Waveguide port realization and S-parameter extraction method, system, device and medium based on FDTD algorithm

Abstract

The present invention discloses a method, system, device and medium for waveguide port realization and S-parameter extraction based on the FDTD algorithm, including: constructing an excitation space model, setting an excitation source and performing FDTD iteration to output the incident wave field; then constructing a target space model and setting a connection boundary, and performing FDTD iteration to obtain the sampling value of the reflected electric field of the m-port and the sampling value of the incident electric field of the n-port, and complete the S-parameter extraction. The present invention completes the process of setting the excitation source and extracting parameters in the port, and realizes the extraction of antenna radiation characteristics; the present invention realizes the implementation of the waveguide port based on the FDTD algorithm in C++, which improves the computational efficiency and application scope. The present invention realizes a complete and systematic design from the excitation space modeling to the parameter extraction part, and stipulates the specific settings for targets of different structures, with the characteristics of simple setting and flexible application.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetics and relates to a method, system, device and medium for realizing a waveguide port and extracting S parameters based on an FDTD algorithm. Background Art

[0002] Computational electromagnetics is a discipline that uses numerical methods to solve increasingly complex electromagnetic field problems in practical electromagnetic engineering, including modeling and simulation, optimization, and design. Three main methods are used in computational electromagnetics: the finite-difference time-domain (FDTD) method, the finite element method (FEM), and the method of moments (MoM). Numerous extensions have been derived from these three main methods. The finite-difference time-domain (FDTD) method, based on the differential form of Maxwell's curl equations, uses Yee cells for differential discretization. The electric and magnetic field components are arranged alternately in space and time, and the spatial electromagnetic field is solved incrementally along the time axis. The initial values ​​and boundary conditions of the electromagnetic problem can be used to gradually determine the spatial electromagnetic field distribution at each subsequent moment.

[0003] Flaws and shortcomings of existing technologies: Since the radiation field of antennas and various microwave devices relies on an excitation source, the source's configuration must be consistent with the antenna's feed method to ensure that the antenna's radiation pattern is consistent with reality. Waveguide ports are among the most commonly used ports in antenna and microwave device simulations. Setting a realistic excitation source and extracting parameters from the port are key to calculating antenna radiation characteristics. FDTD-based software offers similar solutions and results, but a comprehensive and systematic solution is lacking, and no publicly available implementation methods have been reported. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the prior art regarding how to set a practical excitation source and how to extract parameters in a port, for which there is no complete and systematic solution and no relevant implementation method, and to provide a waveguide port implementation and S-parameter extraction method, system, device and medium based on the FDTD algorithm.

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

[0006] Waveguide port implementation and S-parameter extraction methods based on the FDTD algorithm include:

[0007] Step 1: Construct the excitation space model and set the excitation source;

[0008] Step 2: Perform FDTD iteration based on the excitation space model and excitation source to determine whether FDTD is finished. If so, output the incident wave field; if not, repeat step 2 until the iteration is finished.

[0009] Step 3: Build the target space model and set the connection boundary;

[0010] Step 4: Perform FDTD iteration based on the target space model, connection boundary and incident field to determine whether FDTD is finished; if so, obtain the sample value of the reflected electric field at the m-port and the sample value of the incident electric field at the n-port; if not, repeat step 4 until the iteration is finished;

[0011] Step 5: Complete S-parameter extraction based on the m-port reflected electric field sampling value and the n-port incident electric field sampling value.

[0012] A further improvement of the present invention is:

[0013] Furthermore, the excitation space model includes a waveguide excitation space model and a microstrip line excitation space model;

[0014] The waveguide excitation space model includes an excitation source, a CPML absorption layer, and a transmission line. The excitation source plane is located in the excitation space waveguide, the CPML absorption layer occupies 10 grids on the left and right ends respectively, and the excitation source plane is set 10 grids away from the left CPML absorption layer. At the other end of the excitation space waveguide, the incident wave field value is output 10 grids away from the CPML absorption layer. Both ends of the transmission line are inserted into the CPML absorption layer.

