CN104331568A - Method for implementing RFID (radio frequency identification) field strength simulation model - Google Patents

Abstract

Translated fromChinese

本发明公开了一种实现RFID场强仿真模型的方法，包括如下步骤：将RFID发送端电路等效成具有内阻的信号源；将RFID发送端电路等效成具有读写器天线和源阻抗的电路；将RFID标签电路等效成具有标签天线和标签阻抗的电路；通过基尔霍夫电压定律获得标签上的电流电压的耦合系数。通过本发明实施例，该模型能够提供精确仿真，从而模拟出真正的工作模式，从而可以加大研发进度和产品的成功率。

The invention discloses a method for realizing an RFID field strength simulation model, which comprises the following steps: equating the RFID sending end circuit to a signal source with internal resistance; The circuit of the RFID tag is equivalent to a circuit with tag antenna and tag impedance; the coupling coefficient of the current voltage on the tag is obtained by Kirchhoff's voltage law. Through the embodiment of the present invention, the model can provide accurate simulation, thereby simulating a real working mode, thereby increasing the research and development progress and the success rate of products.

Description

Translated fromChinese

一种实现RFID场强仿真模型的方法A method for realizing RFID field strength simulation model

技术领域technical field

本发明涉及RFID技术领域，具体涉及一种实现RFID场强仿真模型的方法。The invention relates to the field of RFID technology, in particular to a method for realizing an RFID field strength simulation model.

背景技术Background technique

射频识别(RadfoFrequencyIdentification，简称RFID)技术是一种非接触式的自动识别技术，它通过电磁波或电感祸合方式传递信号，以完成对目标对象的自动识别。与条形码、磁卡、接触式IC卡等其它自动识别技术相比，即RFID技术具有识别过程无须人工干预、可同时识别多个目标、信息存储量大、可工作于各种恶劣环境等优点。因此，RFID技术已经被广泛地应用于固定资产管理、生产线自动化、动物和车辆识别、公路收费、门禁系统、仓储、商品防伪、航空包裹管理、集装箱管理等领域。典型的射频识别系统可以分为标签、阅读器和后端数据处理系统三个部分。Radio frequency identification (RadfoFrequencyIdentification, referred to as RFID) technology is a non-contact automatic identification technology, which transmits signals through electromagnetic waves or inductive coupling to complete automatic identification of target objects. Compared with other automatic identification technologies such as barcodes, magnetic cards, and contact IC cards, RFID technology has the advantages of no manual intervention in the identification process, multiple targets can be identified at the same time, a large amount of information storage, and it can work in various harsh environments. Therefore, RFID technology has been widely used in fixed asset management, production line automation, animal and vehicle identification, road toll collection, access control system, warehousing, commodity anti-counterfeiting, air parcel management, container management and other fields. A typical RFID system can be divided into three parts: tags, readers and back-end data processing systems.

由于阅读器和卡片之间的信息传输是通过射频天线无线传输的，在设计的时候，如果要精确仿真，就必须要建立一个与实际相符的场强模型。否则，所有仿真数据都会脱离现实中真正的工作模式，导致出现各种问题，大大拖延研发进度和产品成功率。Since the information transmission between the reader and the card is wirelessly transmitted through the radio frequency antenna, at the time of design, if accurate simulation is to be carried out, a field strength model consistent with the actual situation must be established. Otherwise, all simulation data will deviate from the real working mode in reality, causing various problems and greatly delaying the development progress and product success rate.

发明内容Contents of the invention

针对现有技术中的不足，针对现有技术中无法实现精确仿真，本发明提供了一种实现RFID场强仿真模型的方法，从而提高研发进度和产品的成功率。In view of the deficiencies in the prior art and the inability to realize accurate simulation in the prior art, the present invention provides a method for realizing the simulation model of RFID field strength, thereby improving the research and development progress and the success rate of products.

本发明提供了一种实现RFID场强仿真模型的方法，包括如下步骤：The invention provides a kind of method that realizes RFID field intensity simulation model, comprises the steps:

将RFID发送端电路等效成具有内阻的信号源；The RFID transmitter circuit is equivalent to a signal source with internal resistance;

将RFID发送端电路等效成具有读写器天线和源阻抗的电路；The RFID transmitter circuit is equivalent to a circuit with reader antenna and source impedance;

将RFID标签电路等效成具有标签天线和标签阻抗的电路；The RFID tag circuit is equivalent to a circuit with tag antenna and tag impedance;

通过基尔霍夫电压定律获得标签上的电流电压的耦合系数。The coupling coefficient of the current-voltage on the tag is obtained by Kirchhoff's voltage law.

