Design methods, apparatus, equipment and storage media for frequency division multiplexing radio frequency identification tags

Abstract

This invention provides a design method, apparatus, device, and storage medium for frequency division multiplexing (FDM) RFID tags, relating to the field of RFID technology. The method includes: acquiring multiple FDM RFID chips and determining their corresponding operating frequency bands, where each operating frequency band is a sub-frequency band; determining target surface acoustic wave (SAW) filters that meet target quality factors based on a preset number of sub-frequency bands and the target operating frequency band of each RFID chip; directly matching the complex impedance of each target SAW filter to that of each RFID chip through matching networks; integrating each RFID chip, each target SAW filter, matching networks, and an antenna on an FR4 substrate to form each FDM RFID tag. Each tag responds only to the reader's excitation signal within a designated sub-frequency band to achieve FDM communication. This invention utilizes SAW filtering devices to achieve FDM multiplexing of different tags, thereby realizing parallel RFID communication.

Description

Technical Field

[0001] This invention relates to the field of radio frequency identification (RFID) technology, and in particular to a design method, apparatus, device, and storage medium for frequency division multiplexing (FDM) RFID tags. Background Technology

[0002] Radio Frequency Identification (RFID), renowned for its battery-free operation, offers a compelling solution for ubiquitous Internet of Things (IoT) applications. It has experienced explosive growth and widespread adoption in areas such as logistics, supply chain, warehouse management, and wireless sensing.

[0003] In many applications, such as industrial and logistics, real-time and high-throughput tag collection and grouped tag reading are crucial. For example, on high-speed production lines, such as electronics assembly lines, product components arrive in batches and in bursts, requiring the rapid reading of large numbers of tags within extremely short time windows (typically only milliseconds) to achieve real-time status updates. Furthermore, large logistics centers handle large volumes of incoming and outgoing goods, often transported by forklifts. Items entering and leaving in groups require RFID to accurately read tags within each group each time, without misreading tags from adjacent groups.

[0004] Current RFID methods use the Electronic Product Code (EPC) Gen-2 protocol to read tags one by one. However, traditional RFID tags have limited computing power and lack collision detection and avoidance capabilities. To avoid collisions from multiple RFID tags transmitting simultaneously, the EPC protocol requires exchanging a 16-bit random number (RN16) as a handshake process before reading the tag ID. To improve ID collection efficiency, existing methods primarily involve parallel RFID communication, allowing multiple tags to transmit information simultaneously. The reader then decodes conflicting signals to obtain the information transmitted by each tag. To accurately group and read multiple tags, existing methods either limit the antenna's operating range by designing special antennas to read tags only in a specific direction, or utilize RFID wireless sensing to group tags at different locations at the signal level.

[0005] However, existing methods cannot achieve true parallel RFID because the RN16 signal required by the EPC protocol means that tags can only transmit their RN16 data to the reader simultaneously for parallel reading. After that, the reader can only complete a handshake with one tag at a time, so only one tag can send its ID information at a time. Essentially, it is still time-division multiplexing rather than parallel communication.

[0006] Therefore, how to design frequency division multiplexing radio frequency identification tags to achieve parallel radio frequency identification communication has become a technical problem that urgently needs to be solved in the industry. Summary of the Invention

[0007] This invention provides a design method, apparatus, device, and storage medium for frequency division multiplexing (FDM) radio frequency identification (RFID) tags. By using surface acoustic wave (SAW) filtering devices, FDM of different tags can be realized, thereby enabling parallel RFID communication.

[0008] In a first aspect, the present invention provides a design method for a frequency division multiplexing radio frequency identification tag, the method comprising the following steps: Acquire multiple frequency division multiplexing RFID chips and determine the target operating frequency band of each RFID chip; the target operating frequency band is a sub-frequency band among multiple sub-frequency bands. Based on the preset number of sub-bands and the target operating frequency band of each RFID chip, each target surface acoustic wave (SAW) filter that meets the target quality factor is determined; the target SAW filter is a frequency-selective antenna; the target quality factor is determined by the resonant frequency and passband bandwidth, and the higher the value of the target quality factor, the more frequency division multiple access sub-bands the target SAW filter can be divided into. Each target surface acoustic wave (SAW) filter is directly matched to the complex impedance of each RFID chip through a matching network; the matching network is designed using radio frequency simulation software. Each of the RFID chips, each of the target surface acoustic wave (SAW) filters, the matching network, and the antenna are integrated on a glass fiber epoxy resin printed circuit FR4 substrate to form a frequency division multiplexing RFID tag; each tag corresponds to a different sub-frequency band, and each tag only responds to the reader's excitation signal in the designated sub-frequency band to achieve frequency division multiplexing communication.

[0009] According to the design method of the frequency division multiplexing radio frequency identification tag provided by the present invention, the complex impedance of each target surface acoustic wave (SAW) filter is directly matched with the complex impedance of each RFID chip through each matching network; the matching network is designed by radio frequency simulation software and includes: Based on the complex impedance of each RFID chip, the parameters of the parallel inductor in each target SAW filter are determined; the parallel inductor is used to integrate capacitance and inductance parameters to achieve direct matching of the complex impedances of each RFID chip and each target SAW filter; the number of matching network elements in the parallel inductor does not exceed two and no additional capacitor is required. A zigzag dipole antenna is used as the other end of each of the target surface acoustic wave (SAW) filters. The size of the zigzag dipole antenna is the same as that of a regular RFID antenna. The zigzag dipole antenna is used to adjust physical parameters so that the impedance of the zigzag dipole antenna matches the complex impedance of the target SAW filter.

[0010] According to the design method of the frequency division multiplexing radio frequency identification tag provided by the present invention, the target surface acoustic wave (SAW) filter that meets the target quality factor is determined based on the preset number of sub-frequency bands and the target operating frequency band of each RFID chip. The minimum value of the target quality factor is determined based on the center frequency range, the target operating frequency band of each RFID chip, and the number of preset sub-frequency bands; the target operating frequency band of each RFID chip is a sub-frequency band within the center frequency range. The first quality factor corresponding to each of the first surface acoustic filters is determined based on the resonant frequency and communication bandwidth of the preset number of first surface acoustic filters. Each of the first quality factors is compared with the minimum value of the target quality factor, and each of the target surface acoustic wave (SAW) filters is determined based on the first surface acoustic wave filter corresponding to the first quality factor greater than the minimum value.

[0011] According to the design method of the frequency division multiplexing radio frequency identification tag provided by the present invention, the target surface acoustic wave (SAW) filter realizes bidirectional filtering through a piezoelectric transducer to block radio frequency signals in non-operating frequency bands.

[0012] According to a design method for a frequency division multiplexing radio frequency identification tag provided by the present invention, the method further includes: Based on the roll-off characteristics of each target surface acoustic wave (SAW) filter, each tag sub-band is divided into a working area and a roll-off area; the reader operates within the working area of ​​each tag sub-band to avoid interference between roll-off area signals and adjacent frequency bands. Verify the frequency division multiplexing performance of each tag to ensure that the interference suppression between sub-bands is not lower than the preset threshold.

