Time domain analysis method and system for electromagnetic coupling of PCB electromagnetic leakage effect transmission line

Abstract

The application discloses a PCB electromagnetic leakage effect transmission line electromagnetic coupling time domain analysis method and system, relates to the electromagnetic interference analysis field, and has the technical scheme as follows: a mapping relationship between a dipole array and a PCB electromagnetic leakage field is constructed, the mapping relationship is inversely solved, and an equivalent dipole array model of the PCB electromagnetic leakage field is obtained; an electromagnetic radiation of the equivalent dipole array model is simulated by using a FDTD method to obtain a spatial radiation field distribution of the equivalent dipole array, a transmission line equation of the PCB electromagnetic leakage effect transmission line is constructed according to the spatial radiation field distribution; the transmission line equation is differentially dispersed by using a central difference format of the FDTD method, and transient responses of voltage and current generated by coupling of the PCB leakage field on the transmission line are obtained by iterative solution. The application realizes collaborative calculation of spatial electromagnetic fields and transmission line transient responses, and greatly improves the electromagnetic coupling efficiency of analyzing the leakage field effect transmission line.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electromagnetic interference analysis of PCB acting transmission line, more particularly, it relates to a method and system for electromagnetic coupling time domain analysis of PCB electromagnetic leakage acting transmission line. BACKGROUND

[0002] With the rapid development of wireless communication technology, the working frequency of printed circuit board (PCB) is constantly increasing, which causes some components on the PCB circuit to radiate electromagnetic energy outward. The radiation field formed by the PCB electromagnetic leakage in space will be coupled to the transmission line of the device to generate interference signals and flow into the terminating circuit, thereby affecting the normal operation of the device. Therefore, in order to improve the electromagnetic safety of the device, it is of great significance to simulate and analyze the electromagnetic coupling of the transmission line acted by the PCB leakage field. Since the PCB contains a large number of components and a large number of microstrip lines, the structure is fine and complex, and the cable structure used for power and signal transmission in the device is also very fine. Using full-wave algorithm to numerically simulate the electromagnetic coupling process of the transmission line acted by the PCB leakage field results in a large amount of mesh division and low calculation efficiency. At present, the equivalent radiation source modeling algorithm mainly includes equivalent electric / magnetic current source method and equivalent dipole method. The equivalent electric / magnetic current source method is based on the electric field integral equation, and uses the method of moments to construct the matrix relationship between the near-field data and the equivalent electric / magnetic current source, and solves to obtain the equivalent electric / magnetic current source of the radiation field. However, this method cannot effectively analyze the near-field interference of the radiation field of the interference source to the surrounding circuit structure. Compared with the equivalent electric / magnetic current source method, the equivalent dipole method has a simpler analytical formula for calculating the radiation field, and its core idea is to construct an equivalent source model of the integrated circuit leakage field according to the mapping matrix between the array elements and all observation point positions on the scanning plane above the integrated circuit.

[0003] For the electromagnetic coupling problem of space electromagnetic field acting on transmission line, the electromagnetic coupling calculation can be realized by BLT equation, FDTD-SPICE method and FDTD-TL method. The traditional BLT equation is based on electromagnetic topology theory, constructs a transmission line and a reflection matrix, and realizes the fast calculation of the response of the terminal load. However, when the coupling problem of the interference source being a broadband signal is processed, the calculation efficiency is reduced. The FDTD-SPICE method is based on the transmission line equation, constructs the SPICE equivalent circuit model of the transmission line, combines FDTD to obtain the excitation field of the transmission line, and then uses the SPICE software simulation to obtain the transient response of the terminal load. However, in the solving process, a large number of formula derivations are required, and the collaborative calculation of the space electromagnetic field radiation and the transient response of the terminal load cannot be realized. In addition, the existing field-line coupling algorithm cannot be directly applied to the electromagnetic coupling calculation of the electromagnetic leakage of the device integrated circuit acting on the transmission line, because when the full-wave algorithm is used to calculate the excitation field of the transmission line, the fine structure of the device integrated circuit must be directly modeled, which leads to low calculation efficiency. SUMMARY

[0004] In order to solve the problems of the prior art, the present application provides a PCB electromagnetic leakage acting on transmission line electromagnetic coupling time domain analysis method and system, which combines the equivalent dipole method and the FDTD algorithm to form a high-efficiency time domain hybrid algorithm, realizes the fast simulation of the electromagnetic coupling of the PCB leakage field acting on the transmission line, avoids the direct modeling of the fine structure of the PCB and the transmission line, realizes the collaborative calculation of the space electromagnetic field and the transient response of the transmission line, greatly improves the electromagnetic coupling efficiency of the leakage field acting on the transmission line, and provides technical support for the electromagnetic safety evaluation of electronic equipment.

