A universal chipless sensor and design method thereof

Abstract

The present invention discloses a universal chipless sensor and a design method thereof, the method comprising the following steps: constructing a sensor equivalent filter circuit A; calculating the frequency response function and resonant frequency of the sensor equivalent filter circuit A; constructing a sensor equivalent filter circuit B for sensing targets; determining the frequency response function and resonant frequency of the sensing target sensor equivalent filter circuit B; calculating the parameter value range of the sensing target sensor equivalent filter circuit B for the dielectric constant range and the operating frequency range of different sensing targets; the method converts repeated time-consuming simulation operations into low-complexity mathematical model calculations, and can quickly design new chipless sensors for new sensing applications, eliminating a large amount of manpower costs required by traditional design methods and reducing calculation time. The present invention has a strong generalization ability, reduces the complexity of sensor design work, and realizes the design of chipless sensors with low manpower costs and low time costs.

Description

Technical Field

[0001] The present invention belongs to the field of passive perception of the Internet of Things and relates to a universal chipless sensor and a design method thereof. Background Art

[0002] Backscatter tag-based sensing technology attaches backscatter tags to targets and uses the perturbed backscatter signals to sense the properties of the targets. It has recently received a lot of attention due to the battery-free, low-cost and widespread use of backscatter tags (such as RFID). Many attractive applications are realized by backscatter tag-based sensing, such as material sensing, soil moisture sensing, ambient light intensity and temperature sensing, liquid recognition, solid recognition and human input sensing.

[0003] Although existing backscatter tag-based sensing systems have achieved great success, they require a lot of design work, which is both expensive and time-consuming for two main reasons. First, the design of backscatter sensor tags not only requires expert experience in microstrip circuit design, but also requires a long testing process. Second, the existing designed sensor tags can only work in a specific application or a given frequency band. If the sensing application or signal frequency band changes, a new backscatter sensor tag must be redesigned from scratch to meet the new application requirements. Summary of the invention

[0004] In order to save the time of designing chipless sensors and improve the generalization ability of chipless sensors so that they can complete the perception task facing any specific perception target and any specific working frequency band by changing the size of the sensing unit, we propose a universal chipless sensor and its design method.

[0005] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0006] A method for designing a universal chipless sensor, the method comprising the following steps:

[0007] Step 1: Construct sensor equivalent filter circuit A;

[0008] Step 2: Calculate the frequency response function and resonant frequency of the sensor equivalent filter circuit A;

[0009] Step 3: Construct a sensor equivalent filter circuit B for sensing the target;

[0010] Step 4: Determine the frequency response function and resonant frequency of the equivalent filter circuit B of the sensor for sensing the target;

[0011] Step 5: Calculate the parameter value range of the equivalent filter circuit B of the sensing target sensor for different dielectric constant ranges and operating frequency ranges of sensing targets;

[0012] Step 6: Establish a relationship model between the parameter value range of the equivalent filter circuit B of the sensing target sensor and the physical size of the resonator.

[0013] In addition, the method of the present invention further comprises step 7: repeating steps 5 to 6 to form a set of physical dimensions of resonators with different dielectric constant ranges and operating frequency ranges of different sensing targets.

[0014] Further, step 2: calculate the frequency response function and resonant frequency of the sensor equivalent filter circuit A as follows:

[0015]

[0016] Among them, Z x represents the equivalent reactance of the DGS structure,

[0017] R1 represents the equivalent resistance of the defective ground structure; j represents an imaginary unit; C c represents the gap capacitance of the defective ground structure; f represents the frequency of the signal in the circuit; L C Represents the equivalent inductance of the defective ground structure;

[0018]

[0019] Among them, L C represents the equivalent inductance of the defective ground structure; C1 represents the equivalent capacitance between the defective ground structure and the upper microstrip line; C c Represents the gap capacitance of the defective ground structure.

[0020] Step 4: Calculation of the frequency response function and resonant frequency of the equivalent filter circuit B of the sensing target sensor

[0021] Here is how:

[0022]

[0023] Where: Z′ x It represents the impedance after the sensing unit contacts the sensing object.

