Parameter optimization method for W-band coupling multi-band filter

Abstract

The invention discloses a W-band coupling multi-band filter parameter optimization method, which is characterized in that each step from the determination of an ideal characteristic function to the adjustment of a final performance index has a clear guidance and optimization target through a systematic design process, so that the design efficiency is improved, and the design cost is reduced. And the frequency response characteristic of the filter can accurately meet the expectation. The design indexes of the filter, such as center frequency and bandwidth, are determined, so that the design process is more accurate, and the filter can meet the requirements of a specific communication system. And the accurate coupling matrix is automatically generated by utilizing the coupling matrix comprehensive software, so that the design efficiency and accuracy are improved. By converting the coupling matrix into specific physical design parameters, detailed guidance is provided for actual manufacturing of the filter, and seamless joint from design to manufacturing is ensured. The resonant frequency of the resonant cavity is calculated to ensure that the filter works at the predetermined frequency, and the selectivity and insertion loss performance of the filter are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of communication and microwave engineering, and in particular to a W-band coupled multi-band filter system. Background Art

[0002] In the field of communication and microwave engineering, the W band (70-116 GHz) has been widely used in radar, missile terminal guidance, millimeter wave countermeasures and communications due to its small attenuation in atmospheric propagation. With the development of wireless communication technology, there is an increasing demand for multi-band filters that can operate in multiple frequency bands to provide signal separation and interference suppression.

[0003] Traditional W-band filters are often difficult to design to simultaneously meet the requirements of wide bandwidth, low loss, and high integration. For example, although some filters can achieve a wider frequency band response, they have deficiencies in loss and integration, which limits their application in high-performance communication systems. In addition, existing technologies also face challenges in achieving miniaturization and high performance of filters. Traditional filters are relatively large in size and cannot meet the requirements of modern communication equipment for miniaturization, high performance, easy integration, and high stability.

[0004] Secondly, the existing technology has problems with the impedance matching and signal transmission efficiency of the filter. When designing the filter, it is impossible to effectively ensure that the input and output ports can be correctly connected to the external circuit and meet the requirements such as impedance matching, which affects the practicality and signal transmission efficiency of the filter.

[0005] In summary, the existing W-band coupled filter technology has obvious shortcomings in meeting the requirements of modern communication systems for high performance, miniaturization, easy integration and high stability. Summary of the invention

[0006] The present invention aims to provide a W-band coupling filter parameter optimization method to solve the above problems.

[0007] The present invention is achieved through the following technical solutions: A W-band coupling filter parameter optimization method comprises the following steps: S1: Approximation of ideal characteristic function, determining the ideal characteristic function of the filter; The frequency response function of the ideal bandpass filter is: in and are the lower cutoff frequency and the upper cutoff frequency respectively; S2: Coupling matrix calculation: According to the coupling matrix theory, the coupling matrix for designing the filter is optimized; S3: Physical parameter design, after obtaining the coupling matrix, these parameters are converted into specific physical design parameters; S4: Calculate the resonant frequency of the resonant cavity according to the physical size and operating frequency of the resonant cavity; S5: Simulate the coupling between the resonant cavities and determine the coupling coefficient; S6: Simulate the input and output ports of the filter to ensure that they can be correctly connected to the external circuit, and design appropriate port coupling structures through the coupling coefficient determined in S5 to meet the requirements such as impedance matching; S7: Establish the overall model of the filter and perform simulation to verify whether the designed frequency response characteristics meet expectations; S8: According to the simulation results, the structural parameters of the filter are adjusted to achieve the best performance indicators.

[0008] In the present invention, the design process has clear guidance and optimization goals for each step from the determination of the ideal characteristic function to the adjustment of the final performance index. This method not only improves the design efficiency, but also ensures that the frequency response characteristics of the filter can accurately meet expectations through simulation and adjustment, thereby improving the overall performance of the filter. In addition, by ensuring that the input and output ports of the filter can be correctly connected to the external circuit and meet requirements such as impedance matching, the practicality and compatibility of the filter are enhanced, so that it can be better integrated into a wider range of communication systems.