[0005] The above technical purposes of the present application are realized by the following technical solutions:

[0006] In a first aspect of the present application, a PCB electromagnetic leakage acting on transmission line electromagnetic coupling time domain analysis method is provided, and the method comprises the following steps:

[0007] A mapping relationship between a dipole array and a PCB electromagnetic leakage field is constructed, and the mapping relationship is inversely solved to obtain an equivalent dipole array model of the PCB electromagnetic leakage field;

[0008] The electromagnetic radiation of the equivalent dipole array model is simulated by using the FDTD method to obtain the spatial radiation field distribution of the equivalent dipole array, and a transmission line equation of the PCB electromagnetic leakage acting on transmission line is constructed according to the spatial radiation field distribution;

[0009] The transmission line equation is discretized by using the central difference format of the FDTD method, and the transient response of the voltage and current coupled by the PCB leakage field on the transmission line is obtained by iterative solving.

[0010] In an implementation, a mapping relationship between the dipole array and the electromagnetic leakage field of the PCB is constructed, including:

[0011] Near-field information of the electromagnetic leakage of the PCB is acquired, wherein near-field scanning points of the electromagnetic leakage of the PCB are measured by using a near-field scanning technology to obtain the near-field information;

[0012] A radiation source of the electromagnetic leakage of the PCB is equivalently processed by the dipole array, and a near-field information generated by the electromagnetic leakage of the PCB is replaced by a radiation field of the dipole array;

[0013] A relationship matrix of the radiation field of the dipole array at an arbitrary point in space and the magnetic moment and the electric moment of the array element is taken as the mapping relationship between the dipole array and the electromagnetic leakage field of the PCB, wherein the radiation field of the dipole array at the arbitrary point in space is generated by the dipole array itself and its mirror source.

[0014] In an implementation, the number of array elements of the dipole array is N, each array element is composed of two horizontal magnetic dipoles and one vertical electric dipole, wherein N is a positive integer, the two horizontal directions of the magnetic dipoles are x and y directions respectively, and the vertical direction of the electric dipole is z direction.

[0015] In an implementation, the number N of array elements of the dipole array needs to be less than or equal to the number M of near-field scanning points of the near-field scanning technology.

[0016] In an implementation, electromagnetic radiation of the equivalent dipole array model is simulated by using the FDTD method to obtain a spatial radiation field distribution of the equivalent dipole array, including:

[0017] According to the amplitude and phase information of the magnetic dipole moment, magnetic field components generated by the magnetic dipole moment in x direction and y direction are determined;

[0018] The magnetic field components generated by the magnetic dipole moment in x direction and y direction are discretized by using a difference format of the FDTD method, and radiation field distributions of the magnetic dipole in x direction and y direction at the near-field scanning points are obtained respectively;

[0019] According to the relationship between the magnetic current and the magnetic moment, electromagnetic radiation generated by the magnetic dipole is described by using Maxwell equations;

[0020] The Maxwell equations are converted into a scalar equation to obtain electromagnetic radiation generated by the electric dipole;

[0021] According to the amplitude and phase information of the electric dipole moment, magnetic field components generated by the electric dipole moment in z direction are determined;

[0022] The magnetic field component generated by the electric dipole moment in the z direction is discretized by using the difference format of the FDTD method, and the radiation field distribution of the electric dipole in the z direction is obtained.

[0023] The radiation field distribution of the magnetic dipole in the x direction and the y direction and the radiation field distribution of the electric dipole in the z direction are combined to obtain the spatial radiation field distribution of the equivalent dipole array in the x, y and z directions.

[0024] In an implementation scheme, the transmission line equation is discretely solved by using the central difference format of the FDTD method, and the transient response of the voltage and current generated by the coupling of the PCB leakage field on the transmission line is obtained, including:

[0025] The transmission line equation is discretely solved by using the central difference format of the FDTD method, and the iteration formula of the voltage and current on the transmission line is obtained;

[0026] The iteration formula of the voltage and current is iteratively solved by using forward difference and backward difference, and the transient response of the voltage and current generated by the coupling of the PCB leakage field on the transmission line is obtained.

[0027] In an implementation scheme, the transmission line equation includes a distributed voltage source equation and a distributed current source equation.

[0028] In a second aspect of the present application, an electromagnetic coupling time domain analysis system of a PCB electromagnetic leakage transmission line is provided, and the system includes:

[0029] The first module is configured to construct a mapping relationship between the dipole array and the PCB electromagnetic leakage field, inversely solve the mapping relationship, and obtain an equivalent dipole array model of the PCB electromagnetic leakage field.

