Irregular cable field line coupling modeling method and system based on current injection probe testing

Abstract

The application relates to a non-regular cable field line coupling modeling method and system based on current injection probe testing, and the method comprises the following steps: configuring a testing system after a vector network analyzer is calibrated, determining a testing frequency band and a testing point, installing a current injection probe at the testing point and connecting the current injection probe with the vector network analyzer, respectively measuring first S parameters between each injection point, measuring second S parameters between the probe located at each injection point and a right port of a measured cable, removing the current injection probe, connecting two ports of the vector network analyzer with two ends of a measured line respectively, and measuring third S parameters; and constructing a field line coupling effect model according to the obtained first S parameters, second S parameters and third S parameters. The application avoids the limitation that traditional analytic / semi-analytic modeling is difficult to apply to complex conditions, avoids huge calculation amount of direct full-wave calculation, converts an applied field into an equivalent voltage source based on a physical principle, and directly establishes the relationship between the applied field and the coupling magnitude of the port through testing.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic field testing, and in particular to a method and system for modeling field-line coupling of irregular cables based on current injection detection testing. Background Technology

[0002] With the widespread application of new technologies such as 5G, the Internet of Things, and artificial intelligence in society, the electromagnetic environment faced by electronic information systems is becoming increasingly complex, leading to a growing number of electromagnetic compatibility (EMC) problems and posing challenges to the design, development, and use of electronic information systems. Failure to properly address the electromagnetic environment effects generated by electronic information systems in such environments can result in serious self-interference and mutual interference problems, affecting the performance of electronic information systems.

[0003] For electronic information systems in the design and development phase, understanding their electromagnetic environment effect boundaries, clearly describing the environments in which they can operate and the performance they can achieve, and defining their usage boundaries are crucial for the survival and operation of electronic information systems in complex electromagnetic environments. Current electromagnetic compatibility (EMC) tests for electronic information systems, such as GJB 151B-2013, primarily use single-signal testing, which fails to comprehensively examine system boundaries and cannot provide a basis for assessing the electromagnetic environment adaptability of electronic information systems in unknown environments. Cables exposed to external electromagnetic fields couple external interference signals, concentrating at the cable ports as coupled voltage and current, potentially affecting the normal operation of electronic systems—this is known as field-line coupling. Field-line coupling is an indispensable part of EMC analysis and evaluation of electronic systems; therefore, cable field-line coupling models are essential models in EMC analysis and calculation software.

[0004] Currently, the field-line coupling models in electromagnetic compatibility (EMC) analysis software are generally analytical models for cables under regular, simple boundary conditions, such as straight cables on an infinitely large ground plane. However, in reality, cable systems are extremely complex, often exhibiting irregular routing and located under complex boundary conditions (such as complex structural cabins, surrounding metal structures, etc.), making analytical modeling difficult in most cases. Modeling in software necessitates forced simplification, applying analytical models for solution, leading to significant analytical errors. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a method and system for modeling field-line coupling of irregular cables based on current injection probe testing, thereby solving the deficiencies of the prior art.

[0006] The objective of this invention is achieved through the following technical solution: a method for modeling field-line coupling in irregular cables based on current injection probe testing, the method comprising:

[0007] Step 1: After calibrating the vector network analyzer, configure the test system and determine the test frequency band and test points. Install current injection probes at the test points and connect them to the vector network analyzer. Measure the first S-parameter between each injection point. Measure the second S-parameter between the probe at each injection point and the right port of the cable under test. Remove the current injection probes. Connect the two ports of the vector network analyzer to both ends of the line under test and measure the third S-parameter.

[0008] Step 2: Construct a field line coupling effect model based on the first S-parameter, second S-parameter, and third S-parameter obtained in Step 1.

[0009] Step one specifically includes the following:

[0010] Step 1: Perform dual-port calibration of the vector network analyzer with both port 1 and port 2 connected to the test coaxial cable;

[0011] Step 2: For the cable under test, connect matching gate boxes to the left and right sides to achieve interconnection between the core wires of the cable and the coaxial test port. Configure the selected core wires to be interconnected with the left and right ends respectively through the left and right gate boxes. The coaxial output port of the left gate box is interconnected with port 2 of the vector network analyzer through the RF coaxial cable. The coaxial output port of the right gate box is connected to a 50-ohm matching load. The coaxial output port of the left gate box is the left port L, and the coaxial output port of the right gate box is the right port R.

