A time-domain shielding effectiveness measuring device and method for electromagnetic shielding material

Abstract

The present application relates to electromagnetic pulse shielding effectiveness measuring device and method, specifically to a kind of electromagnetic shielding material's time-domain shielding effectiveness measuring device and method, solve the technical problem that the evaluation index of electromagnetic shielding material shielding effectiveness is not comprehensive, measurement result is not accurate.The present application utilizes power divider to divide electromagnetic pulse signal into test signal and shielding signal, the transmission signal and the reflected signal that shielding signal is monitored after the transmission signal, shielding signal through the electromagnetic shielding material to be measured by oscilloscope, gives the shielding effectiveness characterization result under the peak change and pulse energy change based on transmission signal, and can obtain the reflection loss of electromagnetic shielding material to be measured to electromagnetic pulse signal and other detailed information, and the frequency-domain shielding effectiveness curve of electromagnetic shielding material to be measured can be accurately transformed to obtain, the measurement result obtained is more comprehensive, accurate, and need not to carry out frequency-domain shielding effectiveness measurement again.

Description

Technical Field

[0001] This invention relates to an electromagnetic pulse shielding effectiveness measurement device and method, specifically to a time-domain shielding effectiveness measurement device and method for electromagnetic shielding materials. Background Technology

[0002] Electromagnetic shielding, as an effective means of reducing electromagnetic interference, has wide applications in the field of electromagnetic protection. Faced with the increasingly serious threat of electromagnetic pulses, objectively evaluating the electromagnetic pulse protection performance of materials has become a widespread concern in the industry. The attenuation of electromagnetic wave signals by electromagnetic shielding materials mainly manifests in two categories: reflection loss and absorption loss. Therefore, a reasonable and accurate assessment of the shielding performance of electromagnetic protection materials is of great significance and value.

[0003] Currently, domestic and international standards and specifications for measuring the shielding effectiveness of materials mainly specify test methods for frequency domain shielding effectiveness using amplitude-frequency curves. However, test methods for the shielding effectiveness of electromagnetic shielding materials under time-domain electromagnetic pulse signals are rare. Faced with the increasingly serious threat of electromagnetic pulses, objectively evaluating the protective performance of electromagnetic shielding materials against electromagnetic pulse signals is becoming increasingly urgent.

[0004] Chinese patent CN 103926426A discloses a broadband continuous conductor coaxial cable fixture for testing the shielding effectiveness of materials. The design of the broadband continuous conductor coaxial cable provides a time-domain testing system for the shielding effectiveness of materials. However, this testing system cannot monitor electromagnetic pulse test signals. The actual pulse source output has a certain degree of dispersion, resulting in inaccurate measurement results, poor test repeatability, and incomplete evaluation indicators for the shielding performance of materials. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems of incomplete evaluation indicators and inaccurate measurement results of the time-domain electromagnetic pulse shielding effectiveness of electromagnetic shielding materials, and to provide a device and method for measuring the time-domain shielding effectiveness of electromagnetic shielding materials.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A time-domain shielding effectiveness measurement device for electromagnetic shielding materials, characterized in that it includes a high-voltage pulse source 1, a power divider 2, an attenuator 3, a coaxial flange 4, and an oscilloscope 5 connected by a coaxial cable;

[0008] The output terminal of the high-voltage pulse source 1 is connected to the input terminal of the power divider 2 to provide electromagnetic pulse signals to the power divider 2;

[0009] The two output terminals of the power divider 2 are respectively connected to the input terminal of the attenuator 3 and one end of the coaxial flange 4, splitting the electromagnetic pulse signal into two paths: the test signal enters the attenuator 3, and the shielding signal enters the coaxial flange 4; the output terminal of the attenuator 3 and the other end of the coaxial flange 4 are connected to the input terminal of the oscilloscope 5.

[0010] The coaxial flange 4 is used to clamp the electromagnetic shielding material 6 to be tested; the attenuator 3 is used to receive the test signal and the reflected signal of the electromagnetic shielding material 6 to the shielding signal, and send them to the oscilloscope 5.

[0011] The oscilloscope 5 is used to receive and monitor the transmitted signal waveform of the shielding signal through the electromagnetic shielding material 6 under test, the test signal waveform, and the reflected signal waveform of the shielding signal by the electromagnetic shielding material 6 under test.

[0012] Furthermore, the power divider 2 is connected to the coaxial flange 4 via a coaxial cable, and the length of the coaxial cable divided by the electromagnetic wave propagation speed is greater than the time width of the electromagnetic pulse signal output by the high-voltage pulse source 1.