[0030] The second module is configured to simulate electromagnetic radiation of the equivalent dipole array model by using the FDTD method, obtain a spatial radiation field distribution of the equivalent dipole array, and construct a transmission line equation of the PCB electromagnetic leakage transmission line according to the spatial radiation field distribution.

[0031] The analysis module is configured to discretely solve the transmission line equation by using the central difference format of the FDTD method, and iteratively solve the transient response of the voltage and current generated by the coupling of the PCB leakage field on the transmission line.

[0032] In an implementation scheme, the first module includes:

[0033] The information acquisition module is configured to acquire near-field information of the PCB electromagnetic leakage, wherein the near-field scanning points of the PCB electromagnetic leakage are measured by using a near-field scanning technology to obtain the near-field information.

[0034] An equivalent module is configured to equivalently replace the near field of the electromagnetic leakage of the PCB by the dipole array, and replace the near field information generated by the electromagnetic leakage of the PCB by the radiation field of the dipole array.

[0035] A mapping relationship construction module is configured to take the relationship matrix of the radiation field of the dipole array at an arbitrary point in space and the electric moment and the magnetic moment of the array element as the mapping relationship between the dipole array and the electromagnetic leakage field of the PCB, wherein the radiation field of the dipole array at an arbitrary point in space is generated by the common radiation of the dipole array itself and its mirror source.

[0036] In an implementation scheme, the analysis module comprises:

[0037] A difference discretization module is configured to discretize the transmission line equation by using the central difference format of the FDTD method to obtain an iterative formula of the voltage and the current on the transmission line.

[0038] A transient response calculation module is configured to iteratively solve the iterative formula of the voltage and the current by using the forward difference and the backward difference to obtain the transient response of the voltage and the current on the transmission line generated by the coupling of the PCB leakage field.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] The present application combines the equivalent dipole method and the FDTD algorithm to form a high-efficiency time-domain hybrid algorithm, realizes the fast simulation of the electromagnetic coupling of the transmission line under the action of the PCB leakage field, avoids the direct modeling of the fine structures of the PCB and the transmission line, realizes the collaborative calculation of the spatial electromagnetic field and the transient response of the transmission line, greatly improves the electromagnetic coupling efficiency of the analysis of the transmission line under the action of the leakage field, and thus provides technical support for the electromagnetic safety evaluation of electronic equipment. BRIEF DESCRIPTION OF DRAWINGS

[0041] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation of the embodiments of the present application. In the drawings:

[0042] Figure 1 A flowchart of a time-domain analysis method of the electromagnetic coupling of the transmission line under the action of the PCB electromagnetic leakage provided by the embodiments of the present application is shown in the figure;

[0043] Figure 2 A schematic diagram of a field line coupling model of the transmission line under the action of the PCB leakage field provided by the embodiments of the present application is shown in the figure;

[0044] Figure 3 A schematic diagram of the equivalent source modeling of the PCB leakage field provided by the embodiments of the present application is shown in the figure;

[0045] Figure 4A schematic diagram of a packaged PCB circuit model provided by an embodiment of the present application;

[0046] Fig. 5(a) is a magnetic field distribution diagram of a PCB circuit at z=25mm provided by an embodiment of the present application;

[0047] Fig. 5(b) is a magnetic field distribution diagram of an equivalent dipole array model at z=25mm provided by an embodiment of the present application;

[0048] Figure 6 A schematic diagram of an integrated circuit radiation single transmission line field line coupling model provided by an embodiment of the present application with an additional shielding cavity;

[0049] Figure 7 A schematic diagram of a voltage response on a load R2 provided by an embodiment of the present application;

[0050] Figure 8 A structural block diagram of an electromagnetic coupling time domain analysis system of a PCB electromagnetic leakage effect transmission line provided by an embodiment of the present application. DETAILED DESCRIPTION

[0051] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be given to the present application in combination with embodiments and drawings, the illustrative embodiments of the present application and the description thereof are only used to explain the present application, and do not limit the present application.

