A fast solution method for electromagnetic field distribution with varying permittivity

Abstract

This invention belongs to the field of electromagnetic field calculation, and specifically relates to a rapid solution method for electromagnetic field distribution under varying dielectric constants. The method solves for the physical field under initial boundary conditions using full-wave simulation. In subsequent iterative calculations, whenever the dielectric constant of the material changes, a modified calculation formula is used to continuously adjust the electromagnetic field distribution to obtain the corresponding distribution. This algorithm is particularly suitable for situations where the dielectric constant of a material gradually changes under the influence of external environmental factors. This invention solves the problem of the enormous computational burden caused by repetitive full-wave simulation calculations in traditional methods for constantly changing material physical properties and physical fields. By rapidly obtaining the real-time electromagnetic field distribution around the object, the electromagnetic field radiation and electromagnetic wave leakage of the system can be observed, thus resolving systemic electromagnetic compatibility issues.

Description

Technical Field

[0001] The invention relates to the field of electromagnetic field calculation, and more specifically, to a fast solution algorithm for electromagnetic field distribution under a variable dielectric constant. Background Art

[0002] The dielectric constant is a very critical physical quantity in solving electromagnetic fields, and it will change under the influence of the external environment. Usually, the real and imaginary parts of the dielectric constant will change with the electromagnetic field frequency, medium density, external pressure and temperature. As a typical example of the interaction between electromagnetic fields and media, solving the electromagnetic field distribution is a coupled calculation process in which the dielectric constant changes with the temperature and other environments, and the size of the dielectric constant affects the magnetic field distribution. In this process, the temperature field and the electromagnetic field need to be continuously updated. In order to obtain accurate electromagnetic fields and thermal field distributions obtained due to the dissipation of dielectric constants, the general calculation method is to divide the heating process into many small time steps and perform full-wave simulation in each time step.

[0003] Among the current algorithms, full-wave simulation calculation algorithms are usually used. Full-wave simulation methods are usually based on finite-difference time-domain algorithms, moment methods, finite-element time-domain algorithms, finite-product time-domain algorithms, and various other algorithms. These numerical algorithms based on full-wave simulation often have very high speeds when performing a full-wave simulation solution, but when dealing with problems such as those where the dielectric constant is constantly changing, their computing power is somewhat insufficient due to the need for repeated iterative calculations, and they often require a lot of computing time.

[0004] Among the existing fast algorithms, fast numerical calculations of electromagnetic fields based on improved traditional algorithms are used, such as the Born iteration method, the adaptive integration method, the fast multipole algorithm, and the multi-layer fast multipole algorithm based on the fast multipole algorithm. In the fast multipole algorithm and the adaptive integration method, special matrix processing is used to reduce the matrix size and accelerate the calculation. In the Born iteration method, the amount of calculation of the scattered field is reduced by treating the total field in the calculated area as the incident field in the calculation. This type of algorithm can handle complex geometric models and has the characteristics of fastness, but it is still a full-wave simulation algorithm. So far, there is no fast algorithm for dealing with the problem of constantly changing dielectric constants in time-varying electromagnetic fields. Therefore, a new fast algorithm specifically for dealing with such problems is particularly important. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a radio frequency circuit board made of materials such as FR4 epoxy glass fiber substrate and polyvinyl chloride plastic PVC. Under the influence of environmental factors such as external temperature, the electromagnetic field distribution around the circuit board changes due to the change of its dielectric constant. The invention designs an algorithm for quickly obtaining the real-time electromagnetic field distribution around an object.

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

[0007] The algorithm for quickly solving the electromagnetic field distribution with a variable dielectric constant includes the following steps:

[0008] A. In the initial state, a full-wave simulation is performed based on the initial parameters of the material to obtain the initial electromagnetic field distribution;

[0009] B. When the dielectric constant changes slightly, first calculate the corresponding change in the electromagnetic field distribution, and then calculate the corrected new electromagnetic field distribution;

[0010] C. Based on the new electromagnetic field distribution and dielectric constant distribution, repeat step B until a predetermined number of iterations is reached or the dielectric constant of the material is stable.

[0011] Furthermore, in step B, the change in electromagnetic field distribution is calculated according to the following formula:

[0012] ,

[0013] Among them, A N×N and B N×N are matrix coefficients, E N×1 is the electromagnetic field distribution, is the dielectric constant change, ε N×N is the dielectric constant.

[0014] Furthermore, in step B, the corrected new electromagnetic field distribution is calculated according to the following formula:

[0015] .