[0015] The excitation source plane in the microstrip line excitation space model is located in the microstrip line of the excitation space, 10 grids away from the CPML absorption layer, and is a surface current source with arbitrary internal resistance. The excitation waveform is a Gaussian waveform that meets the accuracy of 20 grids of the minimum wavelength. At the other end of the transmission line, the incident wave field value is output 10 grids away from the CPML absorption layer. The CPML absorption layer occupies 10 grids on the left and right ends respectively.

[0016] Furthermore, the excitation sources in the waveguide excitation space model and the microstrip line excitation space model are both surface current sources, which are composed of several horizontal line current sources connected in parallel, and the line current source is composed of a source of fixed current size and a parallel internal resistance.

[0017] Furthermore, the excitation source E in the waveguide excitation space model s The time domain expression of is:

[0018]

[0019] Where a is the waveguide wide wall size, w0 is the center frequency of the waveguide single-mode main mode, t0 = 20ps, and T is the pulse width;

[0020] The center frequency of the waveguide single-mode main mode working state is:

[0021]

[0022] In order to minimize the tail of the pulse waveform when transmitting in the waveguide, the pulse width T needs to satisfy

[0023]

[0024] Where c is the speed of light.

[0025] Furthermore, the microstrip line in the microstrip line excitation space model is an open transmission line, and the lateral field distribution on the microstrip line extends to a very far area. Therefore, the lateral size of the microstrip line incident grid cannot be infinite. For a general microstrip line structure, the lateral size of the incident grid is centered on the strip line in the width direction, and the size is w+10*h, where w is the width of the microstrip line, h is the thickness of the dielectric substrate, and in the height direction, the ground plate is included and extends upward by 2*h.

[0026] Furthermore, a target space model is constructed and a connection boundary is set, including a waveguide target space model and a microstrip line target space model;

[0027] The connection boundary of the waveguide target space model is located 10 grids behind the CPML absorption layer. The incident wave voltage sampling surface of port 1 of the waveguide excitation space is the incident wave field value output surface of the excitation space. The reflected wave sampling surface is located two grids in front of the connection surface. The incident wave voltage sampling surface of port 2 of the waveguide excitation space is located 10 grids away from the CPML absorption layer. The sizes of the two sampling surfaces are the same as the cross-section of the rectangular waveguide.

[0028] The connection boundary of the microstrip line target space model is located at a distance of 10 grids behind the CPML absorption layer, the boundary is located at a distance of 10 grids behind the CPML absorption layer, the 1-port incident wave voltage sampling surface of the microstrip line is the incident wave field value output surface of the excitation space, the reflected wave sampling surface is located two grids in front of the connection surface, and the 2-port incident wave voltage sampling surface of the microstrip line is located 10 grids away from the CPML absorption layer at the other end of the microstrip line. The sizes of the two sampling surfaces are the same as the excitation source plane.

[0029] Furthermore, based on the m-port reflected electric field sampling value and the n-port incident electric field sampling value, the S parameter extraction is completed, specifically:

[0030]

[0031] Where, is the sample value of the reflected electric field at port m, is the incident electric field sample value of the n-port.

[0032] Waveguide port realization and S-parameter extraction system based on FDTD algorithm, including:

[0033] A first construction module, wherein the first construction module constructs an excitation space model and sets an excitation source;

[0034] A first iterative module, which performs FDTD iteration based on the excitation space model and the excitation source, determines whether the FDTD is finished, and if so, outputs the incident wave field; if not, repeats the iteration until the iteration is finished;

[0035] a second construction module, wherein the second construction module constructs a target space model and sets a connection boundary;

[0036] a second iterative module, wherein the second iterative module performs FDTD iteration based on the target space model, the connection boundary, and the incident field, and determines whether the FDTD is terminated; if so, obtains a sample value of the reflected electric field at the m-port and a sample value of the incident electric field at the n-port; if not, repeats the iteration until the iteration is terminated;

[0037] The extraction module extracts S parameters based on the m-port reflected electric field sampling value and the n-port incident electric field sampling value.