[0052] As described in the background, the traditional BLT equation is based on electromagnetic topology theory, constructs a transmission line and a reflection matrix, and realizes fast calculation of terminal load response, but the algorithm reduces the calculation efficiency when dealing with the coupling problem of the interference source being a broadband signal. The FDTD-SPICE method is based on the transmission line equation, constructs a SPICE equivalent circuit model of the transmission line, combines FDTD to obtain the excitation field of the transmission line, and then uses the SPICE software simulation to obtain the transient response of the terminal load. However, the method needs a large number of formula derivations in the solving process, and cannot realize the collaborative calculation of the spatial electromagnetic field radiation and the transient response of the terminal load. In addition, the existing field-line coupling algorithm cannot be directly applied to the electromagnetic coupling calculation of the transmission line of the electromagnetic leakage of the device integrated circuit, because when the full-wave algorithm is used to calculate the excitation field of the transmission line, the fine structure of the device integrated circuit must be directly modeled, which leads to low calculation efficiency. Therefore, the embodiment provides a time-domain analysis method and system for electromagnetic coupling of a PCB electromagnetic leakage transmission line, which combines the equivalent dipole method and the FDTD algorithm to form an efficient time-domain hybrid algorithm, realizes fast simulation of the electromagnetic coupling of the PCB leakage field transmission line, avoids direct modeling of the fine structure of the PCB and the transmission line, realizes the collaborative calculation of the spatial electromagnetic field and the transient response of the transmission line, greatly improves the electromagnetic coupling efficiency of the leakage field transmission line, and thus provides technical support for the electromagnetic safety evaluation of electronic devices.

[0053] The time-domain analysis of the electromagnetic coupling of the PCB electromagnetic leakage transmission line provided by the embodiment will be described below in combination with specific examples. Please refer to Figure 1 , Figure 1 The flowchart of the time-domain analysis method for the electromagnetic coupling of the PCB electromagnetic leakage transmission line provided by the embodiment is shown in Figure 1 , which includes the following steps:

[0054] S110, a mapping relationship between a dipole array and a PCB electromagnetic leakage field is constructed, and the mapping relationship is inversely solved to obtain an equivalent dipole array model of the PCB electromagnetic leakage field.

[0055] As shown in Figure 2 , Figure 2 is a typical electromagnetic coupling model of a printed circuit board leakage field transmission line, and the physical process includes: the PCB generates electromagnetic leakage and radiates in space to form an electromagnetic field distribution; the spatial electromagnetic field acts on the transmission line to generate a current signal, which flows into the terminal load to cause interference. Therefore, the embodiment is based on the mirror principle and the Green function to construct the mapping relationship between the dipole array and the PCB electromagnetic leakage field, and the essence of the mapping relationship is a linear equation. Therefore, the mapping relationship is further inversely solved to obtain the equivalent dipole array model of the PCB electromagnetic leakage field.

[0056] AsFigure 3 As shown in the figure, the PCB is composed of a U-shaped microstrip line, the beginning end is excited by a lumped voltage source, and the terminal end is connected to a load. It should be noted that the embodiment is directed to a PCB with a known design structure, and the near-field magnetic field information of the PCB adjacent observation plane is extracted using commercial electromagnetic simulation software to meet the verification requirements of the confidence level of the time-domain hybrid algorithm.

[0057] In S120, the electromagnetic radiation of the equivalent dipole array model is simulated by using the FDTD method to obtain the spatial radiation field distribution of the equivalent dipole array, and a transmission line equation of the PCB electromagnetic leakage effect transmission line is constructed according to the spatial radiation field distribution.

[0058] In S130, the transmission line equation is discretized by using the central difference format of the FDTD method, and the transient response of the voltage and current generated by the coupling of the PCB leakage field on the transmission line is obtained by iterative solution.

[0059] In the embodiment, the distributed source term of the transmission line equation is irrelevant to the scattering field of the transmission line, so direct modeling of the transmission line structure can be avoided, and the spatial step required for FDTD calculation does not need to be determined according to the fine size of the transmission line, so as to avoid large grid quantity and low calculation efficiency.

[0060] In one embodiment, the mapping relationship between the dipole array and the PCB electromagnetic leakage field is constructed, including: obtaining near-field information of the PCB electromagnetic leakage, wherein the near-field scanning technology is used to measure the near-field scanning points of the PCB electromagnetic leakage to obtain the near-field information; the radiation source of the PCB electromagnetic leakage is equivalent by the dipole array, and the near-field information generated by the PCB electromagnetic leakage is replaced by the radiation field of the dipole array; the relationship matrix of the radiation field of the dipole array at any point in space and the electric moment and magnetic moment of the array element is taken as the mapping relationship between the dipole array and the PCB electromagnetic leakage field, wherein the radiation field of the dipole array at any point in space is generated by the dipole array itself and its mirror source.

[0061] In the embodiment, the equivalent source of the PCB electromagnetic leakage is extracted, and the near-field information of the PCB leakage is obtained, which is usually measured by using the near-field scanning technology. Due to the limitation of experimental conditions, a PCB with a known structure is designed, and the near-field magnetic field of the PCB adjacent observation plane is extracted using commercial electromagnetic simulation software to meet the verification requirements of the confidence level of the time-domain hybrid algorithm. As shown in the figure, Figure 3 As shown in the figure, the PCB is composed of a U-shaped microstrip line, the beginning end is excited by a lumped voltage source, and the terminal end is connected to a load.