[0013] Furthermore, the internal resistance of the high-voltage pulse source 1 and the characteristic impedance of the coaxial flange 4 are matched with the characteristic impedance of the coaxial cable.

[0014] Furthermore, the attenuation value of the attenuator 3 is 40dB-60dB.

[0015] A method for measuring the time-domain shielding effectiveness of an electromagnetic shielding material, based on the aforementioned device for measuring the time-domain shielding effectiveness of electromagnetic shielding materials, is characterized by comprising the following steps:

[0016] Step 1: Place the electromagnetic shielding material 6 to be tested inside the coaxial flange 4;

[0017] Step 2: Start the high voltage pulse source 1 and power divider 2. The oscilloscope 5 collects and records the transmitted signal waveform of the shielding signal through the electromagnetic shielding material 6 under test, the test signal waveform after the attenuator 3, and the reflected signal waveform of the shielding signal by the electromagnetic shielding material 6 under test.

[0018] Step 3: Based on the attenuation factor of attenuator 3, reconstruct the test signal waveform obtained in step 2 after passing through attenuator 3 and the reflected signal waveform of the electromagnetic shielding material 6 to the shielding signal, to obtain the actual test signal waveform and the actual reflected signal waveform of the electromagnetic shielding material 6 to the shielding signal.

[0019] Step 4: Read the peak amplitude U of the actual test signal waveform obtained in Step 3. 测试 The peak amplitude U of the transmitted signal waveform obtained in step 2 透射 Calculate the peak shielding effectiveness SE of the electromagnetic shielding material 6 to be tested.峰值 ;

[0020] Step 5, energy numerical integration is performed on the actual test signal waveform obtained in step 3 and the transmission signal waveform obtained in step 2, to obtain total energy Q 测试 and Q 透射 respectively, and the energy shielding effectiveness SE 能量 of the electromagnetic shielding material 6 to be tested is calculated.

[0021] Step 6, the peak amplitude U 反射 of the actual reflection signal waveform obtained in step 3 is read, and energy numerical integration is performed on the actual reflection signal waveform to obtain total energy Q 反射 of the reflection signal, and the peak shielding effectiveness SE 峰值反射 and the energy shielding effectiveness SE 能量反射 caused by the reflection loss of the electromagnetic shielding material 6 to be tested are calculated respectively.

[0022] Further, in step 2, the outputs of the two outputs of the power divider 2 are equal.

[0023] Further, in step 4, the peak shielding effectiveness SE 峰值 of the electromagnetic shielding material 6 to be tested is calculated by the following formula:

[0024] SE 峰值 = -20log(U 透射 / U 测试 ).

[0025] Further, in step 5, the energy shielding effectiveness SE 能量 of the electromagnetic shielding material 6 to be tested is calculated by the following formula:

[0026] SE 能量 = -10log(Q 透射 / Q 测试 ).

[0027] Further, in step 6, the peak shielding effectiveness SE 峰值反射 and the energy shielding effectiveness SE 能量反射 caused by the reflection loss of the electromagnetic shielding material 6 to be tested are calculated respectively by the following formula:

[0028]

[0029]

[0030] Further, step 7 is further included:

[0031] Step 7, a frequency domain shielding effectiveness curve is drawn

[0032] Step 7.1 Fourier transforms the actual test signal waveform obtained in step 3 and the transmission signal waveform obtained in step 2 respectively to obtain the corresponding frequency domain waveforms;

[0033] Step 7.2 reads the peak amplitude U of the actual test signal at each frequency point 测试 and the peak amplitude U of the transmission signal waveform 透射 The peak shielding effectiveness at each frequency point is calculated by the following formula:

[0034] SE 峰值 = -20log(U 透射 / U 测试 );

[0035] Step 7.3 draws the frequency domain shielding effectiveness curve of the electromagnetic shielding material 6 to be measured according to the calculation results, and obtains the frequency domain shielding effectiveness curve converted from the time domain shielding effectiveness measurement.

