RADIO FREQUENCY IDENTIFICATION TAG AND RADIO FREQUENCY IDENTIFICATION TAG ANTENNA

• US 20090140928A1
• Filed: 06/09/2008
• Published: 06/04/2009
• Est. Priority Date: 11/29/2007
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute, Industrial Cooperation Foundation Chonbuk National University
• Original Assignee: Electronics and Telecommunications Research Institute, Industrial Cooperation Foundation Chonbuk National University
• Inventors: Chae, Jong-Suk, Pyo, Cheol Sig, Kim, Jeong Seok, Choi, Gil Young, Son, Hae Won, Choi, Won Kyu
• Granted Patent: US 8,098,201 B2
• Time in Patent Office: Days
• US Class Current: 343/700.MS
• 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 13/10 Resonant slot antennas
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration

Abstract

An RFID tag includes an antenna and a chip, and the antenna includes a first polygonal dielectric material, first and second microstrip lines partially formed in the first dielectric material, a second polygonal dielectric material stacked on the first dielectric material, and a third microstrip line partially formed in the second dielectric material. According to the present invention, the RFID tag can efficiently receive electromagnetic waves to thereby maximize a readable range.

Claims

1. A radio frequency identification (RFID) tag including an antenna that receives an interrogation signal corresponding to a radio frequency (RF) signal and a chip that generates a response signal corresponding to the interrogation signal,

the antenna comprising:

a first polygonal dielectric material having a first plane corresponding to a ground plane and a second plane that does not contact the first plane;

a first microstrip line formed in a part of the second plane, and having two lateral ends;

a second microstrip line formed in a part of the second plane, and having two lateral ends;

a second polygonal dielectric material having a third plane that partially contacts the second plane and a fourth plane that does not contact the third plane, and that is stacked on the first dielectric material; and

a third microstrip line formed in the fourth plane, and having two lateral ends.

2. The RFID tag of claim 1, wherein the antenna further comprises:

a first feed terminal connected to one of the two lateral ends of the first microstrip line; and

a second feed terminal connected to one of the two lateral ends of the second microstrip line, and

the chip is partially formed in the second plane to contact the third plane, is electrically connected to the first microstrip line through the first feed terminal, and is electrically connected to the second microstrip line through the second feed terminal.

3. The RFID tag of claim 2, wherein impedance of the antenna and impedance of the chip respectively comprise a resistance component and a reactance component, a value of the resistance component of the impedance of the antenna and a value of the resistance component of the impedance of the chip are the same in size and have the same sign, and the value of the resistance component of the impedance of the antenna and the value of the resistance component of the impedance of the chip are the same in size but opposite in sign.

4. The RFID tag of claim 3, wherein the impedance of the antenna corresponds to the length of the first microstrip line, the length of the second microstrip line, and the length of the third microstrip line.

5. The RFID tag of claim 4, wherein the resistance component of the impedance of the antenna corresponds to the width of an end connected to the first feed terminal among the two lateral ends of the first microstrip line and the width of an end connected to the second feed terminal among the two lateral ends of the second microstrip line, and the reactance component of the impedance of the antenna corresponds to the distance of the two lateral ends of the first microstrip lines, the distance of the two lateral ends of the second microstrip lines, and the distance of the two lateral ends of the third microstrip lines.

6. A radio frequency identification (RFID) antenna comprising:

a first polygonal dielectric material having a first plane corresponding to a ground plane and a second plane that does not contact the first plane;

a first microstrip line formed in a part of the second plane, and having two lateral ends;

a second microstrip line formed in a part of the second plane, and having two lateral ends;

a second polygonal dielectric material having a third plane and a fourth plane, and stacked on the first dielectric material, the third plane partially contacting the second plane, the first microstrip line, and the second microstrip line; and

a third microstrip line partially or entirely formed in the fourth plane, and one of the two lateral ends of the first microstrip line and one of the two lateral ends of the second microstrip line face each other.

7. The RFID tag of claim 6, wherein one of the first and second microstrip lines has two lateral ends that are the same in width.

8. The RFID tag of claim 6, wherein one of the first and second microstrip lines has two lateral ends that are different from each other in width.

9. The RFID tag of claim 8, wherein the first microstrip line and the second microstrip line respectively have lateral ends that are different from each other in width, and a shorter one of the two lateral ends of the first microstrip line and a shorter one of the two lateral ends of the second microstrip line face each other.

10. The RFID tag of claim 6, wherein the third microstrip line has a curved circumference.

11. The RFID tag of claim 6, wherein the third microstrip line has a polygonal-shaped circumference.

12. The RFID tag of claim 10, wherein the microstrip line has a ring shape.

13. The RFID tag antenna of claim 6, further comprising:

a first shorting plate formed in a fifth plane that connects the first and second planes, and connecting the first microstrip line and the ground plane so as to disconnect the microstrip line from the ground plane; and

a second shorting plate formed in a sixth plane that connects the first and second planes, and connecting the second microstrip line and the ground line so as to disconnect the second microstrip line from the ground plane.