[0062] Furthermore, based on antenna radiation theory, the microstrip line structure generating electromagnetic leakage on the PCB is equivalently represented by a dipole array, thus replacing the leakage field generated by the actual PCB with the radiation field of the dipole array. As a preferred embodiment, the dipole array has N elements, each element consisting of two horizontal magnetic dipoles and one vertical electric dipole, where N is a positive integer, the two horizontal directions of the magnetic dipoles are x and y, and the vertical direction of the electric dipole is z. Specifically, the dipole array has N elements, each element consisting of two horizontal magnetic dipoles (M... x With M y ) and a vertical electric dipole (P) z Composed of [missing information]. Since the PCB substrate is an ideal conductor ground plane, to reduce the diffraction effect of the dipole array at the substrate edge, the height of the dipole array is h, and it is distributed in a region 6h to 10h smaller than the substrate, where h represents the height of the dipole array from the substrate. According to the mirror principle, the radiation field of the dipole array at any point in space is generated by the combined radiation of the dipole array itself and its mirror source. The relationship matrix between the near-field magnetic field radiated by the dipole array and the polar moments of the array elements is expressed as:

[0063] Among them, [H x ]、[H y ] and [H z [M] represents the magnetic fields in the x, y, and z directions at M near-field scanning points. x ]、[M y ] and [P z Let x, y, and z represent the dipole moments of N array elements respectively. The equivalent dipole array moment is obtained by inverse equation (1). To ensure the uniqueness of the solution, the number of array elements N of the dipole array must be less than or equal to the number of near-field scanning points M of the near-field scanning technique, and the number of dipole units N must be less than or equal to the number of observation points M.

[0064] In one embodiment, the electromagnetic radiation of the equivalent dipole array model is simulated using the FDTD method to obtain the spatial radiation field distribution of the equivalent dipole array. This includes: determining the magnetic field components generated by the magnetic dipole moment in the x and y directions based on the amplitude and phase information of the magnetic dipole moment; discretizing the magnetic field components generated by the magnetic dipole moment in the x and y directions using the difference scheme of the FDTD method to obtain the radiation field distribution of the magnetic dipole at the near-field scanning point in the x and y directions, respectively; and describing the electromagnetic radiation generated by the magnetic dipole using Maxwell's equations based on the relationship between magnetic current and magnetic moment.

[0065] The Maxwell equation is converted into a scalar equation to obtain electromagnetic radiation generated by the electric dipole; the magnetic field component generated by the electric dipole moment in the z direction is determined according to the amplitude and phase information of the electric dipole moment; the magnetic field component generated by the electric dipole moment in the z direction is discretized by using the difference format of the FDTD method to obtain the radiation field distribution of the electric dipole in the z direction of the near-field scanning point;

[0066] The radiation field distribution of the magnetic dipole in the x direction and the y direction of the near-field scanning point and the radiation field distribution of the electric dipole in the z direction of the near-field scanning point are combined to obtain the spatial radiation field distribution of the equivalent dipole array in the x, y and z directions.

[0067] In the embodiment, for the realization of the time-domain analysis of the transmission line electromagnetic coupling, the key lies in how to accurately obtain the spatial electromagnetic field distribution around the transmission line. The electromagnetic field distribution formed by the PCB electromagnetic leakage in space can be obtained by simulating the electromagnetic radiation of the equivalent dipole array by using the FDTD method. The specific process is as follows:

[0068] According to the relationship between the magnetic current J m and the magnetic moment M, the electromagnetic radiation generated by the magnetic dipole can be described by the Maxwell equation as follows:

[0069] Wherein, E and H represent the electric field and magnetic field intensity at any point in space, μ0 represents the magnetic permeability of free space, J m represents the magnetic current density, Δx, Δy and Δz represent the spatial step of the FDTD in the x, y and z directions respectively.

[0070] Here, taking the magnetic moment M x of a dipole as an example, the FDTD calculation formula of the electromagnetic radiation of the dipole array is derived. In this case, equation (2) is converted into a scalar equation and written as

[0071] Wherein, the amplitude and phase information of all element moments of the dipole array are obtained by equation (1). Assuming that the amplitude and phase of a magnetic dipole element moment M ix are A ix and Wherein i=1, 2...N, M ix The magnetic field component generated in the x direction can be represented as:

[0072] Wherein, ω0 is the angular frequency under the working state of the integrated circuit.