[0036] Compared with the prior art, the present application has the beneficial technical effects as follows:

[0037] 1. The time domain shielding effectiveness measuring device for electromagnetic shielding material provided by the present application uses a power divider to divide the electromagnetic pulse signal into a test signal and a shielding signal, uses the test signal as a reference for the transmission signal of the shielding signal after passing through the electromagnetic shielding material and the reflection signal reflected by the electromagnetic shielding material to be measured, so that the measured results are more accurate; at the same time, the oscilloscope is used to monitor the transmission signal of the test signal and the shielding signal after passing through the electromagnetic shielding material to be measured and the reflection signal reflected by the electromagnetic shielding material to be measured, so that the peak shielding effectiveness and the energy shielding effectiveness of the electromagnetic shielding material to be measured on the electromagnetic pulse can be obtained, and detailed information such as the reflection loss of the electromagnetic shielding material to be measured on the electromagnetic pulse can be given, the measured result information obtained is comprehensive, and it has great significance for the development and improvement of the electromagnetic shielding material and the evaluation of the protection performance;

[0038] 2. In the time domain shielding effectiveness measuring device for electromagnetic shielding material provided by the present application, the length of the coaxial cable connected between the power divider and the coaxial flange is greater than the time width of the output signal of the high-voltage pulse source divided by the electromagnetic wave propagation speed, so that the test signal waveform and the reflection signal waveform can be effectively recognized by the oscilloscope, and the measurement accuracy of the measuring device is improved;

[0039] 3. In the time domain shielding effectiveness measuring device for electromagnetic shielding material provided by the present application, the source resistance of the high-voltage pulse source, the characteristic impedance of the coaxial flange and the characteristic impedance of the coaxial cable are matched, so that the impedance matching of the measuring device is ensured, and the measurement accuracy of the measuring device is further improved;

[0040] 4. The time-domain shielding effectiveness measurement method for electromagnetic shielding materials provided by the present invention gives the shielding effectiveness characterization results based on the peak value change and pulse energy change of the electromagnetic pulse signal, and can obtain detailed information such as the reflection loss of the electromagnetic shielding material under test to the electromagnetic pulse signal, and can accurately transform to obtain the frequency domain shielding effectiveness curve of the electromagnetic shielding material under test. The obtained measurement results are more comprehensive and accurate, and there is no need to perform frequency domain shielding effectiveness measurement.

[0041] 5. In the time-domain shielding effectiveness measurement device for electromagnetic shielding materials provided by the present invention, the outputs of the two output terminals of the power divider are equal, so that the electromagnetic pulse signal is divided into two proportionally, making the calculation of shielding effectiveness simpler. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of an embodiment of the time-domain shielding effectiveness measurement device for electromagnetic shielding materials of the present invention;

[0043] Figure 2 This is a schematic diagram of the installation of the coaxial flange and the electromagnetic shielding material under test in an embodiment of the time-domain shielding effectiveness measurement device for electromagnetic shielding materials of the present invention.

[0044] Figure 3 The waveform diagram after restoration is obtained by an oscilloscope in an embodiment of the time-domain shielding effectiveness measurement device for the electromagnetic shielding material of the present invention.

[0045] Figure 4 This is a comparison chart of the frequency domain shielding effectiveness curve obtained by transforming the time domain shielding effectiveness measurement method provided by the present invention and the frequency domain shielding effectiveness curve obtained by the frequency domain shielding effectiveness measurement method.

[0046] The annotations in the attached figures are explained as follows:

[0047] 1-High voltage pulse source, 2-Power divider, 3-Attenuator, 4-Coaxial flange, 5-Oscilloscope, 6-Electromagnetic shielding material under test. Detailed Implementation

[0048] To make the objectives, advantages and features of the present invention clearer, the following describes in further detail, with reference to the accompanying drawings and specific embodiments, a time-domain shielding effectiveness measurement device and method for electromagnetic shielding materials proposed in the present invention.

[0049] like Figure 1 As shown, a time-domain shielding effectiveness measurement device for electromagnetic shielding materials includes a high-voltage pulse source 1, a power divider 2, an attenuator 3, a coaxial flange 4, and an oscilloscope 5 connected by a coaxial cable.

[0050] The output end of the high-voltage pulse source 1 is connected with the input end of the power divider 2 to provide the electromagnetic pulse signal for the power divider 2. In the embodiment, the high-voltage pulse source 1 adopts a single-polarity pulse signal with a bottom width of 3 ns. The two output ends of the power divider 2 are respectively connected with the input ends of the attenuator 3 and the coaxial flange 4 to divide the electromagnetic pulse signal into two paths, the test signal enters the attenuator 3, and the shielding signal enters the coaxial flange 4. The power divider 2 has three ports, any one of which can be selected as the input end, and the other two ports are output ends, and the outputs are equal. The output ends of the attenuator 3 and the coaxial flange 4 are connected with the input end of the oscilloscope 5. In the embodiment, the attenuation value of the attenuator 3 is 60 dB.