所述将RFID发送端电路等效成具有内阻的信号源包括：The equivalent of the RFID transmitting end circuit as a signal source with internal resistance includes:

将RFID发送端电路和EMC滤波器等效成一个具有内阻的信号源。The RFID transmitter circuit and EMC filter are equivalent to a signal source with internal resistance.

在本发明针对实际的RFID电路，提供一种场强仿真模型建立的方法，该模型能够提供精确仿真，从而模拟出真正的工作模式，从而可以加大研发进度和产品的成功率。For the actual RFID circuit, the present invention provides a method for establishing a field strength simulation model. The model can provide accurate simulation, thereby simulating the real working mode, thereby increasing the research and development progress and the success rate of the product.

附图说明Description of drawings

为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其它的附图。In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

图1是本发明实施例中的RFID读卡器和标签电路结构示意图；Fig. 1 is the schematic structural diagram of RFID card reader and label circuit in the embodiment of the present invention;

图2是本发明实施例中的实现RFID场强仿真模型的方法流程图；Fig. 2 is the method flowchart of realizing RFID field intensity simulation model in the embodiment of the present invention;

图3是本发明实施例中的RF电路仿真模型电路原理图；Fig. 3 is the circuit schematic diagram of the RF circuit emulation model in the embodiment of the present invention;

图4是本发明实施例中的RFID场强仿真模型电路原理图。Fig. 4 is a circuit schematic diagram of an RFID field strength simulation model in an embodiment of the present invention.

具体实施方式Detailed ways

下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其它实施例，都属于本发明保护的范围。The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

本发明实施例中的RFID读写器与标签电路结构示意图如图1中所示。其中，MP1、MN1为读写器发送端的功率MOS管，MP1和MN1由多个P管和N管并联组成，并联MOS管的个数决定发送端发送数据的调制深度。13.56M时钟信号接到功率管的栅极上，经过EMC滤波、阻抗匹配和天线后在天线上产生13.56M的正弦载波信号。13.56M时钟信号中包含丰富的谐波成分，需要低通滤波将其滤掉，由L_emc和C_emc组成的EMC滤波器正是起到滤除13.56M谐波成分的作用；Cs_reader和Cp_reader组成阻抗匹配网络，一方面匹配天线和从EMC滤波器及发送端的阻抗，另一方面使天线在载波频率上谐振；R1用于调整天线的Q值，使天线的带宽满足传送数据的要求。The structural schematic diagram of the RFID reader-writer and tag circuit in the embodiment of the present invention is shown in FIG. 1 . Among them, MP1 and MN1 are power MOS transistors at the sending end of the reader. MP1 and MN1 are composed of multiple P transistors and N transistors connected in parallel. The number of parallel MOS transistors determines the modulation depth of the data sent by the sending end. The 13.56M clock signal is connected to the grid of the power tube, and a 13.56M sinusoidal carrier signal is generated on the antenna after EMC filtering, impedance matching and antenna. The 13.56M clock signal contains rich harmonic components, which need to be filtered out by low-pass filtering. The EMC filter composed of L_emc and C_emc is to filter out the 13.56M harmonic components; Cs_reader and Cp_reader form impedance matching The network, on the one hand, matches the impedance of the antenna, the EMC filter and the transmitting end, and on the other hand, makes the antenna resonate at the carrier frequency; R1 is used to adjust the Q value of the antenna so that the bandwidth of the antenna meets the requirements of transmitting data.

针对图1，本发明图2示出了实现RFID场强仿真模型的方法流程图，包括如下步骤：For Fig. 1, Fig. 2 of the present invention shows the flow chart of the method that realizes RFID field strength simulation model, comprises the following steps:

S201、将RFID发送端电路等效成具有内阻的信号源；S201, the RFID sending end circuit is equivalent to a signal source with internal resistance;

进行电路仿真时，很难在读写器发送端通过改变并联功率管的个数来传送调制深度为10％的数据信号。本发明实施例将RFID发送端电路等效成具有内阻的信号源，则改变并联功率管相当于改变信号源的内阻，从而改变了发送端的输出电压。更进一步，将RFID发送电路和EMC滤波器等效成一个具有内阻的信号源，可以得到下图3所示的RF电路仿真模型。When performing circuit simulation, it is difficult to transmit a data signal with a modulation depth of 10% by changing the number of parallel power transistors at the transmitter of the reader. In the embodiment of the present invention, the RFID sending end circuit is equivalent to a signal source with internal resistance, then changing the parallel power tube is equivalent to changing the internal resistance of the signal source, thereby changing the output voltage of the sending end. Furthermore, the RFID sending circuit and EMC filter are equivalent to a signal source with internal resistance, and the RF circuit simulation model shown in Figure 3 below can be obtained.