[0073] At the time t=nΔt and the H x node is at , equation (4) is discretized by using the difference format of the FDTD to obtain Hx In M x The FDTD iterative formula at the position is expressed as:

[0074]

[0075] Similarly, the radiation field expressions of the magnetic dipole in the y direction and the electric dipole in the z direction in the FDTD calculation region are obtained as follows:

[0076]

[0077] where A iy and represent the amplitude and phase of the magnetic dipole M iy , respectively, and A iz and represent the amplitude and phase of the electric dipole P iz , respectively.

[0078] In one embodiment, the transmission line equation is discretized by using the central difference format of the FDTD method, and the transient response of the voltage and current on the transmission line caused by the coupling of the PCB leakage field is obtained by iterative solution, including: discretizing the transmission line equation by using the central difference format of the FDTD method to obtain the iterative formula of the voltage and current on the transmission line; and iteratively solving the iterative formula of the voltage and current by using forward difference and backward difference to obtain the transient response of the voltage and current on the transmission line caused by the coupling of the PCB leakage field.

[0079] In this embodiment, the height of the transmission line in the electronic device from the conductive plate is less than the minimum wavelength of the PCB leakage field, and at this time, the radiation effect of the transmission line can be ignored. The electromagnetic coupling of the PCB leakage field to the multi-conductor transmission line is expressed by using the transmission line equation as:

[0080]

[0081]

[0082] where V(y, t) and I(y, t) are the voltage and current vectors of the multi-conductor line, respectively. R, L, C, and G are the capacitance and inductance parameter matrices per unit length. V F (y, t) and I F (y, t) represent the distributed voltage source and current source terms, respectively.

[0083] The distributed source term of the transmission line equation is irrelevant to the scattering field of the transmission line, and thus direct modeling of the transmission line structure can be avoided. In order to obtain the voltage response of the transmission line termination load, first, the central difference format of the FDTD is used to discretize equations (8) and (9) to obtain the iteration formula of the voltage and current on the transmission line, and then the forward difference and backward difference are combined to calculate the voltage and current response on the transmission line load.

[0084] Further, the transmission line equation includes a distributed voltage source equation and a distributed current source equation.

[0085] The embodiment also provides two specific example modes, as follows:

[0086] Example 1: The packaged PCB structure is equivalently modeled, and the correctness of the method is verified by comparing the radiation magnetic field diagrams of the original model and the equivalent model. The packaged PCB model is as shown in Figure 4 The size of the PCB is 100mm×100mm×1mm, and the dielectric substrate material is set to FR4. The U-shaped microstrip line is used as the main carrier of the PCB circuit, and a 1V sinusoidal voltage signal is fed into the left port of the microstrip line, conducted along the microstrip line and radiated electromagnetic energy outward. A shielding cavity with a size of 120mm×120mm×5mm is packaged around the PCB structure, and a hole with a size of 20mm×20mm is opened on the upper surface of the shielding cavity to simulate the leakage of the PCB, and the working frequency of the electromagnetic leakage PCB is set to 1GHz.

[0087] The defined equivalent source is composed of equivalent electromagnetic hybrid dipoles. According to the size of the packaged PCB structure, the number of equivalent electromagnetic hybrid dipoles is 11×11=121, the size of the plane is 50mm×50mm, the height of the plane is 1mm, and the interval between the dipoles is 5mm. The magnetic field information at the height of z=15mm and z=25mm is obtained by simulation using electromagnetic simulation software, and the size of the plane is selected to be 150mm×150mm, and the interval between the field points in the x and y directions is 5mm.

[0088] Figures 5(a) and 5(b) respectively show the magnetic field distribution comparison diagram of the original packaged model and the equivalent dipole array model at z=25mm, and the size of the plane is 150mm×150mm. It can be seen that the reconstructed magnetic field distribution diagram is in good agreement with the MOM simulation result.

[0089] Example 2: The equivalent dipole array in Example 1 is used as the radiation source to radiate a single transmission line, as shown in Figure 6The PEC plate with the size of L3xW3xH3=200mmx200mmx5mm is placed at the bottom of the package structure, and the ideal conductive plate with the size of L4xW3xH4=5mmx200mmx200mm is placed at the right side of the PEC plate. The material of the ideal conductive plate is PEC. The transmission line is placed along the Y-axis direction, and the length, height and radius of the transmission line are 100mm, 15mm and 1mm respectively. The loads at the two ends of the transmission line are 50 and 100 ohms respectively.

[0090] Figure 7 The voltage response curves obtained by the time-domain hybrid algorithm and the MOM method are given. It can be seen that the time-domain hybrid algorithm can maintain the same calculation accuracy as the MOM method in processing the field line coupling problem of the transmission line affected by the leakage field, verifying the correctness of the hybrid algorithm.

