A method for testing the performance of an anechoic chamber site

Abstract

The present invention discloses a method for testing the performance of an anechoic chamber site, which relates to the field of testing the performance of an anechoic chamber site and includes the following steps: obtaining frequency response data between a transmitting antenna and a receiving antenna in the anechoic chamber site; converting the frequency response data between the transmitting antenna and the receiving antenna to the time domain through inverse discrete Fourier transform; obtaining the response of the direct propagation signal between the transmitting antenna and the receiving antenna in the time domain; obtaining the response of the reflected wave signal from the anechoic chamber in the time domain; converting the response of the direct propagation signal between the transmitting antenna and the receiving antenna in the time domain to the frequency domain through discrete Fourier transform to obtain first frequency domain data; converting the response of the reflected wave signal from the anechoic chamber in the time domain to the frequency domain through discrete Fourier transform to obtain second frequency domain data; testing the performance of the anechoic chamber site according to the first frequency domain data and the second frequency domain data. This method reduces the hardware input cost for verifying the anechoic chamber site.

Description

Technical Field

[0001] The present invention relates to the field of radio anechoic chamber site performance testing, and particularly to a method for testing the performance of a radio anechoic chamber site. Background Art

[0002] The verification of the performance of a radio anechoic chamber site is an important prerequisite for conducting electromagnetic compatibility tests of products using the anechoic chamber. Among them, the SVSWR test is the main method for measuring the radiation emission (RE) performance of an EMC anechoic chamber (electromagnetic compatibility anechoic chamber) in the frequency band above 1 GHz. The physical meaning of SVSWR is the characteristic of the spatial standing wave formed by electromagnetic waves in the quiet zone (QZ) of the anechoic chamber test. Currently, there are mainly three types of measurement methods for SVSWR: the CISPR Spatial Sampling measurement method (spatial sampling method), the ANSI TD-SVSWR measurement method (time domain measurement method), and the Mode Filtering measurement method. Among them, the more widely used one is the Spatial Sampling measurement method described in the standard CISPR 16-1-4. In this method, the receiving antenna is fixedly placed at a position 3 meters away from the front edge of the quiet zone, and at the same time, it is ensured that the lobe of the receiving antenna can cover the range of the measurement quiet zone according to the standard requirements. The omnidirectional antenna is arranged at 4 specified positions on the edge of the quiet zone. The SVSWR is obtained by moving the receiving antenna along the axis at different distances, and the response between the two antennas is measured, and then the maximum value of the spatial standing wave is obtained. The sampling position interval of the spatial standing wave of the CISPR method is 6 fixed distances such as 0 cm, 2 cm, 10 cm, 18 cm, 30 cm, and 40 cm. The purpose is to change the phase relationship between the direct wave and the reflected wave by changing the distance between the transmitting and receiving antennas, so as to sample the spatial standing wave. However, in such a wide frequency range of 1 GHz - 18 GHz, only using these 6 distances cannot fully meet the sampling of all wavelengths. In addition, the frequency step in the CISPR method is 50 MHz, and the relatively wide frequency step may cause the frequency points with poor SVSWR to be ignored.

[0003] In response to the above situations that may affect the measurement results, the ANSI time domain method and the Mode Filtering measurement method have proposed improvement schemes from different technical perspectives. The Mode Filtering measurement method requires placing the transmitting antenna at the edge of the QZ, and then rotating the turntable to perform cylindrical antenna measurement. The transmitting antenna is transformed to the center of its turntable through mathematical transformation, and then the cylindrical mode coefficient of the antenna is calculated. This method can more accurately obtain the spatial standing wave distribution in the QZ through dense spatial sampling, and does not require the test antenna to have a short ring-down time. However, this method has not yet formed an international standard, so it cannot be used as the basis for the recognized performance verification of the anechoic chamber in the industry.

[0004] TD-SVSWR is proposed to overcome the limitations of spatial sampling measurement methods. This is achieved by using broadband antennas and time-domain transformation to distinguish the direct wave between the transmitting and receiving antennas and the multipath reflection signals in the anechoic chamber. This method is contrasted with the previous techniques that rely on the measurement results of the spatial movement of the transmitting antenna. The physical meaning of this method is clear, that is, to distinguish the direct wave between the antennas and the reflected wave of the site in the time domain, and then intercept it through a time gate to calculate the ratio of the reflected wave to the direct wave. On the other hand, the position of the transmitting antenna does not need to be moved during the measurement process, so it has a high measurement efficiency. This method is also an effective method to verify the radiation emission performance of the anechoic chamber site in addition to the CISPR method.