[0009] Preferably, in S2, the coupling matrix calculation specifically includes the following steps: S2.1: Determine the design indicators. Determine the design indicators of the filter according to the requirements of the communication system, including center frequency, bandwidth, insertion loss, return loss, cutoff frequency, relative bandwidth, and standing wave ratio; S.2.2: Establish the coupling matrix topology. Use the coupling matrix synthesis software to establish the topology of the filter. This topology represents the physical connection method of the filter, including the coupling method and coupling strength between the resonators. Specifically, the design indicators of the filter input in S2.1 are used. The software automatically generates an accurate coupling matrix. The present invention makes the design process more accurate by clarifying the design indicators of the filter, such as the center frequency, bandwidth, etc., ensuring that the filter can meet the requirements of a specific communication system. In addition, the coupling matrix synthesis software is used to automatically generate an accurate coupling matrix, which not only improves the design efficiency, but also reduces human errors and improves the accuracy of the design. This method enables designers to quickly respond to system changes and adjust the design in time to adapt to the ever-changing communication technology needs.

[0010] Preferably, S3 specifically includes the following steps: S3.1: Normalized coupling matrix. According to the coupling matrix of S2.2, the normalized coupling matrix m is obtained, where the expression of m is: S3.2: Calculate the actual coupling matrix M ,in M Calculated by the following formula: in, M is the actual coupling matrix; is the identity matrix, which is expressed as: is a matrix of the same dimension as the coupling matrix m, and its expression is, whose elements Indicates n Row and n The elements of the column, where n is the order of the filter; is the actual coupling matrix, is a matrix The inverse matrix of is the frequency deviation factor, is the current frequency, is the center frequency; The present invention takes into account the frequency deviation factor, making the design more adaptable to actual working conditions. This method allows the designer to take into account the frequency changes during the design process, thereby optimizing the performance of the filter at different frequencies. Through this precise calculation, the stability and efficiency of the filter can be ensured over a wide frequency range, improving the adaptability and performance of the filter; S3.3: According to the normalized coupling matrix and the actual coupling matrix, the S parameters are calculated by the formula, where the formula is as follows: in, is the reflection coefficient of port 1, which indicates what proportion of the signal incident from port 1 is reflected back to port 1; is the reflection coefficient of port 2, which indicates what proportion of the signal incident from port 2 is reflected back to port 2; is the reverse gain from port 2 to port 1, which indicates how much of the signal incident from port 2 is transmitted to port 1; is the forward gain from port 1 to port 2, which indicates how much of the signal incident from port 1 is transmitted to port 2, where yes The complex conjugate of is the impedance of port 1, is the characteristic impedance of port 1; is the impedance of port 2, is the characteristic impedance of port 2; is the frequency; is the impedance of the port, Characteristic impedance is an imaginary unit; S3.4: According to the calculated S parameters, the physical size of the resonator and the coupling path are obtained, which includes the length and width of the resonator and the size of the coupling path; The present invention enables designers to analyze the transmission characteristics of signals in filters in detail by calculating the reflection coefficient and gain of the ports. This analysis is crucial for optimizing signal transmission efficiency because it can help identify and reduce signal losses and ensure efficient transmission of signals in filters. In addition, this detailed signal analysis can also help improve the insertion loss performance of the filter, thereby improving the performance of the entire communication system.

[0011] Preferably, in S4, the resonant frequency of the resonant cavity is calculated according to the physical size and operating frequency of the resonant cavity, and the calculation formula is as follows: in, is the resonant frequency in Hertz (Hz); It is the speed of light; is the relative permittivity, which is the ratio of the material permittivity to the vacuum permittivity; is the relative magnetic permeability, which is the ratio of the material's magnetic permeability to the vacuum's magnetic permeability; is the mode number along the x direction; is the mode number along the y direction; is the mode number along the z direction; is the dimension of the cavity along the x direction, in meters (m); is the dimension of the cavity along the y direction, in meters (m); is the dimension of the cavity along the z direction, in meters (m).

