A low-noise electric field radiation sensitivity test system and test method

Abstract

The present invention discloses a low-noise electric field radiation sensitivity test system and test method. The system is a method and device for achieving low-noise output in an electric field radiation sensitivity test based on a conventional power amplifier. A waveguide, a filter, and a narrowband transmitting antenna are combined to achieve low-noise level output outside the operating frequency band of the electric field radiation sensitivity test system, thereby realizing an effective electric field radiation sensitivity test for receiver-type test products. Simultaneously, switching between various sub-frequency bands is performed through a high-power programmable switching switch. In actual electric field radiation sensitivity tests, the test time is not increased, thereby maintaining test efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of low-noise output for electric field radiation sensitivity testing, and in particular to a method and device for achieving low-noise output for electric field radiation sensitivity testing based on a conventional power amplifier. The method achieves low-noise level output outside the operating frequency band of the electric field radiation sensitivity testing system, thereby realizing effective electric field radiation sensitivity testing of receiver-type test products. Background Art

[0002] The electric field radiation sensitivity test project is used to test the ability of the test product to withstand electric field radiation and to test the adaptability of the test product to the electromagnetic environment. The electric field radiation sensitivity test system mainly consists of a signal generator, a power amplifier, a transmitting antenna, an electric field sensor, a field strength monitor, a power meter, a directional coupler, etc. During the test, the signal generator, power amplifier and transmitting antenna generate an electric field that meets the standard requirements at a distance of 1 meter from the electronic and electrical products under test. The electric field sensor and field strength monitor are used to monitor whether the electric field strength meets the standard requirements. The test diagram is as follows Figure 1 shown.

[0003] However, due to the large noise level or harmonic spurs of conventional electric field sensitivity test systems, for example, the harmonic and other spurious suppression of solid-state power amplifiers is generally around -20dBc, and the harmonic and other spurious suppression indicators of traveling wave tube power amplifiers are even worse. The harmonic and other spurious suppression of many traveling wave tube power amplifiers is about -5dBc. When the electric field radiation sensitivity test system is turned on but no sensitivity signal is applied, the out-of-band interference signals such as harmonics will cause the receiver-type test products to malfunction, making it impossible to conduct the test and the electric field radiation sensitivity test cannot be carried out effectively. Currently, in the electric field radiation sensitivity test, when the current test frequency is applied, due to the poor harmonic suppression performance, large spurs, and high noise level of the power amplifier, large interference signals appear in the non-assessment frequency bands outside the test frequency. For example, Figure 2 As shown in the figure, when a test frequency of approximately 1 GHz is applied, harmonics of approximately 2 GHz and other signals appear, causing the receiver operating near the 2 GHz frequency band to not function properly, making the test impossible. The DUT cannot distinguish whether it is sensitive to the 1 GHz test frequency or its harmonics, which can easily lead to test errors and misjudgments. In order to properly implement the electric field radiation sensitivity test assessment, it is necessary to suppress noise such as harmonics of the power amplifier to achieve effective electric field radiation sensitivity testing of receiver-type DUTs.

[0004] There are two main aspects of harmonic generation in power amplifiers. First, at the output, in addition to the fundamental frequency signal being amplified by the power amplifier, the harmonics of the input signal are also amplified. This means that any periodic function (signal) can generally be decomposed into a convergent trigonometric series, known as a Fourier series. For a periodic function f(t), it can be written as follows:

[0005]

[0006]

[0007] in is a constant term, which is the DC component contained in the periodic signal; the second term It is called the fundamental wave, and its angular frequency is the same as the original periodic signal. A1 is the amplitude of the fundamental wave. is the initial phase angle of the fundamental wave; the third term in the formula It is called the second harmonic, and its frequency is twice the fundamental frequency. A2 is the second harmonic amplitude. is its initial phase angle. And so on, the third, fourth, ... and other harmonics. Generally speaking, It is called the nth harmonic, A n is the amplitude of the nth harmonic, is its initial phase angle.