[0013] According to a design method for a frequency division multiplexing radio frequency identification tag provided by the present invention, the method further includes: The communication distance and signal stability of each tag were tested using the reader / writer. Adjust the power parameters of each tag to compensate for insertion loss.

[0014] Secondly, the present invention also provides a design apparatus for frequency division multiplexing radio frequency identification tags, the apparatus comprising the following modules: The filter antenna selection module is used to acquire multiple frequency division multiplexing RFID chips and determine the target operating frequency band of each RFID chip; the target operating frequency band is a sub-frequency band among multiple sub-frequency bands. Based on the preset number of sub-bands and the target operating frequency band of each RFID chip, each target surface acoustic wave (SAW) filter that meets the target quality factor is determined; the target SAW filter is a frequency-selective antenna; the target quality factor is determined by the resonant frequency and passband bandwidth, and the higher the value of the target quality factor, the more frequency division multiple access sub-bands the target SAW filter can be divided into. The filter antenna matching module is used to directly match the complex impedance of each target surface acoustic wave (SAW) filter with that of each RFID chip through each matching network; the matching network is designed by radio frequency simulation software. An integrated module is used to integrate each of the RFID chips, each of the target surface acoustic wave (SAW) filters, the matching network, and the antenna on a glass fiber epoxy resin printed circuit FR4 substrate to form each frequency division multiplexing RFID tag; each tag corresponds to a different sub-frequency band, and each tag responds to the excitation signal of the reader only in the designated sub-frequency band to realize frequency division multiplexing communication.

[0015] Thirdly, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the design method of the frequency division multiplexing radio frequency identification tag as described above.

[0016] Fourthly, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the design method of frequency division multiplexing radio frequency identification tag as described above.

[0017] Fifthly, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the design method of frequency division multiplexing radio frequency identification tag as described above.

[0018] The present invention provides a design method, apparatus, device, and storage medium for frequency division multiplexing (FDM) RFID tags. First, multiple FDM RFID chips are acquired, and the target operating frequency band of each RFID chip is determined. The target operating frequency band is a sub-band among multiple sub-frequency bands. Then, based on the preset number of sub-frequency bands and the target operating frequency band of each RFID chip, target surface acoustic wave (SAW) filters that meet the target quality factor are determined. The target SAW filters are frequency-selective antennas. The target quality factor is determined by the resonant frequency and passband bandwidth; the higher the target quality factor, the more FDM sub-frequency bands the target SAW filters can divide. Further, each target SAW filter is directly matched to the complex impedance of each RFID chip through a matching network, which is designed using RF simulation software. Finally, each RFID chip, each target SAW filter, the matching network, and the antenna are integrated on an FR4 substrate to form FDM RFID tags. Each tag corresponds to a different sub-frequency band, and each tag responds to the reader's excitation signal only within the designated sub-frequency band to achieve FDM communication.

[0019] This invention utilizes existing RFID tag chips and introduces passive filtering surface acoustic wave (SAW) devices and matching network designs to ensure that RFID tags only respond to excitation signals of specific frequencies. With the help of SAW filtering devices, frequency division multiplexing of different tags can be achieved, thereby realizing parallel RFID communication. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating the design method of the frequency division multiplexing radio frequency identification tag provided by the present invention.

[0022] Figure 2 This is a schematic diagram illustrating the application scenario of the frequency division multiplexing radio frequency identification tag provided by the present invention.

[0023] Figure 3 This is a schematic diagram of the principle of the surface acoustic wave filtering device and model provided by the present invention.

[0024] Figure 4 This is a schematic diagram comparing the working modes of traditional RFID tags and frequency division multiplexing RFID tags provided by the present invention.

[0025] Figure 5This is a schematic diagram comparing the decoupling matching network design provided by the present invention with the traditional impedance matching design.

[0026] Figure 6 This is a schematic diagram of impedance adjustment for a zigzag dipole antenna provided by the present invention.

[0027] Figure 7 This is a schematic diagram comparing the frequency response of the downlink excitation signal of the frequency division multiplexing RFID tag provided by the present invention with that of the traditional RFID tag.

[0028] Figure 8 This is a schematic diagram comparing the frequency response of the uplink reflected signal of the frequency division multiplexing RFID tag provided by this invention with that of a traditional RFID tag.

[0029] Figure 9 This is a schematic diagram of the passband loss and frequency band division of all types of frequency division multiplexing tags provided by this invention.

[0030] Figure 10 This is a schematic diagram of the design device for the frequency division multiplexing radio frequency identification tag provided by the present invention.

[0031] Figure 11 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0033] To address the aforementioned problems in existing technologies, this invention proposes a frequency-division multiplexing (FDM) RFID tag based on a frequency-selective antenna. This FDM RFID tag overcomes the time-division multiplexing limitations of traditional RFID tags, enabling frequency-division multiplexing and facilitating scenarios such as parallel frequency domain reading and group reading.

[0034] The following is combined with Figures 1-11 The present invention describes the design method, apparatus, device, and storage medium for frequency division multiplexing radio frequency identification tags.

[0035] Figure 1 This is a flowchart illustrating the design method of the frequency division multiplexing radio frequency identification tag provided by the present invention, as shown below. Figure 1 As shown, the method includes the following: Step 101: Obtain multiple frequency division multiplexing RFID chips and determine the target operating frequency band of each RFID chip; the target operating frequency band is a sub-frequency band among multiple sub-frequency bands; Specifically, it should first be noted that, Figure 2 This is a schematic diagram illustrating the application scenario of the frequency division multiplexing radio frequency identification tag provided by the present invention, such as... Figure 2 As shown, the RFID reader includes the F1-F5 frequency bands, sending excitation signals to the frequency division multiplexing (FDM) RFID tag. The tag responds only to signals within a specific frequency band, where Freq.Domain represents the frequency domain. This FDM RFID tag uses existing RFID tag chips, such as commercial RFID chips, and utilizes a frequency-selective antenna to respond only to excitation signals within a specific frequency band. Various types of this FDM RFID tag are equipped with different frequency-selective antennas, each responding only to excitations specific to its own frequency, all within the RFID frequency band (e.g., 902-928MHz). By using multiple commercial RFID readers configured on the specific frequencies of each FDM RFID tag, parallel reading of tags at different frequencies or group reading of tags can be achieved. It should be noted that the key to realizing the functionality of this FDM RFID tag lies in introducing a frequency-selective antenna while maintaining the battery-free and low-cost characteristics of RFID, namely, a fully passive, high-frequency selective filtering antenna.