[0005] The arrangement of TD-SVSWR measurement is similar to the CISPR method, and there are the following differences in the measurement arrangement and parameter settings.

[0006] a) The transmitting antenna of the TD-SVSWR measurement method completes the measurement at a fixed position, and there is no need to measure the spatial standing wave by moving the antenna anymore.

[0007] b) Due to the transformation from time domain to frequency domain during the measurement process, in order to prevent the truncation effect caused by the Fourier transform during the measurement, it is necessary to set the measurement bandwidth range of the vector network analyzer (VNA) to be greater than the actually required frequency band range. The starting frequency is generally set to 500 MHz, and the ending frequency is generally the upper limit frequency to be measured plus 10% of the measurement frequency band width. If it is necessary to measure 1 GHz - 6 GHz, the measurement ending frequency needs to be set to 6.5 GHz. If it is necessary to measure 1 GHz - 18 GHz, the ending frequency is 19.7 GHz.

[0008] c) The step of the measurement frequency points should not exceed 1.5 MHz. When the measurement start and end frequencies are 500 MHz - 19.7 GHz, the standard recommended frequency step is 1.2 MHz, that is, 16001 frequency points.

[0009] d) It may be necessary to have a lower IF bandwidth or / and a higher output power or a preamplifier to improve the signal-to-noise ratio. The signal-to-system noise ratio should reach at least 20 dB.

[0010] e) Before the measurement, the VNA needs to be calibrated for two ports.

[0011] Through the time-domain option function of the vector network analyzer, the time-domain waveform of the antenna response is obtained. The response of the direct wave between the antennas can be clearly distinguished from the time-domain waveform, that is, the largest peak in the waveform is the direct response between the antennas. After determining the time when the direct wave arrives at the receiving antenna, the band-pass mode of the vector network analyzer can be used to select an appropriate time gate, extract the direct wave response, and convert it to the frequency domain, denoted as Then, the direct response is filtered out using a band-stop mode, and only the part of the reflected wave is extracted. After transformation to the frequency domain, it is denoted as The SVSWR calculation method is as follows:

[0012]

[0013]

[0014] After initially obtaining the SVSWR value, a series of data post-processing is still required. It includes the following steps.

[0015] Moving average processing. A moving average window with a width of 120 MHz is set, and the SVSWR data is smoothed over the entire measurement frequency band. The processed data is denoted as Regarding the design of the width of the moving average window, the principle adhered to by the standard is to select the smallest possible moving window on the premise of ensuring that there are enough independent data points for average calculation.

[0016] Inclusion of the coverage factor. After the moving average processing, the standard deviation of each set of moving average data is calculated and denoted as To match the "undersampled" measurement values of the CISPR method, the TD-SVSWR method adds a coverage factor after obtaining the standard deviation of the moving average data. The final calculation result of TD-SVSWR is: We default that the measurement results follow a normal distribution. By adding a coverage factor b =0.676 representing a one-sided confidence interval of 75%, in principle, an expression form of the measurement result plus the expanded uncertainty is constructed, which enables the time-domain measurement method to achieve a certain degree of consistency with the CISPR method, which is theoretically an undersampled method, in terms of measurement results.

[0017] From the above process, it can be seen that the hardware basis of the TD-SVSWR measurement method requires a VNA with time-domain options. From the confirmation of the peak position of the direct wave between antennas to the setting of the time gate to gate the signal, it all requires the time-domain measurement function of the VNA. However, the VNAs in general testing laboratories may not have the time-domain option function. If the measurement method of this standard is to be adopted, undoubtedly, an increase in the investment in hardware costs is required. Summary of the Invention

[0018] Aiming at the above deficiencies in the prior art, a method for testing the performance of an anechoic chamber site provided by the present invention solves the problem that an ordinary vector network analyzer cannot perform the performance test of an anechoic chamber site through the existing TD-SVSWR measurement method.