[0038] A terminal device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0039] A computer-readable storage medium stores a computer program, which implements the steps of the above method when executed by a processor.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] This method constructs an excitation space model, sets an excitation source, and performs FDTD iteration to output the incident wavefield. It then constructs a target space model, sets a connection boundary, and performs FDTD iteration to obtain sampled values ​​of the reflected electric field at the m-port and the incident electric field at the n-port, completing S-parameter extraction. This method completes the process of setting the excitation source and extracting parameters from the port, enabling the extraction of antenna radiation characteristics. The present invention also implements the waveguide port in C++ based on the FDTD algorithm, improving computational efficiency and application scope.

[0042] Furthermore, the present invention realizes a complete and systematic design from the excitation space modeling to the parameter extraction part, and stipulates the specific settings of the targets of different structures, which has the characteristics of simple setting and flexible application.

[0043] Furthermore, the present invention simulates multiple antennas and microwave devices and compares the results with those calculated by commercial software. The results are highly consistent, demonstrating the effectiveness and accuracy of the algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 Schematic diagram of the process of waveguide port realization and S-parameter extraction method based on FDTD algorithm of the present invention;

[0046] Figure 2 Schematic diagram of the structure of the waveguide port realization and S-parameter extraction system based on the FDTD algorithm of the present invention;

[0047] Figure 3 This is the algorithm implementation process of the present invention;

[0048] Figure 4 is a schematic diagram of a current source;

[0049] Figure 5 FIG. 1 is a diagram of an excitation space setting when the present invention is applied to a waveguide structure;

[0050] Figure 6 This is a diagram of the excitation space setting when the present invention is applied to a microstrip line structure;

[0051] Figure 7 is the lateral size of the incident grid when the present invention is applied to a microstrip line structure;

[0052] Figure 8 A diagram illustrating a target space setting when the present invention is applied to a waveguide structure;

[0053] Figure 9 A target space setting diagram when the present invention is applied to a microstrip line structure;

[0054] Figure 10 Implement a schematic diagram for connecting boundaries;

[0055] Figure 11 A diagram illustrating the excitation space configuration of a three-centimeter rectangular waveguide according to an embodiment of the present invention;

[0056] Figure 12 This is a diagram of the target space setting of a three-centimeter rectangular waveguide according to an embodiment of the present invention;

[0057] Figure 13A comparison chart of the C++ and CST S-parameter calculation results for a 3-cm rectangular waveguide according to an embodiment of the present invention;

[0058] Figure 14 This is a diagram showing the excitation space setting of a 50-ohm microstrip line according to an embodiment of the present invention;

[0059] Figure 15 This is a diagram showing the transverse grid arrangement of an incident wave on a 50-ohm microstrip line according to an embodiment of the present invention;

[0060] Figure 16 This is a diagram of the target space setting of a 50-ohm microstrip line according to an embodiment of the present invention;

[0061] Figure 17 This is a comparison chart of the C++ and CST S-parameter calculation results of a 50-ohm microstrip line according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0063] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0064] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0065] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0066] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0067] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0068] The present invention is described in further detail below with reference to the accompanying drawings:

[0069] See also Figure 1 The present invention discloses a waveguide port realization and S-parameter extraction method based on FDTD algorithm, including:

[0070] S101: Construct an excitation space model and set the excitation source.

[0071] The waveguide excitation space model includes an excitation source, a CPML absorption layer and a transmission line; the excitation source plane is located in the excitation space waveguide, the CPML absorption layer occupies 10 grids on the left and right ends respectively, and the excitation source plane is set 10 grids away from the left CPML absorption layer; at the other end of the excitation space waveguide, the incident wave field value is output 10 grids away from the CPML absorption layer; and both ends of the transmission line are inserted into the CPML absorption layer.

[0072] The excitation source plane in the microstrip line excitation space model is located in the microstrip line of the excitation space, 10 grids away from the CPML absorption layer, and is a surface current source with arbitrary internal resistance; the excitation waveform is a Gaussian waveform that meets the accuracy of 20 grids of the minimum wavelength; at the other end of the transmission line, the incident wave field value is output 10 grids away from the CPML absorption layer; the CPML absorption layer occupies 10 grids on the left and right ends respectively.