[0051] In order to ensure the impedance matching of the system, it is necessary to ensure that the source internal resistance of the high-voltage pulse source 1, the characteristic impedance of the coaxial flange 4 and the characteristic impedance of the coaxial cable are matched. In the embodiment, the source internal resistance of the high-voltage pulse source 1, the characteristic impedance of the coaxial flange 4 and the characteristic impedance of the coaxial cable are all 50 ohms.

[0052] The length of the coaxial cable connected between the power divider 2 and the coaxial flange 4 divided by the electromagnetic wave propagation speed should be greater than the time width of the output signal of the high-voltage pulse source 1. This is because the electromagnetic pulse signal will form a reflection when encountering the to-be-tested electromagnetic shielding material 6 in the coaxial flange 4, and a reflected signal is generated. Therefore, it is necessary to ensure that the coaxial cable is long enough to ensure that the reflected signal enters the oscilloscope 5 through the attenuator 3 and is time-shifted from the original test signal waveform, so as to ensure that the test signal waveform and the reflected signal waveform can be effectively recognized by the oscilloscope 5. In the embodiment, the length of the coaxial cable connected between the power divider 2 and the coaxial flange 4 is 3 meters, which is divided by the electromagnetic wave propagation speed 3.0×10 8 m / s, and the obtained value is 10 ns, which is greater than the pulse signal width 3 ns.

[0053] As shown in Figure 2 , the coaxial flange 4 is used to clamp the to-be-tested electromagnetic shielding material 6. The attenuator 3 is used to receive the test signal and the reflected signal of the shielding signal of the to-be-tested electromagnetic shielding material 6, and send them to the oscilloscope 5. The oscilloscope 5 is used to receive and monitor the transmission waveform of the shielding signal transmitted through the to-be-tested electromagnetic shielding material 6, the test signal waveform and the reflected signal waveform of the shielding signal of the to-be-tested electromagnetic shielding material 6.

[0054] The high-voltage pulse source 1 generates an electromagnetic pulse signal, which is equally divided by the power divider 2 into a shielding signal and a test signal. The shielding signal is transmitted to the coaxial flange 4 holding the electromagnetic shielding material 6 to be measured. Part of the shielding signal is transmitted through the electromagnetic shielding material 6 to be measured, and the other part is reflected by the electromagnetic shielding material 6 to be measured. The reflected signal is received by the attenuator 3. The test signal is transmitted to the attenuator 3. The attenuator 3 processes the received test signal and the reflected signal of the shielding signal by the electromagnetic shielding material 6 to be measured, and sends the processed signals to the oscilloscope.

[0055] The test signal and the shielding signal transmitted through the electromagnetic shielding material 6 to be measured can be used to calculate the peak shielding effectiveness and the energy shielding effectiveness of the electromagnetic shielding material 6 to be measured. Further, the peak reflection loss and the energy reflection loss of the electromagnetic shielding material 6 to be measured can be obtained according to the monitored reflected signal of the shielding signal by the electromagnetic shielding material 6 to be measured. The shielding effectiveness curve of the electromagnetic shielding material 6 to be measured in the frequency domain can also be obtained by performing Fourier transform on the test signal and the shielding signal transmitted through the electromagnetic shielding material 6 to be measured.

[0056] The embodiment also provides a time-domain shielding effectiveness measurement method of an electromagnetic shielding material. Based on the above-described time-domain shielding effectiveness measurement device of an electromagnetic shielding material, the output of the two output ends of the power divider 2 is equal, the output signal of the high-voltage pulse source 1 is a unipolar pulse signal with a bottom width of 3 ns, the attenuation value of the attenuator 3 is 60 dB, the source resistance of the high-voltage pulse source 1, the characteristic impedance of the coaxial flange 4, and the characteristic impedance of the coaxial cable are all 50 ohms, and the length of the coaxial cable connected between the power divider 2 and the coaxial flange 4 is 3 meters. The time-domain shielding effectiveness measurement is performed under the above conditions, and includes the following steps.

[0057] Step 1, placing the electromagnetic shielding material 6 to be measured in the coaxial flange 4.

[0058] Step 2, starting the high-voltage pulse source 1 and the power divider 2, and the oscilloscope 5 collects and records the transmitted signal waveform of the shielding signal transmitted through the electromagnetic shielding material 6 to be measured, the test signal waveform after the attenuator 3, and the reflected signal waveform of the shielding signal by the electromagnetic shielding material 6 to be measured.