[0016] Furthermore, the method of the present invention is applicable to solving electromagnetic field scattering in electronic transceivers and electronic controllers whose dielectric constants vary with external environmental factors.

[0017] Furthermore, the shells of the electronic controller and the electronic transceiver are both made of polyvinyl chloride plastic (PVC plastic); the dielectric plates of the electronic controller and the electronic transceiver can be made of engineering plastics or composite materials, such as polyvinyl chloride plastic FR4, ABS plastic (Acrylonitrile Butadiene Styrene Plastic), nylon (Nylon), PE plastic (Polyethylene Plastic), PP plastic (Polypropylene Plastic), PVC plastic (PolyvinylChloride Plastic), rubber, chemical fiber, etc.

[0018] By adopting the above technical solution, the beneficial effects of the present invention are:

[0019] The present invention solves the physical field under the initial boundary conditions and utilizes the full-wave simulation method. In subsequent iterative calculations, whenever the dielectric constant of the material changes, the electromagnetic field distribution is continuously adjusted using a modified calculation formula to obtain the corresponding electromagnetic field distribution.

[0020] The present invention solves the problem of huge amount of calculation caused by repeated full-wave simulation calculation method in traditional methods for the ever-changing physical properties of materials and physical field environments. By quickly obtaining the real-time electromagnetic field distribution around the object, the electromagnetic field radiation and electromagnetic wave leakage of the system can be observed, and the electromagnetic compatibility problem of the system can be solved.

[0021] Compared with the traditional full-wave simulation method, this algorithm significantly improves the calculation efficiency of the electromagnetic field distribution by reducing repeated calculations; it is particularly suitable for situations where the dielectric constant gradually changes with external environmental factors such as temperature, making the electromagnetic field calculation more accurate and adaptable to different working environments; through comparative verification with the traditional moment method, this algorithm can maintain high calculation accuracy and stability under different changes in the dielectric constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the case where electromagnetic waves are incident on the target.

[0023] Figure 2 The electromagnetic wave is incident on a circular target medium with uniform dielectric constant.

[0024] Figure 3 For circular targets, the radar cross section obtained by the algorithm of the present invention is compared with that obtained by the traditional method of moments.

[0025] Figure 4 The wave is incident on a double-layer circular ring target medium.

[0026] Figure 5For circular targets, the radar cross section obtained by using the algorithm of the present invention is compared with that obtained by using the traditional method of moments.

[0027] Figure 6 The electromagnetic wave is incident on a rectangular non-uniform target medium.

[0028] Figure 7 For rectangular non-uniform targets, the radar cross section obtained by the algorithm of the present invention is compared with that obtained by the traditional method of moments.

[0029] Figure 8 The real part of the dielectric constant of polyvinyl chloride plastic FR4 changes with temperature at 20oC.

[0030] Fig. 9 The real part of the dielectric constant of polyvinyl chloride plastic FR4 varies with temperature at 2.45GHz.

[0031] Fig.10 The real part of the dielectric constant of polyvinyl chloride plastic FR4 changes with temperature and frequency.

[0032] Fig.11 It is a three-dimensional structure view of the vehicle electronic controller ECU (Electronic Control Unit).

[0033] Fig.12 This is the electric field distribution diagram of the vehicle electronic controller at a frequency of 2.4 GHz when the dielectric constant of the dielectric plate is 4.2.

[0034] Fig.13 This is the electric field distribution diagram of the vehicle electronic controller at a frequency of 2.4 GHz when the dielectric constant of the dielectric plate is 4.8.

[0035] Fig.14 The three-dimensional radiation pattern of 2.4GHz electromagnetic waves for the vehicle-mounted electronic controller on the polyvinyl chloride plastic FR4 dielectric board with a dielectric constant of 4.2.

[0036] Fig.15 The three-dimensional radiation pattern of 2.4GHz electromagnetic waves for the vehicle-mounted electronic controller on the polyvinyl chloride plastic FR4 dielectric board with a dielectric constant of 4.8.

[0037] Fig.16 For vehicle electronic controllers, the dielectric constant of PVC plastic FR4 dielectric board is between 4.2 and 4.8, with S11 in the 1.7GHz to 2.7GH frequency band.

[0038] Fig.17 For the vehicle electronic controller, the dielectric constant of the polyvinyl chloride plastic FR4 dielectric board is between 4.2 and 4.8, and the radiation efficiency and overall efficiency of the antenna change with frequency.