[0073] The excitation source in the waveguide excitation space model and the microstrip line excitation space model is a surface current source, which is composed of several horizontal line current sources connected in parallel. The line current source is composed of a source of fixed current magnitude and a parallel internal resistance.

[0074] S102: Perform FDTD iteration based on the excitation space model and the excitation source, and determine whether the FDTD process is finished. If so, output the incident wave field; if not, repeat S102 until the iteration is finished.

[0075] Excitation source E in the waveguide excitation space model s The time domain expression of is:

[0076]

[0077] Where a is the waveguide wide wall size, w0 is the center frequency of the waveguide single-mode main mode, t0 = 20ps, and T is the pulse width;

[0078] The center frequency of the waveguide single-mode main mode working state is:

[0079]

[0080] In order to minimize the tail of the pulse waveform when transmitting in the waveguide, the pulse width T needs to satisfy

[0081]

[0082] Where c is the speed of light.

[0083] The microstrip line in the microstrip line excitation space model is an open transmission line. The lateral field distribution on the microstrip line extends to a very far area, so the lateral size of the microstrip line incident grid cannot be infinite. For a general microstrip line structure, the lateral size of the incident grid is centered on the strip line in the width direction, and the size is w+10*h, where w is the width of the microstrip line, h is the thickness of the dielectric substrate, and in the height direction, the ground plate is included and extends upward by 2*h.

[0084] S103: Construct a target space model and set a connection boundary.

[0085] The connection boundary of the waveguide target space model is located 10 grids behind the CPML absorption layer. The incident wave voltage sampling surface of port 1 of the waveguide excitation space is the incident wave field value output surface of the excitation space. The reflected wave sampling surface is located two grids in front of the connection surface. The incident wave voltage sampling surface of port 2 of the waveguide excitation space is located 10 grids away from the CPML absorption layer. The sizes of the two sampling surfaces are the same as the cross-section of the rectangular waveguide.

[0086] The connection boundary of the microstrip line target space model is located at a distance of 10 grids behind the CPML absorption layer, the boundary is located at a distance of 10 grids behind the CPML absorption layer, the 1-port incident wave voltage sampling surface of the microstrip line is the incident wave field value output surface of the excitation space, the reflected wave sampling surface is located two grids in front of the connection surface, and the 2-port incident wave voltage sampling surface of the microstrip line is located 10 grids away from the CPML absorption layer at the other end of the microstrip line. The sizes of the two sampling surfaces are the same as the excitation source plane.

[0087] S104: Perform FDTD iteration based on the target space model, connection boundary and incident field to determine whether FDTD is finished; if so, obtain the sample value of the reflected electric field of the m-port and the sample value of the incident electric field of the n-port; if not, repeat S104 until the iteration is finished.

[0088] S105: Based on the m-port reflected electric field sampling value and the n-port incident electric field sampling value, complete S parameter extraction.

[0089]

[0090] Where, is the sample value of the reflected electric field at port m, is the incident electric field sample value of the n-port.

[0091] See also Figure 2 The present invention discloses a waveguide port realization and S-parameter extraction system based on FDTD algorithm, comprising:

[0092] A first construction module, wherein the first construction module constructs an excitation space model and sets an excitation source;

[0093] A first iterative module, which performs FDTD iteration based on the excitation space model and the excitation source, determines whether the FDTD is finished, and if so, outputs the incident wave field; if not, repeats the iteration until the iteration is finished;

[0094] a second construction module, wherein the second construction module constructs a target space model and sets a connection boundary;

[0095] a second iterative module, wherein the second iterative module performs FDTD iteration based on the target space model, the connection boundary, and the incident field, and determines whether the FDTD is terminated; if so, obtains a sample value of the reflected electric field at the m-port and a sample value of the incident electric field at the n-port; if not, repeats the iteration until the iteration is terminated;

[0096] The extraction module extracts S parameters based on the m-port reflected electric field sampling value and the n-port incident electric field sampling value.

