ANTENNA DEVICE AND RADIO FREQUENCY IC DEVICE

• US 20110155810A1
• Filed: 03/09/2011
• Published: 06/30/2011
• Est. Priority Date: 12/26/2007
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: TANIGUCHI, Katsumi, KATO, Noboru, SASAKI, Jun
• Granted Patent: US 8,360,330 B2
• Time in Patent Office: Days
• US Class Current: 235/488
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• 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 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

An antenna device is arranged to transmit or receive a radio frequency communication signal to or from an external device such as a reader/writer, and is arranged such that an antenna resonance circuit including an antenna coil and a capacitor is connected to an additional resonance circuit including an inductor and a capacitor. A radio frequency IC device preferably includes the antenna device and a radio frequency IC. The antenna device is constructed such that a change in characteristics thereof caused by a change in the distance between a radio frequency IC device and a reader/writer is minimized, and the radio frequency IC device performs communication with high reliability.

Claims

1. An antenna device included in a radio frequency IC device that is arranged to perform radio frequency communication with an external device, the antenna device comprising:

an antenna element arranged to transmit or receive a radio frequency communication signal to or from the external device; and

an additional resonance circuit connected to the antenna element, including at least one inductor, and having a resonance frequency different from a resonance frequency of the antenna element;

wherein

the resonance frequency of the additional resonance circuit is higher than the resonance frequency of the antenna element, and the resonance frequency of the antenna element is higher than a communication frequency used by the radio frequency IC device.

2. The antenna device according to claim 1, wherein the antenna element and the inductor included in the additional resonance circuit are arranged to be magnetically coupled.

3. The antenna device according to claim 1, wherein the additional resonance circuit is a parallel resonance circuit.

4. The antenna device according to claim 1, wherein the antenna element is connected in series to the additional resonance circuit.

5. The antenna device according to claim 1, wherein the inductor included in the additional resonance circuit is magnetically shielded.

6. The antenna device according to claim 5, wherein the additional resonance circuit is provided in a multilayer substrate including a magnetic substance.

7. The antenna device according to claim 6, further comprising an output inductor that is connected in series to an input portion that is arranged to receive a signal transmitted from a radio frequency IC and is provided in the multilayer substrate.

8. The antenna device according to claim 6, wherein the additional resonance circuit includes a chip capacitor disposed either on a surface of the multilayer substrate, or in the multilayer substrate.

9. A radio frequency IC device comprising:

the antenna device according to claim 6; and

a radio frequency IC disposed either on a surface of the multilayer substrate of the antenna device, or in the multilayer substrate of the antenna device.