A design method for broadband high-rejection miniaturized microstrip filters

Abstract

The present invention provides a method for designing a broadband high-suppression miniaturized microstrip filter, and relates to the technical field of microstrip filter design. The present invention realizes comprehensive optimization of microstrip filter performance by constructing a systematic optimization process, from theoretical calculation to simulation verification, and then to multi-objective scoring screening. On the basis of satisfying impedance matching, this scheme improves compactness through a bending design, and has a significant miniaturization effect; at the same time, the performance of the filter is improved by optimizing insertion loss and enhancing out-of-band signal suppression. In addition, this scheme combines processing cost factors to screen out a final design with excellent performance and good manufacturability, which significantly reduces manufacturing difficulty and cost. Overall, this scheme solves the problem of difficult balance between performance and cost in the prior art, and has broad practical value and reliability.

Description

Technical Field

[0001] The invention relates to the technical field of microstrip filter design, in particular to a broadband high-suppression miniaturized microstrip filter design method. Background Art

[0002] As an important RF device in modern communication systems, microstrip filters are widely used in wireless communications, radar, satellite communications and other fields. The introduction of defective ground structures (DGS) provides an effective means for miniaturization and performance improvement of microstrip filters. However, in actual design, the parameter optimization of DGS structures faces many technical problems: on the one hand, existing design methods mostly rely on experience or single simulation optimization, and it is difficult to achieve a multi-objective balance of impedance matching, out-of-band signal suppression, insertion loss and miniaturization under complex requirements; on the other hand, traditional designs do not take processing costs into consideration enough, which may lead to excessive manufacturing difficulty or costs exceeding expectations. In addition, since the bending design of the DGS structure needs to meet the constraints of a limited etching area, how to achieve a compact design while taking into account performance and manufacturability has become a major problem in existing technologies.

[0003] In the prior art, the publication number CN106785298A discloses a design method for a microstrip filter: the first step is to establish a lumped parameter equivalent network of the microstrip filter, and derive the equivalent relationship between the electrical parameters of the microstrip filter and the components of the lumped parameter equivalent network. The second step is to determine the values ​​of each component of the lumped parameter equivalent network using the lumped parameter filter design method according to the technical indicators of the microstrip filter; the third step is to calculate the electrical parameters of the microstrip filter from the values ​​of each component of the lumped parameter equivalent network according to the equivalent relationship, and then determine the corresponding structural parameter values; the fourth step is to use the calculated structural parameter values ​​of the microstrip filter to model and perform electromagnetic simulation optimization so that the performance of the transmission line filter finally meets the requirements of the technical indicators. Although this method can reveal the physical mechanism of the microstrip filter and shorten its development cycle, it still relies on experience or single simulation optimization, and it is difficult to achieve a multi-objective balance of impedance matching, out-of-band signal suppression, insertion loss and miniaturization under complex requirements. Therefore, there is an urgent need for a design solution that can systematically optimize DGS parameters, improve filter performance and control processing costs to meet the actual needs of modern communication equipment for miniaturization, high performance and low cost.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0005] The object of the present invention is to provide a design method for a broadband high-suppression miniaturized microstrip filter to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for designing a broadband high-suppression miniaturized microstrip filter, the specific steps comprising:

[0008] S1: According to the design requirements, the design parameters and substrate parameters of the microstrip filter are obtained, and the microstrip line width is calculated based on the design parameters of the microstrip filter and simulated;

[0009] S2: Introduce the DGS structure into the microstrip filter, calculate the structural parameters of the DGS structure according to the design parameters of the microstrip filter, substrate parameters and microstrip line width, and calculate the total impedance of the microstrip filter according to the structural parameters of the DGS structure;

[0010] S3: Repeatedly change the microstrip line width and the structural parameters of the DGS structure to optimize the total impedance of the microstrip filter, and obtain the final microstrip line width and structural parameters of the DGS structure;

[0011] S4: generating several groups of bending schemes of DGS structures based on the substrate size, calculating the error coefficient corresponding to each bending scheme, and screening the bending schemes according to the error coefficient to obtain corresponding qualified schemes;

[0012] S5: Calculate the insertion loss of the DGS structure in each qualified solution, and construct a scoring function based on the number of bends, insertion loss and processing cost of the DGS structure in the qualified solution, and take the qualified solution with the largest score of the scoring function as the final solution.