[0039] Fig.18 3D structure of the vehicle-mounted wireless transceiver.

[0040] Fig.19 When the dielectric constant of the polyvinyl chloride plastic FR4 dielectric board of the vehicle-mounted wireless transceiver is 4.2, the electric field distribution of the dielectric board at a frequency of 433MHz.

[0041] Fig. 20 When the dielectric constant of the polyvinyl chloride plastic FR4 dielectric board of the vehicle-mounted wireless transceiver is 4.8, the electric field distribution of the dielectric board at a frequency of 433MHz.

[0042] Fig.21 These are the electromagnetic scattering parameters of the polyvinyl chloride plastic FR4 dielectric board of the vehicle-mounted wireless transceiver when the dielectric constants are 4.2 and 4.8.

[0043] Fig. 22 The total efficiency of the PVC plastic FR4 dielectric board for the vehicle-mounted wireless transceiver when the dielectric constant is 4.2 and 4.8.

[0044] Fig.23 It is the electromagnetic radiation efficiency of the polyvinyl chloride plastic FR4 dielectric board of the vehicle-mounted wireless transceiver when the dielectric constant is 4.2 and 4.8. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Embodiment 1

[0047] For polyvinyl chloride plastic FR4 dielectric material, temperature changes will cause changes in the dielectric constant of the FR4 material. However, for this type of material, its dielectric constant changes little under the external working environment temperature, and its dielectric constant changes very little within a small period of time. This will cause a small electromagnetic field disturbance within a small period of time. In the method of the present invention, the amount of calculation is reduced by superimposing a very small electromagnetic scattering change each time the calculation is calculated to solve, rather than obtaining a new electromagnetic field distribution by recalculating. The method of the present invention is a solution specifically for solving electromagnetic field scattering with a gradually varying dielectric constant.

[0048] like Figure 1 As shown in the figure, a planar time-harmonic electromagnetic wave is incident on a target of arbitrary geometric shape in a two-dimensional view. The electromagnetic wave travels along Direction propagation, frequency is , the electromagnetic wave is a transverse magnetic wave. The target has a non-uniform dielectric constant, and its dielectric constant distribution is For general materials, their magnetic permeability is very similar to that of vacuum, so the target magnetic permeability is set to .here is the relative dielectric constant of the target, and are the dielectric constant and magnetic permeability in vacuum respectively, and the external environment of the target of interest is set to vacuum.

[0049] Because it is a dielectric object, when electromagnetic waves are incident on the object, an equivalent polarization current will be generated, and the polarization current will generate a scattered electromagnetic field. The total electromagnetic field generated in space can be given by the volume integral method:

[0050] (1)

[0051] here and are the incident field and the scattered field respectively, j is the imaginary part in the complex expression, For the total field, is the angular frequency of the electromagnetic wave. The wave equation of the scattered electromagnetic field is given by the Helmholtz equation:

[0052] (2)

[0053] is the Hamiltonian operator, is the wave number of the electromagnetic wave, is the wavelength. The solution to this equation is:

[0054] (3)

[0055] is the scattered field generated by the equivalent polarization current, and are the position vector of the observation point and the position vector of the center coordinate point of the point source, is the second kind zero-order Hankel function, symbol represents the surface integral of the two-dimensional target over the entire two-dimensional solution region.

[0056] From formulas (1)-(3), we can get the integral equation of the electric field:

[0057] (4)

[0058] The integral equation can be solved by the moment method. The calculation area is divided into small calculation areas, each area is numbered from 1 to In this calculation, the simplest impulse function is selected as the basis function, and the weight function is the trigonometric function. For example, for The electric field intensity at the center of the calculation area is It can be expressed as

[0059] (5)

[0060] When the grid is fine enough, the field intensity at the center of each region can be used to represent the average electric field intensity in the region. Each small grid area, and Representative The average relative dielectric constant and the total electric field strength in the region.

[0061] The calculation area is equivalent to a circular domain, and the formula in the rectangular coordinate system is:

[0062] (6)

[0063] In the cylindrical coordinate system it can be converted to:

[0064] (7)

[0065] The integral of the second-order zero-order Hankel function in the circular domain can be approximated as:

[0066] , (8)

[0067] , (9)

[0068] ɑ is the distance from the observation point to the center of the circle, is the radius of the grid circle, It is and The distance between the center points of the circles.