[0024] R1 represents the equivalent resistance of the defective ground structure; j represents an imaginary unit; C c represents the gap capacitance of the defective ground structure; f represents the frequency of the signal in the circuit; L C Represents the equivalent inductance of the defective ground structure; Z t The complex impedance of the equivalent circuit representing the sensing object;

[0025]

[0026] C0 is the vacuum permittivity, γ represents the influence coefficient of the sensing target on the resonator circuit, α and β represent the influence coefficients of the sensing objects with different dielectric constants on the resonant frequency, and ε represents the dielectric constant of the sensing target.

[0027] In particular, the specific calculation process of step 5 is as follows:

[0028] The result obtained in step 4 Transformed into f′0=f(L c ,C1,C c ,ε), input the dielectric constant ε0 and working frequency band [f l ,f h ], we get f l <f(L c ,C1,C c ,ε0) <f h , given the circuit parameters L c , C1, C c The search range can get the circuit parameter range corresponding to the sensor sensing unit size The combination of circuit parameters within this range can satisfy the target resonant frequency of [f l ,f h ] range.

[0029] Step 6 specifically includes:

[0030] First, the sensor frequency response curve S is obtained by simulation.<a,w> corresponds to an S, where a and w represent the length and width of the rectangular strip of the square-like structure surrounding the reconfigurable defective ground structure band-stop filter, respectively;

[0031] Then, each set of frequency response curves is used as input S to construct the fitness function The circuit parameters (L c , C1, C c , R, L), so that fitness continues to decrease until it approaches 0, and obtains (a, w) and circuit parameters (L c , C1, C c , R, L) mapping relationship;

[0032] Thus we get:

[0033] L c =112.2-71.3a-3.273w+19.42a 2-22.2aw+89.87w 2 -2.636a 3 +5.895a 2 w-12.63aw 2 -59.99w 3 +0.1755a 4 -0.5732a 3 w+1.322a 2 w 2 -0.3111aw 3 +34.9a 4 -0.004509a 5 +0.0167a 4 w-0.002057a 3 w 2 -0.4036a 2 w 3 +1.946aw 4 -10.89w 5

[0034] C1=-3.479+4.199a-13.85w-1.563a 2 +8.05aw-5.61w 2 +0.2535a 3 -1.495a 2 w+0.7597aw 2 +3.628w 3 -0.01859a 4 +0.1219a 3 w-0.1387a 2 w 2 +0.4517aw3-3.186w 4 +0.0005053a 5 -0.003559a 4 w+0.005382a 3 w 2 -0.01164a 2 w 3 -0.05703aw 4 +0.7871w 5

[0035] Additionally, step 7 includes:

[0036] Based on (a, w) formed in step 6 and circuit parameters (L c , C1, C c , R, L), and the circuit parameter range that meets the working frequency band requirements obtained in step 4 is Substitute (a, w) and circuit parameters (L c , C1, C c , R, L), the set of sensor unit sizes that meet the frequency band requirements is obtained. The set obtained by taking the intersection of the sets A, B, and C is the set that satisfies any given sensing object with a dielectric constant of ε0 and any given working frequency band [f l , f h ] is a collection of sensing unit sizes.

[0037] The present invention also discloses a universal chipless sensor, comprising a dielectric substrate layer, a microstrip transmission line, and a copper clad layer, wherein the dielectric substrate is attached to one side of the copper clad layer, and the microstrip transmission line runs through the dielectric substrate layer, and is characterized in that: a resettable defective ground structure band-stop filter is provided in the middle of the other side of the copper clad layer, the defective ground structure is a quasi-square structure, and a notch is provided on one of the sides, the quasi-square is surrounded by a×w rectangular strips, and the length a and width w of the rectangular strips of the quasi-square structure surrounding the resettable defective ground structure band-stop filter are determined by executing the sensor design method disclosed in the present invention.

