WO2016049848A1

WO2016049848A1 - Radio frequency identification (rfid) tag

Info

Publication number: WO2016049848A1
Application number: PCT/CN2014/087937
Authority: WO
Inventors: Chi Lun Mak; Jing Tian Xi; Chun wai LEUNG
Original assignee: Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies Limited
Priority date: 2014-09-30
Filing date: 2014-09-30
Publication date: 2016-04-07

Abstract

A radiofrequency identification (RFID) tag comprising an integrated circuit chip electrically coupled with a plurality of radiating elements， wherein the plurality of radiating elements are arranged in an array to provide a resultant RF signal containing information associated with or in the integrated circuit chip for communication with a RFID reader.

Description

RADIO FREQUENCY IDENTIFICATION (RFID) TAG

TECHNICAL FIELD

The present invention relates to a radio frequency identification (RFID) tag and particularly， although not exclusively， to an RFID tag having a single chip and an antenna array with a plurallty of antenna elements.

BACKGROUND

RFID tags can be classified as active， semi-passive， and passive types according to their structural characteristics. Specifically， active RFID tags are the tags which have an internal power source arranged to power the tag for broadcasting RF signals to the RFID reader； semi-passive RFID tags also have a power source but the power source is for powering other sensors or circuitries associated with the tag， not for broadcasting RF signals； and passive RFID tags are the ones without any power source but are powered by the RFID reader to trigger a response.

Dlfferent types of RFID tags are adapted for different applications but generally passive RFID tags are more popular due to their relatlvely low cost and simple design.

The basic structure of an RFID tag includes an integrated circuit chip for storing retrievable information， a single antenna coupled with the circuit chip for enabling communication of RF signals (which may contain information relating to the integrated circuit chip) with an RFID reader， and an optional power source (depending on whether the tag is active or passive) . One of the drawbacks of this RFID tag structure is that the communication distance of the tag is relatively short and that energy/power distribution of the tag is loose and is susceptible to environmental disturbances.

It is an object of the present invention to address the above needs， to overcome or substantially ameliorate the above disadvantages or， more generally， to provide an improved RFID tag.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention， there is provided a radiofrequency identification (RFID) tag comprising an integrated circuit chip electrically coupled with a plurality of radiating elements， wherein the plurality of radiating elements are arranged in an array to provide a resultant RF signal containing information associated with or in the integrated circuit chip for communication with a RFID reader. Preferably， the integrated circuit chip is the only integrated circuit chip in the RFID tag.

In one embodiment of the first aspect， each of the plurality of radiating elements is arranged to provide an individual RF signal having a power and a phase. The RF power and phase of the individual RF signals may be the same or different.

In one embodiment of the first aspect， the plurality of radiating elements are spaced apart with equal separation distance. However， in an alternative embodiment of the first aspect， the plurality of radiating elements are spaced apart with different separation distances. Optionally， the separation distance may depend on the wavelength (operating wavelength) or any other factors.

In one embodiment of the first aspect， the resultant RF signal is dependent on the power and phase of each of the plurality of radiating elements， and the separation distance between the plurality of radiating elements.

In one embodiment of the first aspect， the resultant RF signal is arranged to re-distribute and/or concentrate RF energy in a particular direction to increase a reading distance of the RFID tag.

In one embodiment of the first aspect， the plurality of radiating elements are identical. However， in an alternative embodiment of the first aspect， the plurality of radiating elements are not identical.

In one embodiment of the first aspect， the plurality of radiating elements are arranged with their long axis on the same line in the array. However， in an alternative embodiment of the first aspect， the plurality of radiating elements are arranged with their long axis being parallel and arranged on different parallel lines in the array.

In one embodiment of the first aspect， the plurality of radiating elements are electrically coupled with the integrated circuit chip through a feed network.

In one embodiment of the first aspect， the plurality of radiating elements comprises antennas and/or RF coils.

In one embodiment of the first aspect， the plurality of radiating elements are arranged on one side of the RFID tag.

In one embodiment of the first aspect， the RFID tag is a passive RFID tag.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described， by way of example， with reference to the accompanying drawings in which：

Figure 1 is a block diagram showing the major function components of an RFID tag in accordance with one embodiment of the present invention；

Figure 2 is a is a schematic diagram of an RFID tag in accordance with one embodiment of the present invention； and

Figure 3A shows an embodiment of the arrangement of the antenna array on the RFID tag of Figure 2；

Figure 3B shows an alternative embodiment of the arrangement of the antenna array on the RFID tag of Figure 2；

Figure 3C shows another alternative embodiment of the arrangement of the antenna array on the RFID tag of Figure 2； and

Figure 4 shows yet another alternative embodiment of the arrangement of the antenna array on the RFID tag of Figure 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to Figures 1 and 2， there is provided a radiofrequency identification (RFID) tag comprising an integrated circuit chip electrically coupled with a plurality of radiating elements， wherein the plurality of radiating elements are arranged in an array to provide a resultant RF signal containing information associated with or in the integrated circuit chip for communication with a RFID reader.