[0008] On the other hand, harmonics are caused by the nonlinear operation of the power amplifier. In broadband RF high-power amplification, since the load of the amplifier's final transistor cannot be matched to the optimal state for every frequency within the broadband, in order to obtain the same output power, for those frequency bands where the load is not in the optimal state, the transistor may work in the saturation region or the cutoff region, thereby causing large nonlinear distortion and generating a series of harmonics. At the same time, in an ideal amplifier, the output signal changes linearly with the input signal, but this is not the case in reality. Due to the inherent characteristics of the transistor, when the output signal is within a certain range, it can approximately work in a linear state. When the output signal is large enough, the nonlinear phenomenon becomes the main factor. This phenomenon can be approximately described by the following function:

[0009]

[0010] Where V OUT is the output signal, V IN is the input signal, the first two terms are linear, and the subsequent higher-order terms describe the nonlinear phenomenon of the amplifier.

[0011] Receiver DUTs have high requirements for electromagnetic background within the receiving frequency band, making existing general-purpose electric field sensitivity test systems incapable of assessing receiver DUTs. This phenomenon often occurs during electric field sensitivity tests: even when an electric field sensitivity signal outside the receiver's frequency band is applied, the excessive harmonic noise level of the test system's power amplifier system drowns out the receiver's useful signal, resulting in the inability to assess the receiver DUT or causing false sensitivity errors. To address the current outstanding issues in electric field sensitivity testing, there is an urgent need for electric field sensitivity test systems with low noise levels. Addressing the poor harmonic and spurious suppression performance of electric field sensitivity test systems and enabling the assessment of receiver DUTs is of great engineering significance. Summary of the Invention

[0012] The purpose of the present invention is to provide a low-noise electric field radiation sensitivity test system and test method to ensure low noise level output of the electric field radiation sensitivity test system and realize the assessment of receiver-type test products.

[0013] In a first aspect, the present invention provides a low-noise electric field radiation sensitivity test system, comprising a signal generator, a power amplifier, a programmable high-power switch, a frequency-band waveguide, a frequency-band filter, and a narrowband transmitting antenna, wherein:

[0014] The output end of the signal generator is connected to the input end of the power amplifier;

[0015] The output end of the power amplifier is connected to different frequency band waveguides through the programmable high-power switching switch to switch between the frequency bands;

[0016] The output end of each frequency-division waveguide is connected to a frequency-division filter;

[0017] The output end of each frequency band filter is output through the narrowband transmitting antenna.

[0018] In some embodiments, the frequency-dividing waveguide is a rectangular cutoff waveguide, and the cutoff frequency is calculated according to the following formula:

[0019]

[0020] Where a is the length of the wide side of the rectangular cutoff waveguide, in centimeters; f c It is the cutoff frequency when there is only air in the waveguide, and its unit is Gigahertz (GHz).

[0021] In some embodiments, the frequency band filter is a low-pass filter or a band-pass filter.

[0022] In some embodiments, the narrowband transmitting antenna is a pyramidal horn antenna.

[0023] In some embodiments, the programmable high-power switch is a switch that can withstand the maximum output power of the power amplifier, and the programmable high-power switch is electrically connected to a computer and can achieve automatic switching under computer control.

[0024] In some embodiments, the power of the power amplifier is 20W.

[0025] In some embodiments, the frequency-band waveguide includes waveguides of seven frequency bands, namely 1GHz~1.46GHzBJ12 waveguide, 1.46GHz~1.73GHzBJ14 waveguide, 1.73GHz~2.61GHzBJ22 waveguide, 2.61GHz~5.99GHzBJ48 waveguide, 5.99GHz~8.17GHzBJ70 waveguide, 8.17GHz~12.5GHzBJ100 waveguide, and 12.5GHz~18GHzBJ140 waveguide.

[0026] In some embodiments, the frequency band filter includes seven frequency bands of bandpass filters, namely, 1GHz to 1.46GHz bandpass filter, 1.46GHz to 1.73GHz bandpass filter, 1.73GHz to 2.61GHz bandpass filter, 2.61GHz to 5.99GHz bandpass filter, 5.99GHz to 8.17GHz bandpass filter, 8.17GHz to 12.5GHz bandpass filter, and 12.5GHz to 18.0GHz bandpass filter.

