CHIPLESS MICROWAVE IDENTIFICATION TAG

• US 20090267739A1
• Filed: 03/02/2009
• Published: 10/29/2009
• Est. Priority Date: 04/29/2008
• Status: Active Grant

• Current Assignee: Hong Kong Polytechnic University
• Original Assignee: Hong Kong Polytechnic University
• Inventors: Cheng, David Ki Wai, Chan, Ching Yuen, Yung, Kai Leung
• Granted Patent: US 8,274,368 B2
• Time in Patent Office: Days
• US Class Current: 340/10.100
• CPC Class Codes: H04Q 2209/47 using RFID associated with sensors
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

A chipless microwave identification tag (200) comprising: a dielectric substrate (210); and a plurality of antenna elements (220) made from a conductive material and disposed on at least one surface (205, 255) of the dielectric substrate (210); wherein when the tag (200) is excited by an incident microwave signal (131), a reflected wave (141) to identify the tag (200) is generated with a number of specific frequencies altered by microwave resonation of the antenna elements (220).

Claims

1. A chipless microwave identification tag comprising:

a dielectric substrate; and

a plurality of antenna elements made from a conductive material and disposed on at least one surface of the dielectric substrate;

wherein when the tag is excited by an incident microwave signal, a reflected wave to identify the tag is generated with a number of specific frequencies altered by microwave resonation of the antenna elements.

2. The tag according to claim 1, wherein the antenna elements are pads and have a plurality of extending arms.

3. The tag according to claim 1, wherein the antenna elements are concentric rings.

4. The tag according to claim 1, wherein the tag is encoded based on the specific microwave resonation measured after fabrication of the tag.

5. The tag according to claim 4, wherein a binary coding system is used to encode the tag based on the measurement of the microwave resonation from each tag.

6. The tag according to claim 5, wherein the microwave band of operation for the tag is from about 14 to about 18 GHz and is divided into 100 equal frequency slots, each frequency slot corresponding to a bit occupying 0.04 GHz.

7. The tag according to claim 6, wherein if the strength of any microwave resonation is larger than a predetermined value, a code number “

1”

is assigned to the bit; and

if the strength of any resonation is less than the predetermined value, a code number “

0”

is assigned to the bit.

8. The tag according to claim 7, wherein the predetermined value is 5 dB changes during the frequency slot.

9. The tag according to claim 1, where the reflected wave is decoded to obtain an identification number of the tag.

10. A method for identifying a chipless microwave identification tag having antenna elements, the method comprising:

exciting the tag using an incident microwave signal; and

decoding a reflected wave generated in response to the microwave excitation, the reflected wave having a number of specific frequencies altered by microwave resonation of the antenna elements.

11. The method according to claim 10, wherein the decoding of the reflected wave obtains an identification number of the tag.

12. The method according to claim 10, wherein if the strength of any microwave resonation is larger than a predetermined value, a code number “

1”

is assigned to the bit; and

if the strength of any resonation is less than the predetermined value, a code number “

0”

is assigned to the bit.

13. The method according to claim 12, wherein the predetermined value is 5 dB changes during the frequency slot.

14. A system for identifying a chipless microwave identification tag, the system comprising:

a microwave signal generator to excite the tag using an incident microwave signal; and

a reader to decode a reflected wave generated in response to the microwave excitation, the reflected wave having a number of specific frequencies altered by microwave resonation of the antenna elements.

15. The system according to claim 14, further comprising a signal processing module to obtain an identification number of the tag by determining if the strength of any microwave resonation is larger than a predetermined value, a code number “

1”

is assigned to the bit; and

if the strength of any resonation is less than the predetermined value, a code number “

0”

is assigned to the bit.

16. A method for manufacturing a chipless microwave identification tag, the method comprising:

injection moulding to form the tag;

forming antenna elements on the tag; and

trimming the antenna elements to predetermined sizes;

wherein the tag is encoded with an identification number based on the number of specific frequencies present in a reflected wave generated after excitation of the tag by an incident microwave signal.