Figure 1 shows a functional block diagram of an RFID tag 100 in accordance with an embodiment of the present invention. In this embodiment， the RFID tag 100 as shown is a passive tag， without a power source. As shown in Figure 1， a plurality of radiating elements 102A-102D are electrically coupled with an RFID integrated circuit chip 106 through a feed network 104. In one embodiment， each of the radiating elements 102A-102D is an antenna or RF coil， and each of them is preferably operable to generate an individual RF signal having a power and phase. The individual RF signals may or may not be identical， and can be controlled by the feed network 104. The combination of these individual RF signals gives a resultant RF signal with a resultant power and phase that is emitted by the tag 100. Preferably， the feed network 104 is arranged to coordinate the generation of RF signals in the radiating elements 102A-102D and to facilitate signal/data communication between the radiating elements 102A-102D and the RFID integrated circuit chip 106. In one embodiment， the RFID integrated circuit chip 106 is arranged to store data and enable read/write of data and information from/in the chip 106 by an RFID tag reader (not shown) through the radiating elements 102A-102D. Operation of the RFID tag will be disclosed in more detail with reference to Figure 2.

Figure 2 shows a schematic diagram of an RFID tag 200 ln accordance with one embodiment of the present invention. The RFID tag embodiment shown in Figure 2 is consistent with the functional block diagram of the RFID tag 100 shown and described with reference to Figure 1. As shown in Figure 2， an antenna array with plurality of antennas 202A-202D are arranged to be coupled with a feed network 204. In the present embodiment， the antennas 202A-202D are of the same type (identical) and are spaced apart evenly by the same separation distance. However， in alternative embodiments， the antennas 202A-202D need not be of the same type and/or can be spaced apart by different separation distances. In one example， the antennas are spaced apart evenly from one another by separation distance of 0.5-0.8λ， with λ being the wavelength (operating wavelength) of the antenna. It should also be noted that the antenna 202A-202D (or RF coils in some other embodiments) can have other shape and form that is different from those shown in Figure 2. A feed network 204 is arranged intermediate between the antennas 202A-202D and the integrated circuit chip 206 for coupling the antennas 202A-202D with the integrated circuit chip 206 and hence to allow for signal or data communication therebetween. The RFID integrated circuit chip 206 is arranged to store data and information， and enable read/write of data and information from/in the chip 206. Preferably， although not specifically shown in the schematic diagram of Figure 2， the radiating elements 202A-202D， the feed network 204 and the integrated circuit chip 206 are arranged to be formed on a substrate.

In operation， the tag as shown in Figure 2 is arranged to be powered up by a power signal transmitted from a RFID tag reader as it does not have any internal power source. Specifically， the RFID tag reader transmits an RF signal with a command to the RFID tag 200. The command may be， for example， instructions for reading or writing data and information from or into the chip 206. The RFID tag 200 then responses to the RFID tag reader based on the signals received.

In one example， for a read operation， the antennas 202A-202D receive the read command signal from the RF reader and relay the signal from the RF reader to the feed network 204. The feed network 204 will then determine the data to read based on the read command signal received from the RFID reader. The feed network 204 then retrieves the relevant information and data from the chip 206 and transmits them to the antennas 202A-202D for generation of a response RF signal. Each antenna 202A-202D is operable to generate an individual RF signal with a power and phase， and the resultant (response) RF signal will depend on the combination of these individual RF signals. Preferably， the resultant (response) RF signal also depends on the separation distance between the antennas 202A-202D. By utilizing a beam forming technique controlled by the feed circuit 204， the resultant (response) RF signal emitted by the tag 200 is arranged to be directional or to re-distribute and/or concentrate RF energy in a particular direction， so as to maximize the transmission efficiency and range.

In another example， for a write operation， the antennas 202A-202D receive the write command signal from the RF reader and relay the signal from the RF reader to the feed network 204. The feed network 204 will then determine the data to write to the chip 206 based on the received write command signal from the RFID reader. The feed network 204 then writes the relevant information and data from the chip 206. Preferably， in this example， the feed network 204 is arranged to adjust the sensitivity of the antennas 202A-202D so as to maximize the write command detection efficiency and range and to enhance the reading distance of the tag in a particular direction.

Figures 3A and 3B show respectively the different embodiments of arrangement of the antenna array in the RFID tag of Figure 2. Both Figures 3A and 3B are showing a plan view of the

RFID tag

300， 350. As shown in Figures 3A and 3B， the antennas 302A-302C， 352A-352D are arranged on the same side (e.g. surface) of the

RFID tag

300， 350. In Figure 3A， the antennas 302A-302C are distributed in a straight line， with their long axis being arranged on the same line. In Figure 3B， the antennas 350A-350D are shown to have their long axis arranged parallel with each other and on different parallel lines. Once again it will be appreciated that the separation distance and the type and form of the antennas 302A-302C， 350A-350D in Figures 3A and 3B may vary in some other embodiments.