[0012] The present invention provides a formula for calculating the resonant frequency of the resonant cavity. Through this precise calculation, it can be ensured that the resonant frequency of the filter is consistent with the design target, thereby helping to optimize the design of the filter so that it can achieve the best performance at a specific operating frequency, which is crucial to meet the requirements of a specific communication system. Preferably, in S5, simulating the coupling between the resonant cavities to determine the coupling coefficient specifically includes the following steps: S5.1: Core problem division, decompose the core problem into two main parts, namely, solving the electromagnetic field inside the resonant cavity and analyzing the coupling effect between resonant cavities; The finite element method (FEM) is used to accurately simulate the electromagnetic field inside the resonant cavity, and the moment method (MoM) is used to analyze the coupling effect between resonant cavities to deal with the coupling problems of open structures or complex geometric shapes. S5.2: Problem solving. For the FEM part, establish the geometric model of the resonant cavity, define the material properties and the cavity boundary conditions obtained in S4, perform meshing, and solve the electromagnetic field distribution inside the resonant cavity. For the MoM part of the problem, define the interactions between the resonators and solve their impact on the overall system performance; S5.3: Merge results; The results of FEM and MoM are combined to analyze the coupling coefficient between the resonant cavities.

[0013] The present invention combines the finite element method with the moment method to provide a more accurate method for simulating the electromagnetic field and coupling effects inside the resonant cavity. This method not only improves the accuracy of the simulation, but also enables designers to better understand and control the performance of the filter. By accurately simulating the coupling coefficient between the resonant cavities, designers can optimize the design of the filter, improve its selectivity and out-of-band suppression performance, and thus improve the performance of the entire communication system.

[0014] Preferably, in S5.3, in the process of combining the results of FEM and MoM, in the MoM region, the current coefficient is not obtained by directly solving the linear equations, but by applying the physical optics (PO) approximation method, dividing a few basis functions into the MoM region and the remaining basis functions into the PO region, where there are at least two resonant cavities, and the following formula is obtained by sorting: in, is the self-impedance matrix of the MoM region, representing the interaction between the current coefficients in the MoM region; is the mutual impedance matrix between the MoM region and the PO region, which represents the influence of the MoM region on the current coefficient of the PO region; is the mutual impedance matrix between the PO region and the MoM region, indicating the influence of the PO region on the current coefficient of the MoM region, yes The transpose of is the self-impedance matrix of the PO region, which represents the interaction between the current coefficients in the PO region; is the current coefficient vector of the MoM region; is the current coefficient vector in the PO region; is the excitation vector of the MoM region, which represents the distribution of external sources in the MoM region; is the excitation vector of the PO region, which represents the distribution of the external source in the PO region; is the coupling coefficient; and are the electric fields in the two resonant cavities respectively; is the current density in the first resonant cavity; and is the volume of the two resonant cavities; represents the interaction of electric field and current between two resonant cavities; It is the square root of the product of the electric field energies in the two resonant cavities; In the above formula, the current coefficient calculated in the MoM region and the PO region is and Used to determine the current distribution in each resonant cavity and , is the current density in the second resonant cavity, giving the coupling coefficient .

[0015] Preferably, the establishment of the overall simulation in S7 is specifically to perform a three-dimensional modeling simulation of the filter through HFSS, wherein in the overall model simulation, the frequency tuning screw, the coupling tuning screw and the tap height are all set as variables, and the initial dimensions of the previous simulation are substituted, and parameter scanning and optimization are performed to adjust the frequency response characteristics until the design requirements are met; The present invention uses HFSS for three-dimensional modeling and simulation, so that the designer can intuitively observe and adjust the design of the filter. This method not only improves the design flexibility, but also enables the designer to quickly respond to design changes and adjust parameters in time to meet specific performance requirements. Through parameter scanning and optimization, the frequency response characteristics can be accurately adjusted until the design requirements are met, thereby improving the performance and reliability of the filter.

[0016] Preferably, the specific method of adjusting the structural parameters of the filter in S8 is: A nonlinear algorithm is used to adjust the filter structure. The number of fingers, period length, and aperture of each transducer and reflector in the filter structure are set as optimization variables. During the adjustment, the longitudinal coupling structure and the resonator are taken as a whole so that their structural parameters are optimized simultaneously as independent variables. In addition, the upper limit, lower limit, initial value, and objective function of the adjustment variable are set. In the objective function, different weights are given to indicators such as loss, bandwidth, and out-of-band suppression to adjust the filter structure parameters.