[0069] According to formulas (8) and (9), formula (7) is expressed in discrete form:

[0070] , (10)

[0071] , (11)

[0072] Written in a condensed form:

[0073] , (12)

[0074] , (13)

[0075] This formula is the relationship between the total field and the incident field. There are a total of N equations and matrices composed of unknown numbers, among which are the matrix coefficients:

[0076] , (14)

[0077] , (15)

[0078] Combining (8) and (9) we can get:

[0079] (16)

[0080] In this way, equations (10) and (11) can be expressed in matrix form:

[0081] (17)

[0082] Combining formula (14) can be converted to:

[0083] (18)

[0084] This formula can be simplified as:

[0085] (19)

[0086] The matrix coefficients are:

[0087] ,

[0088] , ,

[0089] In the Matrix Represents the number of dimensions in a square matrix.

[0090] If the dielectric constant of the target changes according to , then formula (19) can be modified as follows:

[0091] (20)

[0092] here,

[0093] ,

[0094] Formula (20) can be written as:

[0095] (twenty one)

[0096] In the formula is a high-order term. If it is ignored, the above formula can be expressed as:

[0097] (twenty two)

[0098] That is:

[0099] (twenty three)

[0100] Every tiny change in dielectric constant , accompanied by corresponding changes in electromagnetic field strength It can be solved according to equation (22). The final total electromagnetic field distribution is can be corrected to:

[0101] (twenty four)

[0102] Combining formulas (23) and (24), the final transient electromagnetic field distribution expression can be obtained:

[0103] (25)

[0104] For the transient electromagnetic field solution of the material with gradient dielectric constant in microwave heating, the solution using this fast algorithm can be divided into three steps:

[0105] (1) Before the initial heating state, a full-wave simulation is performed based on the initial material parameters to obtain the initial electromagnetic field distribution.

[0106] (2) When the dielectric constant of the medium changes slightly When , the corresponding electromagnetic field distribution change is calculated according to formula (23): , and then calculate the corrected new electromagnetic field distribution according to formula (25).

[0107] (3) Based on the new electromagnetic field distribution and dielectric constant distribution, the second step is repeated until the calculation process is completed.

[0108] In this algorithm, it can be seen that during the calculation process, the matrix coefficients and It can be calculated in the first step that in the subsequent calculation process, only the matrix calculation in formula (25) needs to be executed, and each electromagnetic field correction only requires the calculation of a small amount of matrix. It can be clearly seen that compared with the traditional full-wave simulation algorithm that recalculates the matrix each time, this method greatly reduces the calculation burden, thereby greatly shortening the calculation time.

[0109] Use a circular target with a uniform dielectric constant , is incident by electromagnetic waves, such as Figure 2 Its relative dielectric constant is The range is 50 to 80. Figure 3 As shown, given The electromagnetic field distribution of the electrode is shown in Figure 2, and the variation range of different dielectric constants obtained by the fast algorithm is given. The biostatic radar cross section (RCS) of the two stations is compared under different conditions, and the solution results obtained by the method of moments and the finite difference time domain method are given. is the relative dielectric constant of the material. RCS is a commonly used physical quantity to measure the distribution of electromagnetic fields in all directions. It is defined as the ratio of the scattered power of the target in the receiving direction to the plane wave power density incident on the target from a given direction within a unit solid angle. times, that is .

[0110] Depend on Figure 3 It can be seen that under different dielectric constants, the error of the curve obtained by calculation is the same. However, no matter in the case of 0.02, 0.08 or 0.2 (corresponding to 1500, 375 and 150 iterations respectively), the errors of the three curves and the calculation results of the traditional classical method of moments (MoM) are small, which proves the accuracy and stability of the algorithm.

[0111] The case of a non-uniform double-layer annular target (the dielectric constant and dielectric constant change rate of each layer are different) under TM wave incidence. The outer layer and the inner layer have initial dielectric constants of and , with the same number of iterations, the dielectric constant changes to 80 and 50. Figure 5 The RCS distributions calculated by the fast algorithm given in this paper are compared with those calculated by the moment method. and The electromagnetic field distribution under the condition. and In this case, the two calculation results are very consistent, but when When the dielectric constant is large, the fast algorithm will have a certain calculation error.

[0112] The dielectric constant distribution of non-uniform rectangular target is as follows Figure 6 As shown in the figure, the rectangular target is divided into four parts, and the dielectric constants are , , , The values ​​change from the initial 20, 30, 40, 50 to 30, 45, 60, 80. When the corresponding dielectric constant gradients are 0.02, 0.8, and 0.2 (1500, 375, and 150 steps, respectively), the number of steps for the remaining dielectric constant changes remains the same, but the proportion of the dielectric constant change changes accordingly.