Figure 3C shows an alternative embodiment of the arrangement of the antenna array in the RFID tag of Figure 2， illustrated in a plan view of the RFID tag 380. The arrangement and operation of the antenna and the RFID tag of Figure 3C are largely the same as those described with respect to Figures 2-3B， and thus will not be reproduced below. One of the major differences of the design in Figure 3C is that the antenna array includes twelve antennas arranged in a 4 x 3 array， as opposed to a one column or row array. However， it should be noted that the antenna array may include different number of antenna， and the array may be a n x m array， where n， m may be any number in other embodiments.

Figure 4 shows yet another alternative embodiment of the arrangement of the antenna array in the RFID tag of Figure 2. The arrangement and operation of the antenna and the RFID tag 400 in Figure 4 are largely the same as those described with respect to Figures 2-3B， and thus will not be reproduced below. One of the major differences of the design in Figure 4 is that the antenna array is a 3D array. In this specific example there are five antennas. However， it should be noted that the antenna array may include different number of antenna， and the array may be a n x m array， where n， m may be any number in other 3D array embodiments.

The RFID tag in different embodiments of the present invention as shown is a passive RFID tag. However， a person skilled in the art would readily appreciate that the single-chip-multiple-antenna concept in the present invention can be applied to semi-passive or active RFID tags by rendering some minor modifications to the circuitry without deviating from the scope of the invention.

The RFID tag of the present invention is particularly advantageous in that it utilizes multiple antenna/RF coil elements and a single chip on an RFID tag together with the concept of the beam forming technique to redistribute or concentrate energy in a particular desired direction and hence to enhance the reading distance of the tag. The RFID tag in the present invention provides a low cost solution for enhancing the communication distance of RFID tags， in particular passive RFID tags. More importantly， the RFID tag in the present invention allows the tag to be less affected from RF energy disturbances by the environment of which the tag is in. For example， in cases where the tag is arranged adjacent or proximal to an unavoidable surrounding material that disturbs the RF energy distribution， the antenna array can compensate for such disturbances and hence compensate for the reduced transmission or reading distance as a result of such disturbances. The tag in the present invention would also allow for RFID tags with larger size which are adapted to conform to the form factor of the object of which the tag is attached to， in a cheap and effective manner. Other advantages of the present invention in terms of structure， function， cost， effectiveness， efficiency and manufacture， will become apparent to those skilled in the art by reference to the specification.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are， therefore， to be considered in all respects as illustrative and not restrictive.

Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge， unless otherwise indicated.

Claims

A radiofrequency identification (RFID) tag comprising an integrated circuit chip electrically coupled with a plurality of radiating elements， wherein the plurality of radiating elements are arranged in an array to provide a resultant RF signal containing information associated with or in the integrated circuit chip for communication with a RFID reader.
An RFID tag in accordance with claim 1， wherein each of the plurality of radiating elements is arranged to provide an individual RF signal having a power and a phase.
An RFID tag in accordance with claim 2， wherein the plurality of radiating elements are spaced apart with equal separation distance.
An RFID tag in accordance with claim 2， wherein the plurality of radiating elements are spaced apart with different separation distances.
An RFID tag in accordance with claims 3 or 4， wherein the resultant RF signal is dependent on the power and phase of each of the plurality of radiating elements， and the separation distance between the plurality of radiating elements.
An RFID tag in accordance with claim 5， wherein the resultant RF signal is arranged to re-distribute and/or concentrate RF energy in a particular direction to increase a reading distance of the RFID tag.
An RFID tag in accordance with any one of claims 1-6， wherein the plurality of radiating elements are identical.
An RFID tag in accordance with any one of claims 1-6， wherein the plurality of radiating elements are not identical.
An RFID tag in accordance with any one of claims 1-8， wherein the plurality of radiating elements are arranged with their long axis on the same line in the array.
An RFID tag in accordance with any one of claims 1-8， wherein the plurality of radiating elements are arranged with their long axis being parallel and arranged on different parallel lines in the array.
An RFID tag in accordance with any one of the preceding claims， wherein the plurality of radiating elements are electrically coupled with the integrated circuit chip through a feed network.
An RFID tag in accordance with any one of the preceding claims， wherein the plurality of radiating elements comprises antennas and/or RF coils.
An RFID tag in accordance with any one of the preceding claims， wherein the plurality of radiating elements are arranged on one side of the RFID tag.
An RFID tag in accordance with any one of the preceding claims， wherein the RFID tag is a passive RFID tag.
An RFID tag in accordance with any one of the preceding claims， wherein the RFID tag includes only one integrated circuit chip.