A time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects

Abstract

The application discloses a time-domain finite-difference numerical simulation method of electric contact intermodulation and harmonic effect, and belongs to the field of passive intermodulation and harmonic effect of microwave components. The application adopts a time-domain simulation method, regards a contact interface as a secondary excitation source, and the size of the excitation source is controlled by a linear field component. By calculating the nonlinear field distribution under the action of the controlled secondary excitation source, the passive intermodulation and harmonic level is finally obtained. The application provides an accurate full-wave electromagnetic simulation method based on time-domain simulation for how to calculate the passive intermodulation and harmonic effect of macroscopic microwave components by using microscopic contact interface nonlinearity. The calculation method is simple in programming, can be embedded into a traditional time-domain finite-difference electromagnetic calculation program, and can realize the evaluation of contact nonlinear passive intermodulation and harmonic effect while realizing the traditional electric performance calculation of microwave components.

Description

Technical Field

[0001] This invention belongs to the field of passive intermodulation and harmonic effects of microwave components, specifically involving a time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects. Background Technology

[0002] Passive intermodulation and harmonic effects in microwave components caused by parasitic nonlinearity are among the major reliability issues faced by mobile communication equipment in achieving high-quality operation. Establishing analytical calculation and numerical simulation methods to reveal the generation mechanism and transmission law of passive intermodulation and harmonic signals in different microwave components is fundamental to the design of low intermodulation and low harmonic devices. It is well known that electrical contacts in microwave components are a major source of passive intermodulation and harmonic effects. For example, electrical contacts in waveguide flange connections, coaxial connections, cavity filters, and mesh antennas are major sources of passive intermodulation effects, while harmonic effects caused by electrical contacts in mobile phone spring connections are a major source of spurious radiation from mobile phones. To achieve both low intermodulation and low harmonic design while simultaneously considering the electrical performance of microwave components, establishing simulation and evaluation methods for passive intermodulation and harmonic effects in microwave components has significant application value.

[0003] Currently, based on microstructure analysis and modeling, mathematical models can, to a certain extent, describe the relationship between the contact impedance and nonlinear JV (current density-voltage) characteristics of electrical contact structures and the microstructure of the contact interface, oxide layer characteristics, contact pressure, etc. However, after obtaining the contact impedance and nonlinear JV relationship at the microscopic contact interface, it is still necessary to establish their relationship with the passive intermodulation and harmonic levels generated at the ports of macroscopic microwave components. Traditional approximations based on dipole equivalence and other equivalent models can, to some extent, provide calculation methods for the relationship between passive intermodulation and harmonics in microwave components and their structures. However, when applying traditional analysis methods to complex structures, such as filters and MIMO antennas, their accuracy is often difficult to assess. As is well known, the finite-difference time-domain (FDTD) method is one of the most widely used numerical simulation methods in computational electromagnetics. However, how to use the FDTD method to simulate the passive intermodulation and harmonic levels of microwave components remains unsolved. Summary of the Invention

[0004] The purpose of this invention is to provide a time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects. This method can accurately calculate the nonlinear passive intermodulation and harmonic effects of electrical contacts in complex microwave components.

[0005] The present invention is achieved using the following technical solution:

[0006] A time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects includes the following steps:

[0007] 1) Spatial and temporal discretization of the microwave component model to be determined: The spatial arrangement of magnetic field nodes and electric field nodes adopts Yee grid cell structure, and the position of the Yee grid cell element where the contact interface is located is determined; the time step value of the magnetic field component is n+1 / 2, and the time step value of the corresponding electric field component is n+1; the dimensions of the Yee cell in the x, y, and z directions are Δx, Δx, and Δz, respectively; the time step is Δt.

[0008] 2) Set the time-domain carrier excitation source: Use dual-carrier, multi-carrier, or modulated signal waveforms for passive intermodulation calculation; use single-carrier or modulated signal time-domain excitation waveforms for harmonic calculation;

[0009] 3) Update the magnetic field components at time step n+1 / 2: Decompose the magnetic field components into linear components H x0 H y0 and H z0 and the nonlinear part H xp H yp and H zp The subscripts x, y, and z represent the components in the three directions, respectively; the updates of both the linear and nonlinear parts are calculated using the Maxwell curl equation difference algorithm.