[0013] Preferably, the design parameters include the total impedance, target impedance, and resonant frequency of the microstrip filter, the substrate parameters include substrate size, dielectric constant, and dielectric loss angle, and the structural parameters include the width, depth, and total length of the groove in the DGS structure.

[0014] Preferably, the target impedance is used as the initial value of the total impedance of the microstrip filter to calculate and obtain the initial microstrip line width, and the microstrip line width is calculated as follows:

[0015] ;

[0016] In the formula represents the target impedance of the microstrip filter, represents the microstrip line width, represents the substrate thickness, represents the effective dielectric constant, where the effective dielectric constant is calculated as:

[0017] ;

[0018] In the formula Represents the dielectric constant in substrate parameters.

[0019] Preferably, the logic for calculating the structural parameters of the DGS structure is:

[0020] First, calculate the total length of the slots in the DGS structure. The calculation method is:

[0021] ;

[0022] In the formula represents the total length of the slots in the DGS structure, represents the resonant frequency of the microstrip filter, represents the speed of light;

[0023] Then the width and depth are calculated according to the total length of the slot in the DGS structure. The calculation methods are:

[0024] ;

[0025] ;

[0026] In the formula , Respectively represent the width and depth of the slot in the DGS structure, , denote the first scale factor and the second scale factor respectively, where , .

[0027] Preferably, the logic for calculating the total impedance of the microstrip filter is:

[0028] First, calculate the equivalent inductance, equivalent capacitance and equivalent resistance of the DGS structure. The calculation methods are:

[0029] ;

[0030] ;

[0031] ;

[0032] In the formula represents the vacuum permeability, is the dielectric constant of vacuum, Represents the dielectric loss angle in the substrate parameters;

[0033] Then, the equivalent impedance is calculated based on the equivalent inductance, equivalent capacitance and equivalent resistance of the DGS structure. The calculation method is:

[0034] ;

[0035] The total impedance of the microstrip filter is expressed as:

[0036] ;

[0037] In the formula represents the total impedance of the microstrip filter, Represents an imaginary unit.

[0038] Preferably, the logic for obtaining the final microstrip line width and structural parameters of the DGS structure is:

[0039] When optimizing the total impedance of the microstrip filter, the microstrip line width, the depth and width of the slot in the DGS structure are adjusted and updated. The calculation formulas are:

[0040] ;

[0041] ;

[0042] ;

[0043] In the formula Indicates the number of adjustment updates. represents the adjustment step size, and ;

[0044] When the total impedance of the microstrip filter meets the target impedance When , the optimization is considered to be completed, and the corresponding microstrip line width and structural parameters of the DGS structure are considered to be the final microstrip line width and structural parameters of the DGS structure, where represents the coefficient of volatility, and .

[0045] Preferably, several groups of bending schemes are generated based on the structural parameters of the final DGS structure, each bending scheme is a U-shaped groove, and the bending scheme includes the number of bending times, the bending radius and the extension length, wherein the number of bending times, the bending radius and the extension length satisfy the following formula:

[0046] ;

[0047] ;

[0048] ;

[0049] In the formula represents the number of bends, and is a positive integer, Indicates the bending radius, Indicates the extended length, , Respectively represent the width and length of the preset etching area;

[0050] Each bending scheme is simulated in turn, the simulated impedance corresponding to each bending scheme is collected, and the error coefficient between the simulated impedance and the total impedance is calculated as follows:

[0051] ;

[0052] In the formula Represents the simulated impedance, when the error coefficient of the bending scheme , it is marked as a qualified solution.

[0053] Preferably, each qualified solution is simulated, and the insertion loss of the DGS structure in each qualified solution is calculated as follows:

[0054] ;

[0055] In the formula represents the insertion loss, , Respectively represent the input intensity and output intensity of the simulation signal;

[0056] Then, a scoring function is constructed based on the number of bends, insertion loss and processing cost of the DGS structure in the qualified solution. The scoring function is expressed as:

[0057] ;

[0058] In the formula represents the score of the scoring function of the qualified solution, , , Represent the first weight, the second weight, and the third weight respectively. , , are greater than 0, and .

