RF tag and method of manufacturing the RF tag

• US 20080111695A1
• Filed: 01/14/2008
• Published: 05/15/2008
• Est. Priority Date: 07/29/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kai, Manabu, Maniwa, Toru, Yamagajo, Takashi
• Granted Patent: US 7,548,167 B2
• Time in Patent Office: Days
• US Class Current: 340/572.7
• 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 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• 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 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407

Abstract

An RF tag to accompany a conductive object is disclosed that includes an antenna and an integrated circuit connected to the antenna. The antenna includes a first radiating element, a second radiating element, a feeding part connected in series between the first and second radiating elements, and an impedance control part connected parallel to the feeding part. The antenna has an effective length shorter than half of a wavelength used in communication.

Claims

1. An RF tag to accompany a conductive object, comprising:

an antenna; and

an integrated circuit connected to the antenna,

wherein the antenna includes

a first radiating element;

a second radiating element;

a feeding part connected in series between the first and second radiating elements; and

an impedance control part connected parallel to the feeding part, and

wherein the antenna has an effective length shorter than a half of a wavelength used in a communication.

2. The RF tag as claimed in claim 1, wherein the antenna operates as a minute dipole antenna.

3. The RF tag as claimed in claim 1, wherein the first and second radiating elements have a symmetric shape with respect to the feeding part.

4. The RF tag as claimed in claim 1, wherein each of the first and second radiating elements is formed of a conductor extending in a strip shape.

5. The RF tag as claimed in claim 4, wherein the feeding part is connected to a line extending along a side of each of the conductors having the strip shape.

6. The RF tag as claimed in claim 4, wherein two sides of one of the conductors having the strip shape along a direction in which the one of the conductors extends are aligned with two sides of another one of the conductors.

7. The RF tag as claimed in claim 1, wherein the impedance control part is formed of a bent conductive line.

8. The RF tag as claimed in claim 1, wherein the impedance control part is formed of a rectangularly bent conductive line.

9. The RF tag as claimed in claim 1, wherein the impedance control part is formed of an inductive element.

10. The RF tag as claimed in claim 1, wherein an insulating layer supporting the antenna has a multilayer structure including at least a polyethylene terephthalate layer and a spacer layer.

11. The RF tag as claimed in claim 1, wherein a conductive layer is provided on a bottom surface of an insulating layer supporting a layer of the antenna.

12. The RF tag as claimed in claim 11, wherein the conductive layer is provided so as to have a mesh pattern.

13. A method of manufacturing an RF tag to accompany a conductive object, the RF tag having an integrated circuit connected to an antenna, the method comprising:

a first step of forming the antenna of a predetermined shape on one surface of a first insulating layer; and

a second step of joining a second insulating layer to another surface of the first insulating layer,

wherein the antenna is formed so as to have a first radiating element, a second radiating element, a feeding part connected in series between the first and second radiating elements, and an impedance control part connected parallel to the feeding part and to have an effective length shorter than a half of a wavelength used in a communication.

14. The method as claimed in claim 13, further comprising:

a step of removing a part of one or both of the first and second radiating elements between the first step and the second step.