[0038] Compared with the prior art, the present invention has the following beneficial technical effects:

[0039] The present invention uses circuit theory to model the relationship between perception application requirements and sensor design parameters, converting repetitive and time-consuming simulation operations into low-complexity mathematical model calculations, and can quickly design new chipless sensors for new perception applications, eliminating the large amount of manpower required by traditional design methods and reducing calculation time. The present invention includes two relationship models, the first model is used to model the impact of the perception target on the circuit resonant frequency, and the second model is used to model the relationship between the equivalent circuit parameters of the chipless resonator sensor and the physical size of the resonator. The universal chipless sensor design method implemented by the present invention can be extended to different resonator-based chipless sensor designs, has strong generalization capabilities, reduces the complexity of sensor design work, and realizes chipless sensor design with low manpower and time costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A three-dimensional structural diagram of a chip-free sensor model used in the present invention;

[0041] Figure 2 This is a physical picture of the sensor;

[0042] Figure 3 is the equivalent circuit of the sensor;

[0043] Figure 4 It is the equivalent circuit after the sensor contacts the sensing object;

[0044] Figure 5 is the fitting curve of resonant frequency versus dielectric constant;

[0045] Figure 6 A comparison chart of the frequency response curve of the optimized circuit parameters and the simulated frequency response curve;

[0046] Figure 7 is the circuit parameter L C 3D relationship diagram of the sensor unit size (a, w);

[0047] Figure 8 It is a three-dimensional relationship diagram between the circuit parameter C1 and the sensing unit size (a, w);

[0048] Fig. 9 is the circuit parameter C c 3D relationship diagram of the sensor unit size (a, w);

[0049] Fig.10 To meet the band requirements of L C A schematic diagram of the value range of ;

[0050] Fig.11 A schematic diagram of the value range of C1 to meet the frequency band requirements;

[0051] Fig.12 To meet the frequency band requirements of C c A schematic diagram of the value range of ;

[0052] Fig.13 A schematic diagram of the (a, w) set that ultimately enables the sensor to operate in a specified operating frequency band;

[0053] Fig.14 The frequency response curve of the sensor contact with different soil dielectric constants obtained by simulation is a=6mm,w=1mm;

[0054] The present invention is further explained and illustrated in detail below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0055] The present invention provides a design method for a universal chipless sensor, the method comprising the following steps:

[0056] Step 1: Construct sensor equivalent filter circuit A;

[0057] Step 2: Calculate the frequency response function and resonant frequency of the sensor equivalent filter circuit A;

[0058] Step 3: Construct a sensor equivalent filter circuit B for sensing the target;

[0059] Step 4: Determine the frequency response function and resonant frequency of the equivalent filter circuit B of the sensor for sensing the target;

[0060] Step 5: Calculate the parameter value range of the equivalent filter circuit B of the sensing target sensor for different dielectric constant ranges and operating frequency ranges of sensing targets;

[0061] Step 6: Establish a relationship model between the parameter value range of the equivalent filter circuit B of the sensing target sensor and the physical size of the resonator.

[0062] In addition, based on the above steps, the present invention further includes step 7: repeating steps 5 to 6 to form a set of physical dimensions of resonators with different dielectric constant ranges and operating frequency ranges for different sensing targets.

[0063] See also Figure 1 As shown, the universal chipless sensor provided by the present invention includes a dielectric substrate layer, a microstrip transmission line, and a copper clad layer, wherein the dielectric substrate is attached to one side of the copper clad layer, the microstrip transmission line runs through the dielectric substrate layer, and a resettable defective ground structure band-stop filter is arranged in the middle of the other side of the copper clad layer. The defective ground structure is a quasi-square structure, and a notch is arranged on one of the sides, wherein the quasi-square is surrounded by a×w rectangular strips, and the length a and width w of the rectangular strips of the quasi-square structure enclosed in the resettable defective ground structure band-stop filter are achieved by the design method disclosed in the present invention.

[0064] Specifically, the sensor consists of three parts from top to bottom: microstrip transmission line, dielectric substrate, copper cladding layer, such as Figure 2 As shown. The microstrip transmission line is 100mm long, 2.24mm wide, 0.018mm thick, and made of copper. The dielectric substrate is 100mm long, 30mm wide, and 12mm thick. The material is epoxy resin (FR-4) with a dielectric constant of 4.4. The copper clad layer is 100mm long, 30mm wide, and 0.018mm thick. The material is copper. An open ring-shaped air gap is etched in the center of the copper clad layer. The shape and size of the air gap are determined by three physical parameters, namely the length (a), width (w), and opening size (c) of the gap. The air gap is a defective ground structure, which serves as the sensing structure of the sensor. Usually c = 2mm.