[0027] In some embodiments, the narrowband transmitting antenna includes narrowband pyramidal horn antennas of seven frequency bands, namely, 1GHz~1.46GHz pyramidal horn antenna, 1.46GHz~1.73GHz pyramidal horn antenna, 1.73GHz~2.61GHz pyramidal horn antenna, 2.61GHz~5.99GHz pyramidal horn antenna, 5.99GHz~8.17GHz pyramidal horn antenna, 8.17GHz~12.5GHz pyramidal horn antenna, and 12.5GHz~18.0GHz pyramidal horn antenna.

[0028] In a second aspect, the present invention provides a low-noise electric field radiation sensitivity test method, which uses the low-noise electric field radiation sensitivity test system to perform the test, comprising the following steps:

[0029] Step S1, setting the frequency of the signal generator to the first test frequency point, and gradually increasing the output power of the signal generator until the indication of the electric field sensor of the participating laboratory reaches the limit value required by the test;

[0030] Step S2: Turn on the pulse modulation switch of the signal generator to apply pulse modulation with a repetition frequency of 1 kHz and a duty cycle of 50%;

[0031] Step S3: Scan the first sub-frequency band according to the test requirements, the step size and duration, keep the electric field within the limit requirements, and monitor whether the EUT is sensitive;

[0032] Step S4: Repeat the above test for all frequency points in the test sub-frequency bands.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The low-noise electric field radiation sensitivity test system provided by the present invention adopts a combination of waveguides, filters, programmable high-power switching switches, narrowband transmitting antennas, and the number of sub-frequency bands based on the requirements for harmonic and spurious suppression indicators to achieve the low-noise level output of a conventional electric field radiation sensitivity test system without reducing the test efficiency of the original test system. That is, based on the actual requirements for harmonic and spurious suppression indicators, the low-noise output is achieved by adopting waveguide suppression means, filter suppression means, and narrowband transmitting antenna suppression means. At the same time, the switching of each sub-frequency band is performed through a high-power programmable switching switch. In actual electric field radiation sensitivity tests, the test time is not increased, and the test efficiency is maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the test configuration of the electric field radiation sensitivity test system in the prior art;

[0036] Figure 2 It is the noise spectrum of harmonics, spurious, etc. when testing the electric field radiation sensitivity test system in the existing technology;

[0037] Figure 3 This is a schematic diagram of the test configuration of the low-noise electric field radiation sensitivity test system of the present invention;

[0038] Figure 4 is a low-pass filter;

[0039] Figure 5 is a bandpass filter;

[0040] Figure 6 Schematic diagram of the test configuration of the low-noise electric field radiation sensitivity test system of the present invention (1GHz~18GHz).

[0041] In the figure: 1. Signal generator; 2. Power amplifier; 3. Programmable high-power switching switch; 4. Waveguide; 5. Filter; 6. Narrowband transmitting antenna; 7. Electric field sensor. DETAILED DESCRIPTION

[0042] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0043] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0044] For the convenience of description, spatially relative terms may be used herein, such as “on…”, “over…”, “at…”

[0045] "above" or "on top" of another device or structure will be used to describe the spatial relationship of one device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, the device described as "above" or "above" another device or structure would then be positioned "below" or "below" the other device or structure. Thus, the exemplary term "above" can include "above" and "under" another device or structure.

[0046] The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0047] Now, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should not be interpreted as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of this application thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art. In the accompanying drawings, for clarity, the thickness of layers and regions is exaggerated, and the same reference numerals are used to represent the same devices, and thus their descriptions will be omitted.

[0048] like Figure 3 As shown, the present invention provides a low-noise electric field radiation sensitivity test system, including a signal generator 1, a power amplifier 2, a programmable high-power switch 3, a frequency-band waveguide 4, a frequency-band filter 5 and a narrowband transmitting antenna 6, wherein:

[0049] The output end of the signal generator 1 is connected to the input end of the power amplifier 2;

[0050] The output end of the power amplifier 2 is connected to different frequency band waveguides 4 through a programmable high power switch 3 to switch between the frequency bands.

[0051] The output end of each frequency-division waveguide 4 is connected to a frequency-division filter 5;

[0052] The output end of each frequency band filter 5 is output through a narrowband transmitting antenna 6 .