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] The present invention achieves comprehensive optimization of microstrip filter performance by constructing a systematic optimization process, from theoretical calculation to simulation verification, and then to multi-objective scoring screening. On the basis of satisfying impedance matching, this solution improves compactness through bending design, and has a significant miniaturization effect; at the same time, the performance of the filter is improved by optimizing insertion loss and enhancing out-of-band signal suppression. In addition, this solution combines processing cost factors to screen out the final design with excellent performance and good manufacturability, significantly reducing the manufacturing difficulty and cost. Overall, this solution solves the problem of difficult balance between performance and cost in the prior art, and has broad practical value and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a schematic diagram of the overall method flow of the present invention. DETAILED DESCRIPTION

[0062] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0063] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0064] Example:

[0065] A method for designing a broadband high-suppression miniaturized microstrip filter, the specific steps comprising:

[0066] S1: According to the design requirements, the design parameters and substrate parameters of the microstrip filter are obtained. Based on the design parameters of the microstrip filter, the microstrip line width is calculated and simulated. The design parameters include the total impedance, target impedance, and resonant frequency of the microstrip filter. The substrate parameters include substrate size, dielectric constant, and dielectric loss angle. The structural parameters include the width, depth, and total length of the slot in the DGS structure. The substrate size specifically includes the length, width, and thickness of the substrate. The target impedance is used as the initial value of the total impedance of the microstrip filter to calculate the initial microstrip line width. The calculation method of the microstrip line width is:

[0067] ;

[0068] In the formula represents the target impedance of the microstrip filter, represents the microstrip line width, represents the substrate thickness, represents the effective dielectric constant, where the effective dielectric constant is calculated as:

[0069] ;

[0070] In the formula Represents the dielectric constant in substrate parameters.

[0071] The calculation formulas for the microstrip line width and effective dielectric constant are empirical formulas. The relationship between the microstrip line width and the target impedance depends on the width-to-thickness ratio between the microstrip line width and the substrate thickness. When calculating for the first time, it is usually based on The corresponding calculation formula is used for calculation. This is because the calculation formula corresponding to this condition is relatively simple, which can simplify the calculation complexity in the preliminary design stage. The formula can be selected according to the actual width-to-thickness ratio during subsequent optimization. Taking the common FR4 substrate as an example, assuming that the target impedance of the microstrip filter is 50Ω, the thickness of the FR4 substrate is 1.6mm, the dielectric constant is 4.4, and the dielectric loss angle is 0.02, then the formula can be solved jointly to obtain the microstrip line width of 3.1mm after retaining one decimal place, which is equivalent to the initial value of the microstrip line width.

[0072] In this step, the microstrip line width calculation based on the effective dielectric constant ensures that the target impedance of the microstrip filter can more accurately match the required impedance, avoiding the deviation caused by simple approximation or empirical formula in the traditional design method. It also enables designers to flexibly adjust the microstrip line width according to different substrate materials to adapt to diverse design requirements and actual application scenarios, better predict the electrical performance of the filter and optimize the design, reducing the problems that may be encountered in the actual manufacturing process (for example, impedance mismatch, bandwidth problems, etc.), effectively reducing the uncertainty and complexity in the optimization process, and thus accelerating the overall design process.

[0073] S2: Introduce the DGS structure into the microstrip filter, calculate the structural parameters of the DGS structure according to the design parameters of the microstrip filter, substrate parameters and microstrip line width, and calculate the total impedance of the microstrip filter based on the structural parameters of the DGS structure.

[0074] The logic for calculating the structural parameters of the DGS structure is:

[0075] First, calculate the total length of the slots in the DGS structure. The calculation method is:

[0076] ;

[0077] In the formula represents the total length of the slots in the DGS structure, represents the resonant frequency of the microstrip filter, represents the speed of light;

[0078] Then the width and depth are calculated according to the total length of the slot in the DGS structure. The calculation methods are:

[0079] ;

[0080] ;

[0081] In the formula , Respectively represent the width and depth of the slot in the DGS structure, , denote the first scale factor and the second scale factor respectively, where , .

[0082] Assuming that the target frequency of the microstrip filter is 2.4 GHz, the total length of the slot in the DGS structure is 5.12 mm after retaining two decimal places. Assuming that the first scale factor and the second scale factor are 0.25 and 0.3 respectively, the width and depth of the slot in the DGS structure are 1.28 mm and 1.54 mm respectively. The size of the first scale factor and the second scale factor can be adjusted according to the actual situation, and the specific value can be determined based on experience or simulation results.