[0065] Step 1: Construct a sensor equivalent filter circuit A; According to the physical structure and circuit theory of the sensor based on the chipless resonator, a sensor equivalent filter circuit A is constructed, such as Figure 3 shown.

[0066] Step 2: Calculate the frequency response function and resonant frequency of the sensor equivalent filter circuit A. The circuit structure of the sensor equivalent filter circuit A can be regarded as a T-type network circuit structure. The transfer matrix of the network is calculated based on the voltage and current at the input and output ends:

[0067]

[0068]

[0069]

[0070] The S parameters and frequency response function are obtained through transfer matrix calculation.

[0071]

[0072]

[0073] in:

[0074]

[0075] is the impedance of the sensor. If the imaginary part of the equation is set to 0, the resonant frequency of the sensor resonator can be obtained:

[0076]

[0077] Z x represents the equivalent reactance of the DGS structure,

[0078]

[0079] R1 represents the equivalent resistance of the defective ground structure; j represents an imaginary unit; C c represents the gap capacitance of the defective ground structure; f represents the frequency of the signal in the circuit; L C represents the equivalent inductance of the defective ground structure; C1 represents the equivalent capacitance between the defective ground structure and the upper microstrip line.

[0080] Step 3: Construct the sensor equivalent filter circuit B for sensing the target. According to the established resonator equivalent circuit model and the electrical characteristics of the sensing target, the sensor equivalent filter circuit B for sensing the target is established for the contact between the sensor and the sensing target, such as Figure 4 As shown in FIG. 1 , the process of the sensing unit of the sensor contacting the sensing object is equivalent to the coupling of the equivalent circuit of the sensing object with the equivalent circuit of the sensor at the circuit level, thereby affecting the resonant frequency and the frequency response function.

[0081] Step 4: Determine the frequency response function and resonant frequency of the equivalent filter circuit B of the sensing target sensor.

[0082] The equivalent filter circuit B of the sensor that senses the target represents the resonant frequency and frequency response function of the sensor that senses the contact of the object. Z′ x It represents the impedance of the sensing unit after it contacts the sensing object, and its value is related to the dielectric constant of the sensing object. t Represents the complex impedance of the equivalent circuit of the sensing object. Since different sensing objects correspond to different circuit structures, it is very complicated to quantitatively calculate the frequency shift of the resonant frequency through formula (9).

[0083]

[0084]

[0085] R1 represents the equivalent resistance of the defective ground structure; j represents an imaginary unit; f represents the frequency of the signal in the circuit; Z t represents the complex impedance of the equivalent circuit of the sensing object; C0 is the vacuum permittivity, γ represents the influence coefficient of the sensing target on the resonator circuit, α and β represent the influence coefficients of the sensing objects with different dielectric constants on the resonant frequency, L C Represents the equivalent inductance of the defective ground structure; C c represents the gap capacitance of the defective ground structure; C1 represents the equivalent capacitance between the defective ground structure and the upper microstrip line; ε represents the dielectric constant of the sensing target.

[0086] By multiplying the coefficient value and the target dielectric constant value by each circuit element Lc, C1, Cc, the present invention further optimizes the equivalent circuit of the sensor equivalent filter circuit B that senses the target.

[0087]

[0088] in

[0089]

[0090] From (10) and (11), we can obtain:

[0091]

[0092] C0 is the vacuum permittivity, γ represents the influence coefficient of the sensing target on the resonator circuit, α and β represent the influence coefficients of the sensing objects with different dielectric constants on the resonant frequency, α′ represents the inductance coefficient not affected by the sensing target, α″ represents the coefficient of the sensing target affecting the inductance, and L C Represents the equivalent inductance of the defective ground structure; C crepresents the gap capacitance of the defective ground structure; C1 represents the equivalent capacitance between the defective ground structure and the upper microstrip line; ε represents the dielectric constant of the sensing target. We use HFSS to simulate the influence of sensing objects with different dielectric constants on the resonant frequency, and obtain the values ​​of α and β through fitting. The fitting results are shown in the figure below. Figure 5 As shown. Through regression calculation, we get α′=0.9, α″=4.24, β=0.2374, γ=0.005. The coefficient of determination R-square of the regression model is 0.999, indicating that formula (12) can accurately represent the influence of the perceived object on the resonant frequency.