[0017] The present invention uses a nonlinear algorithm to adjust the filter structure, providing a more effective method for optimizing filter performance. This method allows designers to optimize multiple structural parameters, such as the number of fingers, cycle length, etc., at the same time to achieve the best performance indicators. By setting the upper limit, lower limit and initial value of the adjustment variable, and assigning different weights to different performance indicators in the objective function, multi-objective optimization can be achieved to balance the performance indicators such as the filter's loss, bandwidth and out-of-band suppression, thereby improving the performance of the entire communication system.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention adopts a systematic design process, from the determination of the ideal characteristic function to the adjustment of the final performance index, each step has clear guidance and optimization goals, which not only improves the design efficiency, but also ensures that the frequency response characteristics of the filter can accurately meet the expectations. The design indicators of the filter, such as the center frequency, bandwidth, etc., are clarified, so that the design process is more accurate and ensures that the filter can meet the requirements of a specific communication system. The coupling matrix synthesis software is used to automatically generate an accurate coupling matrix, which improves the design efficiency and accuracy. By converting the coupling matrix into specific physical design parameters, detailed guidance is provided for the actual manufacture of the filter, ensuring seamless connection from design to manufacture. The resonant frequency of the resonant cavity is calculated to ensure that the filter works at a predetermined frequency, thereby improving the selectivity and insertion loss performance of the filter. Combining the finite element method and the moment method, a more accurate method for simulating the electromagnetic field and coupling effect inside the resonant cavity is provided, which improves the accuracy of the simulation. By combining the results of FEM and MoM, a more accurate method for determining the coupling coefficient is provided, which optimizes the design of the filter and improves its selectivity and out-of-band suppression performance. Using HFSS for three-dimensional modeling and simulation improves the flexibility of the design, so that the designer can quickly respond to design changes and adjust parameters in time to meet specific performance requirements. Finally, the use of nonlinear algorithms to adjust the filter structure allows designers to optimize multiple structural parameters at the same time to achieve the best performance indicators, balance the filter's loss, bandwidth, and out-of-band suppression performance indicators, thereby improving the performance of the entire communication system. In general, the implementation of these technical solutions not only improves the performance and reliability of the filter, but also enhances its practicality and compatibility in communication systems. DETAILED DESCRIPTION

[0019] The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present invention. It should be noted that relational terms such as the terms "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0020] Moreover, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a list of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of more restrictions, an element defined by the phrase "comprises a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0021] Example This embodiment includes: a W-band coupling filter parameter optimization method, including the following steps: S1: Approximation of ideal characteristic function, determining the ideal characteristic function of the filter; The frequency response function of the ideal bandpass filter is: in and are the lower cutoff frequency and the upper cutoff frequency respectively; S2: Coupling matrix calculation: According to the coupling matrix theory, the coupling matrix for designing the filter is optimized; S3: Physical parameter design, after obtaining the coupling matrix, these parameters are converted into specific physical design parameters; S4: Calculate the resonant frequency of the resonant cavity according to the physical size and operating frequency of the resonant cavity; S5: Simulate the coupling between the resonant cavities and determine the coupling coefficient; S6: Simulate the input and output ports of the filter to ensure that they can be correctly connected to the external circuit, and design appropriate port coupling structures through the coupling coefficient determined in S5 to meet the requirements such as impedance matching; S7: Establish the overall model of the filter and perform simulation to verify whether the designed frequency response characteristics meet expectations; S8: According to the simulation results, the structural parameters of the filter are adjusted to achieve the best performance indicators.

[0022] In the present invention, the design process has clear guidance and optimization goals for each step from the determination of the ideal characteristic function to the adjustment of the final performance index. This method not only improves the design efficiency, but also ensures that the frequency response characteristics of the filter can accurately meet expectations through simulation and adjustment, thereby improving the overall performance of the filter. In addition, by ensuring that the input and output ports of the filter can be correctly connected to the external circuit and meet requirements such as impedance matching, the practicality and compatibility of the filter are enhanced, so that it can be better integrated into a wider range of communication systems.

