna for an RFID tag, comprising: an annular line member that includes one or more meandering parts; anda power feeding part provided on the line member,wherein the annular line member includes the meandering parts thereon at portions except for the vicinity of a position where the power feeding part is provided and at portions except for the vicinity of a position where a path length from the power feeding part is half of an entire path length of the line member.

4. The loop antenna according to claim 3, wherein the annular line member includes at least one of the meandering parts at positions where the path length from the power feeding part is a quarter of the path length of the line member.

5. The loop antenna according to claim 1, wherein the annular line member has a rectangular shape, andthe annular line member includes at least one of the meandering parts on the sides thereof except for a side that includes the power feeding part and a side that faces the side including the power feeding part.

6. The loop antenna according to claim 1, further comprising: a matching circuit that is connected to the power feeding part.

7. An RFID tag comprising: the loop antenna according to claim 1;an integrated circuit that is connected to the power feeding part; anda dielectric substrate on which the loop antenna is disposed.