[0059] Step 3, restoring the test signal waveform after the attenuator 3 and the reflected signal waveform of the shielding signal by the electromagnetic shielding material 6 to be measured obtained in step 2 according to the attenuation multiple of the attenuator 3, to obtain the actual test signal waveform and the actual reflected signal waveform of the shielding signal by the electromagnetic shielding material 6 to be measured. As shown in FIG. 4, the restored test signal waveform and the reflected signal waveform of the shielding signal by the electromagnetic shielding material 6 to be measured, and the transmitted signal waveform of the shielding signal transmitted through the electromagnetic shielding material 6 to be measured measured by the oscilloscope 5. Figure 3 ​

[0060] Step 4, read the peak amplitude U of the actual test signal waveform obtained in Step 3 测试 and the peak amplitude U of the transmission signal waveform obtained in Step 2 透射 , calculate the peak shielding effectiveness SE of the electromagnetic shielding material 6 to be tested by the following formula 峰值 :

[0061] SE 峰值 = -20 log (U 透射 / U 测试 ).

[0062] Step 5, perform energy numerical integration on the actual test signal waveform obtained in Step 3 and the transmission signal waveform obtained in Step 2, respectively, to obtain their total energies Q 测试 and Q 透射 , calculate the energy shielding effectiveness SE of the electromagnetic shielding material 6 to be tested by the following formula 能量 :

[0063] SE 能量 = -10 log (Q 透射 / Q 测试 ).

[0064] Step 6, read the peak amplitude U of the actual reflection signal waveform obtained in Step 3 反射 , and perform energy numerical integration on the actual reflection signal waveform to obtain the total energy Q of the reflection signal 反射 , calculate the peak shielding effectiveness SE 峰值反射 and the energy shielding effectiveness SE 能量反射 caused by the reflection loss of the electromagnetic shielding material 6 to be tested by the following formula respectively

[0065]

[0066]

[0067] Step 7, draw the frequency domain shielding effectiveness curve

[0068] Step 7.1, perform Fourier transform on the actual test signal waveform obtained in Step 3 and the transmission signal waveform obtained in Step 2 respectively to obtain their corresponding frequency domain waveforms;

[0069] Step 7.2, read the peak amplitude U of the actual test signal at each frequency point 测试 and the peak amplitude U of the transmission signal waveform 透射 , calculate the peak shielding effectiveness at each frequency point by the following formula

[0070] SE 峰值 = -20 log (U 透射 / U测试

[0071] Step 7.3. According to the calculation result, a frequency domain shielding effectiveness curve of the electromagnetic shielding material 6 to be measured is drawn, and a frequency domain shielding effectiveness curve converted from the time domain shielding effectiveness measurement is obtained.

[0072] At the same time, the frequency domain shielding effectiveness measurement is carried out according to the flange coaxial device method specified in GJB 8820-2015, and a frequency domain shielding effectiveness curve is obtained.

[0073] As shown in Figure 4 The waveform conversion measured by the method provided by the present application, the calculated frequency domain shielding effectiveness curve and the frequency domain shielding effectiveness curve measured by the frequency domain shielding effectiveness measurement method specified in the national standard have good consistency, which further verifies the accuracy of the time domain shielding effectiveness measurement method provided by the present application.