[0019] To achieve the above invention purpose, the technical solution adopted by the present invention is:

[0020] Provide a method for testing the performance of an anechoic chamber site, which includes the following steps:

[0021] S1. Obtain the frequency response data between the transmitting and receiving antennas in the anechoic chamber site through a vector network analyzer;

[0022] S2. Convert the frequency response data between the transmitting and receiving antennas to the time domain through the inverse discrete Fourier transform to obtain time-domain data;

[0023] S3. Select a time window, intercept the time-domain data through the time-domain gate band-pass mode to obtain the response of the direct propagation signal between the transmitting and receiving antennas in the time domain; select a time window, intercept the time-domain data through the time-domain gate band-stop mode to obtain the response of the reflected wave signal from the anechoic chamber in the time domain;

[0024] S4. Convert the response of the direct propagation signal between the transmitting and receiving antennas in the time domain to the frequency domain through the discrete Fourier transform to obtain the first frequency-domain data; convert the response of the reflected wave signal from the anechoic chamber in the time domain to the frequency domain through the discrete Fourier transform to obtain the second frequency-domain data;

[0025] S5. Test the performance of the anechoic chamber site according to the first frequency-domain data and the second frequency-domain data.

[0026] Further, the expression for converting the frequency response data between the transmitting and receiving antennas to the time domain in step S2 is:

[0027]

[0028] where is the k th data in the frequency response data between the transmitting and receiving antennas measured by the vector network analyzer; is the th time-series corresponding time-domain data; is the total number of the frequency response data between the transmitting and receiving antennas in a single time series; e is the natural constant; j is the imaginary unit; π is the pi; n represents the index of the frequency response data between the transmitting and receiving antennas in a single time series; , is the time interval, , is the lower frequency limit of the measurement bandwidth; the time series range is , is the upper frequency limit of the measurement bandwidth.

[0029] Further, the expression for intercepting the time-domain data through the time-domain gate band-pass mode in step S3 is:

[0030]

[0031] where is the response of the direct propagation signal between the transmitting and receiving antennas in the time domain; represents the time-domain gate function, and the time-domain gate function includes a rectangular window, a Hanning window, and a Hamming window.

[0032] Further, the expression for converting the response of the direct propagation signal between the transmitting and receiving antennas in the time domain to the frequency domain through the discrete Fourier transform in step S4 is:

[0033]

[0034] where is the first frequency-domain data.

[0035] Further, the specific method for testing the performance of the anechoic chamber site according to the first frequency-domain data and the second frequency-domain data in step S5 includes the following sub-steps:

[0036] S5-1. Calculate the site voltage standing wave ratio according to the first frequency-domain data and the second frequency-domain data ;

[0037] S5-2. Set the moving average window to 120 MHz and perform a moving average on the data over the entire frequency range. Designate the moving average data as , and calculate the standard deviation for each set of data within the moving average window; Denote the standard deviation of all sets of standard deviations as ;

[0038] S5-3. Calculate the time-domain site voltage standing wave ratio and according to ;

[0039] S5-4. Take the time-domain site voltage standing wave ratio as the test result of the anechoic chamber site performance.

[0040] Further, the expression for calculating the site voltage standing wave ratio in step S5-1 is:

[0041]

[0042]

[0043] where is an intermediate parameter; is the second frequency-domain data; represents a logarithmic function.

[0044] Furthermore, in step S5-3, the time-domain site voltage standing wave ratio is calculated The expression is:

[0045]

[0046] where is a constant.

[0047] Furthermore, The value of is 0.676.

[0048] Provided is a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor is enabled to execute the radio anechoic chamber site performance test method.

[0049] Provided is a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor is enabled to execute the radio anechoic chamber site performance test method.

[0050] The beneficial effects of the present invention are as follows: By using an ordinary (without time-domain measurement function) vector network analyzer and based on the TD-SVSWR measurement method, the radio anechoic chamber site performance test is carried out, avoiding the increase in hardware costs and enabling the rapid implementation of the radio anechoic chamber site performance test. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic flow diagram of the method;

[0052] Figure 2 is a schematic diagram of the frequency response data between the transmitting and receiving antennas measured by the vector network analyzer;

[0053] Figure 3 is a schematic diagram of converting the frequency response data between the transmitting and receiving antennas to the time domain through the inverse discrete Fourier transform;

