Multiband passive RFID tag

Abstract

The present invention describes an RFID tag comprising: a substrate; at least one antenna for receiving an unmodulated power signal having a first frequency and a modulated query signal having a second frequency different from the first frequency, and transmitting a modulated response signal having a third frequency, wherein the third frequency is one of the harmonics and subharmonics of the first frequency; a storage unit for storing tag data; and a signal processing unit for extracting query information from the modulated query signal, generating the modulated response signal based on the tag data, the query information and a first portion of the unmodulated power signal, transmitting the modulated response signal via the at least one antenna, and converting a second portion of the unmodulated power signal into a DC electrical signal for supplying power to the RFID tag, wherein the at least one antenna, the signal processing unit and the storage unit are mounted on the substrate.

Description

Technical Field

[0001] The technology described in this specification relates to the field of radio frequency identification (RFID) tags, and more particularly to passive RFID tags.

Background Art

[0002] Today, passive RFID tags are widely used for digital IDs. Different from QR codes (registered trademark), passive RFID tags can be read from a distance, and many tags can be read almost instantaneously without ensuring a line of sight between the reader and the tag. Due to these two characteristics, passive RFID technology has become very convenient for a wide range of applications in this industry.

[0003] The maximum distance at which a tag can be read is called the read range. The percentage of tags that can be read normally is called the read rate. In the performance evaluation of the entire system, it is important to improve the read range and read rate of RFID tags. To improve these parameters, it is necessary to strengthen the signal from the tag compared to the noise and interference in the system.

[0004] One of the main obstacles to improving the signal-to-interference-plus-noise ratio in conventional passive RFID tags is the self-interference problem. When a reader attempts to read an RFID tag, it irradiates the tag with the emission of a radio frequency (RF) signal. The RFID tag usually reflects the signal back to the reader, and the returned signal is embedded with low-bandwidth data. In conventional RFID systems, the signal transmitted from the reader and the signal reflected from the RFID tag use the same carrier frequency. With this configuration, the strong signal from the reader may interfere with the reflected signal coming back from the RFID tag.

[0005] In addition to regulatory guidelines, self-interference is one of the main issues that imposes a substantial limit on the maximum transmit power of readers. In conventional RFID systems, increasing the reader's transmit power only further drowns out the tag responses. On the other hand, passive RFID tags backscatter signals from the reader, so if the reader's transmit power is low, the reading range narrows and the system's read rate decreases. [Overview of the project] [Problems that the invention aims to solve]

[0006] Therefore, an improved RFID system is needed. [Means for solving the problem]

[0007] According to a first broad embodiment, an RFID tag is provided, comprising: a substrate; at least one antenna for receiving an unmodulated power signal having a first frequency and a modulated query signal having a second frequency different from the first frequency, and transmitting a modulated response signal having a third frequency, wherein the third frequency is one of the harmonics and subharmonics of the first frequency; a storage unit for storing tag data; and a signal processing unit for extracting query information from the modulated query signal, generating the modulated response signal based on the tag data, the query information and a first portion of the unmodulated power signal, transmitting the modulated response signal via the at least one antenna, and converting a second portion of the unmodulated power signal into a DC electrical signal for supplying power to the RFID tag, wherein the at least one antenna, the signal processing unit and the storage unit are mounted on the substrate.

[0008] In one embodiment, the signal processing unit includes a demodulator for extracting the question information from the modulated question signal; an AC-DC converter for converting the second portion of the unmodulated power signal into a DC electrical signal; a processor for receiving the question information and generating a response data signal based on the tag data and the question information; and a modulator and frequency shift component for modulating the first portion of the unmodulated power signal according to the response data signal and converting the first frequency to the third frequency.

[0009] In one embodiment, the modulator is configured to receive the first portion of the unmodulated power signal and modulate it according to the response data signal in order to obtain the modulated carrier signal, and the frequency shift component is configured to change the first frequency of the modulated carrier signal to the third frequency in order to obtain the modulated response signal.

[0010] In one embodiment, the frequency shift component is configured to receive the first portion of the unmodulated power signal and change the first frequency of the first portion of the unmodulated power signal to the third frequency in order to obtain a frequency shifted signal, and the modulator is configured to modulate the frequency shifted signal according to the response data signal in order to obtain the modulated response signal.

[0011] In one embodiment, the AC-DC converter includes a first rectifier.

[0012] In one embodiment, the frequency shift component includes a nonlinear component.

[0013] In one embodiment, the nonlinear component includes either a diode or a second rectifier.

[0014] In one embodiment, the signal processing unit includes a demodulator for extracting the question information from the modulated question signal; a rectifier for converting the second portion of the unmodulated power signal into a DC electrical signal and changing the first frequency of the first portion of the unmodulated power signal to the third frequency in order to obtain a frequency-shifted signal; a processor for receiving the question information and generating a response data signal based on the tag data and the question information; and a modulator for modulating the frequency-shifted signal according to the response data signal in order to obtain the modulated response signal.