[0012] Step 3: Determine the test frequency band according to actual requirements;

[0013] Step 4: Divide the cable into N segments according to the frequency and the complexity of the cable structure, and take the center point of each segment as the injection point, marked as injection point 1 to injection point N;

[0014] Step 5: Install a current injection probe at injection point 1. The injection probe is interconnected with port 1 of the vector network analyzer via an RF coaxial cable.

[0015] Step 6: Measure the full-band two-port S-parameters between the injection port e and the left port L, denoted as S0. 1L ;

[0016] Step 7: Following the injection point numbering sequence, repeat the measurements from Step 6 and Step 7 at each injection point, and record the results as S. 2L To S NL ;

[0017] Step 8: Connect a 50-ohm matching load to the left port L, and connect the vector network analyzer port 2 to the right port R. Repeat steps 5 to 7, and record the two-port S-parameters between the probe and the right port R when the probe is located at each injection point. These parameters are denoted as S0. 1R To S NR ;

[0018] Step 9: Remove the current injection probe. Connect port 1 and port 2 of the vector network analyzer to the left port L and right port R, respectively. Measure and record the S-parameters of the left and right ports, denoted as S. LR .

[0019] Step two specifically includes the following:

[0020] Input the axial field strength of the cable at all injection point locations, from E1 to E... N The lengths of all cable segments are l1 to l N Select the core wire and terminate it at the left port L with impedance Z. L Select the core wire and terminate it at the right port R with impedance Z. R ;

[0021] Combining the three S-parameters, the mathematical representation of the model is obtained as follows:

[0022] Where Z0 is the characteristic impedance of the test equipment, S xx,ij Let xx represent the element in the i-th row and j-th column of the matrix, and let Z represent a number in 1R-NR and 1L-NL. T The transfer impedance for current injection into the probe.

[0023] Step 2 further includes: if there are multiple core wires in the cable that need to be tested and modeled, then the corresponding core wires are selected by using a left and right gated chassis, and steps 2-10 are repeated to form a field-line coupling effect model for different core wires.

[0024] A modeling system for field-line coupling of irregular cables based on current injection probe testing, the system including an S-parameter measurement module and a field-line coupling effect model construction module;

[0025] The S-parameter measurement module is configured to configure the test system after the vector network analyzer is calibrated, and to determine the test frequency band and test points. A current injection probe is installed at the test point and connected to the vector network analyzer to measure the first S-parameter between each injection point. The second S-parameter is measured between the probe at each injection point and the right port of the cable under test. The current injection probe is removed, and the two ports of the vector network analyzer are connected to the two ends of the line under test to measure the third S-parameter.

[0026] The field line coupling effect model building module is configured to build a field line coupling effect model based on the first S-parameter, the second S-parameter, and the third S-parameter obtained by the S-parameter measurement module.

[0027] The parameter measurement module specifically implements the following steps:

[0028] Step 1: Perform dual-port calibration of the vector network analyzer with both port 1 and port 2 connected to the test coaxial cable;

[0029] Step 2: For the cable under test, connect matching gate boxes to the left and right sides to achieve interconnection between the core wires of the cable and the coaxial test port. Configure the selected core wires to be interconnected with the left and right ends respectively through the left and right gate boxes. The coaxial output port of the left gate box is interconnected with port 2 of the vector network analyzer through the RF coaxial cable. The coaxial output port of the right gate box is connected to a 50-ohm matching load. The coaxial output port of the left gate box is the left port L, and the coaxial output port of the right gate box is the right port R.

[0030] Step 3: Determine the test frequency band according to actual requirements;

[0031] Step 4: Divide the cable into N segments according to the frequency and the complexity of the cable structure, and take the center point of each segment as the injection point, marked as injection point 1 to injection point N;

[0032] Step 5: Install a current injection probe at injection point 1. The injection probe is interconnected with port 1 of the vector network analyzer via an RF coaxial cable.

[0033] Step 6: Measure the full-band two-port S-parameters between the injection port e and the left port L, denoted as S0. 1L ;

[0034] Step 7: Following the injection point numbering sequence, repeat the measurements from Step 6 and Step 7 at each injection point, and record the results as S. 2L To S NL ;

[0035] Step 8: Connect a 50-ohm matching load to the left port L, and connect the vector network analyzer port 2 to the right port R. Repeat steps 5 to 7, and record the two-port S-parameters between the probe and the right port R when the probe is located at each injection point. These parameters are denoted as S0. 1R To S NR ;

[0036] Step 9: Remove the current injection probe. Connect port 1 and port 2 of the vector network analyzer to the left port L and right port R, respectively. Measure and record the S-parameters of the left and right ports, denoted as S. LR .