[0097] Example:

[0098] See also Figure 3 The present invention requires constructing an FDTD space containing only a transmission line identical to the antenna feeder, with both ends of the transmission line extending into the CPML absorbing layer. Excitation is introduced at appropriate locations along the transmission line to generate the antenna feeder's incident wavefield. After transmission over a certain distance, the incident wavefield on the output surface is output to an output file. The antenna structure space is then constructed, with the feeder also extending into the CPML absorbing layer. The incident wavefield is then read and transferred to the antenna structure space via the connection boundary for calculation and S-parameter extraction.

[0099] 1. Incentive Space Modeling

[0100] The function of the excitation space is to iteratively generate the incident wave field of the antenna feed line. In order to make the excitation space contain only the incident wave, the two ends of the transmission line are inserted into the CPML absorption layer, and the transmission line is extended into the CPML. The excitation source is added at the appropriate position of the transmission line to make its lateral field distribution consistent with the main mode of the transmission line.

[0101] 2. Set incentives.

[0102] When this port is used for waveguide problems and Gaussian pulse wave excitation is used, since the waveguide is a dispersive transmission line, the spectrum center of the Gaussian pulse should be at the center frequency of the main mode of the waveguide, and the pulse spectrum should have considerable attenuation in the non-main mode area; for the time domain waveform, the movement of the spectrum center is equivalent to the Gaussian pulse plus sine wave modulation. The narrower the spectrum, the wider the time, and the corresponding calculation time is longer. In addition, since the waveguide transmits a broadband time domain signal, there is no analytical expression for the field distribution in the waveguide. The incident field must be obtained in the excitation space by adding an excitation source to the waveguide and then iterating through FDTD, and then transferred to the target structure space through the connecting boundary. This algorithm is single-mode excitation, and the excitation mode is TE10 mode. A surface current source excitation can be set. The surface current source is composed of multiple horizontal line current sources in parallel. The line current source is composed of a source of fixed current and a parallel internal resistance, such as Figure 4 As shown. The size of the source and the size of the internal resistance jointly determine the size of the current in the external circuit. The excitation source waveform changes uniformly along the narrow wall direction of the waveguide, and the excitation source waveform changes in the wide wall direction of the waveguide as a first-order sine. This setting can make the field distribution of the excitation source on the waveguide cross section consistent with the field distribution of the main mode, so that the excitation source only generates the main mode in the waveguide, as shown in Figure 5 As shown, the excitation source E s The time domain expression of is:

[0103]

[0104] Where a is the wide wall size of the waveguide, w0 is the center frequency of the waveguide single mode (main mode), t0 = 20 ps, ​​and T is the pulse width.

[0105] For a general waveguide, the width and narrow wall dimensions satisfy a ≥ 2b, and the center frequency of the waveguide single-mode main mode working state is:

[0106]

[0107] Generally speaking, the selected pulse width T only needs to satisfy the requirement that the spectral component near the cutoff frequency of the waveguide main mode is less than -40dB. The pulse width T only needs to satisfy the following formula to ensure that the tail of the pulse waveform is very small when it is transmitted in the waveguide.

[0108]

[0109] Where c is the speed of light.

[0110] When this port is used for microstrip line problems, the excitation source is located at a certain position in the microstrip line in the excitation space. Here, a surface current source with the same width as the microstrip line and the same height as the dielectric substrate is used. The waveform selection should include all the spectra of interest, such as Figure 6 shown.

[0111] When the incident wave field at the output port is large, since the waveguide port is a closed transmission line, the size of the incident wave field is the same as the cross-section of the rectangular waveguide; since the microstrip line is an open transmission line, the lateral field distribution on the microstrip line can extend to a very far area, but the lateral size of the microstrip line incident grid cannot be infinite. In order to ensure the accuracy of the calculation results, the reflection field time domain waveform and return loss are observed. The change of the lateral size of the incident grid (connection boundary size) is shown in Figure 2. For a general microstrip line structure, the lateral size of the incident grid is as follows: Figure 7 As shown, it can be determined by this method: the width direction is centered on the strip line, the size = w + 10*h, where w is the width of the microstrip line, h is the thickness of the dielectric substrate, and in the height direction, the ground plane is included and extended upward by 2*h. This calculation accuracy is relatively high.