[0054] Figure 4 is a schematic diagram of selecting an appropriate time-domain gate width according to the impulse response;

[0055] Figure 5 are the band-pass mode and band-stop mode data converted to the frequency domain after being intercepted by the time-domain gate;

[0056] Figure 6 is a schematic diagram of the automatic measurement system interface;

[0057] Figure 7 are the impulse response characteristics of different antennas;

[0058] Figure 8 is the setting of the measurement time-domain gate;

[0059] Figure 9 It is a schematic diagram of the propagation path of the reflected wave for the test site layout and the shortest path;

[0060] Figure 10 It is the result without using moving average;

[0061] Figure 11 It is the result after using moving average. Specific implementation manners

[0062] The following describes the specific implementation manners of the present invention to facilitate those skilled in the art of this technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation manners. For those of ordinary skill in the art of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions created using the concept of the present invention are within the scope of protection.

[0063] As Figure 1 shown, the method for testing the performance of the anechoic chamber site includes the following steps:

[0064] S1. Obtain the frequency response data between the transmitting and receiving antennas in the anechoic chamber site through a vector network analyzer;

[0065] S2. Convert the frequency response data between the transmitting and receiving antennas to the time domain through inverse discrete Fourier transform to obtain time domain data;

[0066] S3. Select a time window, intercept the time domain data through the time domain gate band-pass mode to obtain the response of the direct propagation signal between the transmitting and receiving antennas in the time domain; select a time window, intercept the time domain data through the time domain gate band-stop mode to obtain the response of the reflected wave signal from the anechoic chamber in the time domain;

[0067] S4. Convert the response of the direct propagation signal between the transmitting and receiving antennas in the time domain to the frequency domain through discrete Fourier transform to obtain the first frequency domain data; convert the response of the reflected wave signal from the anechoic chamber in the time domain to the frequency domain through discrete Fourier transform to obtain the second frequency domain data;

[0068] S5. Test the performance of the anechoic chamber site according to the first frequency domain data and the second frequency domain data.

[0069] In the specific implementation process, the frequency response data between the transmitting and receiving antennas measured by the vector network analyzer is as Figure 2 shown, and converting the frequency response data between the transmitting and receiving antennas to the time domain through inverse discrete Fourier transform is as Figure 3 shown, and the expression for converting the frequency response data between the transmitting and receiving antennas to the time domain through inverse discrete Fourier transform is:

[0070]

[0071] wherein is the k th data in the frequency response data between the transmitting and receiving antennas measured by the vector network analyzer; is the th time-domain data corresponding to the time series; is the total number of the frequency response data between the transmitting and receiving antennas in a single time series; e is the natural constant; j is the imaginary unit; π is the pi; n represents the index of the frequency response data between the transmitting and receiving antennas in a single time series; , is the time interval, , is the lower frequency limit of the measurement bandwidth; the time series range is , is the upper frequency limit of the measurement bandwidth.

[0072] The specific method for intercepting the time-domain data through the time-domain gate band-pass mode in step S3 is as follows:

[0073] As Figure 4 shown, select an appropriate time window width and intercept the time-domain data through the time-domain gate band-pass mode. Its expression is:

[0074]

[0075] wherein is the response of the direct propagation signal between the transmitting and receiving antennas in the time domain; represents the time-domain gate function. The time-domain gate function includes a rectangular window, a Hanning window, and a Hamming window. The time-domain expressions of the rectangular window, the Hanning window, and the Hamming window are as follows:

[0076]

[0077]

[0078]

[0079] wherein represents the window function.

[0080] The expression for converting the response of the direct propagation signal between the transmitting and receiving antennas in the time domain to the frequency domain through the discrete Fourier transform in step S4 is:

[0081]

[0082] wherein is the first frequency-domain data.

[0083] Frequency response data between the transmitting and receiving antennas The reflected signal level is obtained by using band-stop filtering processing , and then the frequency-domain response of the reflected signal level is obtained by using the discrete Fourier transform, that is, the second frequency-domain data is obtained , the calculation process is the same as the previous band-pass filtering and discrete Fourier transform, and only the window function needs to be replaced with a window function in the band-stop mode , and the result is as Figure 5 shown.