[0010] 4) Calculate the linear current flowing through the Yee mesh element at the contact interface:

[0011] For the case where the normal direction of the contact interface is the x-direction, calculate the linear current component I flowing through the mesh in the x-direction. x0 :

[0012]

[0013] Where i, j, and k represent the discrete coordinates of the spatial position along the x, y, and z directions, respectively;

[0014] For the case where the normal direction of the contact interface is the y-direction, calculate the linear current component I flowing through the mesh in the y-direction. y0 :

[0015]

[0016] For the case where the normal direction of the contact interface is the z-direction, calculate the linear current component I flowing through the mesh in the z-direction. z0 :

[0017]

[0018] 5) Calculate the nonlinear current density flowing through the Yee mesh element at the contact interface:

[0019] For the case where the normal direction of the contact interface is the x-direction, calculate the nonlinear current density component J in the x-direction flowing through the mesh containing the contact interface. xp :

[0020]

[0021]

[0022] Where V c For the contact junction voltage drop, Z c,s Let f() be the impedance per unit area of ​​the contact interface, and f() represent the nonlinear JV relationship of the contact interface.

[0023] For the case where the normal direction of the contact interface is the y-direction, calculate the nonlinear current density component J in the y-direction of the mesh containing the contact interface. yp :

[0024]

[0025]

[0026] For the case where the normal direction of the contact interface is the z-direction, calculate the nonlinear current density component J in the z-direction of the mesh containing the contact interface. zp :

[0027]

[0028]

[0029] 6) Update the electric field components at time step n+1: Decompose the electric field components into a linear part E x0 E y0 and E z0 and the nonlinear part E xp E yp and E zp Linear component E x0 E y0 and E z0 The update is calculated using the traditional Maxwell curl equation difference algorithm, with the nonlinear component E xp E yp and E zp The following formula is used for calculation;

[0030] For the case where the normal direction of the contact interface is the x-direction, the nonlinear electric field component E in the x-direction of the grid containing the contact interface xp Update using the following equation:

[0031]

[0032] Where the coefficients are:

[0033]

[0034]

[0035]

[0036]

[0037] Where H x0 H y0 and H z0 These represent the linear components of the solutions in the x, y, and z directions, respectively; H xp H yp and H zp These represent the nonlinear components of the solutions in the x, y, and z directions, respectively; ε x and σ x e represent the magnitudes of the dielectric constant and conductivity components in the x-direction, respectively;

[0038] For the case where the normal direction of the contact interface is the y-direction, the nonlinear electric field component E in the y-direction of the mesh containing the contact interface yp Update using the following equation:

[0039]

[0040] Where the coefficients are:

[0041]

[0042]

[0043]

[0044]

[0045] Where ε y and σ y e represent the magnitudes of the dielectric constant and conductivity components in the y-direction, respectively;

[0046] For the case where the normal direction of the contact interface is the z-direction, the nonlinear electric field component E in the z-direction of the mesh containing the contact interface zp Update using the following equation:

[0047]

[0048] Where the coefficients are:

[0049]

[0050]

[0051]

[0052]

[0053] Where ε z and σ z e represent the magnitudes of the dielectric constant and conductivity components in the z-direction, respectively;

[0054] 7) Let n = n + 1, and repeat steps 3) to 6) until the iteration is complete;

[0055] 8) Extract the nonlinear components of the electric and magnetic fields at the port of the microwave component, perform transformation and post-processing to obtain the passive intermodulation and harmonic levels.

[0056] A further improvement of the present invention is that the linear and nonlinear parts of the electric and magnetic fields in steps 3) and 6) are calculated separately.

[0057] A further improvement of this invention is that it employs a time-domain simulation method, treating the contact interface as a secondary excitation source, and the magnitude of the excitation source is controlled by the linear field component.

[0058] A further improvement of this invention is that, by calculating the nonlinear field distribution under the action of the controlled secondary excitation source, the passive intermodulation and harmonic levels are finally obtained.

[0059] A further improvement of the present invention is that, in step 4), each component I of the linear current flowing through the contact interface... x0 I y0 and I z0 The values ​​of Yee cells are respectively related to E x0 E y0 and E z0 The spatial locations of the values ​​coincide.

[0060] A further improvement of the present invention is that, in step 5), Z c,s The contact resistance per unit area of ​​the metal contact interface is approximated by actual measurement; f() represents the functional relationship between the current density flowing through the contact interface after deducting the linear contribution and the voltage drop across the contact interface.

[0061] A further improvement of the present invention is that, in step 5), the contact junction voltage drop V c The linear current flowing through the contact interface and the contact interface impedance per unit area Z c,s Sure.

[0062] A further improvement of the present invention is that, in step 5), Z c,sf() is a function of the contact interface pressure and temperature, used to calculate the effects of pressure and temperature on electrical contact intermodulation and harmonic effects.