[0093] Step 5: Calculate the parameter value range of the equivalent filter circuit B of the sensing target sensor for different dielectric constant ranges and operating frequency ranges of sensing targets.

[0094] After determining the parameters in formula (12), the formula becomes f′0=f(L c , C1, C c , ε), input the dielectric constant ε0 of the sensing target and the working frequency band [f l , f h ], the above formula becomes f l <f(L c , C1, C c ,ε0)<f h , given the circuit parameters L c , C1, C c , the search range can get the circuit parameter range corresponding to the sensor unit size The combination of circuit parameters within this range can satisfy the target resonant frequency of [f l , f h ]Inside.

[0095] Step 6: Establish a relationship model between the parameter value range of the equivalent filter circuit B of the sensing target sensor and the physical size of the resonator.

[0096] HFSS software is used to simulate the different sensor unit sizes (a, w) i The sensor outputs its frequency response curve S i , each (a, w) i Corresponding to an S i Wherein a and w represent the length and width of the rectangular strip of the square-like structure surrounding the reconfigurable defective ground structure band-stop filter, respectively.

[0097] As mentioned above, formula (5) indicates that the frequency response function H(f) of the sensor is obtained by calculating the transfer matrix of the equivalent circuit structure. S is the frequency response curve obtained by HFSS software simulation. If the circuit parameters (L c, C1, C c , R, L) makes H(f) and S as equal as possible, that is, each set of frequency response curves is used as input S to construct the fitness function

[0098]

[0099] The circuit parameters (L c , C1, C c , R, L), so that f continues to decrease until it approaches 0. At this point, we believe that the frequency response curve obtained by calculation and the frequency response curve obtained by simulation are almost the same, such as Figure 6 . , we get (a, w) and circuit parameters (L c , C1, C c , R, L) mapping relationship, at this time the circuit parameters (L c , C1, C c , R, L) can be considered as the sensor unit size is (a, w) i We use the differential evolution algorithm to search for appropriate circuit parameters and establish (a, w) and (L c , C1, C c , R, L) mapping relationship, such as Figure 7 , as shown in Figures 8 and 9.

[0100] Further, fit (a, w) and L respectively c And the functional relationship between (a, w) and C1 is L C =f(a, w), c1=g(a, w). The results are shown in formulas (13) and (14).

[0101]

[0102]

[0103] The fitting coefficients of determination R-square are 0.9309 and 1 respectively. This shows that the fitting effect is very good. c It is the capacitance generated by the sensor unit structure and can be calculated using the parallel plate capacitor calculation formula.

[0104] Step 7: Repeat steps 5 to 6 to form a set of resonator physical sizes with different dielectric constant ranges and operating frequency ranges of different sensing targets.

[0105] Based on (a, w) formed in step 6 and circuit parameters (L c , C1, C c , R, L), and the circuit parameter range that meets the working frequency band requirements obtained in step 4 is Substitute (a, w) and circuit parameters (Lc , C1, C c , R, L), the set of sensor unit sizes A, B, C that meet the frequency band requirements is obtained, such as Fig.10 , 11, 12. A, B, C are respectively satisfied The set of (a, w) of A, B, C is the intersection A∩B∩C, then this set is the set of (a, w) that satisfies the above constraints at the same time, that is, for any given perceptual object with a dielectric constant of ε0 and any given working frequency band [f l , f h ], we obtain a set of suitable sensor unit sizes through the above method, such as Fig.13 shown. Specific embodiments

[0107] The HFSS software was used to simulate the resonant frequencies corresponding to different dielectric constants, and the α′=0.9, α″=4.24, β=0.2374, and γ=0.005 in formula (12) were determined by fitting.

[0108] HFSS software was used to simulate the frequency response curves of different sensor unit sizes, with a = 5-12 mm, 0.5 mm interval, 15 groups in total; w = 0.1-1.5 mm, 0.1 mm interval, 15 groups in total. Therefore, a total of 225 different (a, w) groups were simulated.

[0109] Formula (5) is the calculated frequency response function. Each of the 225 sets of frequency response curves obtained by simulation is used as input S i (0<i<=225), construct fitness function

[0110]

[0111] The circuit parameters (L c , C1, C c , R, L), so that fitness continues to decrease until it approaches 0. At this point, we believe that the frequency response curve obtained by calculation and the frequency response curve obtained by simulation are almost the same, such as Figure 6 The circuit parameters obtained at this time are the circuit parameters corresponding to the size of the sensor unit.