[0036] Traditional tag antennas possess some filtering capability, but they cannot meet the high selectivity requirements of this frequency division multiplexing (FDM) RFID tag. We found that surface acoustic wave (SAW) filters can fulfill this requirement. Furthermore, to achieve optimal efficiency, we carefully fine-tuned the decoupling matching network on both ports of the SAW device. Analysis shows that this antenna has only a slight impact on the read distance performance of this FDM RFID tag. This FDM RFID tag maintains compatibility with conventional RFID systems because it is essentially a tag using a commercially available RFID chip. Commercial readers can read this FDM RFID tag using frequency hopping mechanisms or active frequency adjustment.

[0037] The design method of the frequency division multiplexing radio frequency identification tag provided by the present invention is described in detail below: First, acquire multiple frequency division multiplexing radio frequency identification (RFID) chips and determine the target operating frequency band of each RFID chip.

[0038] The selected RFID chip is any type of commercial RFID chip, such as NXP UCODE 7, and the printed circuit board (PCB) implementation is a packaged version.

[0039] RFID chips operate within the 902-928MHz ISM band. The Industrial, Scientific, and Medical (ISM) band refers to the wireless frequency band used for industrial, scientific research, and medical applications; 902-928MHz is the radio frequency identification (RFID) band. To enable frequency division multiplexing (FDM) for RFID tags, this RFID band needs to be divided into multiple sub-bands, and a single FDM RFID tag operates on only one of these sub-bands. That is, the target operating frequency band is also one of the sub-bands. For example, the target operating frequency band could be 902-907 MHz, or 908-913 MHz, or 914-919 MHz. Correspondingly, this requires the filter antenna selected in this invention to have high frequency selectivity.

[0040] Step 102: Based on the preset number of sub-bands and the target operating frequency band of each RFID chip, determine each target surface acoustic wave (SAW) filter that meets the target quality factor; the target SAW filter is a frequency-selective antenna; the target quality factor is determined by the resonant frequency and passband bandwidth. The higher the value of the target quality factor, the more frequency division multiple access sub-bands the target SAW filter can be divided into. Specifically, after determining the target operating frequency band of each RFID chip, i.e., the sub-frequency band corresponding to each RFID chip, it is necessary to further select a filtering antenna. The filtering antenna selected in this invention needs to have high frequency selectivity. Specifically, the requirements for selecting a filtering antenna that meets the requirements of this invention are as follows: 1. The filter antenna must have high frequency selectivity; 2. Size and cost: RFID applications require tags to be lightweight and easy to manufacture, and the filtering antennas must also meet the same requirements.

[0041] In frequency division multiplexing RFID tags, we use SAW filters to implement the antenna filtering function, and the target surface acoustic wave (SAW) filter is a frequency-selective antenna.

[0042] Radio frequency circuits require a certain resonant structure to achieve filtering capability, and their frequency selectivity is quantified by their quality factor (Q factor): in The resonant frequency, This represents the passband bandwidth, corresponding to the 3dB attenuation point. A higher Q value results in a steeper frequency response, allowing for the division of more FDMA sub-bands.

[0043] As can be seen from the above formula, the target quality factor is determined by the resonant frequency and the passband bandwidth. The higher the value of the target quality factor, the more frequency division multiple access sub-bands can be divided by the target surface acoustic wave (SAW) filter.

[0044] Therefore, in the design process of frequency division multiplexing RFID tags, the target surface acoustic wave (SAW) filters that meet the target quality factor can be determined according to the preset number of sub-bands and the target operating frequency band of each RFID chip. That is, the SAW filters corresponding to each tag are configured. For example, if 5 sub-bands are required, the tag needs to have a selectivity of less than 5 MHz (megahertz), corresponding to a Q value of at least 200 for the target quality factor.

[0045] Step 103: Directly match the complex impedance of each target SAW filter with each RFID chip through each matching network; the matching network is designed by radio frequency simulation software. Specifically, after selecting a target surface acoustic wave (SAW) filter as the filtering antenna, it is necessary to further apply the SAW filter to a frequency division multiplexing (FDM) RFID tag. It should be noted that in order to apply the aforementioned SAW device to the RFID tag, impedance matching with the integrated circuit (IC) chip must be achieved to maximize power transfer. Specifically, the impedance of the filtering antenna within the operating frequency band should be equal to the conjugate of the chip impedance; this precise matching is crucial in SAW-based filtering antennas.

[0046] The target surface acoustic wave (SAW) filter converts electrical energy into sound waves using a piezoelectric transducer. Figure 3 This is a schematic diagram of the principle of the surface acoustic wave filtering device and model provided by the present invention, as shown below. Figure 3 As shown in (a), a SAW filter made of piezoelectric material is observed from the input and output signals of sensor 1 and sensor 2. It can be seen that the transducer oscillates only when the RF signal approaches the resonant frequency, achieving a Q value as high as 1000. The corresponding inductors are Z1, C1, Z2, and C2, and resistors are R1 and R2. It also possesses bidirectional filtering capability, supporting uplink and downlink communication. Furthermore, the SAW filter is small (IC-level), low-cost, and simple to manufacture.

[0047] The target surface acoustic wave (SAW) filter achieves filtering through internal transducers. Each transducer consists of two interleaved metal electrodes, exhibiting parallel resistive-capacitive (RC) electrical characteristics, such as... Figure 3 As shown in (b), the two transducers are not physically connected, thus creating two different and independent capacitive impedances (Z1 and Z2) in the circuit. Furthermore, SAW devices operating at different frequencies will also produce different impedances due to differences in transducer structure. Figure 3(c) Shows characteristic examples (impedance values) of two SAW device series: SAW device B3934 has a resonant frequency of 902.8MHz, R1 is 400 ohms (Ω), C1 is 1.1pF, R2 is 380Ω, C2 is 1.2pF, Z1 is 55.3-138.1jΩ, and Z2 is 49.7-127.8jΩ; SAW device B3949 has a resonant frequency of 921.4MHz, R1 is 260Ω, C1 is 1.6pF, R2 is 270Ω, C2 is 1.3pF, Z1 is 38.2-92.1jΩ, and Z2 is 52.6-107.0jΩ.

[0048] Given this impedance inconsistency, a common design approach is to uniformly match both ends of the SAW device to 50 ohms. One end connects to a standard antenna, and the other end connects to the RFID chip via a matching circuit. However, this traditional matching method does not achieve optimal performance. The entire tag requires up to six matching components (capacitors, inductors), whose parasitic effects lead to significant energy loss. Furthermore, the presence of these components significantly increases the cost of mass production of the tag.

[0049] However, in this invention, the matching network is designed to directly match the complex impedance of the RFID chip and the SAW filter to achieve optimal performance of the SAW filter antenna. The matching network is designed using RF simulation software, for example, using the advanced design system software PathWave (Advanced Design System, ADS) to simulate an inductor-based matching network. ADS software is mainly used for the design, simulation, and analysis of RF, microwave, and millimeter-wave circuits. The inductor is from muRata, and its specific values ​​are optimized using ADS.