[0113] Figure 7 The comparison between the fast algorithm and the moment method is given in . Similar to the previous results, when When is 0.02 and 0.08, the algorithm is in good agreement with the results calculated by the method of moments. When it is 0.2, a large error begins to appear. Unlike the above two examples, since the dielectric constant in this example is asymmetrically distributed, it can be seen that the solved RCS and electromagnetic field intensity distribution are also asymmetrical, and their amplitudes vary with different scattering angles, electric field phase and other related information. Due to reflection and diffraction, it can be seen from this calculation that the amplitude of the field intensity is the largest at 0 degrees and 180 degrees. Embodiment 2

[0114] The electronic controller device for vehicle information collection and communication is designed by the method of the present invention. The shell of the electronic controller is made of polyvinyl chloride plastic (PVC) plastic, and the dielectric board is made of polyvinyl chloride plastic FR4 medium. Fig.11As shown, the electronic controller uses a 4G internal antenna, which is placed under the top cover of the electronic controller and adhered to the bottom of the top cover. The antenna radiates electromagnetic waves omnidirectionally to achieve the electromagnetic wave receiving and transmitting effect with the maximum coverage.

[0115] During the operation of the device, firstly, the full-wave electromagnetic wave simulation is carried out according to the set material properties to obtain the antenna design that meets the performance indicators, the circuit board design of the electronic controller device and the structural design. The working environment of the electronic controller is the vehicle operating environment, and the working temperature is -20 O C( O C represents Celsius) to +85 O C. The communication electronic controller in the present invention has an operating bandwidth of 1.7 GHz to 2.7 GHz in the 4G wireless communication frequency band, and the design target is that the electromagnetic scattering parameter S11 is less than -6 dB, and the electromagnetic wave is omnidirectionally radiated. The design radiation efficiency target is greater than 20%.

[0116] The dielectric constant of FR4 material medium will change with the change of frequency, and its dielectric constant will also change with the change of the temperature of the object itself. Figure 8 Demonstrates the FR4 material dielectric in 20 O C, the curve of the real part of the dielectric constant changing with frequency shows that the real part of the dielectric constant decreases with the increase of frequency. The dielectric constant variation range decreases from 4.70 corresponding to 2GHz to 4.30 corresponding to 20GHz in the form of a concave curve. Fig. 9 The dielectric constant of FR4 material changes with temperature. o The curve corresponding to 4.2 at C shows a nearly linear relationship, which gradually increases to 4.8 corresponding to 140OC. Fig.10 The three-dimensional mapping relationship of the dielectric constant of FR4 material medium changing with temperature and frequency is shown.

[0117] In order to ensure that the electromagnetic field of the electronic controller can achieve effective radiation and work normally in the entire working frequency band, the dielectric constant electromagnetic field numerical calculation of PVC medium and FR4 medium at room temperature is carried out in the early design. O C is the structure model of the communication electronic controller. The model includes communication module, positioning chip, FR4 dielectric board, speaker and shell.

[0118] As the ambient temperature rises, the dielectric constant of FR4 medium will slowly increase. This change in dielectric constant will affect the overall circuit performance of the electronic controller. In the high frequency band, due to the increase in dielectric constant, the circuit performance will change significantly due to the change in dielectric constant. Based on the design, the circuit performance is quickly calculated to predict the overall electrical performance within the temperature range.

[0119] For frequency simulation, 1.7 GHz is taken as the starting frequency, and a corresponding o C, that is, the electromagnetic field calculation corresponding to the dielectric constant of FR4 medium in the corresponding frequency band is performed 11 times. At the same time, for each selected frequency point, at 20 o C to 85 o Within the temperature range of 5 o C selects the corresponding FR4 dielectric constant to calculate the electromagnetic field distribution. In this embodiment, from 20 o Starting from the dielectric constant corresponding to C, for each frequency point, a total of 14 frequency points were calculated for the dielectric constant. In this embodiment, for the modeled structure, in the frequency range of 1.7 GHz to 2.7 GHz, at 20 o C to 85 o A total of 154 electromagnetic field solutions were performed within the temperature range of C.

