A simulation-based method for optimizing powder filter structure

Abstract

The present invention relates to a simulation-based powder filter structure optimization method, comprising: obtaining initial structural parameters of the powder filter; setting configuration parameters of a simulation environment; modeling the powder filter based on the initial structural parameters and configuration parameters to obtain a powder filter simulation model; performing a time-domain solution on the powder filter simulation model to obtain a transmission characteristic curve of the powder filter; and optimizing the initial structural parameters of the powder filter based on the transmission characteristic curve. The present invention improves the efficiency of powder filter development while also helping to increase the iteration speed of the powder filter.

Description

Technical Field

[0001] The present invention relates to the field of filters, and in particular to a simulation-based powder filter structure optimization method. Background Art

[0002] With the development of cryogenic technology, many low-temperature experiments have been widely conducted, among which superconducting quantum experiments have become a hot topic. In order to measure weak DC signals during superconducting quantum experiments, it is necessary to effectively filter out high-frequency noise from the signals. Powder filters with low-pass filtering characteristics have an advantageous position in superconducting quantum experiments due to their stable performance and simple fabrication.

[0003] The earliest powder filter was the copper powder filter reported by Martinis et al. Its main principle is to exploit the skin effect of metal powder to significantly attenuate high-frequency components in the signal. Specifically, when an electromagnetic wave signal passes through a cavity filled with metal powder, the high-frequency electromagnetic wave is sharply attenuated when passing through the metal powder surface, while the corresponding DC signal is attenuated very little, thus achieving the powder filter's low-pass filtering effect. Its manufacturing process is briefly described as follows: a central conductor with a specific structure, such as a zigzag or spiral, is formed within a rectangular or cylindrical metal cavity. The cavity is then filled with copper powder or other ferromagnetic powder. Appropriate microwave adapters are then installed on both sides of the cavity, and the powder filter is finally packaged.

[0004] All existing research literature on powder filters relies on experimental measurements to characterize the filtering performance of powder filters. No simulation methods for powder filters have been reported, which has delayed the iterative update speed of powder filters to a certain extent. In actual measurements, it is difficult to achieve dynamic parameter optimization of the designed and manufactured shell, wound center conductor, used filling material, etc., which increases the research cost of powder filters. Summary of the Invention

[0005] The purpose of the present invention is to provide a powder filter structure optimization method based on simulation, which helps to improve the development efficiency of the powder filter while increasing the iteration speed of the powder filter.

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

[0007] A powder filter structure optimization method based on simulation, comprising:

[0008] Obtaining the initial structural parameters of the powder filter;

[0009] Set the configuration parameters of the simulation environment;

[0010] Modeling the powder filter based on the initial structural parameters and configuration parameters to obtain a powder filter simulation model;

[0011] Performing a time domain solution on the powder filter simulation model to obtain a transmission characteristic curve of the powder filter;

[0012] The initial structural parameters of the powder filter are optimized according to the transmission characteristic curve.

[0013] Optionally, the powder filter includes a shell, a center conductor and a filling material, an opening is respectively provided at the center of two opposite side walls of the shell, the center conductor is located at the center of the shell, the end face of the center conductor is coplanar with the outer surface of the side wall and the center coincides, and the filling material is used to fill the space in the shell except the center conductor.

[0014] Optionally, the configuration parameters for setting the simulation environment specifically include: setting the length unit, temperature unit, frequency unit and time unit of the powder filter simulation model to mm, Kelvin, GHz and s respectively, setting the simulation frequency to 0GHz to 10GHz, setting the background material to normal, and setting the boundary condition to electrostatic shielding state.

[0015] Optionally, the simulation environment is three-dimensional electromagnetic field simulation software CST.

[0016] Optionally, when performing a time domain solution on the powder filter simulation model, a port resistance of 50Ω is set.

[0017] Optionally, the transmission characteristic curve includes an S11 curve, an S12 curve, an S21 curve and an S22 curve.

[0018] Optionally, the modeling sequence is center conductor, filling material and shell.

[0019] Optionally, the center conductor modeling process includes:

[0020] Create a new circular surface at the space origin (0, 0, 0);

[0021] Stretching, rotating and performing Boolean operations on the circular surface to construct a single helical central conductor;

[0022] The geometric midline of the center conductor is set to coincide with the positive half axis of the Z axis.