[0015] In one embodiment, the at least one antenna includes one of a single antenna, two antennas, and three antennas.

[0016] In one embodiment, the at least one antenna includes one of a single antenna, two antennas, and three antennas.

[0017] In one embodiment, the at least one antenna further receives a second modulated interrogation signal having the first frequency and transmits a second modulated response signal having the first frequency.

[0018] In one embodiment, the signal processing unit further extracts second question information from the second modulated question signal, generates a second modulated response signal based on the tag data, the second question information, and a first portion of the second modulated question signal, transmits the second modulated response signal via at least one antenna, and converts a second portion of the second modulated question signal into a DC electrical signal for supplying power to the RFID tag.

[0019] In one embodiment, the signal processing unit includes a demodulator for extracting the second question information from the second modulated question signal, a rectifier for converting the second portion of the second modulated question signal into a DC electrical signal, a processor for receiving the second question information and generating a response data signal based on the tag data and the question information, and a modulator for modulating the second modulated question signal according to the response data signal in order to obtain the second modulated response signal.

[0020] In another broader embodiment, a radio frequency identification (RFID) system is provided, comprising a reader comprising at least one antenna, a signal processing unit and a storage unit, wherein the processing unit is configured to generate an unmodulated power signal having a first frequency, a modulated query signal having a second frequency different from the first frequency, and a modulated response signal having a third frequency, the third frequency being one of the harmonics and subharmonics of the first frequency; and the RFID tag described above.

[0021] In other broader embodiments, a method is provided for operating a radio frequency identification (RFID) tag, comprising: receiving an unmodulated power signal having a first frequency and a modulated query signal having a second frequency different from the first frequency; extracting query information from the modulated query signal; generating a modulated response signal having a third frequency based on tag data, the query information and a first portion of the unmodulated power signal, wherein the third frequency is one of the harmonics and subharmonics of the first frequency; converting the second portion of the unmodulated power signal into a DC electrical signal for powering the RFID tag; and transmitting the modulated response signal via at least one antenna, wherein the receiving and transmitting are performed via at least one antenna.

[0022] In one embodiment, the method further includes receiving a second modulated interrogation signal having the first frequency and transmitting a second modulated response signal having the first frequency.

[0023] In one embodiment, the method further includes extracting second interrogation information from the second modulated interrogation signal, generating the second modulated response signal based on the tag data, the second interrogation information, and a first portion of the second modulated interrogation signal, transmitting the second modulated response signal via the at least one antenna, and converting a second portion of the second modulated interrogation signal into a DC electrical signal for powering the RFID tag.

[0024] Each embodiment of the technology herein has at least one of the above objects and / or aspects, but not necessarily all of them. It should be understood that some aspects of the technology herein obtained as a result of attempting to achieve the above objects may not satisfy the above objects and / or may satisfy other objects not specifically described herein.

[0025] Additional and / or alternative features, aspects, and advantages of embodiments of the technology herein will become apparent from the following description, the accompanying drawings, and the appended claims.

[0026] To further understand the technology herein and other aspects and additional features of the technology herein, please refer to the following description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0027] [Figure 1] FIG. 1 is a schematic diagram of an RFID system including an RFID reader and an RFID tag according to one embodiment. [Figure 2] FIG. 2 is a diagram of an RFID tag including a single antenna according to one embodiment. [Figure 3]This is a diagram of an RFID tag including two antennas according to the first embodiment. [Figure 4] This is a diagram of an RFID tag including two antennas according to a second embodiment. [Figure 5] This is a diagram of an RFID tag including two antennas according to a third embodiment. [Figure 6] This is a diagram of an RFID tag including three antennas according to the fourth embodiment. [Figure 7] This is a diagram of an RFID tag including three antennas according to the fifth embodiment. [Figure 8] This is a diagram of an RFID tag including three antennas according to the sixth embodiment. [Figure 9] This is a diagram of an RFID tag including three antennas according to the seventh embodiment. [Figure 10] This is a flowchart of a method for operating an RFID tag according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0028] The examples and conditional statements described herein are primarily intended to help the reader understand the principles of the art herein and do not limit the scope of the art herein to such specifically described examples and conditions. Those skilled in the art will understand that various configurations, not expressly described or presented herein, can be devised to embody the principles of the art herein and fall within the spirit and scope of the art herein.

[0029] Furthermore, for the sake of understanding, the following description may include relatively simplified embodiments of the technology described herein. As those skilled in the art will understand, various embodiments of the technology described herein can be more complex.

[0030] In some cases, examples of useful modifications to the art described herein may be provided. These are provided solely for the purpose of aiding understanding and, again, do not define or present the scope of the art described herein. These modifications are not exhaustive, and those skilled in the art can make other modifications without departing from the scope of the art described herein. Furthermore, where examples of modifications are not provided, it should not be construed that modifications are impossible and / or that what is described is the only way to implement that element of the art described herein.

[0031] Figure 1 shows one embodiment of the RFID system 10. The RFID system 10 includes an RFID reader 12 (hereinafter referred to as the "reader") and at least one RFID tag 14 (hereinafter referred to as the "tag").