[0120] The antenna is at 20 O Under the condition of temperature C, the electromagnetic field distribution at 1.7 GHz is solved. According to formula (17), the electromagnetic field distribution is first solved based on the initial dielectric constant of FR4 corresponding to the 1.7 GHz frequency, that is, when the dielectric constant is 4.2. The corresponding 1.7 GHz electromagnetic wave field distribution is obtained through normal electromagnetic wave full-wave simulation calculation. When the frequency increases by 0.1 GHz, based on the existing 1.7 GHz field distribution and the changed dielectric constant , use formula (25) to quickly iterate the field distribution. The corresponding field distribution at 1.8 GHz is obtained, and by analogy, the electromagnetic field distribution at every 0.1 GHz step in the 1.7 GHz to 2.7 GHz frequency band is obtained.

[0121] The electric field distribution is compared. Fig.12 and Fig.13 As shown, the electric field distribution diagram on the vehicle electronic controller structure based on the present invention in this embodiment is displayed. Fig.12 The electric field distribution of the vehicle electronic controller is shown when the dielectric constant is 4.2 and the frequency is 2.4 GHz. Fig.13The electric field distribution of the vehicle-mounted electronic controller is shown when the dielectric constant is 4.2 and the frequency is 2.4GHz. It can be seen from the figure that when the dielectric constant of FR4 changes due to ambient temperature, it will eventually lead to a change in the electric field distribution on the electronic controller. In this embodiment, the minimum value of the electric field distribution changes from -89.5V / m to -103.8V / m, and the maximum value changes from 102.3V / m to 111.9V / m. It can be seen from the entire electric field distribution diagram that the entire distribution trend is the same. On the FR4 board on the far right of the controller, when the dielectric constant is 4.2, its electric field strength is relatively large.

[0122] Calculate the direction map. Fig.14 and Fig.15 The three-dimensional pattern distribution is shown at 2.4GHz frequency when the dielectric constant is 4.2 and 4.8 respectively. The calculated patterns have the same distribution trend when the dielectric constant is 4.2 and 4.8. When the dielectric constant of FR4 medium is 4.2, the maximum field strength value is 5.05, and the radiation pattern has better omnidirectionality than when the dielectric constant is 4.8; when the dielectric constant is 4.8, the maximum field strength value is 4.84, and the omnidirectional radiation of the radiation pattern is inferior to the pattern when the dielectric constant is 4.2.

[0123] Calculate the electromagnetic scattering parameter S11 of the antenna in the electronic controller environment. Extract the electric field strength at the antenna feed port based on the field distribution solution. , and compare it with the input voltage, using the formula Calculate the electromagnetic scattering parameters S11, V of the antenna in the electronic controller environment port represents the volume of the calculated area, E input It represents the initial input field strength of the antenna port when it is fed. Fig.16 It is shown that when the dielectric constant of FR4 medium is 4.2 and 4.8, the S11 parameter curve has obvious drift. The parameter S11 in the 1.7GHz to 2.7GHz frequency band is below -6dB, meeting the technical index requirements of IoT products and vehicle-mounted wireless products. It can be further judged that based on the electromagnetic scattering parameter S11 solved by this fast algorithm, when the dielectric constant of FR4 medium changes due to the external temperature environment, the solved parameter S11 meets the design requirement of less than -6dB.

[0124] Calculate the radiation efficiency of the antenna in the electronic controller environment. From formula (17), extract all the electric fields in the whole space , using the formula Solve the integrated energy. Using the formula To calculate the total efficiency of the wireless transceiver, use the formula Solve the radiation efficiency of the antenna. Among them, P radiationExpressed as antenna radiated power, P input Expressed as the total input power to the antenna, P loss It represents the power loss of the antenna, V represents the volume of the calculated space, and η represents the intrinsic impedance of the electromagnetic wave in the propagation space. In this embodiment, it is the intrinsic impedance of the electromagnetic wave in the air propagation.

[0125] Based on the field distribution solution, the electromagnetic radiation efficiency and total efficiency of the antenna in the electronic controller environment are calculated when the dielectric constant is 4.2 and 4.8 respectively. Fig.17 It can be seen that the radiation efficiency (Radiation Efficiency) of the antenna in the electronic controller environment is greater than 85% in the frequency range of 1.7GHz to 2.7GH. The total efficiency (Total Efficiency) of the antenna in the electronic controller environment is greater than 40%. Therefore, it can be judged that due to the change in the dielectric constant of FR4 caused by the external environment, the radiation efficiency meets the requirement of greater than 20%, and the total efficiency meets the requirement of greater than 10%.