[0037] The field line coupling effect model construction module specifically implements the following steps:

[0038] Input the axial field strength of the cable at all injection point locations, from E1 to E... N The lengths of all cable segments are l1 to l N Select the core wire and terminate it at the left port L with impedance Z. L Select the core wire and terminate it at the right port R with impedance Z. R ;

[0039] Combining the three S-parameters, the mathematical representation of the model is obtained as follows:

[0040] Where Z0 is the characteristic impedance of the test equipment, S xx,ij Let xx represent the element in the i-th row and j-th column of the matrix, and let Z represent a number in 1R-NR and 1L-NL. T The transfer impedance for current injection into the probe.

[0041] The field-line coupling effect model construction module further includes: if there are multiple core wires in the cable that need to be tested and modeled, the corresponding core wires are selected by using a left and right gate chassis, and steps 2-10 are repeated to form a field-line coupling effect model for different core wires.

[0042] This invention has the following advantages: a method and system for modeling field-line coupling of irregular cables based on current injection probe testing, which avoids the limitations of traditional analytical / semi-analytical modeling in applying complex conditions, avoids the huge computational load of direct full-wave calculation, converts the applied field into an equivalent voltage source based on physical principles, and directly establishes the relationship between the applied field and the port coupling value through testing. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the test configuration for the method of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is not intended to limit the scope of protection of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The present invention will be further described below with reference to the accompanying drawings.

[0045] This invention specifically relates to a method for modeling the field-line coupling of irregular cables based on current injection probe testing. It utilizes the fundamental principle that both the current injection probe and the applied electromagnetic field can be equivalent to a series voltage source on the line. By using current injection probe coupling testing, the scattering parameter matrix of each injection port and cable terminal port on the cable is measured in advance. The mathematical relationship between the equivalent voltage source at the injection point and the coupling current at the cable port is obtained, and a characterization model is established. This enables the ability to predict the coupling current of the cable under any applied field conditions.

[0046] like Figure 1 As shown, the test object is the cable under test, and the test equipment includes: a two-port vector network analyzer (VNA), a current injection probe, a gating chassis matched to the cable under test, an RF coaxial cable and adapter, and a 50-ohm matching load; the specific test and modeling process is as follows:

[0047] Step 1, Vector Grid Calibration: Perform dual-port calibration with both port 1 and port 2 connected to the test coaxial line.

[0048] Step 2, Configure the test system: According to Figure 1 As shown, for the cable under test, matching gate boxes are connected to the left and right sides to realize the interconnection between each core wire of the cable and the coaxial test port; through the left and right gate boxes, the left and right ends of the selected core wires are configured to be interconnected with the left and right ports respectively; the coaxial output port (left port) of the left gate box is interconnected with the vector network port 2 through the RF coaxial line, and the coaxial output port (right port) of the right gate box is connected to a 50-ohm matching load.

[0049] Step 3: Determine the test frequency band: Usually, 1MHz-400MHz is selected, but it can also be defined by the user.

[0050] Step 4: Determine the test points; Divide the cable into N segments according to the frequency and the complexity of the cable structure, and take the center point of each segment as the injection point (marked by the black dot in the figure), and mark them as injection point 1 to injection point N; The cable segments should be as equal in length as possible, and the interval between injection points should not be less than 1 / 4 of the wavelength corresponding to the highest frequency.

[0051] Step 5: Install a current injection probe at injection point 1. The injection probe is interconnected with vector network port 1 via an RF coaxial cable.

[0052] Step 6: Measure the full-band two-port scattering parameters (S-parameters) between the injection port e and the left port L, denoted as S. 1L .

[0053] Step 7: Following the injection point numbering sequence, repeat the measurements from Steps 6-7 at each injection point, and record them as S. 2L To S NL .

[0054] Step 8: Connect a 50-ohm matching load to the left port L, and connect the vector network interface gauging port 2 to the right port R. Repeat steps 5-7, and record the dual-port S-parameters between the probe and the right port R when the probe is located at each injection point. These parameters are denoted as S0. 1R To S NR .