[0091] Based on the same inventive concept, corresponding to the electromagnetic coupling time-domain analysis method of the PCB electromagnetic leakage-affected transmission line described in the above embodiment, the present embodiment also provides a PCB electromagnetic leakage-affected transmission line electromagnetic coupling time-domain analysis system, please refer to Figure 8 , Figure 8 The structural block diagram of a PCB electromagnetic leakage-affected transmission line electromagnetic coupling time-domain analysis system provided for the present application is shown in Figure 8 , the system comprises:

[0092] The first module 810 is configured to construct the mapping relationship between the dipole array and the PCB electromagnetic leakage field, inversely solve the mapping relationship, and obtain the equivalent dipole array model of the PCB electromagnetic leakage field.

[0093] The second module 820 is configured to simulate the electromagnetic radiation of the equivalent dipole array model by using the FDTD method to obtain the spatial radiation field distribution of the equivalent dipole array, and construct the transmission line equation of the PCB electromagnetic leakage-affected transmission line according to the spatial radiation field distribution.

[0094] The analysis module 830 is configured to use the central difference format of the FDTD method to perform difference discretization on the transmission line equation, and iteratively solve to obtain the transient response of the voltage and current generated by the coupling of the PCB leakage field on the transmission line.

[0095] The PCB electromagnetic leakage-affected transmission line electromagnetic coupling time-domain analysis system provided by the present embodiment combines the equivalent dipole method and the FDTD algorithm to form a high-efficiency time-domain hybrid algorithm, realizes the fast simulation of the electromagnetic coupling of the PCB leakage field-affected transmission line, avoids the direct modeling of the fine structures of the PCB and the transmission line, realizes the collaborative calculation of the spatial electromagnetic field and the transient response of the transmission line, greatly improves the electromagnetic coupling efficiency of the analysis of the leakage field-affected transmission line, and thus provides technical support for the electromagnetic safety evaluation of electronic equipment.

[0096] In one embodiment, the first module comprises: an information acquisition module for acquiring near-field information of PCB electromagnetic leakage, wherein near-field scanning technology is used to measure near-field scanning points of PCB electromagnetic leakage to obtain the near-field information; an equivalent module for equivalently converting a transmission line structure corresponding to the near-field information of PCB electromagnetic leakage through a dipole array, and replacing the near-field information generated by PCB electromagnetic leakage with a radiation field of the dipole array; and a mapping relationship construction module for taking a relationship matrix of the radiation field of the dipole array at any point in space with the electric moment and the magnetic moment of the array element as a mapping relationship between the dipole array and the PCB electromagnetic leakage field, wherein the radiation field of the dipole array at any point in space is generated by the dipole array itself and its mirror source.

[0097] In one embodiment, the analysis module comprises: a difference discrete module for differentially discretizing the transmission line equation by using a central difference format of the FDTD method to obtain an iteration formula of voltage and current on the transmission line; and a transient response calculation module for iteratively solving the iteration formula of voltage and current by using forward difference and backward difference to obtain a transient response of voltage and current on the transmission line generated by coupling of the PCB leakage field.

[0098] The above detailed description further explains the purpose, technical solutions and advantages of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for time-domain analysis of electromagnetic coupling in PCB transmission lines due to electromagnetic leakage, characterized in that the method... include: A mapping relationship between a dipole array and the electromagnetic leakage field of a PCB is constructed, and the mapping relationship is solved inversely to obtain an equivalent dipole array model of the electromagnetic leakage field of the PCB. The construction of the mapping relationship between the dipole array and the leakage field of the transmission line acting on the PCB electromagnetic leakage includes: acquiring near-field information of the PCB electromagnetic leakage, wherein near-field scanning technology is used to measure the near-field scanning points of the PCB electromagnetic leakage to obtain near-field information; the radiation source of the PCB electromagnetic leakage is equivalently represented by the dipole array, with the radiation field of the dipole array replacing the near-field information generated by the PCB electromagnetic leakage; and the relationship matrix between the radiation field of the dipole array at any point in space and the polar moment and magnetic moment of the array elements is used as the mapping relationship between the dipole array and the PCB electromagnetic leakage field, wherein the radiation field of the dipole array at any point in space is generated by the combined radiation of the dipole array itself and its mirror source. The electromagnetic radiation of the equivalent dipole array model is simulated using the FDTD method to obtain the spatial radiation field distribution of the equivalent dipole array. Based on the spatial radiation field distribution, the transmission line equation of the transmission line for electromagnetic leakage in the PCB is constructed. The transmission line equations are differentially discretized using the central difference scheme of the FDTD method, and the transient response of voltage and current coupled by the PCB leakage field on the transmission line is obtained by iterative solution.