[0084] The specific method for testing the performance of the anechoic chamber site according to the first frequency-domain data and the second frequency-domain data in step S5 includes the following sub-steps:

[0085] S5-1. Calculate the site voltage standing wave ratio according to the first frequency-domain data and the second frequency-domain data , and its expression is:

[0086]

[0087]

[0088] where is an intermediate parameter; is the second frequency-domain data; represents the logarithmic function;

[0089] S5-2. Set the moving average window to 120 MHz and perform a sliding average on the data within the entire frequency range, specify the sliding average data as , and calculate the standard deviation for each group of data within the sliding average window; denote the standard deviation of all groups of standard deviations as ;

[0090] S5-3. Calculate the time-domain site voltage standing wave ratio , and its expression is:

[0091]

[0092] S5-4. Use the time-domain site voltage standing wave ratio as the test result of the anechoic chamber site performance; The value of

[0093] According to the above calculation process, as Figure 6 shown, in this embodiment, an automatic measurement system is compiled, and by remotely controlling the VNA and calculating and processing the measurement data, the automatic measurement of the time-domain site voltage standing wave ratio without relying on the VNA time-domain option is realized.

[0094] In the specific implementation process, the purpose of using the time domain gate to intercept data is to effectively distinguish the direct signal between antennas and the reflected signals in the surrounding environment. The factors affecting the selection of the time domain gate width are mainly two aspects. One is the ring down time of the antenna itself, and the other is the time when the reflected electromagnetic wave reaches the receiving antenna fastest.

[0095] Ring down time is a phenomenon caused by the structural characteristics of the antenna itself. Figure 7 It can be seen that after the antenna receives a broadband pulse signal, there will be varying degrees of oscillation after the main peak of the signal, which is the so-called ring down time. For antennas of different types, the duration of the oscillation is different. In theory, the ring down time should be as small as possible. If the ring down time is too large, it will be mixed with the reflected signal, and the responses of the direct wave and the reflected wave cannot be effectively distinguished, thus affecting the result of the site voltage standing wave ratio (SVSWR).

[0096] Then, to obtain an accurate SVSWR, it is necessary to know how much less time the ring down time of the antenna needs to be than the time delay of the reflected wave reaching the antenna compared to the direct wave. As long as the ring down time is less than this duration, the direct wave and the reflected wave can be distinguished by the time domain gate, as Figure 8 shown.

[0097] In this embodiment, as Figure 9 shown, the straight-line distance between the antennas is d1. The height of the absorbers is h1, and the height of the antenna is h2. The path of the electromagnetic wave reaching the receiving antenna after being reflected by the surface of the absorbers in the figure should be the shortest among all the reflected paths. The time difference between this path and the direct wave path is calculated as follows:

[0098]

[0099] where , is the speed of light. When the transmitting antenna is at the front point of the quiet zone, d1 is 3m. Generally, h1 is 0.4 and h2 is 1.2m. The calculated It is about 1.4 ns. Therefore, the ring downtime of the test antenna selected should be less than this value. Here, the position of the point before the quiet zone is calculated. For other test points, since the distance of d1 becomes longer, the distance traveled by the reflected wave also becomes longer accordingly. Therefore, the position of the point before is the position point where the path delay between the reflected wave and the direct wave is the shortest. In the standard ANSI C63.25, it is recommended that the time domain gate setting takes 2 ns to the left and right centered on the peak of the time domain response. According to the above calculation, in the actual test environment, the width of the time domain gate can be appropriately adjusted. Based on the two factors of the shortest reflection path and the ring down time, the setting of the time window width is weighed to ensure the accuracy of the measurement data. In this embodiment, the time window width is less than the reflection time of the shortest path and greater than the ring down time of the antenna, and an antenna with a short enough ringing time is selected, such as less than 1 ns.

[0100] As Figure 10 and Figure 11 shown, the measurement results are processed using the above three time windows respectively, and the differences between the time windows are compared. It can be seen from the figure that using different types of time windows will have a certain impact on the results, but the differences between the results are not significant.

[0101] In other embodiments of the present invention, a computer device is further provided, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor executes the method for testing the performance of an anechoic chamber site.

[0102] In other embodiments of the present invention, a computer-readable storage medium is further provided, on which a computer program is stored. When the computer program is executed by the processor, the processor executes the method for testing the performance of an anechoic chamber site.