[0126] The method of the invention can ensure that the vehicle information collection and communication electronic controller device can maintain good electromagnetic performance under different ambient temperatures and meet the needs of wireless communication. The method can not only predict the change of electromagnetic performance, but also quickly adjust the design to adapt to different working environments. Embodiment 3

[0127] The electronic transceiver for wirelessly transmitting and receiving vehicle information is designed by the method of the present invention. The shell of the electronic controller is made of polyvinyl chloride plastic (PVC plastic), and the dielectric board is made of polyvinyl chloride plastic (FR4 medium). Fig.18 As shown in the figure, a built-in inverted PIFA antenna (Planar Inverted F-shaped Antenna) is designed and placed above the transmitter. The outer shell is encapsulated with PVC plastic. The vehicle controller is located under the baffle in front of the vehicle's central control and is required to have omnidirectional radiation capability of wireless signals to achieve omnidirectional wireless reception capability of signals around the vehicle.

[0128] Full-scale 3D modeling is performed, and the dielectric constant physical properties of the material are set to perform full-wave simulation of the initial conditions. The working environment of the wireless transceiver is the vehicle operating environment, and the working temperature is -20 O C to +85 OC. Since the Lora band bandwidth in the design indicators of this product has extremely narrow band characteristics in the frequency bands of 433MHz and 868MHz, when the dielectric constant of the FR4 dielectric board changes, it will have a very large impact on its operating frequency band, and the resonant frequency of the system radiation is very likely to drift with the change of the dielectric constant of the FR4 medium and other materials. In order to ensure that the designed wireless transmitter works normally under the corresponding ambient temperature, it is necessary to perform electromagnetic field radiation modeling calculations at different temperatures and frequency bands on its radiation characteristics.

[0129] The antenna frequency band design requirements are 433MHz (433.05MHz~434.7MHz) and 868MHz (863MHz~870MHz) of the Lora band. The design target is S11 port) less than -6dB, and the electromagnetic wave is omnidirectional. Since the working frequency band of this design indicator is Sub-1GHz (frequency band below 1GHz), the design radiation efficiency is greater than 10%.

[0130] Calculate the electromagnetic field distribution of the initial boundary conditions. Calculate the wireless transmitter at 20 o C, electromagnetic wave radiation characteristics at frequencies of 433 MHz and 868 MHz. According to formula (17), the initial electromagnetic field distribution of FR4 medium when the dielectric constant is 4.2 is solved.

[0131] Calculate the field distribution of the electromagnetic field as the dielectric constant changes, and analyze the frequency characteristics of the wireless transmitter. Due to the narrowband characteristics of the 433MHz frequency band, the value of the FR4 medium dielectric constant that changes with frequency is relatively small in the 433.05MHz to 434.7MHz frequency band. In this embodiment, since FR4 is in the low-frequency band, its dielectric constant changes less with frequency, so the dielectric constant value corresponding to the 433MHz frequency point is used in the calculation to solve the electromagnetic field distribution. From the dielectric constant from 4.2 to 4.8, the value is taken every 0.1, and the field distribution corresponding to different dielectric constants is calculated. Formula (25) is used for rapid iterative calculation of the field distribution. In this embodiment, a total of 7 calculations are performed. When the dielectric constant changes by 0.1.

[0132] The electromagnetic field strength analysis and comparison of FR4 medium under the condition of changing dielectric constant is carried out. Fig.19 and Fig. 20As shown, it shows the electric field distribution of the wireless transmitter dielectric board at 433MHz frequency when the dielectric constant of the FR4 medium is 4.2 and 4.8 respectively. From the calculated field distribution results, it can be seen that when the dielectric constant is 4.2, the electric field distribution on the board is stronger, and its value range is 34.5V / m to 111.1V / m. When the dielectric constant is 4.8, the electric field strength range is 7V / m to 8V / m. That is, when the dielectric constant of the FR4 medium is 4.2, it is easier to achieve electromagnetic wave radiation. When the dielectric constant of the FR4 medium is 4.2, the electric field distribution on the upper metal of its dielectric board is more uniform than when the dielectric constant is 4.2. The metal strip antenna above the dielectric board has a stronger electromagnetic field when the dielectric constant of the FR4 medium is 4.2 than when the dielectric constant is 4.8, which also means that it has a stronger field radiation capability.