[0074] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.​

Claims

1. A method for measuring the time-domain shielding effectiveness of an electromagnetic shielding material, wherein the time-domain shielding effectiveness measuring device includes a high-voltage pulse source (1), a power divider (2), an attenuator (3), a coaxial flange (4), and an oscilloscope (5) connected by a coaxial cable; The output terminal of the high-voltage pulse source (1) is connected to the input terminal of the power divider (2) to provide electromagnetic pulse signals to the power divider (2); The two output terminals of the power divider (2) are respectively connected to the input terminal of the attenuator (3) and one end of the coaxial flange (4), splitting the electromagnetic pulse signal into two paths. The test signal enters the attenuator (3), and the shielding signal enters the coaxial flange (4). The output terminal of the attenuator (3) and the other end of the coaxial flange (4) are respectively connected to the input terminal of the oscilloscope (5). The coaxial flange (4) is used to clamp the electromagnetic shielding material (6) to be tested; the attenuator (3) is used to receive the test signal and the reflected signal of the electromagnetic shielding material (6) to the shielding signal, and send it to the oscilloscope (5); The oscilloscope (5) is used to receive and monitor the transmitted signal waveform, test signal waveform, and reflected signal waveform of the electromagnetic shielding material (6) to the shielding signal. Its features are, Includes the following steps: Step 1: Place the electromagnetic shielding material (6) to be tested inside the coaxial flange (4); Step 2: Start the high voltage pulse source (1) and power divider (2), and use the oscilloscope (5) to collect and record the transmitted signal waveform of the shielding signal through the electromagnetic shielding material (6) under test, the test signal waveform after passing through the attenuator (3), and the reflected signal waveform of the electromagnetic shielding material (6) under test to the shielding signal. Step 3: Based on the attenuation factor of the attenuator (3), restore the test signal waveform obtained in step 2 after passing through the attenuator (3) and the reflected signal waveform of the electromagnetic shielding material (6) to the shielding signal, and obtain the actual test signal waveform and the actual reflected signal waveform of the electromagnetic shielding material (6) to the shielding signal. Step 4: Read the peak amplitude U of the actual test signal waveform obtained in Step 3. 测试 The peak amplitude U of the transmitted signal waveform obtained in step 2 透射 Calculate the peak shielding effectiveness SE of the electromagnetic shielding material (6) under test. 峰值 ; Step 5: Perform energy numerical integration on the actual test signal waveform obtained in Step 3 and the transmission signal waveform obtained in Step 2 to obtain their total energy Q. 测试 and Q 透射 Calculate the energy shielding effectiveness (SE) of the electromagnetic shielding material (6) under test. 能量 ; Step 6: Read the peak amplitude U of the actual reflected signal waveform obtained in Step 3. 反射 The total energy Q of the reflected signal is obtained by numerically integrating the energy of the actual reflected signal waveform. 反射 The peak shielding effectiveness SE caused by the reflection loss of the electromagnetic shielding material (6) under test is calculated using the following formulas. 峰值反射 and energy shielding effectiveness SE 能量反射 :

2. The method for measuring the time-domain shielding effectiveness of electromagnetic shielding materials according to claim 1, characterized in that: The power divider (2) is connected to the coaxial flange (4) by a coaxial cable. The length of the coaxial cable divided by the electromagnetic wave propagation speed is greater than the time width of the electromagnetic pulse signal output by the high voltage pulse source (1).

3. The method for measuring the time-domain shielding effectiveness of electromagnetic shielding materials according to claim 2, characterized in that: The source resistance of the high-voltage pulse source (1) and the characteristic impedance of the coaxial flange (4) are matched with the characteristic impedance of the coaxial cable.

4. The method for measuring the time-domain shielding effectiveness of electromagnetic shielding materials according to claim 3, characterized in that: The attenuation value of the attenuator (3) is 40dB-60dB.

5. The method for measuring the time-domain shielding effectiveness of electromagnetic shielding materials according to any one of claims 1-4, characterized in that: In step 2, the outputs of the two output terminals of the power divider (2) are equal.

6. The method for measuring the time-domain shielding effectiveness of electromagnetic shielding materials according to claim 5, characterized in that: In step 4, the peak shielding effectiveness SE of the electromagnetic shielding material (6) under test is calculated using the following formula. 峰值 : SE 峰值 =-20log(U 透射 / IN 测试 )。 7. The method for measuring the time-domain shielding effectiveness of electromagnetic shielding materials according to claim 6, characterized in that: In step 5, the energy shielding effectiveness SE of the electromagnetic shielding material (6) under test is calculated using the following formula. 能量 : SE 能量 =-10log(Q 透射 / Q 测试 )。 8. The method for measuring the time-domain shielding effectiveness of electromagnetic shielding materials according to claim 7, characterized in that, It also includes step 7: Step 7: Plot the frequency domain shielding effectiveness curve. Step 7.1 Perform Fourier transform on the actual test signal waveform obtained in Step 3 and the transmission signal waveform obtained in Step 2 respectively to obtain their corresponding frequency domain waveforms; Step 7.2 Read the peak amplitude U of the actual test signal at each frequency point in the frequency domain waveform. 测试 and the peak amplitude U of the transmitted signal waveform 透射 The peak shielding effectiveness of the electromagnetic shielding material (6) under test at each frequency point is calculated using the following formula: SE 峰值 =-20log(U 透射 / IN 测试 ); Step 7.3 Based on the calculation results, plot the frequency domain shielding effectiveness curve of the electromagnetic shielding material (6) to be tested.

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