[0083] In this step, by calculating the length, width and depth of the DGS structure, the design process of the microstrip filter is made more systematic, which can effectively reduce the design cycle and make the structural parameters of the designed DGS structure more accurate, thereby optimizing the performance, size and impedance matching effect of the microstrip filter. Compared with traditional technologies, it can improve design efficiency and make the design more systematic and efficient.

[0084] S3: Repeatedly change the microstrip line width and the structural parameters of the DGS structure to optimize the total impedance of the microstrip filter and obtain the final microstrip line width and structural parameters of the DGS structure.

[0085] The logic for calculating the total impedance of a microstrip filter is:

[0086] First, calculate the equivalent inductance, equivalent capacitance and equivalent resistance of the DGS structure. The calculation methods are:

[0087] ;

[0088] ;

[0089] ;

[0090] In the formula represents the vacuum permeability, is the dielectric constant of vacuum, Represents the dielectric loss angle in the substrate parameters;

[0091] Then, the equivalent impedance is calculated based on the equivalent inductance, equivalent capacitance and equivalent resistance of the DGS structure. The calculation method is:

[0092] ;

[0093] The total impedance of the microstrip filter is expressed as:

[0094] ;

[0095] In the formula represents the total impedance of the microstrip filter, Represents an imaginary unit.

[0096] The equivalent impedance of the DGS structure is a complex number, including the real part and the imaginary part The real part represents the equivalent resistance, which is used to characterize the power loss caused by conductor loss and dielectric loss in DGS technology. The imaginary part represents the total imaginary impedance, which is generated by the combined effect of inductance and capacitance and is used to represent the characteristics of the equivalent impedance of the DGS structure changing with frequency. This formula reflects the total impedance of the DGS structure in the resonant state. , the impedance is pure resistance.

[0097] The logic for obtaining the final microstrip line width and structural parameters of the DGS structure is:

[0098] When optimizing the total impedance of the microstrip filter, the microstrip line width, the depth and width of the slot in the DGS structure are adjusted and updated. The calculation formulas are:

[0099] ;

[0100] ;

[0101] ;

[0102] In the formula Indicates the number of adjustment updates. represents the adjustment step size, and ;

[0103] When the total impedance of the microstrip filter meets the target impedance When , the optimization is considered to be completed, and the corresponding microstrip line width and structural parameters of the DGS structure are considered to be the final microstrip line width and structural parameters of the DGS structure, where represents the coefficient of volatility, and .

[0104] In this step, the total impedance of the microstrip filter is accurately matched by combining theoretical calculation with dynamic parameter optimization, overcoming the problems of low efficiency and insufficient precision in traditional technology. This not only significantly improves the efficiency and accuracy of the filter design, but also plays an important role in promoting the overall solution, ensuring that the final design results can meet the requirements of modern communications, radar, sensors and other scenarios.

[0105] S4: generating several groups of bending schemes of the DGS structure based on the substrate size, calculating the error coefficient corresponding to each bending scheme, and screening the bending schemes according to the error coefficient to obtain corresponding qualified schemes.

[0106] Based on the structural parameters of the final DGS structure, several sets of bending schemes are generated. Each bending scheme is a U-shaped groove. The bending scheme includes the number of bends, the bending radius and the extension length, where the number of bends, the bending radius and the extension length satisfy the following formula:

[0107] ;

[0108] ;

[0109] ;

[0110] In the formula represents the number of bends, and is a positive integer, represents the bending radius, Indicates the extended length, , Respectively represent the width and length of the preset etching area. The bending radius here specifically refers to the distance between the center lines of the grooves on both sides of the U-shaped groove, and the extension length refers to the length of the connecting line between two adjacent bends. In each bending scheme, the grooves of the DGS structure are all set and aligned up and down. It can be understood that the total length of the groove in the DGS structure after bending is composed of the semicircular bending part, the extension part connected to each other between the bends, and the parts at both ends for up and down alignment. Corresponding to the formula, that is, , as well as The position, width and length of the moment area are set in advance by the designer, and the specific size is determined according to the size of the substrate. It can be understood that since the etching area is attached to the substrate, the size of the etching area is naturally smaller than the substrate size.

[0111] Each bending scheme is simulated in turn, the simulated impedance corresponding to each bending scheme is collected, and the error coefficient between the simulated impedance and the total impedance is calculated as follows:

[0112] ;

[0113] In the formula Represents the simulated impedance, when the error coefficient of the bending scheme , it is marked as a qualified solution.