[0032] The RFID reader 12 is configured to generate and emit a modulated interrogation signal and an unmodulated power signal, and to receive a modulated response signal from the tag 14. The modulated interrogation signal, unmodulated power signal, and modulated response signal should be understood as radio frequency (RF) signals. The modulated interrogation signal has a first frequency selected from a first frequency band and is modulated to contain encoded information / data. The unmodulated power signal is a continuous wave (CW) RF signal and has a second frequency selected from a second frequency band. Since the first and second frequency bands are clearly distinct and do not overlap, the first and second frequencies are different. The modulated response signal has a third frequency and is modulated to contain encoded information / data. Since the third frequency is selected to be a harmonic or subharmonic of the second frequency, the modulated response signal is a harmonic or subharmonic signal of the unmodulated power signal.

[0033] Tag 14 is configured to receive the modulated interrogation signal and the unmodulated power signal, and to generate and emit the modulated response signal. As will be described in detail below, Tag 14 uses a first portion of the received unmodulated power signal to supply power to all of its components, and uses a second portion of the unmodulated power signal to generate the modulated response signal.

[0034] The RFID reader 12 is connected to a power source (not shown) and includes a signal processing unit 20, a storage unit or memory 22, and at least one antenna 24. The storage unit 22 may store information about the RFID reader 12 and / or the tag 14. This memory 22 can be used, for example, when the RFID reader 12 needs to locally track the tag before transmitting information to a user. The signal processing unit 20 is configured to generate a modulated query signal and an unmodulated power signal to send to the tag 14. As is known in the art, the modulated query signal may represent a command and / or query. The modulated query signal may be any of the required, optional, or proprietary commands expected in a standard RFID protocol. The signal processing unit is further configured to emit the modulated query signal and the unmodulated power signal via the antenna 24.

[0035] In one embodiment, the signal processing unit 20 is configured to generate and emit a power signal substantially continuously, independently of the emission of the modulated interrogation signal. In another embodiment, the signal processing unit 20 is configured to emit the power signal and the modulated interrogation signal substantially simultaneously. In one embodiment, the emission of the power signal and the modulated interrogation signal may start and end simultaneously. In another embodiment, the emission of the power signal may start slightly before the emission of the modulated interrogation signal and / or end slightly after the emission of the modulated interrogation signal.

[0036] It should be understood that the number of antennas included in the RFID reader 12 can take on various values, as long as the RFID reader 12 includes at least one antenna. In one embodiment, the RFID reader 12 includes a single antenna, and therefore the power signal and the modulated query signal are emitted from that single antenna, and the modulated response signal is also received by that single antenna. In another embodiment, the RFID reader 12 includes two antennas. In this case, one antenna is shared between two of the three signals, and the other antenna is specialized for only the remaining one of the three signals. In one embodiment, the first antenna may be specialized for transmitting the power signal and the query signal, and the second antenna may be specialized for receiving the response signal from the tag 14. In another embodiment, the first antenna may be specialized for transmitting the query signal and receiving the response signal, and the second antenna may be specialized only for transmitting the power signal. In yet another embodiment, the RFID reader 12 includes three different antennas. In this case, the first antenna is specialized for transmitting power signals, the second antenna is specialized for transmitting interrogation signals, and the third antenna is specialized for receiving response signals.

[0037] In some embodiments, the signal processing unit 20 is configured to vary the frequency of the power signal within a second frequency band. In some embodiments, the frequency of the power signal varies between a predetermined set of frequencies. In one embodiment, the frequency of the power signal alternates between two predetermined frequencies. This alternation between two predetermined frequencies allows for the determination of the location of the tag 14, as is known in the art.

[0038] In some embodiments, the RFID reader 12 includes a monostatic RFID reader. In other embodiments, the RFID reader 12 includes a bistatic RFID reader.

[0039] The tag 14 includes a signal processing unit 30, a storage unit or memory 32, and at least one antenna 34. The storage unit 32 may store information, such as a tag ID, information about the product to which the tag 14 is associated, and information received from the RFID reader 12. The signal processing unit 30 is configured to extract information from the received modulated interrogation signal, convert a first part or part of the power signal into power to supply power to the tag 14, generate the response signal based on the received interrogation signal using a second part or part of the power signal, and transmit this response signal by the antenna 34. The generation of the response signal is performed by modulating the second part of the received power signal to encode response information or response data, and by changing the frequency of the second part of the power signal to a harmonic or subharmonic of the original frequency, i.e., a harmonic or subharmonic of the received power signal.

[0040] In some embodiments where the modulated interrogation signal represents a command, tag 14 may not generate a response signal. In other embodiments where the modulated interrogation signal represents a command or query, a signal response is generated based on information extracted from the interrogation signal.

[0041] In some embodiments, the signal processing unit 30 is configured to first modulate the second portion of the power signal to obtain a modulated signal, and then change the frequency of the modulated signal. In other embodiments, the signal processing unit 30 is configured to first change the frequency of the second portion of the power signal to obtain a frequency-changed signal, and then modulate the frequency-changed signal.