[0063] A further improvement of the present invention is that, in step 8), FFT or Prony transformation and post-processing are performed to obtain passive intermodulation and harmonic levels.

[0064] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0065] This invention employs a time-domain simulation method, treating the contact interface as a secondary excitation source, with the magnitude of the excitation source controlled by linear field components. By calculating the nonlinear field distribution under the influence of this controlled secondary excitation source, the passive intermodulation and harmonic levels are ultimately obtained. This provides an accurate full-wave electromagnetic simulation method for calculating the passive intermodulation and harmonic effects of macroscopic microwave components using the nonlinearity of microscopic contact interfaces. This calculation method is simple to program and can be embedded into traditional time-domain finite-difference electromagnetic calculation programs, enabling the simultaneous calculation of the conventional electrical performance of microwave components and the evaluation of contact nonlinear passive intermodulation and harmonic effects. Attached Figure Description

[0066] Figure 1 This is a flowchart of the implementation steps described in this invention;

[0067] Figure 2 This is a schematic diagram of the contact interface structure according to an embodiment of the present invention;

[0068] Figure 3 This is a schematic diagram of a parallel metal plate simulation model according to an embodiment of the present invention;

[0069] Figure 4 This is a waveform diagram of the dual-carrier time-domain excitation according to an embodiment of the present invention;

[0070] Figure 5 This is a linear voltage waveform diagram at the load end of an embodiment of the present invention;

[0071] Figure 6 This is a diagram showing the nonlinear voltage waveform at the load end in an embodiment of the present invention.

[0072] Figure 7 The result of the FFT transformation of the linear voltage at the load end in an embodiment of the present invention;

[0073] Figure 8 This is the FFT transformation result of the nonlinear voltage at the load end in an embodiment of the present invention. Detailed Implementation

[0074] The present invention will be further described in detail below with reference to specific accompanying drawings and embodiments. These descriptions are for illustrative purposes only and are not intended to limit the scope of the invention.

[0075] like Figure 1 This is a flowchart illustrating the implementation steps of the present invention. For example... Figure 2 As shown, metal 1 and metal 2 are in contact, and the normal direction of the contact surface is the z-direction. For the mesh (i,j,k), the nonlinear current density J needs to be calculated using formulas (3), (8) and (9). zp (i,j,k).

[0076] Depend on Figure 1 The calculation flowchart shown illustrates the main steps of the finite-difference time-domain numerical simulation method for electrical contact intermodulation and harmonic effects described in this invention:

[0077] 1) Spatial and temporal discretization of the microwave component model to be determined: The spatial arrangement of magnetic field nodes and electric field nodes adopts Yee grid cell structure, and the position of the Yee grid cell element where the contact interface is located is determined; the time step of the magnetic field component is n+1 / 2, and the time step of the corresponding electric field component is n+1; the dimensions of the Yee cell in the x, y and z directions are Δx, Δx and Δz, respectively; the time step is Δt.

[0078] 2) Set the time-domain carrier excitation source: When calculating passive intermodulation, dual-carrier, multi-carrier, or modulated signal waveforms can be used; when calculating harmonics, single-carrier or modulated signal time-domain excitation waveforms can be used.

[0079] 3) Update the magnetic field components at time step n+1 / 2: Decompose the magnetic field components into linear components H x0 H y0 and H z0 and the nonlinear part H xp H yp and H zp The subscripts x, y, and z represent the components in the three directions, respectively; the updates of both the linear and nonlinear parts are calculated using the traditional Maxwell curl equation difference algorithm.

[0080] 4) Calculate the linear current flowing through the Yee mesh element at the contact interface:

[0081] For the case where the normal direction of the contact interface is the x-direction, calculate the linear current component I flowing through the mesh in the x-direction. x0 :

[0082]

[0083] Where i, j, and k represent the discrete coordinates of the spatial position along the x, y, and z directions, respectively;

[0084] For the case where the normal direction of the contact interface is the y-direction, calculate the linear current component I flowing through the mesh in the y-direction. y0 :

[0085]

[0086] For the case where the normal direction of the contact interface is the z-direction, calculate the linear current component I flowing through the mesh in the z-direction. z0 :

[0087]

[0088] 5) Calculate the nonlinear current density flowing through the Yee mesh element at the contact interface:

[0089] For the case where the normal direction of the contact interface is the x-direction, calculate the nonlinear current density component J in the x-direction flowing through the mesh containing the contact interface. xp :

[0090]

[0091]

[0092] Where V c For the contact junction voltage drop, Z c,s Let f be the impedance per unit area of ​​the contact interface, and f() represent the nonlinear JV relationship of the contact interface.