[0114] In this step, the bending design can achieve a compact structure by increasing the number of bends or reducing the bending radius to meet the needs of some small microstrip filters. When the number of bends increases, the capacitance effect between adjacent conductors may be enhanced, especially at the bends of the slots, which may form local capacitive coupling. Moreover, more bends mean that the current needs to bypass more bends, which will enhance the inductance effect. Therefore, the filter can suppress out-of-band signals more effectively, but at the same time, the equivalent impedance of the DGS structure will change. By combining simulation data and error coefficient calculation, not only can the actual electromagnetic effect of the DGS bending structure be taken into account, making the actual performance more consistent with the theoretical design, but also the generated bending schemes can be scientifically screened, and the best design scheme can be quickly located, avoiding the inefficiency of blind trial and error and repeated iterations in traditional methods, reducing the debugging workload in the production process, and thus improving the consistency and reliability of the product.

[0115] S5: Calculate the insertion loss of the DGS structure in each qualified solution, and construct a scoring function based on the number of bends, insertion loss and processing cost of the DGS structure in the qualified solution, and take the qualified solution with the largest score of the scoring function as the final solution.

[0116] Each qualified solution is simulated and the insertion loss of the DGS structure in each qualified solution is calculated as follows:

[0117] ;

[0118] In the formula represents the insertion loss, , Respectively represent the input intensity and output intensity of the simulation signal;

[0119] Then, a scoring function is constructed based on the number of bends, insertion loss and processing cost of the DGS structure in the qualified solution. The scoring function is expressed as:

[0120] ;

[0121] In the formula represents the score of the scoring function of the qualified solution, , , Represent the first weight, the second weight, and the third weight respectively. , , are greater than 0, and .

[0122] It can be seen from the calculation formula of the score function that the first part is proportional to the number of bends of the DGS structure, because more bends can more effectively suppress out-of-band signals; the second part is inversely proportional to the insertion loss of the DGS structure, because a smaller insertion loss is required to reduce the impact on the signal; the third part is inversely proportional to the number of bends, the width and depth of the slot in the DGS structure, and the microstrip line width, because these parameters can be used to reflect the processing cost. The more bends, the wider the width, and the deeper the depth, the longer the processing time required, and the corresponding processing cost is naturally higher.

[0123] In this step, by constructing a multi-objective scoring function and comprehensively considering key indicators such as the number of bends, insertion loss and processing cost, the optimal solution can be selected from multiple dimensions. Compared with traditional design methods, the optimal solution screened out by this method not only has good electromagnetic performance, but also has high economy and manufacturability, is more suitable for practical applications, and can also reduce the time and energy of manual trial and error in traditional design methods.

[0124] In summary, the present invention realizes the comprehensive optimization of microstrip filter performance by constructing a systematic optimization process, from theoretical calculation to simulation verification, and then to multi-objective scoring screening. On the basis of satisfying impedance matching, this scheme improves compactness through bending design, and the miniaturization effect is significant; at the same time, the performance of the filter is improved by optimizing insertion loss and enhancing out-of-band signal suppression. In addition, this scheme combines processing cost factors to screen out the final design with excellent performance and good manufacturability, which significantly reduces the manufacturing difficulty and cost. Overall, this scheme solves the problem of difficult balance between performance and cost in the prior art, and has broad practical value and reliability.