[0112] 3. Target Space Modeling

[0113] For the target structure space, after the target structure is modeled by FDTD, its reflection region terminal needs to be inserted into CPML. For the waveguide structure and microstrip structure, Figure 8 and Figure 9 shown.

[0114] 4. Connection boundary settings

[0115] Since both ends of the transmission line are connected to the absorbing boundary, the connecting boundary is the RF / TF boundary. The implementation method is that when the electromagnetic wave propagates in the forward direction along the k-axis, the incident magnetic field H v,inc Coupled to E u Iteration, and the incident electric field E u,inc Coupled to H v When the electromagnetic wave propagates in the negative direction along the k-axis, the coupling mode of the incident field is the same, but at this time H is half a grid longer than E along the propagation direction, as shown in Figure 2. Figure 10 shown.

[0116] For waveguide problems, since waveguides are closed transmission lines, the size of the connection boundary is the same as the cross-section of the rectangular waveguide. For microstrip line problems, since microstrip lines are open transmission lines, the size of the connection boundary needs to be of a certain size, and the method for determining its size is the same as the method for determining the incident grid size mentioned above.

[0117] 5. S parameter calculation

[0118] S parameters are network parameters based on the relationship between incident waves and reflected waves. It should be noted that in FDTD simulations, only one port can be excited. Therefore, for circuits with multiple ports excited, it may be necessary to run FDTD multiple times to obtain a complete set of S parameters, depending on the type of problem and the symmetry conditions of the problem. For closed transmission lines (waveguides, coaxial lines, etc.), the cross-sectional size of the excitation space is the size of the transmission line cross-sectional area, and the electric field sampling point of the incident wave and reflected wave at each port is the center point of the cross-sectional area; for laterally open transmission lines (microstrip lines, parallel double lines, dielectric rod waveguides, etc.), the electric field sampling point of the incident wave and reflected wave at each port should be the center point of the surface corresponding to the excitation plane at the sampling position.

[0119] Define the waveguide scattering parameter S m,n for:

[0120]

[0121] Where, is the sample value of the reflected electric field at port m, is the incident electric field sample value of the n-port.

[0122] After completing the settings of each part and performing FDTD iterations, it is possible to use waveguide ports to excite electromagnetic simulations of typical microwave devices and extract port parameters.

[0123] Take the three-centimeter waveguide as an example. Figure 11 As shown, the inner wall dimensions of the waveguide are 22.86 mm × 10.16 mm, with the wide wall in the x-direction and the narrow wall in the y-direction. The transmission direction is the z-direction. The FDTD excitation and target spaces are both composed of grid cells with dimensions of Δx = 0.4082 mm, Δy = 0.4233 mm, and Δz = 0.4 mm. Both ends of the waveguide are inserted into the CPML absorption layer.

[0124] The excitation source plane is located in the excitation space waveguide. The CPML absorption layers occupy 10 grid cells on each end. The surface current source plane is set 10 grid cells away from the left CPML absorption layer. At the other end of the waveguide, 10 grid cells away from the CPML absorption layer, the incident wavefield value is output. The excitation source waveform uses a modulated Gaussian waveform centered around the waveguide's main mode frequency. Its distribution matches the field distribution of the waveguide's main mode: the excitation waveform varies uniformly along the waveguide's narrow walls and follows a first-order sinusoidal pattern along its wide walls.

[0125] See also Figure 12 In the target space, the connection boundary is located 10 grids behind the CPML absorption layer. The incident wave voltage sampling surface of the waveguide port 1 is the output surface of the incident wave field value in the excitation space. The reflected wave sampling surface is located two grids before the connection surface (port 1). The incident wave voltage sampling surface of port 2 is located 10 grids away from the CPML absorption layer. The size of the surface is the same as the cross section of the rectangular waveguide. Figure 2 The S parameters are calculated and compared with the CST simulation results. Figure 13 As shown:

[0126] The specific settings applied to the microstrip line are as follows:

[0127] Take a 50 ohm microstrip line as an example. Figure 14 As shown, the microstrip line width w = 1 mm, the dielectric substrate thickness is 1 mm, and the floor and microstrip line thickness is 0.2 mm. The FDTD excitation and target spaces are both composed of grid cells with dimensions of Δx = 0.25 mm, Δy = 1.5 mm, and Δz = 0.2 mm. Both ends of the microstrip line are inserted into the CPML absorption layer.