[0112] Repeat the above operation until 225 sets of circuit parameters corresponding to (a, w) are obtained. Construct (a, w) and circuit parameters (L c , C1, C c , R, L) is constructed.

[0113] Fit (a, w) and L respectively cAnd the functional relationship L between (a, w) and C1 C = f(a, w), c1 = g(a, w). The results are shown in formulas (13) and (14). The determined coefficients R-square of the fitting are: 0.9309 and 1 respectively. It shows that the fitting effect is very good. C c is the capacitance generated by the sensing unit structure and can be calculated by the parallel plate capacitor calculation formula.

[0114] For any given dielectric constant and frequency band range, substitute them into the formula solved in Step 1. For example, substitute ε = 5, 4.9 GHz < f < 5.8 GHz into formula (12), and the value range of the circuit parameters obtained is: 0.56 nH < L c < 1.37 nH, 0.1 pF < C1 < 0.7 pF, 0.001 pF < C c < 0.05 pF.

[0115] Substitute the obtained value ranges of the circuit parameters into formulas (13), (14) and the parallel plate capacitor formula respectively to obtain three sets A, B, and C of (a, w), as Fig.10 shown in Figures 11 and 12. Take the intersection of the three sets to obtain the set of sensor unit sizes for the sensing object with a dielectric constant of 5 and a working frequency in the range of 4.9 GHz - 5.8 GHz. Take any three points for verification, such as (a, w) = (5.7, 1.34), (5.3, 1), (5.26, 1.09). Use the HFSS simulation software to simulate the center frequencies of three sensors with different sizes as 5.145 GHz, 5.1 GHz, and 5.315 GHz in the range of 4.8 GHz - 5.8 GHz, which proves the effectiveness of our design. Through the above steps, the appropriate size values of the sensing unit can be obtained to complete the design task of the sensor.

[0116] In this embodiment, the chip-free sensor designed by the above method is applied to the design and verification of a sensor for soil moisture sensing. The dielectric constant range of mineral soil with a humidity of 28% - 33% is 22 - 26, and the working frequency band is set to the Wi-Fi frequency band (2.4 - 2.48 GHz).

[0117] To make as many frequency response curves as possible within the working frequency band, we set ε = 24, and after calculation by the above method, we get a = 6 mm and w = 1 mm. Use the HFSS software to simulate the sensor with a = 6 mm and w = 1 mm, and the results are as Fig.14 shown. The center frequency of the curve with a dielectric constant of 24 is within the Wi-Fi frequency band.

Claims

1. A design method for a universal chipless sensor, characterized in that: The method comprises the following steps: Step 1: Construct sensor equivalent filter circuit A; Step 2: Calculate the frequency response function and resonant frequency of the sensor equivalent filter circuit A, which are: Among them, Z x represents the equivalent reactance of the DGS structure, R1 represents the equivalent resistance of the defective ground structure; j represents an imaginary unit; C c represents the gap capacitance of the defective ground structure; f represents the frequency of the signal in the circuit; L C Represents the equivalent inductance of the defective ground structure; Among them, L C represents the equivalent inductance of the defective ground structure; C1 represents the equivalent capacitance between the defective ground structure and the upper microstrip line; C c Represents the gap capacitance of the defective ground structure; Step 3: Construct a sensor equivalent filter circuit B for sensing the target; Step 4: Determine the frequency response function and resonant frequency of the equivalent filter circuit B of the sensing target sensor. The calculation method is as follows: Where: Z′ x It represents the impedance after the sensing unit contacts the sensing object. R1 represents the equivalent resistance of the defective ground structure; j represents an imaginary unit; C c represents the gap capacitance of the defective ground structure; f represents the frequency of the signal in the circuit; L C Represents the equivalent inductance of the defective ground structure; Z t The complex impedance representing the equivalent circuit of the sensing object; C0 is the vacuum permittivity, γ represents the influence coefficient of the sensing target on the resonator circuit, α and β represent the influence coefficients of the sensing objects with different dielectric constants on the resonant frequency, and ε represents the dielectric constant of the sensing target; Step 5: Calculate the parameter value range of the equivalent filter circuit B of the sensing target sensor for different dielectric constant ranges and operating frequency ranges of sensing targets. The specific calculation process is as follows: The result obtained in step 4 Transformed into f′0=f(L c ,C1,C c ,ε), input the dielectric constant ε0 and working frequency band [f l ,f h ], we get f l <f(L c ,C1,C c ,ε0) <f h , given the circuit parameters L c , C1, C c The search range can get the circuit parameter range corresponding to the sensor sensing unit size The combination of circuit parameters within this range can satisfy the target resonant frequency of [f l ,f h ] within the scope; Step 6: Establish a relationship model between the parameter value range of the equivalent filter circuit B of the sensing target sensor and the physical size of the resonator.