[0023] Optionally, the modeling process of the filling material includes:

[0024] Modeling the filling material by adopting a cuboid modeling method;

[0025] removing the portion of the filling material that overlaps with the center conductor by a Boolean operation;

[0026] The geometric center line of the filling material is set to coincide with the positive half axis of the Z axis.

[0027] Optionally, the shell modeling process includes:

[0028] Modeling the shell by adopting a cuboid modeling method;

[0029] removing the portion of the housing that overlaps with the center conductor and the filling material through a Boolean operation;

[0030] An opening is respectively provided at the center of two side walls of the housing through Boolean operation;

[0031] The geometric center line of the shell is set to coincide with the positive half axis of the Z axis.

[0032] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0033] Using the simulation-based powder filter structure optimization method proposed in the present invention, the simulation results obtained are consistent with the test results of the corresponding powder filter entity, which provides a simple but reliable simulation means for optimizing the performance of the powder filter, improves the development efficiency of the powder filter, and helps to increase the iteration speed of the powder filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a flow chart of the powder filter structure optimization method based on simulation of the present invention;

[0036] Figure 2 This is a schematic diagram of the modeling process of the present invention;

[0037] Figure 3 This is a schematic diagram of the modeling structure of the present invention;

[0038] Figure 4 Schematic diagram of the S21 characteristic simulation results of different center conductor structures of the present invention.

[0039] Figure 5 Schematic diagram of the simulation results of the S21 characteristics of the spiral center conductor structure of the present invention with different wire lengths (number of turns).

[0040] Explanation of symbols: 1-shell; 2-center conductor; 3-filling material; 4-circular opening. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] The purpose of the present invention is to provide a powder filter structure optimization method based on simulation, which helps to improve the development efficiency of the powder filter while increasing the iteration speed of the powder filter.

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Figure 1 The figure is a flow chart of the powder filter structure optimization method based on simulation of the present invention, which is implemented with the help of three-dimensional electromagnetic field simulation software CST Studio Suite (CST), specifically the version CST Studio Suite 2018. Figure 1 As shown, a simulation-based powder filter structure optimization method includes:

[0045] Step 101: Obtain initial structural parameters of the powder filter.

[0046] Among them, the powder filter includes a shell, a center conductor and filling material inside the powder filter. An opening is respectively provided at the center of the two opposite side walls of the shell. The center conductor is located in the center of the shell. The end face of the center conductor is coplanar with the outer surface of the side wall and the center coincides. The filling material is used to fill the space in the shell except the center conductor.

[0047] The height of the shell is 54mm, the width and side length of the shell are both 14mm, the radius of the fillets at the four long corners of the outer wall of the shell is 1mm, the thickness of the four rectangular outer walls of the shell is 1mm, the thickness of the two square outer walls of the shell is 2mm, and there is a circular opening on each of the two square outer walls of the shell. The center of the circular opening coincides with the center of the square outer wall, and the radius of the circular opening is 2.5mm.

[0048] The center conductor has a single helix structure with a helix radius of 2.5 mm, a helix pitch of 0.45 mm, and 40 turns. The center conductor has a wire radius of 0.11 mm and a height of 54 mm. The center conductor is located at the center of the open-ended housing. The circular cross-sections at both ends of the center conductor are coplanar with the square outer wall of the open-ended housing, and the center of the circular cross-sections coincides with the center of the square outer wall of the open-ended housing.

[0049] The height of the filling material is 50 mm, and the width and side length of the filling material are both 12 mm. The filling material is collinear with the geometric center of the shell with openings at both ends and the center conductor.

[0050] Specifically, the initial structural parameters include the shell size of the powder filter, the structural type, radius size, length parameters of the central conductor, and the size parameters of the filling material.

[0051] Step 102: Set the configuration parameters of the simulation environment.

[0052] Specifically, the method includes creating a high-frequency 3D simulation file in the three-dimensional electromagnetic field simulation software CST Studio Suite 2018, setting the length unit, temperature unit, frequency unit, and time unit of the simulation model in the 3D simulation file to mm, Kelvin, GHz, and s, respectively, setting the simulation frequency to 0 GHz to 10 GHz, setting the background material to normal, and setting the boundary condition to an electrostatic shielding state, i.e., all directions are set to electric (Et = 0).

