Wireless communication device

• US 8,960,561 B2
• Filed: 02/24/2014
• Issued: 02/24/2015
• Est. Priority Date: 02/28/2011
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Kimura, Ikuhei, Ikemoto, Nobuo
• Primary Examiner(s): LEE, SEUNG H
• Application Number:
  US14/187,364
• Publication Number:
  US 20140166764A1
• Time in Patent Office: 365 Days
• Field of Search: 235/492, 343/700.R, 343/700.MS
• US Class Current: 235/492
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• CPC Class Codes: G06K 19/07786 the antenna being of the HF type, such as a dipole
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• 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 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

A wireless communication device includes a wireless IC chip that processes a high-frequency signal and a feeding substrate including a coil conductor, a plane conductor, and a matching circuit that is connected to the wireless IC chip and that has a predetermined resonant frequency. The coil conductor and the plane conductor are connected to the matching circuit. The wireless communication device, when used by itself, operates as a monopole antenna in which the plane conductor functions as a ground and the coil conductor functions as a radiation element. When a conductive object is in a vicinity of the plane conductor, the plane conductor is coupled to the conductive object, and the wireless communication device operates as a dipole antenna in which the plane conductor and the conductive object function as a first radiation element and the coil conductor functions as a second radiation element.

Claims

1. An RFID system comprising:

an article including a conductive object; and

a wireless communication device attached to the article;

wherein

the wireless communication device includes;

a wireless IC chip that processes a high-frequency signal; and

a feeding substrate including a first conductor, a second conductor, and a matching circuit, in which the matching circuit is connected to the wireless IC chip, and the first and second conductors are connected to the matching circuit;

wherein

the first conductor is connected to the conductive object and one end of the second conductor is an open-end such that the conductive object functions as a first radiation element and the second conductor functions as a second radiation element.

2. The RFID system according to claim 1, wherein the first conductor and the conductive object are connected to each other by at least one of magnetic coupling, capacitive coupling, electric field coupling, electromagnetic coupling, and direct current coupling.

3. The RFID system according to claim 2, wherein the first conductor is capacitively coupled to the conductive object.

4. The RFID system according to claim 1, wherein the matching circuit includes an inductance element which is provided between the first and second conductor.

5. The RFID system according to claim 1, wherein the matching circuit includes a first inductance element and a second inductance element, and the first and second inductance elements are electrically connected in parallel with the wireless IC chip and are magnetically coupled to each other.

6. The RFID system according to claim 1, wherein the feeding substrate includes a multilayer body including a plurality of dielectric layers or magnetic layers stacked on each other, and the matching circuit is located within the multilayer body.

7. The RFID system according to claim 1, wherein the second conductor comprises a multilayer coil pattern including a plurality of loop-shaped conductors stacked on and connected to each other in a spiral shape.

8. The RFID system according to claim 1, wherein the wireless IC chip is a silicon semiconductor integrated circuit chip including a clock circuit, a logic circuit, and a memory circuit.

9. The RFID system according to claim 1, wherein the article is a printed circuit board and the conductive object is a ground plate of the printed circuit board.

10. The RFID system according to claim 1, wherein the wireless IC chip is mounted on or disposed within the feeding substrate.

11. The RFID system according to claim 1, which is used in a UHF band RFID system.