[0042] In some embodiments, the signal processing unit 30 includes an AC-to-DC converter (e.g., a rectifier). This converter converts the first portion of the power signal into an electrical power signal used to supply power to the tag 14.

[0043] In some embodiments, the signal processing unit 30 includes a modulator for modulating a second portion of the power signal and a frequency shift component configured to change the frequency of the RF signal to a harmonic or subharmonic frequency. For example, the frequency shift component may be a nonlinear component that introduces nonlinearity. In one embodiment, the nonlinear component is a nonlinear passive component such as a diode or a rectifier.

[0044] In one embodiment, AC-DC conversion and frequency shifting are performed by a single component, such as a rectifier. In this case, the rectifier receives an unmodulated power signal from the antenna 34 and generates two signals: a DC power signal for supplying power to the tag 14 and an unmodulated carrier signal. The frequency of this carrier signal is a harmonic or subharmonic of the frequency of the received unmodulated power signal. A first filter can be used to extract the DC power signal from the output of the rectifier, and a second filter can be used to extract the unmodulated carrier signal from the output of the rectifier. The unmodulated carrier signal is then modulated to generate a modulated response signal.

[0045] Tag 14 further includes a circuit board, on which various components that make up Tag 14, such as a signal processing unit 30, an antenna 34, and a memory 32, are mounted.

[0046] The following describes several different embodiments of the RFID tag 14 described above.

[0047] Figure 2 shows one embodiment of an RFID tag 50 including a single antenna 52. In addition to the antenna 52, the tag 50 includes a processor or processing unit 54 (such as a microprocessor), memory 56, demodulator 58, rectifier 60, modulator 62, and nonlinear components 64 (such as diodes). The tag 50 further includes a substrate 66 on which all other elements 52-64 are mounted.

[0048] Antenna 52 is configured to receive a modulated query signal having a first frequency emitted from the RFID reader, and an unmodulated power signal having a different second frequency, also emitted from the RFID reader.

[0049] Memory 56 is configured to store information or data (such as identification information of tag 50 or information received from an RFID reader). Processing unit 54 is connected to this memory 56 to operate. Processing unit 54 is configured to interpret the modulated signal from the reader, perform necessary operations, and optionally generate response data (i.e., a response to the query signal) based on the information stored in memory 56 (such as the tag ID or query data extracted from the modulated query signal).

[0050] The demodulator 58 is connected to the antenna 52 to operate, thereby receiving the modulated interrogation signal from the antenna 52. The demodulator 58 is also connected to the processing unit 54 to operate. The demodulator 58 is configured to extract interrogation information or interrogation data from the modulated interrogation signal and send the extracted interrogation data to the processing unit 54.

[0051] The input of the rectifier 60 is connected to the antenna 52 to operate, thereby receiving a first portion of the unmodulated power signal from the antenna 52. The output of the rectifier 60 is connected to the processing unit 54, memory 56, demodulator 58, and modulator 62 to operate, thereby supplying power to these components 54, 56, 58, and 62. The rectifier 60 is configured to convert the first portion of the unmodulated power signal into a DC power signal, which is used to supply power to the processing unit 54, memory 56, demodulator 58, and modulator 62.

[0052] Modulator 62 receives a second portion or part of the unmodulated power signal. Modulator 62 is also connected to a processing unit 54 to receive the response data signal from the processing unit 54, modulates the second portion of the unmodulated power signal based on the received response data signal, and generates a modulated signal having the same carrier frequency as the received unmodulated power signal. A nonlinear component 64 is connected to modulator 62 to receive the modulated signal from modulator 62. The nonlinear component 64 is configured to change the carrier frequency of the modulated signal received from modulator 62 to a harmonic or subharmonic frequency, thereby obtaining a modulated response signal in which the response to the question is encoded. This modulated response signal is then transmitted to antenna 52 and emitted from it.

[0053] In another embodiment, a nonlinear component 64 is configured to receive a second portion of the received unmodulated power signal and change the frequency of this signal to a harmonic or subharmonic frequency, thereby obtaining a frequency-shifted signal. A modulator 62 is connected to the nonlinear component 64 to operate and thereby receive the frequency-shifted signal from the nonlinear component 64. The modulator 62 is also connected to the processing unit 54 to operate and thereby receive a response data signal from the processing unit 54. The modulator 62 is configured to modulate the frequency-shifted signal based on the received response data signal to generate a modulated response signal. This modulated response signal is transmitted to the antenna 52 and transmitted simultaneously.

[0054] Tag 50 should be understood to further include components that split and / or direct signals, such as circulators and diplexers (not shown).

[0055] While the tag 52 includes a single antenna, the embodiments shown in Figures 3-5 include two antennas. When the tag includes two antennas, the first antenna is specialized for two of the three signals (i.e., the modulated interrogation signal, the unmodulated power signal, and the modulated response signal), and the second antenna is specialized for one of the three signals.