2. The method according to claim 1, characterized in that, The dipole array has N elements, and each element consists of two horizontal magnetic dipoles and one vertical electric dipole, where N is a positive integer. The two horizontal directions of the magnetic dipoles are the x and y directions, and the vertical direction of the electric dipoles is the z direction.

3. The method according to claim 2, characterized in that, The number of elements N in the dipole array must be less than or equal to the number of near-field scanning points M in the near-field scanning technique.

4. The method according to claim 2, characterized in that, The electromagnetic radiation of the equivalent dipole array model is simulated using the FDTD method to obtain the spatial radiation field distribution of the equivalent dipole array, including: Based on the amplitude and phase information of the magnetic dipole moment, determine the magnetic field components generated by the magnetic dipole moment in the x and y directions; The magnetic field components generated by the magnetic dipole moment in the x and y directions are discretized using the difference scheme of the FDTD method, and the radiation field distribution of the magnetic dipole in the x and y directions at the near-field scanning point is obtained respectively. Based on the relationship between magnetic current and magnetic moment, Maxwell's equations are used to describe the electromagnetic radiation generated by a magnetic dipole. By transforming Maxwell's equations into a scalar equation, we can obtain the electromagnetic radiation produced by an electric dipole. Based on the amplitude and phase information of the electric dipole moment, determine the magnetic field component generated by the electric dipole moment in the z direction; The magnetic field component generated by the electric dipole moment in the z-direction is discretized using the difference scheme of the FDTD method, and the radiation field distribution of the electric dipole in the z-direction at the near-field scanning point is obtained. The radiation field distributions of the magnetic dipoles at the near-field scanning point in the x and y directions and the radiation field distributions of the electric dipoles at the near-field scanning point in the z direction are combined to obtain the spatial radiation field distributions of the equivalent dipole array in the x, y, and z directions.

5. The method according to claim 1, characterized in that, The transmission line equations are differentially discretized using the central difference scheme of the FDTD method, and the transient responses of voltage and current coupled by the PCB leakage field on the transmission line are obtained through iterative solution, including: The transmission line equations are differentially discretized using the central difference scheme of the FDTD method to obtain iterative formulas for voltage and current on the transmission line. The transient response of voltage and current generated by the coupling of the PCB leakage field on the transmission line is obtained by iteratively solving the iterative formulas of voltage and current using forward and backward differential methods.

6. The method according to claim 5, characterized in that, The transmission line equations include distributed voltage source equations and distributed current source equations.

7. A time-domain analysis system for electromagnetic coupling of transmission lines affected by electromagnetic leakage in PCBs, characterized in that the system... include: The first module is used to construct the mapping relationship between the dipole array and the electromagnetic leakage field of the PCB, and to solve the mapping relationship inversely to obtain the equivalent dipole array model of the electromagnetic leakage field of the PCB; wherein, the first module includes: The information acquisition module is used to acquire near-field information of PCB electromagnetic leakage, wherein near-field scanning technology is used to measure the near-field scanning points of PCB electromagnetic leakage to obtain near-field information; the equivalence module is used to equivalence the near-field of the PCB electromagnetic leakage through a dipole array, wherein the radiation field of the dipole array replaces the near-field information generated by the PCB electromagnetic leakage; the mapping relationship construction module is used to use the relationship matrix between the radiation field of the dipole array at any point in space and the polar moment and magnetic moment of the array element as the mapping relationship between the dipole array and the PCB electromagnetic leakage field, wherein the radiation field of the dipole array at any point in space is generated by the combined radiation of the dipole array itself and its mirror source; The second module is used to simulate the electromagnetic radiation of the equivalent dipole array model using the FDTD method to obtain the spatial radiation field distribution of the equivalent dipole array, and to construct the transmission line equation of the transmission line for electromagnetic leakage in the PCB based on the spatial radiation field distribution. The analysis module is used to perform differential discretization on the transmission line equation using the central difference scheme of the FDTD method, and iteratively solve to obtain the transient response of voltage and current generated by the coupling of the PCB leakage field on the transmission line.

8. The system according to claim 7, characterized in that, The analysis module includes: The differential discretization module is used to perform differential discretization on the transmission line equation using the central difference scheme of the FDTD method to obtain iterative formulas for voltage and current on the transmission line. The transient response calculation module is used to iteratively solve the iterative formulas for voltage and current using forward and backward differential methods to obtain the transient response of voltage and current generated by the coupling of the PCB leakage field on the transmission line.

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