在仿真过程中，将Rin_reader视为不变，而改变信号源的幅度，这与实际情况刚好相反，但都可以使读写器天线上产生相同的波形信号，因此二者是等效的。In the simulation process, the Rin_reader is regarded as unchanged, and the amplitude of the signal source is changed, which is just the opposite of the actual situation, but both can make the reader antenna generate the same waveform signal, so the two are equivalent.

S202、将RFID发送端电路等效成具有读写器天线和源阻抗的电路；S202, the RFID sending end circuit is equivalent to a circuit having a reader-writer antenna and a source impedance;

S203、将RFID标签电路等效成具有标签天线和标签阻抗的电路；S203, the RFID tag circuit is equivalent to a circuit having a tag antenna and a tag impedance;

需要对S202和S203说明的是，根据电磁场与电磁波知识，(由毕奥-萨伐尔定律结合微积分可以求出)边长为a、b的矩形天线场强分布计算公式为：What needs to be explained for S202 and S203 is that, according to the knowledge of electromagnetic fields and electromagnetic waves, the formula for calculating the field strength distribution of a rectangular antenna with side lengths a and b (obtained by Biot-Savart law combined with calculus) is:

$\mathrm{<span><span>H</span>h</span>}<span><span>=</span>=</span>\frac{\mathrm{<span><span>INab</span>INab</span>}}{\mathrm{<span><span>4</span>4</span>}\mathrm{<span><span>\&pi;</span>\&pi;</span>}\sqrt{{<span><span>(</span>(</span>\frac{\mathrm{<span><span>a</span>a</span>}}{\mathrm{<span><span>2</span>2</span>}}<span><span>)</span>)</span>}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{<span><span>(</span>(</span>\frac{\mathrm{<span><span>b</span>b</span>}}{\mathrm{<span><span>2</span>2</span>}}<span><span>)</span>)</span>}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>x</span>x</span>}}^{\mathrm{<span><span>2</span>2</span>}}}}<span><span>[</span>[</span>\frac{\mathrm{<span><span>1</span>1</span>}}{{<span><span>(</span>(</span>\frac{\mathrm{<span><span>a</span>a</span>}}{\mathrm{<span><span>2</span>2</span>}}<span><span>)</span>)</span>}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>x</span>x</span>}}^{\mathrm{<span><span>2</span>2</span>}}}<span><span>+</span>+</span>\frac{\mathrm{<span><span>1</span>1</span>}}{{<span><span>(</span>(</span>\frac{\mathrm{<span><span>b</span>b</span>}}{\mathrm{<span><span>2</span>2</span>}}<span><span>)</span>)</span>}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>x</span>x</span>}}^{\mathrm{<span><span>2</span>2</span>}}}<span><span>]</span>]</span><span><span>=</span>=</span>\mathrm{<span><span>I</span>I</span>}<span><span>*</span>*</span>\mathrm{<span><span>f</span>f</span>}<span><span>(</span>(</span>\mathrm{<span><span>x</span>x</span>}<span><span>)</span>)</span>$

其中，N为天线匝数，x为垂直矩形线圈平面的中心轴向的距离，R为圆形天线的半径圆形天线的磁场分布计算公式为：Among them, N is the number of turns of the antenna, x is the distance from the center axis of the vertical rectangular coil plane, and R is the radius of the circular antenna. The calculation formula of the magnetic field distribution of the circular antenna is:

$\mathrm{<span><span>H</span>h</span>}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>INR</span>INR</span>}}^{\mathrm{<span><span>2</span>2</span>}}}{\mathrm{<span><span>2</span>2</span>}{<span><span>(</span>(</span>{\mathrm{<span><span>R</span>R</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>x</span>x</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>)</span>)</span>}^{\frac{\mathrm{<span><span>3</span>3</span>}}{\mathrm{<span><span>2</span>2</span>}}}}<span><span>=</span>=</span>\mathrm{<span><span>I</span>I</span>}<span><span>*</span>*</span>\mathrm{<span><span>f</span>f</span>}<span><span>(</span>(</span>\mathrm{<span><span>x</span>x</span>}<span><span>)</span>)</span>$