[0056] Figure 3 shows an RFID tag 70 including a first antenna 72 and a second antenna 74 mounted on a substrate 66. The remaining components of the tag 70 are the same as those included in the tag 50. Antenna 72 is specialized for receiving modulated query signals and emitting modulated response signals, and antenna 74 is specialized for receiving unmodulated power signals. Antenna 72 is connected to operate with the demodulator 58 and a nonlinear component 64. Antenna 74 is connected to operate with the rectifier 60 and a modulator 62. As a result, the modulated query signal is received by antenna 72 and transmitted to the demodulator 58, and the unmodulated power signal is received by antenna 74 and divided into a first part and a second part, the first part transmitted to the rectifier 60 and the second part transmitted to the modulator 62. The modulated response signal output from the nonlinear component 64 is transmitted to antenna 72 and emitted from there. The remaining parts of Tag 70 should be understood to function similarly to those of Tag 50.

[0057] Figure 4 shows an RFID tag 80 including a first antenna 82 and a second antenna 84 mounted on a substrate 66. The remaining components of tag 80 are the same as those included in tag 50. Antenna 82 is specialized for receiving the modulated interrogation signal, and antenna 84 is specialized for receiving the unmodulated power signal and emitting the modulated response signal. Antenna 82 is connected to operate with demodulator 58. Antenna 84 is connected to operate with rectifier 60 and modulator 62. As a result, the modulated interrogation signal is received by antenna 82 and transmitted to demodulator 58. The unmodulated power signal is received by antenna 72 and split into a first and second part, the first part transmitted to rectifier 60 and the second part to modulator 62. The modulated response signal output from nonlinear component 64 is transmitted to antenna 84 and emitted from there. The remaining components of tag 80 should be understood to operate in the same way as tag 50.

[0058] Figure 5 shows an RFID tag 90 including a first antenna 92 ​​and a second antenna 94 mounted on a substrate 66. The remaining components of tag 90 are the same as those included in tag 50. Antenna 92 ​​is specialized for receiving the modulated interrogation signal and the unmodulated power signal, and antenna 94 is specialized for emitting the modulated response signal. Antenna 92 ​​is connected to operate with the demodulator 58, rectifier 60, and modulator 62. Antenna 94 is connected to operate with the nonlinear component 64. As a result, the modulated interrogation signal is received by antenna 92 ​​and transmitted to the demodulator 58, and the unmodulated power signal is also received by antenna 92 ​​and split into a first and second part, the first part transmitted to the rectifier 60 and the second part transmitted to the modulator 62. The modulated response signal output from the nonlinear component 64 is transmitted to antenna 94 and emitted from there. The remaining components of tag 90 should be understood to operate in the same way as tag 50.

[0059] Figure 6 shows one embodiment of an RFID tag 100 including a first antenna 102, a second antenna 104, and a third antenna 106. The remaining components of the tag 100 are the same as those included in the tag 50. Antenna 102 is specialized for receiving the modulated interrogation signal, antenna 104 is specialized for receiving the unmodulated power signal, and antenna 106 is specialized for emitting the modulated response signal. Antenna 102 is connected to operate with the demodulator 58. Antenna 104 is connected to operate with the rectifier 60 and the modulator 62. Antenna 106 is connected to operate with the nonlinear component 64. As a result, the modulated interrogation signal is received by antenna 102 and transmitted to the demodulator 58. The unmodulated power signal is received by antenna 104 and divided into a first part and a second part, the first part transmitted to the rectifier 60 and the second part transmitted to the modulator 62. The modulated response signal output from the nonlinear component 64 is transmitted to the antenna 106 and emitted from there. The remaining components of tag 100 should be understood to operate in the same way as tag 50.

[0060] In some embodiments, the various RFID tags shown in Figures 2-6 can be further adapted to operate with multiple different RFID readers, as will be described later. Figures 7-9 show various embodiments of RFID tags configured to operate with multiple different RFID readers.

[0061] In one embodiment, a first RFID reader (not shown) is configured to transmit two signals and receive a third signal. The first transmit signal is an unmodulated power signal having a first frequency. The second transmit signal is a modulated query signal having a second frequency different from the first frequency. The received signal is a modulated response signal having a third frequency generated by an RFID tag, the third frequency being one of the harmonics or subharmonics of the first frequency. Without limiting the scope of this disclosure, the first frequency can be about 915 MHz and the second frequency can be about 2.4 GHz.

[0062] In another embodiment, a second RFID reader (not shown) is configured to transmit a first signal and receive a second signal. In this embodiment, the first transmitted signal is a modulated interrogation signal, which consists of an unmodulated portion and a modulated portion in sequence. The modulated interrogation signal has the first frequency (e.g., 915 MHz). The received signal is a modulated response signal generated by the RFID tag, which has the same frequency as the first transmitted signal.

[0063] The RFID tags shown in Figures 7-9 can operate with either the first RFID reader or the second RFID reader. When operating with the first RFID reader, the RFID tags generate a modulated response signal having a third frequency, the third frequency being either a harmonic or a subharmonic of the first frequency. When operating with the second RFID reader, the RFID tags generate a modulated response signal having the same frequency as the first transmission signal.