[0050] Step 104: Integrate each RFID chip, each target surface acoustic wave (SAW) filter, matching network, and antenna on the glass fiber epoxy resin printed circuit FR4 substrate to form each frequency division multiplexing RFID tag; each tag corresponds to a different sub-frequency band, and each tag only responds to the reader's excitation signal in the designated sub-frequency band to realize frequency division multiplexing communication.

[0051] Specifically, after completing the structural design of the filter antenna and its application in the tag, the aforementioned devices can be further integrated onto the FR4 substrate to generate frequency division multiplexing RFID tags.

[0052] For example, RFID chips, surface acoustic wave (SAW) filters for each target, matching networks, and antennas are integrated on an FR4 substrate to form frequency division multiplexing (FDM) RFID tags. Different tags correspond to different sub-frequency bands, each measuring 100mm × 20mm. These tags are all passively designed and require no external power source. Different tags respond to the reader's excitation signal only within their designated sub-frequency band to achieve FDM communication. More specifically, each tag responds only to the excitation signal within one frequency band, thus realizing FDM for different tags.

[0053] Figure 4 This is a schematic diagram comparing the working modes of traditional RFID tags and frequency division multiplexing RFID tags provided by the present invention. Figure 4 (a) illustrates the working mode of a traditional RFID tag. Figure 4 (b) demonstrates the working mode of the frequency division multiplexing radio frequency identification tag.

[0054] Traditional RFID tags consist of a fixed IC chip and a customizable antenna. Due to power consumption limitations, the chip does not have the ability to distinguish carrier frequencies. Therefore, traditional RFID tags operate across the entire radio frequency identification band (typically 902-928MHz), and any carrier signal within the band will excite the traditional tag and be reflected and modulated by it, thus modulating the tag's data.

[0055] The frequency division multiplexing (FDM) RFID tag of this invention adds a highly selective passive filter antenna to a conventional IC chip, selectively exciting and reflecting radio frequency (RF) signals within a narrow band. Specifically, the filter antenna allows RF signals to enter and exit the IC chip within its operating frequency band, while blocking RF signals outside the operating frequency band. Thus, only a carrier signal with the correct frequency can excite the FDM RFID tag and transmit information to it. When the FDM RFID tag reflects and modulates data, the signal modulated is only on this carrier signal.

[0056] The method provided in this embodiment first acquires multiple frequency division multiplexing (FDM) RFID chips and determines the target operating frequency band of each RFID chip. The target operating frequency band is a sub-frequency band among multiple sub-frequency bands. Then, based on the preset number of sub-frequency bands and the target operating frequency band of each RFID chip, each target surface acoustic wave (SAW) filter that meets the target quality factor is determined. The target SAW filter is a frequency-selective antenna. The target quality factor is determined by the resonant frequency and passband bandwidth. The higher the value of the target quality factor, the more FDM sub-frequency bands the target SAW filter can be divided into. Further, each target SAW filter is directly matched with the complex impedance of each RFID chip through each matching network. This matching network is designed by radio frequency simulation software. Finally, each RFID chip, each target SAW filter, the matching network, and the antenna are integrated on an FR4 substrate to form each FDM RFID tag. Each tag corresponds to a different sub-frequency band, and each tag only responds to the reader's excitation signal within the specified sub-frequency band to achieve FDM communication.

[0057] This invention utilizes existing RFID tag chips and introduces passive filtering surface acoustic wave (SAW) devices and matching network designs to ensure that RFID tags only respond to excitation signals of specific frequencies. With the help of SAW filtering devices, frequency division multiplexing of different tags can be achieved, thereby realizing parallel RFID communication.

[0058] According to the design method of the frequency division multiplexing radio frequency identification tag provided by the present invention, the complex impedance of each target surface acoustic wave (SAW) filter and each RFID chip is directly matched through each matching network; the matching network is designed by radio frequency simulation software and includes: Based on the complex impedance of each RFID chip, the parameters of the parallel inductor in each target SAW filter are determined; the parallel inductor is used to integrate the capacitance and inductance parameters to achieve direct matching of the complex impedance between each RFID chip and each target SAW filter; the number of matching network elements in the parallel inductor does not exceed two and no additional capacitor is required. The zigzag dipole antenna serves as the other end of the surface acoustic wave (SAW) filter for each target. The size of the zigzag dipole antenna is the same as that of a regular RFID antenna. The zigzag dipole antenna is used to adjust the physical parameters so that the impedance of the zigzag dipole antenna matches the complex impedance of the target SAW filter.

[0059] Specifically, in some embodiments, the design process of the matching network in step 103 is implemented through the following steps: In frequency division multiplexing RFID tags, we designed a decoupling matching network to achieve optimal performance of the SAW filter antenna by directly matching the complex impedance.

[0060] Figure 5 This is a schematic diagram comparing the decoupling matching network design provided by the present invention with the traditional impedance matching design. Figure 5 (a) shows a schematic diagram of a conventional matching design under standard 50Ω. Figure 5 (b) shows a schematic diagram of the network design for decoupling matching, such as Figure 5 As shown in (a), the system includes capacitors F1 and F2, and inductors R1 and R2. The matching path from the RFID IC chip to the SAW in the figure contains redundant curves; the impedance point of the SAW represents the conjugate of its complex impedance. Eliminating redundant matching simplifies the design of the matching network and reduces the number of matching components. Unlike equating both ends to 50 ohms (Ω), this invention directly matches the complex impedance at both ends. For example... Figure 5 As shown in (b), capacitors F1 and F2, along with inductor R2, are integrated into a single parallel inductor R2 to achieve matching between the chip and the SAW. Then, the 50-ohm antenna at the other end of the SAW is replaced with a zigzag dipole antenna, which has a 2dBi gain and is comparable in size to a standard RFID antenna. Its physical parameters are adjusted to precisely match the impedance of the SAW. Ultimately, optimal matching is achieved using only two inductors.

[0061] Specifically, firstly, based on the complex impedance of each RFID chip, the parameters of the parallel inductor in each target SAW filter are determined. The parallel inductor integrates the capacitance and inductance parameters to achieve direct complex impedance matching between each RFID chip and each target SAW filter. The number of matching network elements in the parallel inductor does not exceed two, and no additional capacitors are required. Figure 5 As shown in (b), capacitors F1 and F2 and inductor W2 are integrated into a single parallel inductor element W2, and the parameters of the parallel inductor element are adjusted to achieve direct matching between the chip and the SAW.

[0062] Furthermore, the tortuous dipole antenna is used as the other end of the surface acoustic wave (SAW) filter for each target; that is, the 50-ohm antenna at the other end is replaced with... Figure 6 The diagram shows a zigzag dipole antenna. The dimensions of the zigzag dipole antenna are the same as those of a standard RFID antenna. Figure 6 This is a schematic diagram of impedance adjustment for a tortuous line dipole antenna provided by the present invention, as shown below. Figure 6 As shown, by adjusting the physical parameters of the zigzag dipole antenna, such as W... i S i To make the zircon dipole antenna (such as the impedance fine-tuning antenna Z) A The impedance of the surface acoustic wave filter is precisely matched with the complex impedance of the surface acoustic wave filter.