[0133] Calculate the electromagnetic scattering parameter S11 when the dielectric constant of FR4 medium is 4.2 and 4.8 respectively to ensure that the vehicle-mounted wireless transceiver can work normally under the preset external environment. According to the field distribution solution, extract the electric field strength at the antenna feed port , and compare it with the input voltage, using the formula Calculate the electromagnetic scattering parameter S11 of the antenna in the electronic controller environment. Fig.21 It can be seen that based on the initial design of the RF transceiver, the FR4 dielectric board has a good resonance effect at 433MHz and 868MHz when the dielectric constant is 4.4. 4.4 is a typical dielectric constant value of FR4 medium at normal ambient temperature. When the dielectric constant of FR4 medium changes to 4.2 and 4.8, its resonant frequency points near 433MHz and 868MHz drift. When the dielectric constant of FR4 medium is 4.8, the resonant frequency point of 868MHz is increased by 30MHz. However, in the entire working frequency band, its electromagnetic scattering parameter S11 index meets the design requirements.

[0134] Calculate the radiation efficiency when the dielectric constant of FR4 medium increases from 4.2 to 4.8. According to formula (17), extract all the electric fields in the whole space , using the formula Solve the integrated energy. Using the formula Solve the total efficiency of the wireless transceiver. Fig. 22It can be seen that when the dielectric constant of FR4 is 4.2, 4.4, 4.6, and 4.8, the total radiation efficiency at 433MHz is higher than that with a large change. At the dielectric constant value of 4.4 in the typical working environment of FR4, the antenna has the best total radiation efficiency at 433MHz; in the case of 4.2, the antenna radiation efficiency at 433MHz decreases. When the dielectric constant of the FR4 medium is 4.8, the total radiation efficiency of the antenna is reduced to less than 3%. For the frequency of 868MHz, the total radiation efficiency of the antenna is greater than 20%.

[0135] Calculate the antenna radiation efficiency. Using the formula Solve the radiation efficiency of the antenna. Fig.23 It can be seen that when the dielectric constant of FR4 is 4.2, 4.4, 4.6, and 4.8, the radiation efficiency trend remains constant, and near 433MHz and 868MHz, the radiation efficiency is higher than 15%, meeting the radiation efficiency index requirement of greater than 10%.

[0136] The total radiation effect analysis in this embodiment has important reference significance for the wireless transceiver. In this embodiment, since the antenna can operate in the operating frequency band of 433MHz or 8686MHz, the radiation efficiency is higher than 15%, and the antenna design meets the system index requirements.

[0137] The invention can be used to evaluate and predict the performance of vehicle-mounted wireless transceivers under different environmental conditions, especially in the rapid calculation of the effect of dielectric constant changes on electromagnetic field distribution. In this way, it can be ensured that the wireless transceiver can work reliably under various environmental conditions in which the vehicle is operated.

[0138] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A fast solution algorithm for electromagnetic field distribution under varying dielectric constants, characterized by: Includes steps: A. In the initial state, a full-wave simulation is performed based on the initial parameters of the material to obtain the initial electromagnetic field distribution; B. When the dielectric constant changes slightly, first calculate the corresponding change in the electromagnetic field distribution, and then calculate the corrected new electromagnetic field distribution; C. Based on the new electromagnetic field distribution and dielectric constant distribution, repeat step B until a predetermined number of iterations is reached or the dielectric constant of the material is stable.

2. The fast solution algorithm for electromagnetic field distribution with a variable dielectric constant according to claim 1 is characterized in that: In step B, the change in electromagnetic field distribution is calculated according to the following formula: ， in, A N×N and B N×N are matrix coefficients, E N×1 is the electromagnetic field distribution, is the dielectric constant change, ε N×N is the dielectric constant.

3. The fast solution algorithm for electromagnetic field distribution with a variable dielectric constant according to claim 2 is characterized in that: In step B, the corrected new electromagnetic field distribution is calculated according to the following formula: 。 4. The fast solution algorithm for electromagnetic field distribution under variable dielectric constant according to claim 1 or 3, characterized in that: The method is suitable for solving electromagnetic field scattering in electronic transceivers and electronic controllers whose dielectric constants vary with external environmental factors.

5. The fast solution algorithm for electromagnetic field distribution with variable dielectric constant according to claim 4 is characterized in that: The shells of the electronic controller and the electronic transceiver are both made of polyvinyl chloride plastic (PVC) plastic, and the dielectric plate can be made of polyvinyl chloride plastic FR4, ABS plastic, nylon, PE plastic, PP plastic, PVC plastic, rubber or chemical fiber.

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