[0064] Figure 7 shows one embodiment of an RFID tag 110 including a second demodulator 108. The remaining components of the tag 110 are the same as those included in the tag 100. The demodulator 108 is connected to the antenna 104 to operate, thereby receiving the modulated query signal having a first frequency from the antenna 104. The demodulator 108 is also connected to the processing unit 54 to operate. The demodulator 108 is configured to extract query information or query data from the modulated query signal and send the extracted query data to the processing unit 54. The processing unit 54 is configured to generate a response data signal based on the query information. In some embodiments, the demodulators 108 and 58 may be different, so that the demodulator 108 can be configured to operate at a first frequency and the demodulator 58 can be configured to operate at a second frequency.

[0065] Antenna 104 is further connected to operate with the rectifier 60 and the combination of modulator 62 and nonlinear component 64. As a result, the modulated interrogation signal received by antenna 104 is propagated to the rectifier 60 and the combination of modulator 62 and nonlinear component 64.

[0066] The input of the rectifier 60 is connected to the antenna 104 to operate it, thereby receiving the modulated interrogation signal from the antenna 104. The output of the rectifier 60 is connected to the processing unit 54, memory 56, demodulator 108, and modulator 62 to operate them, thereby supplying power to these components. The rectifier 60 is configured to convert at least a portion of the modulated interrogation signal into a DC power signal, which is used to supply power to the processing unit 54, memory 56, demodulator 108, and modulator 62.

[0067] The modulator 62 and the nonlinear component 64 are configured to perform frequency shifting and modulation of the modulated interrogation signal based on the response data signal received from the processing unit 54. This combination of modulator 62 and the nonlinear component 64 generates the modulated response signal. Note that not the entire modulated interrogation signal is frequency shifted by the nonlinear component 64. As a result, at least a portion or component of the modulated interrogation signal is modulated at a first frequency. The modulated response signal is then transmitted to antennas 104 and 106 and emitted from there. At the same time, at least a portion or component of the modulated response signal that has been modulated at the first frequency is transmitted by antenna 104 and detected by an RFID reader configured to detect signals of the first frequency. The remaining components of tag 110 should be understood to operate similarly to tag 100.

[0068] When the RFID tag 110 operates with the first RFID reader described above, the antenna 102 receives the modulated query signal of the second frequency, the antenna 104 receives the unmodulated power signal of the first frequency, and the remaining components of the tag 110 operate in the same manner as the tag 100 as described above.

[0069] When the RFID tag 110 operates with the second RFID reader, the antenna 104 is specialized to receive a modulated query signal having the first frequency. This modulated query signal is generated by the second RFID reader at the first frequency. The modulated query signal includes a sequence of signal parts, each of which includes at least a first signal part and a second signal part. The first signal part is unmodulated and corresponds to a DC signal. The second signal part, on the other hand, is modulated and contains encoded query information. The antenna 104 is specialized to emit a modulated response signal. The component of this modulated response signal is the first frequency and is therefore detected by the second RFID reader that emitted the query signal at the first frequency. The modulated response signal is generated by the RFID tag 110 in response to the modulated query signal.

[0070] Figure 8 shows one embodiment of the RFID tag 120. The components of the tag 120 are the same as those included in the tag 110, except that the antenna 102 is further coupled to the rectifier 60 and the modulator 62 and nonlinear component 64.

[0071] When the RFID tag 120 operates with the first RFID reader (corresponding to the first operating mode of the tag 120), the antenna 102 receives a modulated query signal having the first frequency, the antenna 104 receives an unmodulated power signal having the second frequency, and the remaining components of the tag 130 operate in the same manner as the tag 100.

[0072] When the RFID tag 120 operates with the second RFID reader (corresponding to the second operating mode of the tag 120), the input of the rectifier 60 is connected to the antenna 102 to operate, thereby receiving the modulated query signal having the first frequency from the antenna 102, and the output of the rectifier 60 is connected to the processing unit 54, memory 56, demodulator 58 and modulator 62 to operate, thereby supplying power to these components 54, 56, 58 and 62. The rectifier 60 is configured to convert at least a portion of the modulated query signal into a DC power signal, which is used to supply power to the processing unit 54, memory 56, demodulator 58 and modulator 62.

[0073] Furthermore, the modulator 62 and the nonlinear component 64 together generate a modulated response signal, which is then transmitted to the antenna 106 and emitted from there. At least a portion of the modulated response signal is modulated at a first frequency. At this time, at least a portion or component of the modulated response signal modulated at the first frequency is transmitted by the antenna 102 and detected by the second RFID reader configured to detect signals of the first frequency. The remaining components of the tag 120 should be understood to operate in the same manner as the tag 110.