2. The method for designing a universal chipless sensor according to claim 1, characterized in that: The method further comprises step 7: repeating steps 5 and 6 to form a set of physical sizes of resonators with different dielectric constant ranges and operating frequency ranges of different sensing targets.

3. The method for designing a universal chipless sensor according to claim 1, characterized in that: The step 6 specifically includes: First, the sensor frequency response curve S is obtained by simulation.<a,w> corresponds to an S, where a and w represent the length and width of the rectangular strip of the square-like structure surrounding the reconfigurable defective ground structure band-stop filter, respectively; Then, each set of frequency response curves is used as input S to construct the fitness function The circuit parameters (L c ,C1,C c ,R,L), so that fitness continues to decrease until it approaches 0, and (a,w) and circuit parameters (L c ,C1,C c ,R,L) mapping relationship; Thus we get: <h2 style=";text-align:left;direction:ltr">L<h2 style=";text-align:left;direction:ltr"> c <h2 style=";text-align:left;direction:ltr"> =112.2-71.3a-3.273w+19.42a<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> -22.2aw+89.87w<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> -2.636a<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> +5.895a<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> w-12.63aw<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> -59.99w<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> +0.1755a<h2 style=";text-align:left;direction:ltr"> 4 <h2 style=";text-align:left;direction:ltr"> -0.5732a<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> w+1.322a<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> w<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> -0.3111aw<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> +34.9a<h2 style=";text-align:left;direction:ltr"> 4 -0.004509a 5 +0.0167a 4 w-0.002057a 3 In 2 -0.4036a 2 In 3 +1.946aw 4 -10.89w 5 C1=-3.479+4.199a-13.85w-1.563a 2 +8.05aw-5.61w 2 +0.2535a 3 -1.495a 2 w+0.7597aw 2 +3.628w 3 -0.01859a 4 +0.1219a 3 w-0.1387a 2 In 2 +0.4517aw3-3.186w 4 +0.0005053a 5 -0.003559a 4 in+0.005382a 3 In 2 -0.01164a 2 In 3 -0.05703aw 4 +0.7871w 5 。 4. The method for designing a universal chipless sensor according to claim 1, characterized in that: The step 7 comprises: Based on the (a, w) formed in step 6 and the circuit parameters (L c ,C1,C c ,R,L) mapping relationship, and the circuit parameter range that meets the working frequency band requirements obtained in step 4 Substitute (a, w) and circuit parameters (L c ,C1,C c , R, L), we get the set A, B, C of sensor unit sizes that meet the frequency band requirements. The set obtained by taking the intersection of the sets A, B, and C is the set that satisfies any given sensing object with a dielectric constant of ε0 and any given working frequency band [f l ,f h ] is a collection of sensing unit sizes.

5. A universal chipless sensor, comprising a dielectric substrate layer, a microstrip transmission line, and a copper cladding layer, wherein: The dielectric substrate is attached to one side of the copper clad layer, and the microstrip transmission line runs through the dielectric substrate layer. It is characterized in that: a resettable defective ground structure band-stop filter is arranged in the middle of the other side of the copper clad layer, and the defective ground structure is a quasi-square structure, and a notch is arranged on one of the sides. The quasi-square is surrounded by a×w rectangular strips, and the length a and width w of the rectangular strips of the quasi-square structure surrounding the resettable defective ground structure band-stop filter are determined by executing the design method described in any one of claims 1 to 4.

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