[0053] Step 103: Modeling the powder filter based on the initial structural parameters and configuration parameters to obtain a powder filter simulation model.

[0054] The modeling process is as follows Figure 2 As shown, the modeling order is the central conductor 2, the filling material 3 in the powder filter and the shell 1 with openings at both ends.

[0055] The process of modeling center conductor 2 is as follows: first, a circular surface with a radius of 0.11mm is created at the spatial origin (0, 0, 0). Then, a single helix center conductor 2 with 40 turns of spiral pitch of 0.45mm and a spiral radius of 2.5mm is constructed through stretching, rotating, and Boolean operations on the circular surface. The material is set to copper, and the geometric midline of center conductor 2 coincides with the positive half axis of the Z axis.

[0056] The process of modeling the filling material 3 is as follows: modeling is performed by modeling a rectangular parallelepiped. The material parameters of the filling material 3 are mainly determined by the properties of the actual filling material. The filling material 3 in the powder filter must use Boolean operations to remove the part that coincides with the center conductor. The geometric center line of the filling material 3 in the powder filter coincides with the positive half axis of the Z axis.

[0057] The process of modeling the shell 1 is as follows: the shell 1 with openings at both ends is modeled by modeling a rectangular parallelepiped. The shell 1 with openings at both ends needs to use Boolean operations to remove the parts that overlap with the center conductor 1 and the filling material 3 in the powder filter. The shell 1 with openings at both ends needs to use Boolean operations to set a circular opening 4 with a radius of 2.5 mm at the center of each of the two square outer walls of the shell 1. The material of the shell 1 with openings at both ends is selected as steel, and the geometric center line of the shell 1 with openings at both ends coincides with the positive half axis of the Z axis.

[0058] After completing the above process, you need to set a waveguide port (Waveguide Port) on the model. The first port of the waveguide port is set at the upper interface of the model (Zmax), which is the upper square outer wall of the shell with openings at both ends. The second port of the waveguide port is set at the lower interface of the model (Zmin), which is the lower square outer wall of the shell with openings at both ends.

[0059] After the simulation modeling process of the powder filter is completed, Figure 3 The complete model structure of the powder filter is shown in Figure 2. The powder filter with three different central conductor structures, straight conductor, zigzag conductor and unidirectional spiral conductor, was simulated and the S21 characteristic curves of the three structures were obtained as shown in Figure 2. Figure 4 As shown, the simulation results show that the low-pass characteristic of the spiral line is better than the meander line and the straight wire, which is consistent with the measured results reported in the literature, verifying the accuracy of the simulation method of the powder filter.

[0060] Step 104: performing a time domain solution on the powder filter simulation model to obtain a transmission characteristic curve of the powder filter.

[0061] When solving the time domain conditions, a port resistance of 50Ω is set, and the transmission characteristic curves include S11, S12, S21, and S22 curves.

[0062] Step 105: Optimizing the initial structural parameters of the powder filter according to the transmission characteristic curve.

[0063] Specifically, the performance of the powder filter is measured based on the quality of its low-pass characteristics. The S21 transmission characteristic curve is a direct parameter that describes the low-pass characteristics of the powder filter. The greater the attenuation amplitude of S21 and the faster the attenuation speed, the better the low-pass characteristics of the powder filter, that is, the better the performance of the powder filter.

[0064] For the above initial structural parameters including the shell size of the powder filter, the structural type of the center conductor, the radius size, the length parameter and the size parameter of the filling material, the S21 transmission characteristic curve under the corresponding parameter conditions can be obtained by optimizing each parameter one by one in the simulation environment with the help of the control variable method, as shown in the attached figure. Figure 4As shown in the figure, while keeping the shell size and filling material size consistent, a center conductor with the same conductor radius size is selected. By changing the structural type of the center conductor, namely straight conductor, zigzag line and spiral line, the S21 transmission characteristic curves of the three structures are obtained. It can be seen that the spiral curve has the fastest attenuation rate, and the corresponding powder filter performance of this structure is the best, which is completely consistent with the test results of the actual production of the corresponding center conductor structure. Specifically, a powder filter with a straight conductor center conductor structure was first constructed. It can be seen that the corresponding curve only achieves -30dB attenuation of the signal at 6GHz, which obviously shows that the low-pass performance of this structure is not good; further, a powder filter with a folded conductor structure center conductor structure was constructed. It can be seen that the corresponding curve achieves -30dB attenuation of the signal at 3.5GHz, which intuitively shows that the low-pass performance of the folded conductor structure is better than that of the straight conductor structure; further, a powder filter with a spiral conductor structure center conductor structure was constructed. It can be seen that the corresponding curve can achieve -30dB attenuation of the signal at 1.7GHz, which intuitively shows that the low-pass performance of the spiral conductor structure is the best among the three structures. In summary, through the parameter optimization process of the “central conductor structure”, it can be concluded that the optimal structure type in this embodiment is the “helical structure”, which is consistent with the currently reported experimental results.