[0023] Preferably, in S2, the coupling matrix calculation specifically includes the following steps: S2.1: Determine the design indicators. Determine the design indicators of the filter according to the requirements of the communication system, including center frequency, bandwidth, insertion loss, return loss, cutoff frequency, relative bandwidth, and standing wave ratio; S.2.2: Establish the coupling matrix topology. Use the coupling matrix synthesis software to establish the topology of the filter. This topology represents the physical connection method of the filter, including the coupling method and coupling strength between the resonators. Specifically, the design indicators of the filter input in S2.1 are used. The software automatically generates an accurate coupling matrix. The present invention makes the design process more accurate by clarifying the design indicators of the filter, such as the center frequency, bandwidth, etc., ensuring that the filter can meet the requirements of a specific communication system. In addition, the coupling matrix synthesis software is used to automatically generate an accurate coupling matrix, which not only improves the design efficiency, but also reduces human errors and improves the accuracy of the design. This method enables designers to quickly respond to system changes and adjust the design in time to adapt to the ever-changing communication technology needs.

[0024] Preferably, S3 specifically includes the following steps: S3.1: Normalized coupling matrix. According to the coupling matrix of S2.2, the normalized coupling matrix m is obtained, where the expression of m is: S3.2: Calculate the actual coupling matrix M ,in M Calculated by the following formula: in, M is the actual coupling matrix; is the identity matrix, which is expressed as: is a matrix of the same dimension as the coupling matrix m, and its expression is, whose elements Indicates n Row and n The elements of the column, where n is the order of the filter; is the actual coupling matrix, is a matrix The inverse matrix of is the frequency deviation factor, is the current frequency, is the center frequency; The present invention takes into account the frequency deviation factor, making the design more adaptable to actual working conditions. This method allows the designer to take into account the frequency changes during the design process, thereby optimizing the performance of the filter at different frequencies. Through this precise calculation, the stability and efficiency of the filter can be ensured over a wide frequency range, improving the adaptability and performance of the filter; S3.3: According to the normalized coupling matrix and the actual coupling matrix, the S parameters are calculated by the formula, where the formula is as follows: in, is the reflection coefficient of port 1, which indicates what proportion of the signal incident from port 1 is reflected back to port 1; is the reflection coefficient of port 2, which indicates what proportion of the signal incident from port 2 is reflected back to port 2; is the reverse gain from port 2 to port 1, which indicates how much of the signal incident from port 2 is transmitted to port 1; is the forward gain from port 1 to port 2, which indicates how much of the signal incident from port 1 is transmitted to port 2, where yes The complex conjugate of is the impedance of port 1, is the characteristic impedance of port 1; is the impedance of port 2, is the characteristic impedance of port 2; is the frequency; is the impedance of the port, Characteristic impedance is an imaginary unit; It can be understood that the parameter S, also known as the scattering parameter, is a set of parameters used to describe the interaction between microwave network ports, including reflection coefficient and gain; S3.4: According to the calculated S parameters, the physical size of the resonator and the coupling path are obtained, which includes the length and width of the resonator and the size of the coupling path; The present invention enables designers to analyze the transmission characteristics of signals in filters in detail by calculating the reflection coefficient and gain of the ports. This analysis is crucial for optimizing signal transmission efficiency because it can help identify and reduce signal losses and ensure efficient transmission of signals in filters. In addition, this detailed signal analysis can also help improve the insertion loss performance of the filter, thereby improving the performance of the entire communication system.

[0025] Preferably, in S4, the resonant frequency of the resonant cavity is calculated according to the physical size and operating frequency of the resonant cavity, and the calculation formula is as follows: in, is the resonant frequency in Hertz (Hz); It is the speed of light; is the relative permittivity, which is the ratio of the material permittivity to the vacuum permittivity; is the relative magnetic permeability, which is the ratio of the material's magnetic permeability to the vacuum's magnetic permeability; is the mode number along the x direction; is the mode number along the y direction; is the mode number along the z direction; is the dimension of the cavity along the x direction, in meters (m); is the dimension of the cavity along the y direction, in meters (m); is the dimension of the cavity along the z direction, in meters (m).