由上式可以知道，天线产生的磁场由天线的尺寸、匝数以及流经天线的电流决定。这里可以根据实测场强的数据来拟合出产生该磁场的天线上的电流I，由此推出RF电路仿真模型中的信号源幅度Reader_vin。至此，可以利用RF仿真模型模拟与实际相符的读写器天线产生的磁场。It can be known from the above formula that the magnetic field generated by the antenna is determined by the size of the antenna, the number of turns and the current flowing through the antenna. Here, the current I on the antenna that generates the magnetic field can be fitted according to the data of the measured field strength, and thus the signal source amplitude Reader_vin in the RF circuit simulation model can be deduced. So far, the RF simulation model can be used to simulate the magnetic field generated by the reader antenna that matches the actual situation.

不同距离下对应的耦合系数可以通过仿真拟合测试的方法得到，其原理可以由下图4及公式说明，其中：L1为读写器天线，L2为标签天线，ZS为源阻抗，ZL为标签阻抗。The corresponding coupling coefficients at different distances can be obtained by simulation fitting test. The principle can be explained by the following figure 4 and the formula, where: L1 is the reader antenna, L2 is the tag antenna, ZS is the source impedance, and ZL is the tag impedance.

S204、通过基尔霍夫电压定律获得标签上的电流电压的耦合系数。S204. Obtain the coupling coefficient of the current and voltage on the label through Kirchhoff's voltage law.

根据基尔霍夫电压定律可得：According to Kirchhoff's voltage law:

-V_S+I₁Z_S+jωL₁I₁+jωMI₂＝0-V_S +I₁ Z_S +jωL₁ I₁ +jωMI₂ ＝0

jωMI₁+jωL₂I₂+Z_LI₂＝0jωMI₁ +jωL₂ I₂ +Z_L I₂ ＝0

由上两式可以得出：It can be obtained from the above two formulas:

${\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>1</span>1</span>}}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>V</span>V</span>}}_{\mathrm{<span><span>S</span>S</span>}}}{{\mathrm{<span><span>Z</span>Z</span>}}_{\mathrm{<span><span>S</span>S</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>j\&omega;L</span>j\&omega;L</span>}}_{\mathrm{<span><span>1</span>1</span>}}<span><span>+</span>+</span>\frac{{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}^{\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>M</span>m</span>}}^{\mathrm{<span><span>2</span>2</span>}}}{{\mathrm{<span><span>j\&omega;L</span>j\&omega;L</span>}}_{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>Z</span>Z</span>}}_{\mathrm{<span><span>L</span>L</span>}}}}$

${\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>2</span>2</span>}}<span><span>=</span>=</span>\frac{<span><span>-</span>-</span>{\mathrm{<span><span>j\&omega;MI</span>j\&omega;MI</span>}}_{\mathrm{<span><span>1</span>1</span>}}}{{\mathrm{<span><span>j\&omega;L</span>j\&omega;L</span>}}_{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>Z</span>Z</span>}}_{\mathrm{<span><span>L</span>L</span>}}}$

可以得知，在天线电路确定的情况下，标签天线上的电流电压完全由耦合系数k决定，这样，我们就可以通过改变仿真电路的耦合系数来拟合测试的数据，从而得到不同距离下的耦合系数。It can be known that, when the antenna circuit is determined, the current and voltage on the tag antenna is completely determined by the coupling coefficient k, so that we can fit the test data by changing the coupling coefficient of the simulation circuit, so as to obtain different distances coupling coefficient.

在完成整个仿真模型建立之后，基于该仿真模型可以进行仿真模型数据测试，相关步骤如下：After the entire simulation model is established, the simulation model data test can be performed based on the simulation model. The relevant steps are as follows:

步骤1：测量读写器、标签及校准天线的电感值(标签天线与校准天线相同)Step 1: Measure the inductance of the reader, tag and calibration antenna (the tag antenna is the same as the calibration antenna)

利用MFJ269阻抗分析仪测量出相关天线的电感值，为了减少天线并联寄生电容对测量电感值的影响，在低频段测量天线电感。The MFJ269 impedance analyzer is used to measure the inductance value of the relevant antenna. In order to reduce the influence of the parallel parasitic capacitance of the antenna on the measured inductance value, the antenna inductance is measured in the low frequency band.