[0053] The low-noise electric field radiation sensitivity test system provided by the present invention adopts a combination of waveguides, filters, programmable high-power switching switches, narrowband transmitting antennas, and the number of sub-frequency bands based on the requirements for harmonic and spurious suppression indicators to achieve the low-noise level output of a conventional electric field radiation sensitivity test system without reducing the test efficiency of the original test system. That is, based on the actual requirements for harmonic and spurious suppression indicators, the low-noise output is achieved by adopting waveguide suppression means, filter suppression means, and narrowband transmitting antenna suppression means. At the same time, the switching of each sub-frequency band is performed through a high-power programmable switching switch. In actual electric field radiation sensitivity tests, the test time is not increased, and the test efficiency is maintained.

[0054] The design and selection of waveguides are as follows:

[0055] Furthermore, in this embodiment, the frequency-dividing waveguide 4 is a rectangular cutoff waveguide, and the cutoff frequency is calculated according to the following formula:

[0056]

[0057] Where a is the length of the wide side of the rectangular cutoff waveguide, in centimeters; f c It is the cutoff frequency when there is only air in the waveguide, and its unit is Gigahertz (GHz).

[0058] Specifically, for example, for a BJ12 rectangular waveguide, its inner cross-sectional dimensions are 195.58mm×97.79mm, and its wide side length is 195.58mm. The cutoff frequency can be calculated according to the above formula:

[0059]

[0060] The BJ12 rectangular waveguide (wide side length 19.558cm) has a cutoff frequency of 0.77GHz. This means that frequencies below 0.77GHz have difficulty passing through this rectangular waveguide. Using this rectangular cutoff waveguide can effectively suppress harmonic and spurious frequency components below 0.77GHz. The waveguide selection is shown in Table 1 below (see GB / T 11450.2-1989 Hollow Metal Waveguides Part 2: Ordinary Rectangular Waveguides).

[0061] Table 1

[0062]

[0063] like Figure 6 As shown, in some embodiments, the frequency-band waveguide 4 includes waveguides of seven frequency bands, namely, 1GHz~1.46GHzBJ12 waveguide, 1.46GHz~1.73GHzBJ14 waveguide, 1.73GHz~2.61GHzBJ22 waveguide, 2.61GHz~5.99GHzBJ48 waveguide, 5.99GHz~8.17GHzBJ70 waveguide, 8.17GHz~12.5GHzBJ100 waveguide, and 12.5GHz~18GHzBJ140 waveguide.

[0064] The filter design and selection are as follows:

[0065] like Figure 4 and Figure 5 As shown, the frequency-dividing filter 5 is a low-pass filter or a band-pass filter, which realizes a larger transmission coefficient within the frequency-dividing working frequency.

[0066] like Figure 6 As shown, further, when the bandpass filter is selected, the frequency band filter 5 includes bandpass filters of seven frequency bands, namely, 1GHz~1.46GHz bandpass filter, 1.46GHz~1.73GHz bandpass filter, 1.73GHz~2.61GHz bandpass filter, 2.61GHz~5.99GHz bandpass filter, 5.99GHz~8.17GHz bandpass filter, 8.17GHz~12.5GHz bandpass filter, and 12.5GHz~18.0GHz bandpass filter.

[0067] The design and selection of narrowband transmitting antennas are as follows:

[0068] In this embodiment, the narrowband transmitting antenna 6 is a pyramidal horn antenna. According to different sub-frequency bands, a narrowband transmitting antenna with an operating frequency in the sub-frequency band is selected.

[0069] like Figure 6 As shown, specifically, the narrowband transmitting antenna includes narrowband pyramidal horn antennas of seven frequency bands, namely, 1GHz~1.46GHz pyramidal horn antenna, 1.46GHz~1.73GHz pyramidal horn antenna, 1.73GHz~2.61GHz pyramidal horn antenna, 2.61GHz~5.99GHz pyramidal horn antenna, 5.99GHz~8.17GHz pyramidal horn antenna, 8.17GHz~12.5GHz pyramidal horn antenna, and 12.5GHz~18.0GHz pyramidal horn antenna.