[0063] This invention uses RF simulation and full-wave analysis software to construct and simulate the frequency-selective antenna of the tag. For example, a commercially available Qualcomm SAW filter B3300 is used as the filtering device. After optimizing the inductor matching and fine-tuning the dipole antenna, the antenna operates at 916.5MHz with a passband of approximately 1.6MHz.

[0064] Figure 7 This is a schematic diagram comparing the frequency response of the downlink excitation signal of the frequency division multiplexing (FDM) RFID tag provided by this invention with that of a traditional RFID tag, as shown in the figure. Figure 7 As shown, Figure 7 The responses of frequency division multiplexing (FDM) tags and RFID tags to excitation signals (or downlink signals) were compared. FDM tags respond to excitation signals only within a specific frequency band, while RFID tags respond to excitation signals across the entire frequency band. The figure shows that the FDM tag only responds to excitation signals in its operating frequency band, and the roll band does not respond.

[0065] Because the tag chip achieves binary amplitude keying (OOK) modulation by adjusting the absorption and reflection states. Figure 8 This is a schematic diagram comparing the frequency response of the uplink reflected signal of the frequency division multiplexing (FDM) RFID tag provided by this invention with that of a traditional RFID tag, as shown in the figure. Figure 8 As shown, the reflection frequency response of the two types of tags under two states is illustrated. It can be seen that the frequency division multiplexing (FDM) RFID tag achieves frequency selection in uplink and downlink communication through the SAW filter antenna, while the reflection amplitude of traditional tags is smaller.

[0066] The method provided in this embodiment first determines the parameters of the parallel inductor in each target SAW filter based on the complex impedance of each RFID chip. The parallel inductor integrates capacitance and inductance parameters to achieve direct impedance matching between the RFID chip and the target SAW filter. The number of matching network elements in the parallel inductor does not exceed two, and no additional capacitor is required. Then, a zigzag dipole antenna is used as the other end of each target SAW filter. The zigzag dipole antenna has the same dimensions as a regular RFID antenna and is used to adjust physical parameters to match its impedance with the complex impedance of the target SAW filter. This invention designs a decoupling matching network that achieves optimal performance for the SAW filter antenna by directly matching the complex impedance of the RFID chip and the target SAW filter.

[0067] According to the design method of the frequency division multiplexing radio frequency identification tag provided by the present invention, the target surface acoustic wave (SAW) filters that meet the target quality factor are determined based on the preset number of sub-frequency bands and the target operating frequency band of each RFID chip. The minimum value of the target quality factor is determined based on the center frequency range, the target operating frequency band of each RFID chip, and the number of preset sub-frequency bands; the target operating frequency band of each RFID chip is a sub-frequency band within the center frequency range. The first quality factor corresponding to each first surface acoustic wave filter is determined based on the resonant frequency and communication bandwidth of the preset number of first surface acoustic wave filters. Each first quality factor is compared with the minimum value of the target quality factor, and each target surface acoustic wave (SAW) filter is determined based on the first surface acoustic wave filter corresponding to the first quality factor greater than the minimum value.

[0068] Specifically, in some embodiments, the process of configuring the SAW filter in step 102 is exemplified as follows: First, based on the center frequency range, the target operating frequency band of each RFID chip, and the number of preset sub-frequency bands, determine the minimum value of the target quality factor. The center frequency range is the entire operating frequency band of radio frequency identification (902-928MHz), and the target operating frequency band of each RFID chip is a sub-band within the center frequency range. According to formula (1), the higher the quality factor Q value, the steeper the frequency response, thus enabling the division of more FDMA sub-bands. Therefore, the minimum quality factor can be determined based on the planned number of sub-bands. For example, if 5 sub-bands need to be implemented in parallel, the frequency division multiplexing tag needs to have a selectivity of less than 5MHz, corresponding to a Q value of at least 200.

[0069] Furthermore, based on the resonant frequencies and communication bandwidths corresponding to a preset number of first surface acoustic wave (SAW) filters, the first quality factor corresponding to each SAW filter is determined. For example, if there are currently 10 selectable filters, their respective first quality factors need to be calculated by substituting them into formula (1).

[0070] Each first quality factor is compared with the minimum value of the target quality factor, and each target SAW filter is determined based on the first quality factor corresponding to the first surface acoustic wave (SAW) filter that is greater than the minimum value. For example, a first SAW filter with a first quality factor greater than 200 is determined as a usable target SAW filter and used as a filter antenna in a frequency division multiplexing tag to achieve frequency selection.

[0071] The method provided in this embodiment first determines the minimum value of the target quality factor based on the center frequency range, the target operating frequency band of each RFID chip, and the preset number of sub-frequency bands; the target operating frequency band of each RFID chip is a sub-frequency band within the center frequency range; then, based on the resonant frequencies and communication bandwidths corresponding to a preset number of first surface acoustic wave (SAW) filters, the first quality factor corresponding to each first SAW filter is determined; furthermore, each first quality factor is compared with the minimum value of the target quality factor, and each target SAW filter is determined based on the first quality factor corresponding to the first SAW filter with a first quality factor greater than the minimum value. This invention uses existing RFID tag chips and achieves frequency selection through a frequency-selective antenna (surface acoustic wave filter), enabling different tags to respond only to excitation signals within a specific frequency band, thus achieving parallel frequency division multiplexing communication.

[0072] According to the design method of the frequency division multiplexing radio frequency identification tag provided by the present invention, the target surface acoustic wave (SAW) filter realizes bidirectional filtering through a piezoelectric transducer to block radio frequency signals in non-operating frequency bands.

[0073] Specifically, the target surface acoustic wave (SAW) filter in this invention achieves bidirectional filtering through a piezoelectric transducer to block radio frequency signals in non-operating frequency bands. The core of this method lies in utilizing the propagation characteristics of sound waves, the structural design of the interdigital transducer (IDT), and the piezoelectric effect of the material. The following are the detailed steps of its implementation process: (1) Signal input and electro-acoustic conversion Input signal: The radio frequency signal is applied to the piezoelectric substrate (such as lithium niobate) through the IDT (interdigital transducer) at the input terminal.

[0074] Electro-acoustic conversion: The interleaved electrodes of the IDT excite surface acoustic waves (SAW) on the surface of the piezoelectric material, and the frequency is determined by the electrode spacing (λ) of the IDT and the sound velocity (v) of the material (f0=v / λ).

[0075] (2) Sound wave propagation and frequency selection Sound wave path: The sound wave propagates along the surface of the substrate to the output terminal IDT. During the propagation, the sound wave energy in the non-operating frequency band is attenuated or reflected.