[0026] The present invention provides a formula for calculating the resonant frequency of the resonant cavity. Through this precise calculation, it can be ensured that the resonant frequency of the filter is consistent with the design target, thereby helping to optimize the design of the filter so that it can achieve the best performance at a specific operating frequency, which is crucial to meet the requirements of a specific communication system. Preferably, in S5, simulating the coupling between the resonant cavities to determine the coupling coefficient specifically includes the following steps: S5.1: Core problem division, decompose the core problem into two main parts, namely, solving the electromagnetic field inside the resonant cavity and analyzing the coupling effect between resonant cavities; The finite element method (FEM) is used to accurately simulate the electromagnetic field inside the resonant cavity, and the moment method (MoM) is used to analyze the coupling effect between resonant cavities to deal with the coupling problems of open structures or complex geometric shapes. It can be understood that the finite element method (FEM) is a numerical analysis method that solves partial differential equations by discretizing a continuous domain into a finite number of small elements; Method of moments (MoM): is a numerical calculation method used to solve electromagnetic field problems; S5.2: Problem solving. For the FEM part, establish the geometric model of the resonant cavity, define the material properties and the cavity boundary conditions obtained in S4, perform meshing, and solve the electromagnetic field distribution inside the resonant cavity. For the MoM part of the problem, define the interactions between the resonators and solve their impact on the overall system performance; S5.3: Merge results; The results of FEM and MoM are combined to analyze the coupling coefficient between the resonant cavities.

[0027] The present invention combines the finite element method with the moment method to provide a more accurate method for simulating the electromagnetic field and coupling effects inside the resonant cavity. This method not only improves the accuracy of the simulation, but also enables designers to better understand and control the performance of the filter. By accurately simulating the coupling coefficient between the resonant cavities, designers can optimize the design of the filter, improve its selectivity and out-of-band suppression performance, and thus improve the performance of the entire communication system.

[0028] Preferably, in S5.3, in the process of combining the results of FEM and MoM, in the MoM region, the current coefficient is not obtained by directly solving the linear equations, but by applying the physical optics (PO) approximation method, dividing a few basis functions into the MoM region and the remaining basis functions into the PO region, where there are at least two resonant cavities, and the following formula is obtained by sorting: in, is the self-impedance matrix of the MoM region, representing the interaction between the current coefficients in the MoM region; is the mutual impedance matrix between the MoM region and the PO region, which represents the influence of the MoM region on the current coefficient of the PO region; is the mutual impedance matrix between the PO region and the MoM region, indicating the influence of the PO region on the current coefficient of the MoM region, yes The transpose of is the self-impedance matrix of the PO region, which represents the interaction between the current coefficients in the PO region; is the current coefficient vector of the MoM region; is the current coefficient vector in the PO region; is the excitation vector of the MoM region, which represents the distribution of external sources in the MoM region; is the excitation vector of the PO region, which represents the distribution of the external source in the PO region; is the coupling coefficient; and are the electric fields in the two resonant cavities respectively; is the current density in the first resonant cavity; and is the volume of the two resonant cavities; represents the interaction of electric field and current between two resonant cavities; It is the square root of the product of the electric field energies in the two resonant cavities; In the above formula, the current coefficient calculated in the MoM region and the PO region is and Used to determine the current distribution in each resonant cavity and , is the current density in the second resonant cavity, giving the coupling coefficient .

[0029] Preferably, the establishment of the overall simulation in S7 is specifically to perform a three-dimensional modeling simulation of the filter through HFSS, wherein in the overall model simulation, the frequency tuning screw, the coupling tuning screw and the tap height are all set as variables, and the initial dimensions of the previous simulation are substituted, and parameter scanning and optimization are performed to adjust the frequency response characteristics until the design requirements are met; The present invention uses HFSS for three-dimensional modeling and simulation, so that the designer can intuitively observe and adjust the design of the filter. This method not only improves the design flexibility, but also enables the designer to quickly respond to design changes and adjust parameters in time to meet specific performance requirements. Through parameter scanning and optimization, the frequency response characteristics can be accurately adjusted until the design requirements are met, thereby improving the performance and reliability of the filter.

[0030] Preferably, the specific method of adjusting the structural parameters of the filter in S8 is: A nonlinear algorithm is used to adjust the filter structure. The number of fingers, period length, and aperture of each transducer and reflector in the filter structure are set as optimization variables. During the adjustment, the longitudinal coupling structure and the resonator are taken as a whole so that their structural parameters are optimized simultaneously as independent variables. In addition, the upper limit, lower limit, initial value, and objective function of the adjustment variable are set. In the objective function, different weights are given to indicators such as loss, bandwidth, and out-of-band suppression to adjust the filter structure parameters.