[0070] The design and selection of programmable high power transfer switches are as follows:

[0071] Furthermore, the programmable high-power switch is designed to withstand the maximum output power of the power amplifier and is electrically connected to a computer, enabling automatic switching under computer control. Specifically, the programmable switch must be selected based on the maximum output power of the power amplifier in the electric field radiation sensitivity test system. Specifically, the programmable switch must be able to withstand the maximum output power of the power amplifier, be able to automatically switch under computer control, and meet system requirements for both standing wave ratio (SWR) and insertion loss.

[0072] In some embodiments, the power amplifier is a 20W power amplifier.

[0073] For the existing 1GHz~18GHz frequency band electric field radiation sensitivity test system, such as Figure 1 and Figure 2 As shown, the system includes a signal generator 1, a 20W power amplifier 2, a 1GHz to 18GHz transmitting antenna, and an electric field sensor 7. The system's harmonic and spurious suppression is only -15dBc. When testing a navigation receiver DUT, the operating frequency applied during the electric field radiation sensitivity test is insensitive, while the harmonics of the test cause the navigation receiver DUT to be sensitive.

[0074] In order to properly implement the electric field radiation sensitivity test assessment, the harmonics and other noises of the electric field radiation sensitivity test system are suppressed. Waveguide 4, bandpass filter 5, and narrowband transmitting antenna 6 are used to achieve harmonic and other noise suppression. The harmonic and other noise suppression index reaches above -40dBc, meeting the electric field sensitivity test requirements of the navigation receiver. At the same time, the program-controlled switching method does not increase the test time, ensuring the original efficiency of the test. The specific steps are as follows:

[0075] Seven frequency bands of waveguides are used to cover the 1GHz to 18GHz band: BJ12 waveguide (covering the 1GHz to 1.46GHz band), BJ14 waveguide (covering the 1.46GHz to 1.73GHz band), BJ22 waveguide (covering the 1.73GHz to 2.61GHz band), BJ48 waveguide (covering the 2.61GHz to 5.99GHz band), BJ70 waveguide (covering the 5.99GHz to 8.17GHz band), BJ100 waveguide (covering the 8.17GHz to 12.5GHz band), and BJ140 waveguide (covering the 12.5GHz to 18GHz band).

[0076] Seven frequency bands of bandpass filters are used to cover the 1GHz to 18GHz band: 1GHz to 1.46GHz bandpass filter, 1.46GHz to 1.73GHz bandpass filter, 1.73GHz to 2.61GHz bandpass filter, 2.61GHz to 5.99GHz bandpass filter, 5.99GHz to 8.17GHz bandpass filter, 8.17GHz to 12.5GHz bandpass filter, and 12.5GHz to 18.0GHz bandpass filter.

[0077] Seven frequency bands of narrowband pyramidal horn antennas are used to cover the 1GHz~18GHz frequency band: 1GHz~1.46GHz pyramidal horn antenna, 1.46GHz~1.73GHz pyramidal horn antenna, 1.73GHz~2.61GHz pyramidal horn antenna, 2.61GHz~5.99GHz pyramidal horn antenna, 5.99GHz~8.17GHz pyramidal horn antenna, 8.17GHz~12.5GHz pyramidal horn antenna, 12.5GHz~18.0GHz pyramidal horn antenna.

[0078] A programmable switch is used to switch the signal amplified by the power amplifier to waveguides of different frequency bands.

[0079] The specific test arrangement is as follows Figure 6 Make the connections as shown.

[0080] The present invention provides a low-noise electric field radiation sensitivity test method, which uses a low-noise electric field radiation sensitivity test system for testing, comprising the following steps:

[0081] Step S1, setting the frequency of the signal generator to the first test frequency point, and gradually increasing the output power of the signal generator until the indication of the electric field sensor of the participating laboratory reaches the limit value required by the test;

[0082] Step S2: Turn on the pulse modulation switch of the signal generator to apply pulse modulation with a repetition frequency of 1 kHz and a duty cycle of 50%;

[0083] Step S3: Scan the first sub-frequency band according to the test requirements, the step size and duration, keep the electric field within the limit requirements, and monitor whether the EUT is sensitive;

[0084] Step S4: Repeat the above test for all frequency points in the test sub-frequency bands.