[0065] In order to further illustrate the optimization effect of the simulation process of the present invention on the design parameters of the powder filter, the S21 characteristic parameters of different wire lengths under the central structure of the spiral wire are simulated. Figure 5 Specifically, it can be seen that the overall attenuation of the transmitted signal by the 4-turn spiral wire is significantly less than that of the 10-turn and 20-turn spiral wires. It is clear that the wire length is too short to achieve rapid signal attenuation. Further comparison of the attenuation of the 10-turn and 20-turn spiral wires reveals that the attenuation of the signal by the 20-turn spiral wire is slightly better than that of the 10-turn spiral wire in the 1.9-5GHz signal frequency band, but the S21 curves of the two are generally similar. Therefore, when actually making a powder filter, either 10 turns or 20 turns of the spiral wire can be selected. Similarly, the present invention can be used to optimize other parameters of the powder filter.

[0066] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0067] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A powder filter structure optimization method based on simulation, characterized in that: include: Obtaining initial structural parameters of the powder filter; the initial structural parameters include the shell size of the powder filter, the structural type, radius size, length parameters of the center conductor, and the size parameters of the filling material; Setting the configuration parameters of the simulation environment; the simulation environment is the three-dimensional electromagnetic field simulation software CST; The powder filter is modeled based on the initial structural parameters and configuration parameters to obtain a powder filter simulation model; the powder filter includes a housing, a center conductor, and a filling material, wherein an opening is respectively provided at the center of two opposing side walls of the housing, the center conductor is located at the center of the housing, an end face of the center conductor is coplanar with an outer surface of the side wall, and the centers coincide with each other, and the filling material is used to fill the space in the housing except for the center conductor; The modeling sequence is center conductor, filling material and shell; The modeling process of the center conductor includes: creating a circular surface at the spatial origin (0, 0, 0); stretching, rotating and performing Boolean operations on the circular surface to construct a single helical center conductor; setting the geometric midline of the center conductor to coincide with the positive half axis of the Z axis; The modeling process of the filling material includes: modeling the filling material in a rectangular parallelepiped manner; removing the portion of the filling material that overlaps with the center conductor through Boolean operations; setting the geometric center line of the filling material to coincide with the positive half axis of the Z axis; The modeling process of the shell includes: modeling the shell by modeling a rectangular parallelepiped; removing the portion of the shell that overlaps with the center conductor and the filling material through Boolean operations; setting an opening at the center of each of the two side walls of the shell through Boolean operations; and setting the geometric center line of the shell to coincide with the positive half axis of the Z axis; After the above process is completed, it is necessary to set the waveguide port on the model. The first port of the waveguide port is set at the upper interface of the model, which is the upper square outer wall of the shell with openings at both ends. The second port of the waveguide port is set at the lower interface of the model, which is the lower square outer wall of the shell with openings at both ends. Performing a time domain solution on the powder filter simulation model to obtain a transmission characteristic curve of the powder filter; when performing the time domain solution on the powder filter simulation model, setting a port resistance of 50Ω; the transmission characteristic curve includes an S11 curve, an S12 curve, an S21 curve, and an S22 curve; The initial structural parameters of the powder filter are optimized according to the transmission characteristic curve.

2. The method for optimizing the powder filter structure based on simulation according to claim 1, characterized in that: The configuration parameters for setting the simulation environment specifically include: setting the length unit, temperature unit, frequency unit and time unit of the powder filter simulation model to mm, Kelvin, GHz and s respectively, setting the simulation frequency to 0GHz to 10GHz, setting the background material to normal, and setting the boundary condition to electrostatic shielding state.

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