[0103] In summary, the present invention provides a method for testing the performance of an anechoic chamber site that does not rely on the time domain option of a VNA. Based on post-processing of frequency domain data, TD-SVSWR measurement is realized, which reduces the hardware input cost for verifying the anechoic chamber site using this method, develops an automated measurement system, improves the measurement efficiency, and clarifies the parameter setting principle not specifically described in the standard method, providing an analysis and verification result with reference value for users who use this method to conduct anechoic chamber site evaluation.

Claims

1. A method for testing field performance of an anechoic chamber, characterized in that: The following steps are involved: S1. Obtain the frequency response data between the transmitting and receiving antennas in the anechoic chamber through a vector network analyzer that does not have a time domain measurement function; S2, converting the frequency response data between the transmitting and receiving antennas into the time domain through inverse discrete Fourier transform to obtain time domain data; S3, select a time window, intercept the time domain data through the time domain gate bandpass mode, and obtain the response of the linear propagation signal between the transmitting and receiving antennas in the time domain; select a time window, intercept the time domain data through the time domain gate bandstop mode, and obtain the response of the reflected wave signal from the radio darkroom in the time domain; The expression for intercepting the time domain data by the time domain gate bandpass mode in step S3 is: in is the response of the linear propagation signal between the transmitting and receiving antennas in the time domain; For the Time domain data corresponding to a time series; represents a time domain gate function, which includes a rectangular window, a Hanning window, and a Hamming window; the width of the time domain gate is greater than the ringing time of the antenna and less than the shortest path reflection time; S4, converting the response of the linear propagation signal between the transmitting and receiving antennas in the time domain into the frequency domain by discrete Fourier transform, and obtaining first frequency domain data; converting the response of the reflected wave signal from the radio wave darkroom in the time domain into the frequency domain by discrete Fourier transform, and obtaining second frequency domain data; S5. Test the performance of the anechoic chamber according to the first frequency domain data and the second frequency domain data.

2. The method for testing the field performance of an anechoic chamber according to claim 1, characterized in that: In step S2, the frequency response data between the transmitting and receiving antennas is converted to the time domain through the inverse discrete Fourier transform. The expression is: in The frequency response data between the transmitting and receiving antennas measured by the vector network analyzer is k individual data; For the Time domain data corresponding to a time series; is the total number of frequency response data between the transmitting and receiving antennas in a single time series; e is a natural constant; j is the imaginary unit; π is the circumference of a circle; n Represents the index of the frequency response data between the transmitting and receiving antennas in a single time series; , is the time interval, , is the lower frequency limit of the measurement bandwidth; the time series range is , is the upper frequency limit of the measurement bandwidth.

3. The method for testing the field performance of an anechoic chamber according to claim 2, characterized in that: In step S4, the response of the linear propagation signal between the transmitting and receiving antennas in the time domain is converted to the frequency domain by discrete Fourier transform: in is the first frequency domain data.

4. The method for testing the field performance of an anechoic chamber according to claim 3, characterized in that: The specific method for testing the performance of the anechoic chamber according to the first frequency domain data and the second frequency domain data in step S5 includes the following sub-steps: S5-1. Calculating the site voltage standing wave ratio according to the first frequency domain data and the second frequency domain data ; S5-2, set the moving average window to 120 MHz and perform The data is moved averaged and the moving average data is specified as , and calculate the standard deviation of each group of data in the sliding average window; the standard deviation of the standard deviation of all groups is recorded as ; S5-3, according to and Calculate the time domain site VSWR ; S5-4, the time domain site voltage standing wave ratio As the result of the anechoic chamber field performance test.

5. The method for testing the field performance of an anechoic chamber according to claim 4, characterized in that: Step S5-1 calculates the site voltage standing wave ratio The expression is: in is the intermediate parameter; is the second frequency domain data; Represents a logarithmic function.

6. The method for testing the field performance of an anechoic chamber according to claim 5, characterized in that: Step S5-3 calculates the time domain site voltage standing wave ratio The expression is: in is a constant.

7. The method for testing the field performance of an anechoic chamber according to claim 6, characterized in that: The value of is 0.

676.

8. A computer device, characterized in that: The invention comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the method for testing field performance of an anechoic chamber as claimed in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the processor executes the anechoic chamber field performance testing method described in any one of claims 1 to 7.

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