[0128] The excitation source plane is located in the microstrip line of the excitation space, 10 grids away from the CPML absorption layer. It is a surface current source with arbitrary internal resistance, with the same width as the microstrip line and the same height as the dielectric substrate. The excitation waveform is a Gaussian waveform that meets the accuracy of 20 grids of the minimum wavelength. At the other end of the transmission line, the incident wave field value is output at 10 grids away from the CPML absorption layer. The horizontal grid size of the incident wave is as follows: Figure 15 shown.

[0129] In the target space, the connection boundary is located 10 grids behind the CPML absorption layer. The incident wave voltage sampling surface of the microstrip line port 1 is the incident wave field value output surface of the excitation space. The reflected wave sampling surface is located two grids before the connection surface (port 1). The incident wave voltage sampling surface of the 2-port is located 10 grids away from the CPML absorption layer at the other end of the microstrip line. The size of the surface is the same as the excitation source plane. Figure 16 shown.

[0130] The S parameters are calculated and compared with the CST simulation results. Figure 17 shown.

[0131] An embodiment of the present invention provides a terminal device. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of each of the aforementioned method embodiments are implemented. Alternatively, when the processor executes the computer program, the functions of each module / unit in each of the aforementioned device embodiments are implemented.

[0132] The computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor to accomplish the present invention.

[0133] The terminal device may be a computing device such as a desktop computer, a notebook computer, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0134] The processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0135] The memory may be used to store the computer programs and / or modules, and the processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory.

[0136] If the module / unit integrated in the terminal device is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of each of the above-mentioned method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0137] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. The waveguide port realization and S-parameter extraction method based on FDTD algorithm is characterized by: include: Step 1: Construct the excitation space model and set the excitation source; The excitation space model includes a waveguide excitation space model and a microstrip line excitation space model. The waveguide excitation space model includes an excitation source, a CPML absorption layer, and a transmission line. The microstrip line excitation space model includes an excitation source, a CPML absorption layer, and a microstrip line. The excitation source plane is located in the excitation space waveguide. The CPML absorption layer occupies 10 grids on the left and right ends respectively. Both ends of the transmission line are inserted into the CPML absorption layer. The microstrip line is an open transmission line. Step 2: Perform FDTD iteration based on the excitation space model and excitation source to determine whether FDTD is finished. If so, output the incident wave field; if not, repeat step 2 until the iteration is finished. Step 3: Construct the target space model and set the connection boundary, including the waveguide target space model and the microstrip line target space model. The connection boundary of the waveguide target space model is located 10 grid distances behind the CPML absorption layer, and the connection boundary of the microstrip line target space model is located 10 grid distances behind the CPML absorption layer. Step 4: Perform FDTD iteration based on the target space model, connection boundary and incident field to determine whether FDTD is finished; if so, obtain the sample value of the reflected electric field at the m-port and the sample value of the incident electric field at the n-port; if not, repeat step 4 until the iteration is finished; Step 5: Complete S-parameter extraction based on the m-port reflected electric field sampling value and the n-port incident electric field sampling value.

2. The waveguide port realization and S-parameter extraction method based on the FDTD algorithm according to claim 1 is characterized in that: The excitation source plane is set at a distance of 10 grids from the left CPML absorption layer; at the other end of the excitation space waveguide, the incident wave field value is output at a distance of 10 grids from the CPML absorption layer; The excitation source plane in the microstrip line excitation space model is located in the microstrip line of the excitation space 10 grids away from the CPML absorption layer, and is a surface current source with arbitrary internal resistance; the excitation waveform is a Gaussian waveform that meets the accuracy of 20 grids of the minimum wavelength; the other end of the transmission line outputs the incident wave field value 10 grids away from the CPML absorption layer.