步骤2：估计读写器信号源等效阻抗Rin_readerStep 2: Estimate the equivalent impedance of the reader signal source Rin_reader

一般地，信号源的阻抗约为40～80欧姆(参考NXP读写器天线设计资料)，可以利用阻抗分析仪测出EMC级的输出阻抗作为信号源的等效阻抗，这里采用常用值50欧姆。Generally, the impedance of the signal source is about 40-80 ohms (refer to the NXP reader antenna design data), and the impedance analyzer can be used to measure the EMC-level output impedance as the equivalent impedance of the signal source. Here, the common value of 50 ohms is used. .

步骤3：记录下阻抗匹配网络电容值，这一步也可以通过理论计算出最佳匹配网络电容值Step 3: Record the impedance matching network capacitance value, this step can also calculate the best matching network capacitance value through theory

步骤4：测量读写器场强分布值以及校准天线上的电压值Step 4: Measure the field strength distribution value of the reader and the voltage value on the calibration antenna

步骤5：利用曲线拟合方法得出读写器天线电流I(使用MATLAB曲线拟合工具箱做线性拟合，用f(x)去拟合场强H，得到拟合系数I)，之后推出信号源电压值Reader_vinStep 5: Use the curve fitting method to obtain the reader antenna current I (use the MATLAB curve fitting toolbox to do linear fitting, use f(x) to fit the field strength H to obtain the fitting coefficient I), and then deduce Signal source voltage value Reader_vin

步骤6：通过改变仿真电路的耦合系数来拟合校准天线上感应的电压，得到不同距离下的读写器与标签芯片天线的耦合系数。Step 6: Fit the induced voltage on the calibration antenna by changing the coupling coefficient of the simulation circuit, and obtain the coupling coefficients of the reader-writer and the tag chip antenna at different distances.

综上，本发明实施例针对实际的RFID电路，提供一种场强仿真模型建立的方法，该模型能够提供精确仿真，从而模拟出真正的工作模式，从而可以加大研发进度和产品的成功率。To sum up, the embodiment of the present invention provides a method for establishing a field strength simulation model for the actual RFID circuit. The model can provide accurate simulation, thereby simulating the real working mode, thereby increasing the research and development progress and the success rate of the product. .

本领域普通技术人员可以理解上述实施例的各种方法中的全部或部分步骤是可以通过程序来指令相关的硬件来完成，该程序可以存储于一计算机可读存储介质中，存储介质可以包括：只读存储器(ROM，Read Only Memory)、随机存取存储器(RAM，Random Access Memory)、磁盘或光盘等。Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above-mentioned embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the storage medium can include: Read Only Memory (ROM, Read Only Memory), Random Access Memory (RAM, Random Access Memory), disk or CD, etc.

以上对本发明实施例所提供的实现RFID场强仿真模型的方法进行了详细介绍，本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本发明的限制。The method for realizing the RFID field strength simulation model provided by the embodiments of the present invention has been introduced in detail above. The principles and implementation methods of the present invention have been explained by using specific examples in this paper. The descriptions of the above embodiments are only used to help understand the present invention. The method of the invention and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and scope of application. In summary, the content of this specification should not be understood To limit the present invention.

Claims (2)

Translated fromChinese

1.一种实现RFID场强仿真模型的方法，其特征在于，包括如下步骤：1. a method for realizing the RFID field strength simulation model, is characterized in that, comprises the steps:将RFID发送端电路等效成具有内阻的信号源；The RFID transmitter circuit is equivalent to a signal source with internal resistance;将RFID发送端电路等效成具有读写器天线和源阻抗的电路；The RFID transmitter circuit is equivalent to a circuit with reader antenna and source impedance;将RFID标签电路等效成具有标签天线和标签阻抗的电路；The RFID tag circuit is equivalent to a circuit with tag antenna and tag impedance;通过基尔霍夫电压定律获得标签上的电流电压的耦合系数。The coupling coefficient of the current-voltage on the tag is obtained by Kirchhoff's voltage law.2.如权利要求1所述的实现RFID场强仿真模型测试的方法，其特征在于，所述将RFID发送端电路等效成具有内阻的信号源包括：2. the method for realizing the RFID field strength simulation model test as claimed in claim 1, is characterized in that, described RFID transmitter circuit is equivalent to the signal source with internal resistance and comprises:将RFID发送端电路和EMC滤波器等效成一个具有内阻的信号源。The RFID transmitter circuit and EMC filter are equivalent to a signal source with internal resistance.