[0055] Step 9: Remove the current injection probe. Connect vector network interface card (VNIC) ports 1 and 2 to the left port L and right port R, respectively. Measure and record the S-parameters of the left and right ports, denoted as S. LR.

[0056] Step 10: Based on the above data, form a field line coupling effect model.

[0057] Step 11: If there are multiple core wires in the cable, test modeling is required. Use the left and right gate chassis to select and connect the corresponding core wires, and repeat steps 2-10 above to form a model for different core wires.

[0058] Furthermore, after obtaining the parameter data according to the testing procedures, the field-line coupling effect can be modeled using the following method. The specific model representation is as follows:

[0059] Model input parameters: axial electric field strength of the cable at all injection points, from E1 to E... N The lengths of all cable segments are l1 to l N Select the core wire and terminate it at the left port with impedance Z. L Select the core wire and terminate it with impedance Z at the right end. R ;

[0060] Model output parameters: Coupling current I at the left port L The coupling current I at the right port R ;

[0061] Mathematical representation of the model:

[0062]

[0063] Where Z0 is the characteristic impedance of the test equipment (50 ohms); S xx,ij Let xx represent the element in the i-th row and j-th column of the matrix, and let xx represent a number in 1R-NR and 1L-NL; Z T The transfer impedance of the current injection probe represents the equivalent voltage source coupled on the cable per unit injected current value. It can be obtained from the overcurrent probe product manual or calibration.

[0064] Furthermore, the constructed model is primarily used for analyzing field-line coupling effects in electromagnetic calculation software. Through calculations such as full-wave simulation, the software can obtain the field distribution at and near the cable's location. Under these conditions, the software can call upon this model to calculate the coupling current at the cable terminal, thereby obtaining coupling voltage, power, etc., and realizing the analysis of field-line coupling effects.

[0065] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and improvements, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for modeling field-line coupling in irregular cables based on current injection probe testing, characterized in that: The method includes: Step 1: After calibrating the vector network analyzer, configure the test system and determine the test frequency band and test points. Install current injection probes at the test points and connect them to the vector network analyzer. Measure the first S-parameter between each injection point. Measure the second S-parameter between the probe at each injection point and the right port of the cable under test. Remove the current injection probes. Connect the two ports of the vector network analyzer to both ends of the line under test and measure the third S-parameter. Step 2: Construct a field-line coupling effect model based on the first S-parameter, second S-parameter, and third S-parameter obtained in Step 1; Step one specifically includes the following: Step 1: Perform dual-port calibration of the vector network analyzer with both port 1 and port 2 connected to the test coaxial cable; Step 2: For the cable under test, connect matching gate boxes to the left and right sides to achieve interconnection between the core wires of the cable and the coaxial test port. Configure the selected core wires to be interconnected with the left and right ends respectively through the left and right gate boxes. The coaxial output port of the left gate box is interconnected with port 2 of the vector network analyzer through the RF coaxial cable. The coaxial output port of the right gate box is connected to a 50-ohm matching load. The coaxial output port of the left gate box is the left port L, and the coaxial output port of the right gate box is the right port R. Step 3: Determine the test frequency band according to actual requirements; Step 4: Divide the cable into N segments according to the frequency and the complexity of the cable structure, and take the center point of each segment as the injection point, marked as injection point 1 to injection point N; Step 5: Install a current injection probe at injection point 1. The injection probe is interconnected with port 1 of the vector network analyzer via an RF coaxial cable. Step 6: Measure the full-band two-port S-parameters between the injection port e and the left port L, denoted as S0. 1L ; Step 7: Following the injection point numbering sequence, repeat the measurements from Step 6 and Step 7 at each injection point, and record the results as S. 2L To S NL ; Step 8: Connect a 50-ohm matching load to the left port L, and connect the vector network analyzer port 2 to the right port R. Repeat steps 5 to 7, and record the two-port S-parameters between the probe and the right port R when the probe is located at each injection point. These parameters are denoted as S0. 1R To S NR ; Step 9: Remove the current injection probe. Connect port 1 and port 2 of the vector network analyzer to the left port L and right port R, respectively. Measure and record the S-parameters of the left and right ports, denoted as S. LR； Step 10: Based on the above data, form a field line coupling effect model.