[0093] For the case where the normal direction of the contact interface is the y-direction, calculate the nonlinear current density component J in the y-direction of the mesh containing the contact interface. yp :

[0094]

[0095]

[0096] For the case where the normal direction of the contact interface is the z-direction, calculate the nonlinear current density component J in the z-direction of the mesh containing the contact interface. zp :

[0097]

[0098]

[0099] 6) Update the electric field components at time step n+1: Decompose the electric field components into a linear part E x0 E y0 and E z0 and the nonlinear part E xp E yp and E zp Linear component E x0 E y0 and E z0 The update is calculated using the traditional Maxwell curl equation difference algorithm, with the nonlinear component E xp Eyp and E zp The following formula is used for calculation.

[0100] For the case where the normal direction of the contact interface is the x-direction, the nonlinear electric field component E in the x-direction of the grid containing the contact interface xp Update using the following equation:

[0101]

[0102] Where the coefficients are:

[0103]

[0104]

[0105]

[0106]

[0107] Where H x0 H y0 and H z0 These represent the linear components of the solutions in the x, y, and z directions, respectively; H xp H yp and H zp These represent the nonlinear components of the solutions in the x, y, and z directions, respectively; ε x and σ x e represent the magnitudes of the dielectric constant and conductivity components in the x-direction, respectively;

[0108] For the case where the normal direction of the contact interface is the y-direction, the nonlinear electric field component E in the y-direction of the mesh containing the contact interface yp Update using the following equation:

[0109]

[0110] Where the coefficients are:

[0111]

[0112]

[0113]

[0114]

[0115] Where ε y and σ y e represent the magnitudes of the dielectric constant and conductivity components in the y-direction, respectively;

[0116] For the case where the normal direction of the contact interface is the z-direction, the nonlinear electric field component E in the z-direction of the mesh containing the contact interface zp Update using the following equation:

[0117]

[0118] Where the coefficients are:

[0119]

[0120]

[0121]

[0122]

[0123] Where ε z and σ z e represent the magnitudes of the dielectric constant and conductivity components in the z-direction, respectively;

[0124] 7) Let n = n + 1, and repeat steps 3) to 6) until the iteration is complete.

[0125] 8) Extract the nonlinear components of the electric and magnetic fields at the port of the microwave component, perform FFT or Prony transformation and post-processing to obtain the passive intermodulation and harmonic levels.

[0126] right Figure 3 The parallel metal plate structure shown has an upper metal plate composed of metal 1 and metal 2 in contact. The passive intermodulation effect caused by the nonlinearity of the contact interface is calculated using the finite-difference time-domain method. A dual-carrier time-domain signal is used for excitation, and the excitation waveform is shown below. Figure 4 As shown. After as Figure 1 The simulation process shown is illustrated. After simulation, the time-domain waveforms of the linear and nonlinear voltages at the load resistor are obtained as follows: Figure 5 and Figure 6 As shown, the corresponding FFT transformation results are as follows: Figure 7 and Figure 8 As shown. From Figure 8 As can be seen, the FFT transformation can ultimately extract... Figure 3 The passive intermodulation level generated by the contact structure shown.

