Tag-use antenna and tag using the same

• US 20070252770A1
• Filed: 08/31/2006
• Published: 11/01/2007
• Est. Priority Date: 04/26/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kai, Manabu, Maniwa, Toru, Yamagajo, Takashi
• Granted Patent: US 7,538,738 B2
• Time in Patent Office: Days
• US Class Current: 343/795
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 9/16 with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole H01Q9/44 takes precedence

Abstract

The present invention relates to a tag-use antenna allowing a miniaturization while maintaining a constant minimal change of a communication distance. The tag-use antenna has a feed part of a folded dipole antenna of a size of 53 mm long and 7 mm wide being connected to, and equipped with, an LSI chip of Rc=500 ohms and Cc=1.4 pF and is covered with plastic resin 13 of the dielectric constant εr=3 and thickness of t=0.75 mm on both sides of the antenna. The dipole part of 1 mm wire path width of the tag-use antenna is formed in a rectangular spiral by being bent inward from both ends at bending parts at four places. The entire length of the dipole antenna when extending the four bending parts straight is featured so as to be shorter than one half of a resonance wavelength of the antenna. An inductance part is featured in the intermediate part of the both dipole parts in the neighborhood of the center of the antenna. The inductance part is connected to the chip equipment part in parallel with the both dipole parts.

Claims

1. A tag-use antenna comprising a dipole antenna, a feed part and an inductance part which are featured by a conductor in the same flat plane, wherein

the feed part is featured at the center of the dipole antenna in a manner capable of equipping with a chip,

the inductance part is connected to the feed part in parallel with a dipole of the dipole antenna, and

the dipole antenna is formed in a rectangular spiral by being bent inward from both ends at bending parts which bend the dipole at least in four places respectively, with the entire length of each of the bending parts of the four places being shorter than one half of a resonance wavelength of the antenna when the bending parts are extended to a straight line.

2. The tag-use antenna according to claim 1, wherein

said inductance part is featured in the neighborhood of the center of said dipole antenna and placed in the middle of said dipole, which is formed in said rectangular spiral, of the dipole antenna.

3. The tag-use antenna according to claim 1, wherein

the entire length of the antenna and said inductance part are adjusted so as to make an impedance of a tag at a reader/writer operation frequency of 953 MHz come close to an antenna'"'"'s most optimum value.

4. The tag-use antenna according to claim 1, wherein

said conductor is either copper, silver or aluminum.

5. The tag-use antenna according to claim 1, wherein

said feed part is connected to, and equipped with, a large scale integration (LSI) chip.

6. A tag sandwiching the tag-use antenna according to claim 5 by a plastic resin or paper from both surface of the tag-use antenna.

7. The tag according to claim 6, wherein

said plastic resin is an ethylene terephthalate film.