[0076] Frequency selectivity: Operating frequency band: The frequency corresponding to the wavelength (λ) of the acoustic wave that matches the IDT electrode spacing is transmitted efficiently. Non-operating frequency band: Acoustic waves with mismatched wavelengths are suppressed due to phase mismatch or reflection.

[0077] (3) Sound-to-electric conversion and output The output IDT converts the sound waves back into electrical signals, retaining only the signals in the operating frequency band and filtering out energy in the non-operating frequency band.

[0078] SAW filters achieve highly efficient suppression of non-operating frequency bands during bidirectional propagation through techniques such as IDT structure optimization (symmetrical design, apodized weighting), reflective grating blocking, cascaded filtering, and temperature compensation. Their core lies in utilizing the wavelength selectivity of sound waves and the energy conversion characteristics of piezoelectric materials, combined with precision manufacturing processes to ensure high-frequency stability. In the future, with the development of new materials (such as diamond substrates) and integration technologies (such as SiP), SAW filters will continue to play a crucial role in 5G / 6G communications.

[0079] The method provided in this embodiment achieves bidirectional filtering through a piezoelectric transducer in the target surface acoustic wave (SAW) filter, blocking radio frequency signals in non-operating frequency bands, thereby obtaining a frequency division multiplexed radio frequency identification tag.

[0080] According to the present invention, a design method for a frequency division multiplexing radio frequency identification tag is provided, the method further includes: Based on the roll-off characteristics of the surface acoustic wave (SAW) filters of each target, each tag sub-band is divided into a working area and a roll-off area; the reader operates within the working area of ​​each tag sub-band to avoid interference between roll-off area signals and adjacent frequency bands. Verify the frequency division multiplexing performance of each tag to ensure that the interference suppression between sub-bands is not lower than the preset threshold.

[0081] Specifically, it's important to understand that the capacity of FDMA depends on the number of sub-bands into which the RFID frequency band is divided, while also requiring no interference between the bands. Although the SAW filter has a steep frequency response, it is not an ideal rectangle and exhibits a roll-off as the frequency moves away from the resonant frequency.

[0082] Therefore, the frequency band of the frequency division multiplexing tag needs to be divided into a working area and a roll-off area, such as Figure 7 As shown. Readers should avoid reading tags in the roll-off area to prevent potential interference with adjacent sub-bands.

[0083] The method further includes: Based on the roll-off characteristics of the surface acoustic wave (SAW) filters for each target, each tag's sub-frequency band is divided into a working area and a roll-off area. The reader operates within the working area of ​​each tag's sub-frequency band to avoid interference from the roll-off area signal to adjacent frequency bands. The frequency division multiplexing performance of each tag is verified to ensure that the interference suppression between sub-frequency bands is not lower than a preset threshold, such as 30dB.

[0084] Figure 9 This is a schematic diagram showing the passband loss and frequency band division of all types of frequency division multiplexing tags provided by this invention, as follows: Figure 9 As shown, Figure 9 The data includes labels F1, F2, F3, F4, and F5, corresponding to frequency bands F1, F2, F3, F4, and F5. The corresponding passband loss is shown in the figure. There is more than 30dB of interference suppression between different frequency bands.

[0085] The method provided in this embodiment divides the frequency band of a frequency division multiplexing tag into a working area and a roll-off area. The reader operates within the working area of ​​each tag's sub-frequency band to avoid interference between roll-off area signals and adjacent frequency bands.

[0086] According to the present invention, a design method for a frequency division multiplexing radio frequency identification tag is provided, the method further includes: The communication distance and signal stability of each tag were tested using a reader / writer. Adjust the power parameters of each tag to compensate for insertion loss.

[0087] Specifically, in some embodiments, the method further includes: The communication distance and signal stability of each frequency division multiplexing tag were tested using a reader / writer. Based on the test results, the power parameters of each tag were further adjusted to compensate for insertion loss.

[0088] SAW filter antennas offer excellent frequency selectivity, but inevitably introduce approximately 3dB of insertion loss, potentially affecting tag reading distance. However, the filtering characteristics can partially offset this loss. The reading distance of an RFID system is primarily determined by downlink communication. At critical distances, the reader can still activate the tag and receive its backscattered signal, but the tag cannot demodulate downlink commands. This is because broadband noise introduced along with the signal creates self-mixing noise in the tag's envelope detection. The broadband characteristics of traditional tags result in thermal noise up to 100MHz, while frequency division multiplexing (FDM) tags effectively filter this noise to approximately 2MHz using a filter antenna, increasing downlink detectable power by about 2dB. While this cannot completely offset the reduced distance, it still ensures acceptable communication range in RFID applications.

[0089] For example, the test procedure for multi-band concurrent bit error rate testing is as follows: 1. Activate multiple frequency bands simultaneously via the reader (e.g., 4 frequency bands: 915 MHz, 920 MHz, 925 MHz, 930 MHz).

[0090] 2. Send known data packets (such as EPC codes) to the tag via a reader / writer and calculate the bit error rate.

[0091] 3. Gradually increase the number of frequency bands (up to the capacity limit) and record the BER changes.

[0092] Optimization strategy: If the BER increases significantly with the number of frequency bands, the demodulation circuit of the tag or the time slot allocation algorithm of the reader needs to be optimized.

[0093] For example, the test procedure for label dynamic range testing is as follows: 1. Set a power difference between adjacent frequency bands (e.g., +30 dBm for band A and +27 dBm for band B).

[0094] 2. Verify whether the success rate of the tag's response in frequency band A is affected by the power in frequency band B.

[0095] Tolerance standards: When the power difference is ±3dB, the tag response success rate decreases by ≤5%.

[0096] The method provided in this embodiment can test the communication distance and signal stability of each tag using a reader / writer, thereby improving tag performance.

[0097] The design apparatus for frequency division multiplexing (FDM) RFID tags provided by the present invention is described below. The design apparatus for FDM RFID tags described below can be referred to in correspondence with the design method for FDM RFID tags described above.

[0098] Figure 10 This is a schematic diagram of the design device for the frequency division multiplexing radio frequency identification tag provided by the present invention, as shown below. Figure 10 As shown, the design device 1000 for the frequency division multiplexing radio frequency identification tag includes the following modules: The filter antenna selection module 1010 is used to acquire multiple frequency division multiplexing RFID chips and determine the target operating frequency band of each RFID chip; the target operating frequency band is a sub-frequency band among multiple sub-frequency bands. Based on the preset number of sub-bands and the target operating frequency band of each RFID chip, each target surface acoustic wave (SAW) filter that meets the target quality factor is determined; the target SAW filter is a frequency-selective antenna; the target quality factor is determined by the resonant frequency and passband bandwidth, and the higher the value of the target quality factor, the more frequency division multiple access sub-bands the target SAW filter can be divided into. The filter antenna matching module 1020 is used to directly match the complex impedance of each target surface acoustic wave (SAW) filter with that of each RFID chip through each matching network; the matching network is designed by radio frequency simulation software. The integrated module 1030 is used to integrate each of the RFID chips, each of the target surface acoustic wave (SAW) filters, the matching network, and the antenna on a glass fiber epoxy resin printed circuit FR4 substrate to form each frequency division multiplexing RFID tag; each tag corresponds to a different sub-frequency band, and each tag only responds to the excitation signal of the reader in the designated sub-frequency band to realize frequency division multiplexing communication.