[0125] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0126] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. Those skilled in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0127] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0128] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A method for designing a broadband high-suppression miniaturized microstrip filter, characterized in that: The specific steps include: S1: According to the design requirements, the design parameters and substrate parameters of the microstrip filter are obtained, and the microstrip line width is calculated based on the design parameters of the microstrip filter and simulated; S2: Introduce the DGS structure into the microstrip filter, calculate the structural parameters of the DGS structure according to the design parameters of the microstrip filter, substrate parameters and microstrip line width, and calculate the total impedance of the microstrip filter according to the structural parameters of the DGS structure; S3: Repeatedly change the microstrip line width and the structural parameters of the DGS structure to optimize the total impedance of the microstrip filter, and obtain the final microstrip line width and structural parameters of the DGS structure; S4: generating several groups of bending schemes of DGS structures based on the substrate size, calculating the error coefficient corresponding to each bending scheme, and screening the bending schemes according to the error coefficient to obtain corresponding qualified schemes; Based on the structural parameters of the final DGS structure, several sets of bending schemes are generated. Each bending scheme is a U-shaped groove. The bending scheme includes the number of bends, the bending radius and the extension length, where the number of bends, the bending radius and the extension length satisfy the following formula: In the formula represents the number of bends, and is a positive integer, represents the bending radius, Indicates the extended length, , Respectively represent the width and length of the preset etching area, represents the total length of the slots in the DGS structure, Indicates the width of the slot in the DGS structure; Each bending scheme is simulated in turn, the simulated impedance corresponding to each bending scheme is collected, and the error coefficient between the simulated impedance and the total impedance is calculated as follows: In the formula Represents the simulated impedance, when the error coefficient of the bending scheme When the solution is , it is marked as a qualified solution; S5: Calculate the insertion loss of the DGS structure in each qualified solution, and construct a scoring function based on the number of bends, insertion loss and processing cost of the DGS structure in the qualified solution, and take the qualified solution with the largest score of the scoring function as the final solution.

2. A method for designing a broadband high-suppression miniaturized microstrip filter according to claim 1, characterized in that: The design parameters include the total impedance, target impedance, and resonant frequency of the microstrip filter; the substrate parameters include substrate size, dielectric constant, and dielectric loss angle; and the structural parameters include the width, depth, and total length of the groove in the DGS structure.

3. A method for designing a broadband high-suppression miniaturized microstrip filter according to claim 2, characterized in that: The target impedance is used as the initial value of the total impedance of the microstrip filter to calculate the initial microstrip line width. The calculation method of the microstrip line width is: In the formula represents the target impedance of the microstrip filter, represents the microstrip line width, represents the substrate thickness, represents the effective dielectric constant, where the effective dielectric constant is calculated as: In the formula Represents the dielectric constant in substrate parameters.

4. The method for designing a broadband high-suppression miniaturized microstrip filter according to claim 3, characterized in that: The logic for calculating the structural parameters of the DGS structure is: First, calculate the total length of the slots in the DGS structure. The calculation method is: In the formula represents the resonant frequency of the microstrip filter, represents the speed of light; Then the width and depth are calculated according to the total length of the slot in the DGS structure. The calculation methods are: In the formula represents the depth of the slot in the DGS structure, , denote the first scale factor and the second scale factor respectively, where , .

5. The method for designing a broadband high-suppression miniaturized microstrip filter according to claim 4, characterized in that: The logic for calculating the total impedance of a microstrip filter is: First, calculate the equivalent inductance, equivalent capacitance and equivalent resistance of the DGS structure. The calculation methods are: In the formula represents the vacuum permeability, is the dielectric constant of vacuum, Represents the dielectric loss angle in the substrate parameters; Then, the equivalent impedance is calculated based on the equivalent inductance, equivalent capacitance and equivalent resistance of the DGS structure. The calculation method is: The total impedance of the microstrip filter is expressed as: In the formula represents the total impedance of the microstrip filter, Represents an imaginary unit.

6. The method for designing a broadband high-suppression miniaturized microstrip filter according to claim 5, characterized in that: The logic for obtaining the final microstrip line width and structural parameters of the DGS structure is: When optimizing the total impedance of the microstrip filter, the microstrip line width, the depth and width of the slot in the DGS structure are adjusted and updated. The calculation formulas are: In the formula Indicates the number of adjustment updates. represents the adjustment step size, and ; When the total impedance of the microstrip filter meets the target impedance When , the optimization is considered to be completed, and the corresponding microstrip line width and structural parameters of the DGS structure are considered to be the final microstrip line width and structural parameters of the DGS structure, where represents the coefficient of volatility, and .

7. A method for designing a broadband high-suppression miniaturized microstrip filter according to claim 6, characterized in that: Each qualified solution is simulated and the insertion loss of the DGS structure in each qualified solution is calculated as follows: In the formula represents the insertion loss, , Respectively represent the input intensity and output intensity of the simulation signal; Then, a scoring function is constructed based on the number of bends, insertion loss and processing cost of the DGS structure in the qualified solution. The scoring function is expressed as: In the formula represents the score of the scoring function of the qualified solution, , , Represent the first weight, the second weight, and the third weight respectively. , , are greater than 0, and .

Images