[0074] Figure 9 shows one embodiment of an RFID tag 130 including a second rectifier 112. The remaining components and connections of the tag 130 are the same as those included in the tag 120. The rectifier 112 is connected to operate the antenna 102, thereby receiving the modulated interrogation signal having the first frequency from the antenna 102. The output of the rectifier 112 is connected to operate the processing unit 54, memory 56, demodulator 58, and modulator 62, thereby supplying power to these components 54, 56, 58, and 62. The rectifier 60 is configured to convert at least a portion of the modulated interrogation signal into a DC power signal, which is used to supply power to the processing unit 54, memory 56, demodulator 58, and modulator 62. In some embodiments, the rectifiers 112 and 60 may be different, so that the rectifier 60 can be configured to operate at the first frequency and the rectifier 112 can be configured to operate at the second frequency.

[0075] When the RFID tag 130 operates with the first RFID reader, the antenna 102 receives a modulated query signal having the second frequency, the antenna 104 receives an unmodulated power signal having the first frequency, and the remaining components of the tag 130 operate in the same manner as the tag 100.

[0076] When the RFID tag 130 operates with the second RFID reader, the antenna 102 receives a modulated query signal having the first frequency. Similar to the RFID tag 110, this modulated query signal is used to power the various components of the RFID tag 130.

[0077] Furthermore, the modulator 62 and the nonlinear component 64 together generate a modulated response signal, which is then transmitted to antennas 102 and 106 and emitted from there. At least a portion of the modulated response signal is modulated at a first frequency. At this time, at least a portion or component of the modulated response signal modulated at the first frequency is transmitted by antenna 102 and detected by the second RFID reader configured to detect signals of the first frequency. The remaining components of tag 130 should be understood to operate in the same manner as tag 110.

[0078] Referring to Figures 2-9, it will also be understood that by reversing the positions of the modulator 62 and the nonlinear component 64, the nonlinear component 64 can receive the second portion of the unmodulated power signal.

[0079] Similar to RFID tags, the number of antennas included in an RFID reader can be varied, as long as the RFID reader contains at least one antenna. For example, an RFID reader may contain one, two, or three antennas for emitting the modulated query signal and the unmodulated power signal, and for receiving the modulated response signal.

[0080] In some embodiments, the RFID tag described above can transmit and receive a low-power modulated signal while simultaneously receiving a high-power unmodulated signal. The modulated and unmodulated signals have different frequencies, as described above. The low-power modulated signal from the reader to the tag is used to transmit query data to the tag. This data transfer is necessary to establish a handshake between the tag and the reader. The high-power unmodulated signal is used as a power signal for activating the tag and as a carrier signal for the tag's response.

[0081] In some embodiments, the RFID systems described herein provide a practical solution for realizing ultra-long-range passive RFID systems with high read rates. By using an unmodulated power signal in conjunction with the modulated signal, the inefficiencies inherent in harmonic tags can be eliminated, and the signal-to-interference noise ratio is improved.

[0082] Figure 10 shows a flowchart of a method 200 for operating an RFID tag according to various embodiments of the present disclosure. As shown in the figure, the method 200 begins in step 202, in which the RFID tag 50 receives an unmodulated power signal having a first frequency and a modulated query signal having a second frequency different from the first frequency.

[0083] The above method proceeds to step 204, where the RFID tag 50 extracts the question information from the modulated question signal.

[0084] The above method proceeds to step 206, in which the RFID tag 50 generates a modulated response signal having a third frequency based on the tag data, the above query information, and the first portion of the above unmodulated power signal, wherein the third frequency is one of the harmonics and subharmonics of the first frequency.

[0085] The above method proceeds to step 208, in which the RFID tag 50 converts the second portion of the unmodulated power signal into a DC electrical signal to supply power to the RFID tag.

[0086] Finally, in step 210, the RFID tag 50 transmits the modulated response signal via at least one antenna, and the reception and transmission are performed via at least one antenna.

[0087] Modifications and improvements to the embodiments of the technology described herein will be apparent to those skilled in the art. The foregoing description is illustrative and not limiting. [Explanation of Symbols]

[0088] 10 RFID Systems 12 RFID readers 14 RFID tags 20 Leader signal processing unit 22 Reader memory unit, memory 24 Leader's Antenna 30 tag signal processing units 32 tag memory units 34 tagged antennas 50 RFID tags 52 Antennas 54 processing units, processors 56 memory 58 Demodulator 60 rectifier 62 Modulators 64 Nonlinear components 66 circuit boards 70 RFID tags 72 First Antenna 74 Second Antenna 80 RFID tags 82 First Antenna 84 Second Antenna 90 RFID tags 92 First Antenna 94 Second Antenna 100 RFID tags 102 First Antenna 104 Second Antenna 106 The third antenna 110 RFID tags 108 Second demodulator 120 RFID tags 130 RFID tags 112 Second rectifier

Claims

1. Radio frequency identification (RFID) tags, circuit board and At least one antenna for receiving an unmodulated power signal having a first frequency and a modulated interrogation signal having a second frequency different from the first frequency, and transmitting a modulated response signal having a third frequency, wherein the third frequency is one of the harmonics and subharmonics of the first frequency, A storage unit for storing tag data, A signal processing unit, Extracting question information from the modulated question signal, Based on the tag data, the question information, and the first portion of the unmodulated power signal, the modulated response signal is generated. The modulated response signal is transmitted through the at least one antenna, A signal processing unit for converting a second portion of the unmodulated power signal into a DC electrical signal for supplying power to the RFID tag, Includes, The at least one antenna, the signal processing unit, and the storage unit are mounted on the circuit board. RFID tags.