[0099] The device provided in this embodiment includes a filter antenna selection module, a filter antenna matching module, and an integration module. First, the filter antenna selection module acquires multiple frequency division multiplexing RFID chips and determines the target operating frequency band for each RFID chip. The target operating frequency band is a sub-band among multiple sub-frequency bands. Then, based on the preset number of sub-frequency bands and the target operating frequency band of each RFID chip, it determines target surface acoustic wave (SAW) filters that meet the target quality factor. The target SAW filters are frequency-selective antennas, and the target quality factor is determined by the resonant frequency and passband bandwidth. A higher target quality factor value indicates a better quality. The target surface acoustic wave (SAW) filter can be divided into more frequency division multiple access (FDMA) sub-bands. Furthermore, the filter antenna matching module directly matches the complex impedance of each target SAW filter with that of each RFID chip through each matching network, which is designed using RF simulation software. Then, the integration module integrates each RFID chip, each target SAW filter, the matching network, and the antenna on the FR4 substrate to form each FDMA RFID tag. Each tag corresponds to a different sub-band, and each tag only responds to the reader's excitation signal within the designated sub-band to achieve FDMA communication.

[0100] This invention utilizes existing RFID tag chips and introduces passive filtering surface acoustic wave (SAW) devices and matching network designs to ensure that RFID tags only respond to excitation signals of specific frequencies. With the help of SAW filtering devices, frequency division multiplexing of different tags can be achieved, thereby realizing parallel RFID communication.

[0101] According to the design apparatus 1000 for a frequency division multiplexing radio frequency identification tag provided by the present invention, the filter antenna matching module 1020 is specifically used for: Based on the complex impedance of each RFID chip, the parameters of the parallel inductor in each target surface acoustic wave (SAW) filter are determined; the parallel inductor is used to integrate capacitance and inductance parameters to achieve direct matching of the complex impedances of each RFID chip and each target SAW filter; the number of matching network elements in the parallel inductor does not exceed two and no additional capacitor is required. A zigzag dipole antenna is used as the other end of each of the target surface acoustic wave (SAW) filters. The size of the zigzag dipole antenna is the same as that of a regular RFID antenna. The zigzag dipole antenna is used to adjust physical parameters so that the impedance of the zigzag dipole antenna matches the complex impedance of the target SAW filter.

[0102] According to the design apparatus 1000 for frequency division multiplexing radio frequency identification tags provided by the present invention, the filter antenna selection module 1010 is specifically used for: The minimum value of the target quality factor is determined based on the center frequency range, the target operating frequency band of each RFID chip, and the number of preset sub-frequency bands; the target operating frequency band of each RFID chip is a sub-frequency band within the center frequency range. The first quality factor corresponding to each of the first surface acoustic filters is determined based on the resonant frequency and communication bandwidth of the preset number of first surface acoustic filters. Each of the first quality factors is compared with the minimum value of the target quality factor, and each of the target surface acoustic wave (SAW) filters is determined based on the first surface acoustic wave filter corresponding to the first quality factor greater than the minimum value.

[0103] According to the present invention, a design device 1000 for a frequency division multiplexing radio frequency identification tag is provided, wherein the target surface acoustic wave (SAW) filter achieves bidirectional filtering through a piezoelectric transducer to block radio frequency signals in non-operating frequency bands.

[0104] According to the present invention, a design device 1000 for a frequency division multiplexing radio frequency identification tag is provided, the device further comprising an interference avoidance module; The interference avoidance module is used for: Based on the roll-off characteristics of each target surface acoustic wave (SAW) filter, each tag sub-band is divided into a working area and a roll-off area; the reader operates within the working area of ​​each tag sub-band to avoid interference between roll-off area signals and adjacent frequency bands. Verify the frequency division multiplexing performance of each tag to ensure that the interference suppression between sub-bands is not lower than the preset threshold.

[0105] According to the present invention, a design device 1000 for a frequency division multiplexing radio frequency identification tag is provided, the device further comprising a testing module; The test module is used for: The communication distance and signal stability of each tag were tested using the reader / writer. Adjust the power parameters of each tag to compensate for insertion loss.

[0106] Figure 11 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 11 As shown, the electronic device may include: a processor 1110, a communications interface 1120, a memory 1130, and a communication bus 1140, wherein the processor 1110, the communications interface 1120, and the memory 1130 communicate with each other via the communication bus 1140. The processor 1110 can call logic instructions in the memory 1130 to execute a design method for a frequency division multiplexing (FDM) RFID tag, the method including: Acquire multiple frequency division multiplexing RFID chips and determine the target operating frequency band of each RFID chip; the target operating frequency band is a sub-frequency band among multiple sub-frequency bands; Based on the preset number of sub-bands and the target operating frequency band of each RFID chip, each target surface acoustic wave (SAW) filter that meets the target quality factor is determined; the target SAW filter is a frequency-selective antenna; the target quality factor is determined by the resonant frequency and passband bandwidth, and the higher the value of the target quality factor, the more frequency division multiple access sub-bands the target SAW filter can be divided into. Each target surface acoustic wave (SAW) filter is directly matched to the complex impedance of each RFID chip through a matching network; the matching network is designed using radio frequency simulation software. Each of the RFID chips, each of the target surface acoustic wave (SAW) filters, the matching network, and the antenna are integrated on a glass fiber epoxy resin printed circuit FR4 substrate to form a frequency division multiplexing RFID tag; each tag corresponds to a different sub-frequency band, and each tag only responds to the reader's excitation signal in the designated sub-frequency band to achieve frequency division multiplexing communication.

[0107] Furthermore, the logical instructions in the aforementioned memory 1130 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0108] On the other hand, the present invention also provides a computer program product, the computer program product comprising a computer program that can be stored on a non-transitory computer-readable storage medium, wherein when the computer program is executed by a processor, the computer is able to execute the design method for frequency division multiplexing radio frequency identification tags provided by the above methods, the method comprising: Acquire multiple frequency division multiplexing RFID chips and determine the target operating frequency band of each RFID chip; the target operating frequency band is a sub-frequency band among multiple sub-frequency bands; Based on the preset number of sub-bands and the target operating frequency band of each RFID chip, each target surface acoustic wave (SAW) filter that meets the target quality factor is determined; the target SAW filter is a frequency-selective antenna; the target quality factor is determined by the resonant frequency and passband bandwidth, and the higher the value of the target quality factor, the more frequency division multiple access sub-bands the target SAW filter can be divided into. Each target surface acoustic wave (SAW) filter is directly matched to the complex impedance of each RFID chip through a matching network; the matching network is designed using radio frequency simulation software. Each of the RFID chips, each of the target surface acoustic wave (SAW) filters, the matching network, and the antenna are integrated on a glass fiber epoxy resin printed circuit FR4 substrate to form a frequency division multiplexing RFID tag; each tag corresponds to a different sub-frequency band, and each tag only responds to the reader's excitation signal in the designated sub-frequency band to achieve frequency division multiplexing communication.