[0031] The present invention uses a nonlinear algorithm to adjust the filter structure, providing a more effective method for optimizing filter performance. This method allows designers to optimize multiple structural parameters, such as the number of fingers, cycle length, etc., at the same time to achieve the best performance indicators. By setting the upper limit, lower limit and initial value of the adjustment variable, and assigning different weights to different performance indicators in the objective function, multi-objective optimization can be achieved to balance the performance indicators such as the filter's loss, bandwidth and out-of-band suppression, thereby improving the performance of the entire communication system.

[0032] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A W-band coupled filter parameter optimization method, characterized in that: The following steps are involved: S1: Approximation of ideal characteristic function, determining the ideal characteristic function of the filter; The frequency response function of the ideal bandpass filter is: in and are the lower cutoff frequency and the upper cutoff frequency respectively; S2: Coupling matrix calculation: According to the coupling matrix theory, the coupling matrix for designing the filter is optimized; S3: Physical parameter design, after obtaining the coupling matrix, these parameters are converted into specific physical design parameters; S4: Calculate the resonant frequency of the resonant cavity according to the physical size and operating frequency of the resonant cavity; S5: Simulate the coupling between the resonant cavities and determine the coupling coefficient; S6: Simulate the input and output ports of the filter to ensure that they can be correctly connected to the external circuit and meet the requirements such as impedance matching; S7: Establish the overall model of the filter and perform simulation to verify whether the designed frequency response characteristics meet expectations; S8: According to the simulation results, the structural parameters of the filter are adjusted to achieve the best performance indicators.

2. A W-band coupled filter parameter optimization method according to claim 1, characterized in that: In S2, the coupling matrix calculation specifically includes the following steps: S2.1: Determine the design indicators. Determine the design indicators of the filter according to the requirements of the communication system, including center frequency, bandwidth, insertion loss, return loss, cutoff frequency, relative bandwidth, and standing wave ratio; S.2.2: Establish the coupling matrix topology. Use the coupling matrix synthesis software to establish the topology of the filter. This topology represents the physical connection method of the filter, including the coupling method and coupling strength between the resonators. Specifically, it is the design index of the filter input in S2.

1. The software automatically generates an accurate coupling matrix.

3. A W-band coupled filter parameter optimization method according to claim 2, characterized in that: S3 specifically includes the following steps: S3.1: Normalized coupling matrix. According to the coupling matrix of S2.2, the normalized coupling matrix m is obtained, where the expression of m is: Where n is the order of the filter; S3.2: Calculate the actual coupling matrix M ; S3.3: Obtain S parameters based on the normalized coupling matrix and the actual coupling matrix; S3.4: Based on the calculated S parameters, the physical dimensions of the resonator and the coupling path are obtained, which include the length and width of the resonator, and the dimensions of the coupling path.

4. The W-band coupled filter parameter optimization method according to claim 3, characterized in that: in M Calculated by the following formula: in, M is the actual coupling matrix; is the identity matrix, which is expressed as: is a matrix of the same dimension as the coupling matrix m, and its expression is, whose elements Indicates n Row and n The elements of the column, where n is the order of the filter; is the actual coupling matrix, is a matrix The inverse matrix of is the frequency deviation factor, is the current frequency, is the center frequency.

5. A W-band coupling filter parameter optimization method according to claim 4, characterized in that: The formula for calculating S is as follows: in, is the reflection coefficient of port 1, which indicates what proportion of the signal incident from port 1 is reflected back to port 1; is the reflection coefficient of port 2, which indicates what proportion of the signal incident from port 2 is reflected back to port 2; is the reverse gain from port 2 to port 1, which indicates how much of the signal incident from port 2 is transmitted to port 1; is the forward gain from port 1 to port 2, which indicates how much of the signal incident from port 1 is transmitted to port 2, where yes The complex conjugate of is the impedance of port 1, is the characteristic impedance of port 1; is the impedance of port 2, is the characteristic impedance of port 2; is the frequency; is the impedance of the port, Characteristic impedance Is an imaginary unit.