2. The aforementioned signal processing unit is A demodulator for extracting the question information from the modulated question signal, An AC-DC converter for converting the second portion of the unmodulated power signal into a DC electrical signal, A processor for receiving the aforementioned question information and generating a response data signal based on the tag data and the aforementioned question information, A modulator and frequency shift component for modulating the first portion of the unmodulated power signal according to the response data signal and converting the first frequency to the third frequency, The RFID tag according to claim 1, including the following:

3. The RFID tag according to claim 2, wherein the modulator is configured to receive a first portion of the unmodulated power signal and modulate it according to the response data signal in order to obtain a modulated carrier signal, and the frequency shift component is configured to change the first frequency of the modulated carrier signal to a third frequency in order to obtain a modulated response signal.

4. The RFID tag according to claim 2, wherein the frequency shift component is configured to receive the first portion of the unmodulated power signal and change the first frequency of the first portion of the unmodulated power signal to the third frequency in order to obtain a frequency shifted signal, and the modulator is configured to modulate the frequency shifted signal according to the response data signal in order to obtain the modulated response signal.

5. The RFID tag according to any one of claims 2 to 4, wherein the AC-DC converter includes a first rectifier.

6. The RFID tag according to any one of claims 2 to 5, wherein the frequency shift component includes a nonlinear component.

7. The RFID tag according to claim 6, wherein the nonlinear component includes one of a diode and a second rectifier.

8. The aforementioned signal processing unit is A demodulator for extracting the question information from the modulated question signal, A rectifier for converting the second portion of the unmodulated power signal into a DC electrical signal and changing the first frequency of the first portion of the unmodulated power signal to the third frequency in order to obtain a frequency-shifted signal, A processor for receiving the aforementioned question information and generating a response data signal based on the tag data and the aforementioned question information, A modulator for modulating the frequency-shifted signal according to the response data signal in order to obtain the modulated response signal, The RFID tag according to claim 1, including the following:

9. The RFID tag according to any one of claims 1 to 8, wherein the at least one antenna includes one of a single antenna, two antennas, and three antennas.

10. The RFID tag according to claim 1, wherein the at least one antenna further receives a second modulated interrogation signal having the first frequency and transmits a second modulated response signal having the first frequency.

11. The signal processing unit further, Extracting second question information from the second modulated question signal, Based on the tag data, the second question information, and the first portion of the second modulated question signal, the second modulated response signal is generated. Transmitting the second modulated response signal via at least one of the antennas, The second portion of the second modulated interrogation signal is converted into a DC electrical signal for supplying power to the RFID tag, The RFID tag according to claim 10, which performs the following actions.

12. The aforementioned signal processing unit is A demodulator for extracting the second question information from the second modulated question signal, A rectifier for converting the second portion of the second modulated interrogation signal into the DC electrical signal, A processor for receiving the second question information and generating a response data signal based on the tag data and the question information, A modulator for modulating the second modulated response signal according to the response data signal, in order to obtain the second modulated interrogation signal, The RFID tag according to claim 11, including the following:

13. A radio frequency identification (RFID) system, A leader comprising at least one antenna, a signal processing unit and a memory unit, wherein the processing unit is configured to generate an unmodulated power signal having a first frequency and a modulated interrogation signal having a second frequency different from the first frequency, and to receive a modulated response signal having a third frequency, the third frequency being one of the harmonics and subharmonics of the first frequency, An RFID tag according to any one of claims 1 to 12, A radio frequency identification (RFID) system, including [the specified element].

14. A method for operating a radio frequency identification (RFID) tag, Receiving an unmodulated power signal having a first frequency and a modulated interrogation signal having a second frequency different from the first frequency, Extracting question information from the modulated question signal, A modulated response signal having a third frequency is generated based on tag data, the query information, and a first portion of the unmodulated power signal, wherein the third frequency is one of the harmonics and subharmonics of the first frequency. The second portion of the unmodulated power signal is converted into a DC electrical signal for supplying power to the RFID tag, The modulated response signal is transmitted via at least one antenna, wherein the reception and transmission are performed via the at least one antenna. Methods that include...

15. The method according to claim 14, further comprising receiving a second modulated interrogation signal having the first frequency and transmitting a second modulated response signal having the first frequency.

16. Extracting second question information from the second modulated question signal, Based on the tag data, the second question information, and the first portion of the second modulated question signal, the second modulated response signal is generated. Transmitting the second modulated response signal via at least one of the antennas, The second portion of the second modulated interrogation signal is converted into a DC electrical signal for supplying power to the RFID tag, The method according to claim 15, further comprising:

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