2. The method for modeling irregular cable field-line coupling based on current injection probe testing according to claim 1, characterized in that: Step two specifically includes the following: Input the axial field strength of the cable at all injection point locations, from E1 to E... N The lengths of all cable segments are l1 to l N Select the core wire and terminate it at the left port L with impedance Z. L Select the core wire and terminate it at the right port R with impedance Z. R ; Combining the three S-parameters, the mathematical representation of the model is obtained as follows: Where Z0 is the characteristic impedance of the test equipment, S xx,ij Let xx represent the element in the i-th row and j-th column of the matrix, and let Z represent a number in 1R-NR and 1L-NL. T The transfer impedance for current injection into the probe.

3. The method for modeling irregular cable field-line coupling based on current injection probe testing according to claim 1, characterized in that: Step 2 further includes: if there are multiple core wires in the cable that need to be tested and modeled, then the corresponding core wires are selected by using a left and right gated chassis, and steps 2-10 are repeated to form a field-line coupling effect model for different core wires.

4. A modeling system for field-line coupling of irregular cables based on current injection probe testing, characterized in that: The system includes an S-parameter measurement module and a field-line coupling effect model construction module; The S-parameter measurement module is configured to configure the test system after the vector network analyzer is calibrated, and to determine the test frequency band and test points. A current injection probe is installed at the test point and connected to the vector network analyzer to measure the first S-parameter between each injection point. The second S-parameter is measured between the probe at each injection point and the right port of the cable under test. The current injection probe is removed, and the two ports of the vector network analyzer are connected to the two ends of the line under test to measure the third S-parameter. The field line coupling effect model building module is configured to build a field line coupling effect model based on the first S-parameter, the second S-parameter, and the third S-parameter obtained by the S-parameter measurement module. The parameter measurement module specifically implements the following steps: Step 1: Perform dual-port calibration of the vector network analyzer with both port 1 and port 2 connected to the test coaxial cable; Step 2: For the cable under test, connect matching gate boxes to the left and right sides to achieve interconnection between the core wires of the cable and the coaxial test port. Configure the selected core wires to be interconnected with the left and right ends respectively through the left and right gate boxes. The coaxial output port of the left gate box is interconnected with port 2 of the vector network analyzer through the RF coaxial cable. The coaxial output port of the right gate box is connected to a 50-ohm matching load. The coaxial output port of the left gate box is the left port L, and the coaxial output port of the right gate box is the right port R. Step 3: Determine the test frequency band according to actual requirements; Step 4: Divide the cable into N segments according to the frequency and the complexity of the cable structure, and take the center point of each segment as the injection point, marked as injection point 1 to injection point N; Step 5: Install a current injection probe at injection point 1. The injection probe is interconnected with port 1 of the vector network analyzer via an RF coaxial cable. Step 6: Measure the full-band two-port S-parameters between the injection port e and the left port L, denoted as S0. 1L ; Step 7: Following the injection point numbering sequence, repeat the measurements from Step 6 and Step 7 at each injection point, and record the results as S. 2L To S NL ; Step 8: Connect a 50-ohm matching load to the left port L, and connect the vector network analyzer port 2 to the right port R. Repeat steps 5 to 7, and record the two-port S-parameters between the probe and the right port R when the probe is located at each injection point. These parameters are denoted as S0. 1R To S NR ; Step 9: Remove the current injection probe. Connect port 1 and port 2 of the vector network analyzer to the left port L and right port R, respectively. Measure and record the S-parameters of the left and right ports, denoted as S. LR； Step 10: Based on the above data, form a field line coupling effect model.

5. The irregular cable field-line coupling modeling system based on current injection probe testing according to claim 4, characterized in that: The field line coupling effect model construction module specifically implements the following steps: Input the axial field strength of the cable at all injection point locations, from E1 to E... N The lengths of all cable segments are l1 to l N Select the core wire and terminate it at the left port L with impedance Z. L Select the core wire and terminate it at the right port R with impedance Z. R ; Combining the three S-parameters, the mathematical representation of the model is obtained as follows: Where Z0 is the characteristic impedance of the test equipment, S xx,ij Let xx represent the element in the i-th row and j-th column of the matrix, and let Z represent a number in 1R-NR and 1L-NL. T The transfer impedance for current injection into the probe.

6. The irregular cable field-line coupling modeling system based on current injection probe testing according to claim 4, characterized in that: The field-line coupling effect model construction module further includes: if there are multiple core wires in the cable that need to be tested and modeled, the corresponding core wires are selected by using a left and right gate chassis, and steps 2-10 are repeated to form a field-line coupling effect model for different core wires.

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