[0109] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a design method for frequency division multiplexing radio frequency identification tags provided by the methods described above, the method comprising: Acquire multiple frequency division multiplexing RFID chips and determine the target operating frequency band of each RFID chip; the target operating frequency band is a sub-frequency band among multiple sub-frequency bands; Based on the preset number of sub-bands and the target operating frequency band of each RFID chip, each target surface acoustic wave (SAW) filter that meets the target quality factor is determined; the target SAW filter is a frequency-selective antenna; the target quality factor is determined by the resonant frequency and passband bandwidth, and the higher the value of the target quality factor, the more frequency division multiple access sub-bands the target SAW filter can be divided into. Each target surface acoustic wave (SAW) filter is directly matched to the complex impedance of each RFID chip through a matching network; the matching network is designed using radio frequency simulation software. Each of the RFID chips, each of the target surface acoustic wave (SAW) filters, the matching network, and the antenna are integrated on a glass fiber epoxy resin printed circuit FR4 substrate to form a frequency division multiplexing RFID tag; each tag corresponds to a different sub-frequency band, and each tag only responds to the reader's excitation signal in the designated sub-frequency band to achieve frequency division multiplexing communication.

[0110] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0111] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for a frequency division multiplexing radio frequency identification tag, characterized in that, include: Acquire multiple frequency division multiplexing RFID chips and determine the target operating frequency band of each RFID chip; the target operating frequency band is a sub-frequency band among multiple sub-frequency bands. Based on the preset number of sub-bands and the target operating frequency band of each RFID chip, determine each target surface acoustic wave (SAW) filter that meets the target quality factor. The target surface acoustic wave (SAW) filter is a frequency-selective antenna; the target quality factor is determined by the resonant frequency and passband bandwidth. The higher the value of the target quality factor, the more frequency division multiple access sub-bands the target SAW filter can be divided into. Each target surface acoustic wave (SAW) filter is directly matched to the complex impedance of each RFID chip through a matching network; the matching network is designed using radio frequency simulation software. Each of the RFID chips, each of the target surface acoustic wave (SAW) filters, the matching network, and the antenna are integrated on a glass fiber epoxy resin printed circuit FR4 substrate to form a frequency division multiplexing RFID tag; each tag corresponds to a different sub-frequency band, and each tag only responds to the reader's excitation signal in the designated sub-frequency band to achieve frequency division multiplexing communication.

2. The design method for frequency division multiplexing radio frequency identification tags according to claim 1, characterized in that, The method involves directly matching the complex impedance of each target surface acoustic wave (SAW) filter with that of each RFID chip using matching networks. These matching networks are designed using radio frequency simulation software and include: Based on the complex impedance of each RFID chip, the parameters of the parallel inductor in each target SAW filter are determined; the parallel inductor is used to integrate capacitance and inductance parameters to achieve direct matching of the complex impedances of each RFID chip and each target SAW filter; the number of matching network elements in the parallel inductor does not exceed two and no additional capacitor is required. A zigzag dipole antenna is used as the other end of each of the target surface acoustic wave (SAW) filters. The size of the zigzag dipole antenna is the same as that of a regular RFID antenna. The zigzag dipole antenna is used to adjust physical parameters so that the impedance of the zigzag dipole antenna matches the complex impedance of the target SAW filter.

3. The design method for frequency division multiplexing radio frequency identification tags according to claim 1, characterized in that, The step involves determining each target surface acoustic wave (SAW) filter that meets the target quality factor based on the preset number of sub-bands and the target operating frequency band of each RFID chip. The minimum value of the target quality factor is determined based on the center frequency range, the target operating frequency band of each RFID chip, and the number of preset sub-frequency bands; the target operating frequency band of each RFID chip is a sub-frequency band within the center frequency range. The first quality factor corresponding to each of the first surface acoustic filters is determined based on the resonant frequency and communication bandwidth of the preset number of first surface acoustic filters. Each of the first quality factors is compared with the minimum value of the target quality factor, and each of the target surface acoustic wave (SAW) filters is determined based on the first surface acoustic wave filter corresponding to the first quality factor greater than the minimum value.

4. The design method for frequency division multiplexing radio frequency identification tags according to claim 1, characterized in that, The target surface acoustic wave (SAW) filter uses a piezoelectric transducer to achieve bidirectional filtering, blocking radio frequency signals in non-operating frequency bands.

5. The design method for frequency division multiplexing radio frequency identification tags according to claim 1, characterized in that, The method further includes: Based on the roll-off characteristics of each target surface acoustic wave (SAW) filter, each tag sub-band is divided into a working area and a roll-off area; the reader operates within the working area of ​​each tag sub-band to avoid interference between roll-off area signals and adjacent frequency bands. Verify the frequency division multiplexing performance of each tag to ensure that the interference suppression between sub-bands is not lower than the preset threshold.

6. The design method for frequency division multiplexing radio frequency identification tags according to claim 1, characterized in that, The method further includes: The communication distance and signal stability of each tag were tested using the reader / writer. Adjust the power parameters of each tag to compensate for insertion loss.

7. A design device for a frequency division multiplexing radio frequency identification tag, characterized in that, include: The filter antenna selection module is used to acquire multiple frequency division multiplexing RFID chips and determine the target operating frequency band of each RFID chip; the target operating frequency band is a sub-frequency band among multiple sub-frequency bands. Based on the preset number of sub-bands and the target operating frequency band of each RFID chip, determine each target surface acoustic wave (SAW) filter that meets the target quality factor. The target surface acoustic wave (SAW) filter is a frequency-selective antenna; the target quality factor is determined by the resonant frequency and passband bandwidth. The higher the value of the target quality factor, the more frequency division multiple access sub-bands the target SAW filter can be divided into. The filter antenna matching module is used to directly match the complex impedance of each target surface acoustic wave (SAW) filter with that of each RFID chip through each matching network; the matching network is designed by radio frequency simulation software. An integrated module is used to integrate each of the RFID chips, each of the target surface acoustic wave (SAW) filters, the matching network, and the antenna on a glass fiber epoxy resin printed circuit FR4 substrate to form each frequency division multiplexing RFID tag; each tag corresponds to a different sub-frequency band, and each tag responds to the excitation signal of the reader only in the designated sub-frequency band to realize frequency division multiplexing communication.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the design method of the frequency division multiplexing radio frequency identification tag as described in any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the design method of the frequency division multiplexing radio frequency identification tag as described in any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the design method of the frequency division multiplexing radio frequency identification tag as described in any one of claims 1 to 6.

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