3. The waveguide port realization and S-parameter extraction method based on the FDTD algorithm according to claim 2 is characterized in that: The excitation sources in the waveguide excitation space model and the microstrip line excitation space model are both surface current sources, which are composed of several horizontal line current sources connected in parallel, and the line current source is composed of a source with a fixed current size and a parallel internal resistance.

4. The waveguide port realization and S-parameter extraction method based on the FDTD algorithm according to claim 3 is characterized in that: The excitation source in the waveguide excitation space model The time domain expression of is: Where a is the wide wall size of the waveguide, is the center frequency of the waveguide single-mode main mode, , T is the pulse width; The center frequency of the waveguide single-mode main mode working state is: In order to minimize the tail of the pulse waveform when transmitting in the waveguide, the pulse width T needs to satisfy Where c is the speed of light.

5. The waveguide port realization and S-parameter extraction method based on the FDTD algorithm according to claim 4 is characterized in that: The lateral field distribution on the microstrip line in the microstrip line excitation space model extends to a very far area, so the lateral size of the microstrip line incident grid cannot be infinite. For a general microstrip line structure, the lateral size of the incident grid is centered on the strip line in the width direction, and the size is w+10*h, where w is the width of the microstrip line, h is the thickness of the dielectric substrate, and in the height direction, the ground plate is included and extends upward by 2*h.

6. The waveguide port realization and S-parameter extraction method based on the FDTD algorithm according to claim 5, characterized in that: The incident wave voltage sampling surface of the 1-port waveguide excitation space is the incident wave field value output surface of the excitation space, the reflected wave sampling surface is located two grids in front of the connection surface, and the incident wave voltage sampling surface of the 2-port waveguide excitation space is located 10 grids away from the CPML absorption layer. The sizes of the two sampling surfaces are the same as the cross-section of the rectangular waveguide; The boundary is located 10 grids behind the CPML absorption layer. The 1-port incident wave voltage sampling surface of the microstrip line is the incident wave field value output surface of the excitation space. The reflected wave sampling surface is located two grids before the connection surface. The 2-port incident wave voltage sampling surface of the microstrip line is located 10 grids away from the CPML absorption layer at the other end of the microstrip line. The sizes of the two sampling surfaces are the same as the excitation source plane.

7. The waveguide port realization and S-parameter extraction method based on the FDTD algorithm according to claim 6, characterized in that: The S parameter extraction is completed based on the m-port reflected electric field sampling value and the n-port incident electric field sampling value, specifically: Where, is the sample value of the reflected electric field at port m, is the incident electric field sample value of the n-port.

8. Waveguide port realization and S-parameter extraction system based on FDTD algorithm, characterized by: include: A first construction module, wherein the first construction module constructs an excitation space model and sets an excitation source; The excitation space model includes a waveguide excitation space model and a microstrip line excitation space model. The waveguide excitation space model includes an excitation source, a CPML absorption layer, and a transmission line. The microstrip line excitation space model includes an excitation source, a CPML absorption layer, and a microstrip line. The excitation source plane is located in the excitation space waveguide. The CPML absorption layer occupies 10 grids on the left and right ends respectively. Both ends of the transmission line are inserted into the CPML absorption layer. The microstrip line is an open transmission line. a first iterative module, which performs FDTD iteration based on the excitation space model and the excitation source, determines whether the FDTD is terminated, and if so, outputs an incident wave field; If not, repeat the iteration until the iteration ends; A second construction module, wherein the second construction module constructs a target space model and sets a connection boundary, including a waveguide target space model and a microstrip line target space model; The connection boundary of the waveguide target space model is located at a distance of 10 grids behind the CPML absorption layer, and the connection boundary of the microstrip line target space model is located at a distance of 10 grids behind the CPML absorption layer; A second iteration module, which performs FDTD iteration based on the target space model, the connection boundary and the incident field, and determines whether the FDTD is finished; If yes, obtain the sampled value of the reflected electric field at the m-port and the sampled value of the incident electric field at the n-port; if no, repeat the iteration until the iteration ends; The extraction module extracts S parameters based on the m-port reflected electric field sampling value and the n-port incident electric field sampling value.

9. A terminal device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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