[0127] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects, characterized in that, Includes the following steps: 1) Spatial and temporal discretization of the microwave component model to be determined: The spatial arrangement of magnetic field nodes and electric field nodes adopts Yee grid cell structure, and the position of the Yee grid cell element where the contact interface is located is determined; the time step value of the magnetic field component is n+1 / 2, and the time step value of the corresponding electric field component is n+1; the dimensions of the Yee cell in the x, y, and z directions are Δx, Δx, and Δz, respectively; the time step is Δt. 2) Set the time-domain carrier excitation source: Use dual-carrier, multi-carrier, or modulated signal waveforms for passive intermodulation calculation; use single-carrier or modulated signal time-domain excitation waveforms for harmonic calculation; 3) Update the magnetic field components at time step n+1 / 2: Decompose the magnetic field components into linear components H x0 H y0 and H z0 and the nonlinear part H xp H yp and H zp The subscripts x, y, and z represent the components in the three directions, respectively; the updates of both the linear and nonlinear parts are calculated using the Maxwell curl equation difference algorithm. 4) Calculate the linear current flowing through the Yee mesh element at the contact interface: For the case where the normal direction of the contact interface is the x-direction, calculate the linear current component I flowing through the mesh in the x-direction. x0 : Where i, j, and k represent the discrete coordinates of the spatial position along the x, y, and z directions, respectively; For the case where the normal direction of the contact interface is the y-direction, calculate the linear current component I flowing through the mesh in the y-direction. y0 : For the case where the normal direction of the contact interface is the z-direction, calculate the linear current component I flowing through the mesh in the z-direction. z0 : 5) Calculate the nonlinear current density flowing through the Yee mesh element at the contact interface: For the case where the normal direction of the contact interface is the x-direction, calculate the nonlinear current density component J in the x-direction flowing through the mesh containing the contact interface. xp : Where V c For the contact junction voltage drop, Z c,s Let f() be the impedance per unit area of ​​the contact interface, and f() represent the nonlinear JV relationship of the contact interface. For the case where the normal direction of the contact interface is the y-direction, calculate the nonlinear current density component J in the y-direction of the mesh containing the contact interface. yp : For the case where the normal direction of the contact interface is the z-direction, calculate the nonlinear current density component J in the z-direction of the mesh containing the contact interface. zp : 6) Update the electric field components at time step n+1: Decompose the electric field components into a linear part E x0 E y0 and E z0 and the nonlinear part E xp E yp and E zp Linear component E x0 E y0 and E z0 The update is calculated using the traditional Maxwell curl equation difference algorithm, with the nonlinear component E xp E yp and E zp The following formula is used for calculation; For the case where the normal direction of the contact interface is the x-direction, the nonlinear electric field component E in the x-direction of the grid containing the contact interface xp Update using the following equation: Where the coefficients are: Where H x0 H y0 and H z0 These represent the linear components of the solutions in the x, y, and z directions, respectively; H xp H yp and H zp These represent the nonlinear components of the solutions in the x, y, and z directions, respectively; ε x and σ x e represent the magnitudes of the dielectric constant and conductivity components in the x-direction, respectively; For the case where the normal direction of the contact interface is the y-direction, the nonlinear electric field component E in the y-direction of the mesh containing the contact interface yp Update using the following equation: Where the coefficients are: Where ε y and σ y e represent the magnitudes of the dielectric constant and conductivity components in the y-direction, respectively; For the case where the normal direction of the contact interface is the z-direction, the nonlinear electric field component E in the z-direction of the mesh containing the contact interface zp Update using the following equation: Where the coefficients are: Where ε z and σ z e represent the magnitudes of the dielectric constant and conductivity components in the z-direction, respectively; 7) Let n = n + 1, and repeat steps 3) to 6) until the iteration is complete; 8) Extract the nonlinear components of the electric and magnetic fields at the port of the microwave component, perform transformation and post-processing to obtain the passive intermodulation and harmonic levels.

2. The time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects according to claim 1, characterized in that, The linear and nonlinear components of the electric and magnetic fields in steps 3) and 6) are calculated separately.

3. The time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects according to claim 1, characterized in that, The time-domain simulation method is adopted, and the contact interface is regarded as a secondary excitation source, and the magnitude of the excitation source is controlled by the linear field component.

4. The time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects according to claim 3, characterized in that, By calculating the nonlinear field distribution under the action of the controlled secondary excitation source, the passive intermodulation and harmonic levels are finally obtained.

5. The time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects according to claim 1, characterized in that, The components I of the linear current flowing through the contact interface in step 4) x0 I y0 and I z0 The values ​​of Yee cells are respectively related to E x0 E y0 and E z0 The spatial locations of the values ​​coincide.

6. The time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects according to claim 1, characterized in that, In step 5), Z c,s The contact resistance per unit area of ​​the actual measured metal contact interface is used as an approximation.

7. The time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects according to claim 1, characterized in that, In step 5), f() represents the functional relationship between the current density flowing through the contact interface after deducting the contribution of the linear component and the voltage drop across the contact interface.

8. The time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects according to claim 1, characterized in that, In step 5), the contact junction voltage drop V c The linear current flowing through the contact interface and the contact interface impedance per unit area Z c,s Sure.

9. The time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects according to claim 1, characterized in that, In step 5), Z c,s f() is a function of the contact interface pressure and temperature, used to calculate the effects of pressure and temperature on electrical contact intermodulation and harmonic effects.

10. The time-domain finite-difference numerical simulation method for electrical contact intermodulation and harmonic effects according to claim 1, characterized in that, Step 8) involves FFT or Prony transformation and post-processing to obtain passive intermodulation and harmonic levels.

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