6. A W-band coupling filter parameter optimization method according to claim 5, characterized in that: In S4, the resonant frequency of the resonant cavity is calculated according to the physical size and operating frequency of the resonant cavity. The calculation formula is as follows: in, is the resonant frequency, in Hertz, Hz; It is the speed of light; is the relative permittivity, which is the ratio of the material permittivity to the vacuum permittivity; is the relative magnetic permeability, which is the ratio of the material's magnetic permeability to the vacuum's magnetic permeability; is the mode number along the x direction; is the mode number along the y direction; is the mode number along the z direction; is the dimension of the cavity along the x direction, in meters, m; is the dimension of the cavity along the y direction, in meters, m; is the dimension of the cavity along the z direction, in meters, m.

7. A W-band coupling filter parameter optimization method according to claim 6, characterized in that: In S5, the coupling between the resonant cavities is simulated, and the specific steps of determining the coupling coefficient include the following: S5.1: Core problem division, decompose the core problem into two main parts, namely, solving the electromagnetic field inside the resonant cavity and analyzing the coupling effect between resonant cavities; The finite element method (FEM) is used to accurately simulate the electromagnetic field inside the resonant cavity, and the moment method (MoM) is used to analyze the coupling effect between resonant cavities to deal with the coupling problems of open structures or complex geometric shapes. S5.2: Problem solving. For the FEM part, establish the geometric model of the resonant cavity, define the material properties and the cavity boundary conditions obtained in S4, perform meshing, and solve the electromagnetic field distribution inside the resonant cavity. For the MoM part of the problem, define the interactions between the resonators and solve their impact on the overall system performance; S5.3: Merge results; The results of FEM and MoM are combined to analyze the coupling coefficient between the resonant cavities.

8. A W-band coupling filter parameter optimization method according to claim 7, characterized in that: In S5.3, in the process of combining the results of FEM and MoM, in the MoM region, the current coefficient is not obtained by directly solving the linear equations, but by applying the physical optics approximation method to divide a few basis functions into the MoM region and the rest into the PO region, where there are at least two resonant cavities. The following formula is obtained by rearranging: in, is the self-impedance matrix of the MoM region, representing the interaction between the current coefficients in the MoM region; is the mutual impedance matrix between the MoM region and the PO region, which represents the influence of the MoM region on the current coefficient of the PO region; is the mutual impedance matrix between the PO region and the MoM region, indicating the influence of the PO region on the current coefficient of the MoM region, yes The transpose of is the self-impedance matrix of the PO region, representing the interaction between the current coefficients in the PO region; is the current coefficient vector of the MoM region; is the current coefficient vector in the PO region; is the excitation vector of the MoM region, which represents the distribution of external sources in the MoM region; is the excitation vector of the PO region, which represents the distribution of the external source in the PO region; is the coupling coefficient; and are the electric fields in the two resonant cavities respectively; is the current density in the first resonant cavity; and is the volume of the two resonant cavities; represents the interaction of electric field and current between two resonant cavities; It is the square root of the product of the electric field energies in the two resonant cavities; In the above formula, the current coefficient calculated in the MoM region and the PO region is and Used to determine the current distribution in each resonant cavity and , is the current density in the second resonant cavity, giving the coupling coefficient .

9. A W-band coupling filter parameter optimization method according to claim 8, characterized in that: The establishment of the overall simulation in S7 is specifically to perform three-dimensional modeling simulation of the filter through HFSS. In the overall model simulation, the frequency tuning screw, coupling tuning screw and tap height are set as variables, and the initial dimensions of the previous simulation are substituted for parameter scanning and optimization to adjust the frequency response characteristics until the design requirements are met.

10. A W-band coupling filter parameter optimization method according to claim 9, characterized in that: The specific method of adjusting the structural parameters of the filter in S8 is: A nonlinear algorithm is used to adjust the filter structure. The number of fingers, period length, and aperture of each transducer and reflector in the filter structure are set as optimization variables. During the adjustment, the longitudinal coupling structure and the resonator are taken as a whole so that their structural parameters are optimized simultaneously as independent variables. In addition, the upper limit, lower limit, initial value, and objective function of the adjustment variable are set. In the objective function, different weights are given to indicators such as loss, bandwidth, and out-of-band suppression to adjust the filter structure parameters.

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