Claims

1. Low noise electric field radiation sensitivity test system, characterized by: It includes a signal generator, a power amplifier, a programmable high-power switch, a frequency-band waveguide, a frequency-band filter and a narrowband transmitting antenna, wherein: The output end of the signal generator is connected to the input end of the power amplifier; The output end of the power amplifier is connected to different frequency band waveguides through the programmable high-power switching switch to switch between the frequency bands; The output end of each frequency-division waveguide is connected to a frequency-division filter; The output end of each frequency band filter is output through the narrowband transmitting antenna.

2. The low-noise electric field radiation sensitivity test system according to claim 1, characterized in that: The frequency-dividing waveguide is a rectangular cutoff waveguide, and the cutoff frequency is calculated according to the following formula: Where a is the length of the wide side of the rectangular cutoff waveguide, in centimeters; f c It is the cutoff frequency when there is only air in the waveguide, and its unit is Gigahertz (GHz).

3. The low-noise electric field radiation sensitivity test system according to claim 1, characterized in that: The frequency band filter is a low-pass filter or a band-pass filter.

4. The low-noise electric field radiation sensitivity test system according to claim 1, characterized in that: The narrowband transmitting antenna is a pyramidal horn antenna.

5. The low-noise electric field radiation sensitivity test system according to claim 1, characterized in that: The program-controlled high-power switch is a switch that can withstand the maximum output power of the power amplifier, and the program-controlled high-power switch is electrically connected to a computer and can achieve automatic switching under computer control.

6. The low-noise electric field radiation sensitivity test system according to claim 1, characterized in that: The power of the power amplifier is 20W.

7. The low-noise electric field radiation sensitivity test system according to claim 1, characterized in that: The frequency band waveguides include waveguides of seven frequency bands, namely 1GHz~1.46GHzBJ12 waveguide, 1.46GHz~1.73GHzBJ14 waveguide, 1.73GHz~2.61GHzBJ22 waveguide, 2.61GHz~5.99GHzBJ48 waveguide, 5.99GHz~8.17GHzBJ70 waveguide, 8.17GHz~12.5GHzBJ100 waveguide, and 12.5GHz~18GHzBJ140 waveguide.

8. The low-noise electric field radiation sensitivity test system according to claim 3, characterized in that: The frequency band filter includes seven frequency bands of bandpass filters, namely, 1GHz to 1.46GHz bandpass filter, 1.46GHz to 1.73GHz bandpass filter, 1.73GHz to 2.61GHz bandpass filter, 2.61GHz to 5.99GHz bandpass filter, 5.99GHz to 8.17GHz bandpass filter, 8.17GHz to 12.5GHz bandpass filter, and 12.5GHz to 18.0GHz bandpass filter.

9. The low-noise electric field radiation sensitivity test system according to claim 4, characterized in that: The narrowband transmitting antenna includes narrowband pyramidal horn antennas of seven frequency bands, namely, 1GHz~1.46GHz pyramidal horn antenna, 1.46GHz~1.73GHz pyramidal horn antenna, 1.73GHz~2.61GHz pyramidal horn antenna, 2.61GHz~5.99GHz pyramidal horn antenna, 5.99GHz~8.17GHz pyramidal horn antenna, 8.17GHz~12.5GHz pyramidal horn antenna, and 12.5GHz~18.0GHz pyramidal horn antenna.

10. A low-noise electric field radiation sensitivity test method, characterized in that: A method for testing using the low-noise electric field radiation sensitivity test system according to any one of claims 1 to 9 comprises the following steps: Step S1, setting the frequency of the signal generator to the first test frequency point, and gradually increasing the output power of the signal generator until the indication of the electric field sensor of the participating laboratory reaches the limit value required by the test; Step S2: Turn on the pulse modulation switch of the signal generator to apply pulse modulation with a repetition frequency of 1 kHz and a duty cycle of 50%; Step S3: Scan the first sub-frequency band according to the test requirements, the step size and duration, keep the electric field within the limit requirements, and monitor whether the EUT is sensitive; Step S4: Repeat the above test for all frequency points in the test sub-frequency bands.

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