A Phase Stirred Reverberation Chamber, Testing Device and Method

Abstract

The present invention discloses a phase-stirred reverberation chamber, a testing device and a method. In the present invention, a phased array antenna is placed in the reverberation chamber cavity, and a device under test is placed in the testing area within the reverberation chamber cavity. The phased array antenna is used for beam scanning to change the state within the reverberation chamber, and a statistically uniform field is formed within the testing area, which can achieve the effect of a mechanical stirring device in the reverberation chamber, providing a highly operable and low-cost method for electromagnetic compatibility simulation and testing in the reverberation chamber. The testing process of the present invention does not require a mechanical stirrer, so the volume of the reverberation chamber cavity can be reduced and the volume of the testing area can be increased. At the same time, it has the characteristics of high speed and easy operation, and can be widely applied to the situation of EMC testing in a conventional reverberation chamber.

Description

Technical Field

[0001] The present invention relates to a reverberation chamber in the field of electromagnetic compatibility testing, and particularly to a phase stirring reverberation chamber, a testing device and a method. Background Art

[0002] With the rapid development of high-tech, the level of electronization and informatization has been continuously improved, and various electronic devices are widely used in daily life and industrial production. However, the complex electromagnetic environment has also brought serious electromagnetic interference problems to electronic devices, affecting the normal operation and performance of the devices. Traditional electromagnetic compatibility testing technologies can no longer meet the requirements of the new era's integrated communication systems. Especially for the testing of the radiation emission and radiation immunity of electronic devices, a testing technology capable of simulating a complex electromagnetic environment is needed.

[0003] A radio wave reverberation chamber is an electromagnetic compatibility testing environment, characterized in that all boundaries can reflect electromagnetic waves, thus forming a statistically uniform electromagnetic field within a certain area. The purpose of the reverberation chamber is to change the electromagnetic field boundary conditions of the radiation source through a specially designed shielding cavity and a stirrer, by rotating or tuning the stirrer, so that the field strength value in a certain area within the cavity is statistically uniformly distributed in the time domain, thereby forming a testing area for testing the radiation emission, radiation sensitivity and other performances of electronic components.

[0004] The IEC 61000-4-21 standard stipulates the principles, design requirements, calibration methods, testing methods, etc. of the radio wave reverberation chamber. A reverberation chamber usually consists of the following parts: a stirrer, a driving motor, a transceiver antenna, an electric field probe, a filter, a measuring device, a control device, etc.

[0005] However, the mechanical stirrer has problems such as difficult construction and inconvenient operation, and the stirrer has a relatively large size, requiring a relatively large reverberation chamber cavity, which will also lead to a reduction in the size of the testing area; within a certain bandwidth, a single frequency stirring method is difficult to provide enough independent sample points, otherwise it will lead to an excessive stirring bandwidth. Therefore, a source stirring technology with lower cost and easy implementation is needed. Summary of the Invention

[0006] The object of the present invention is to overcome the deficiencies of the prior art and provide a phase stirring reverberation chamber, a testing device and a method to solve the problem that a mechanical stirring device needs to be set in the reverberation chamber, resulting in a relatively large volume, high cost and increased testing difficulty of the reverberation chamber. The present invention uses a phased array antenna for beam scanning, which can achieve the effect of a mechanical stirring device in the reverberation chamber, and provides a method with strong operability and low cost for electromagnetic compatibility simulation and testing in the reverberation chamber.

[0007] The technical solution adopted by the present invention to solve the above technical problems is:

[0008] 1. A phase-stirred reverberation chamber

[0009] The phase-stirred reverberation chamber includes a phased array antenna. The phased array antenna is placed inside the reverberation chamber cavity. The test area inside the reverberation chamber cavity is arranged at an interval from the phased array antenna, and the test area is used to place the device under test.

[0010] The distance between the test area and the inner wall of the reverberation chamber and the phased array antenna is more than λ / 4, where λ is the wavelength corresponding to the lowest available frequency of the reverberation chamber.

[0011] The phased array antenna includes an array antenna and a phase shifter. The array antenna is a linear array or a planar array. The array antenna includes n antenna elements arranged in an array, n≥4, and each antenna element is connected to the phase shifter.

[0012] In the phased array antenna, the phase difference between adjacent antenna elements is the same. By changing the value of the phase difference between the antenna elements, the beam pointing angle of the phased array antenna is adjusted so that the field strength distribution in the test area meets the test conditions.

[0013] 2. A test system for a phase-stirred reverberation chamber

[0014] The test system includes a phase-stirred reverberation chamber, a control device and a monitoring device. The control device is connected to the phased array antenna of the phase-stirred reverberation chamber. The monitoring device is connected to the control device. The monitoring device is used to collect the field strength in the test area of the phase-stirred reverberation chamber, and the control device is used to generate a control signal for adjusting the phase difference of the phased array antenna.

[0015] The monitoring device includes a receiving antenna and a vector network analyzer. Several receiving antennas are placed in the test area of the phase-stirred reverberation chamber, and the vector network analyzer is placed outside the phase-stirred reverberation chamber and the vector network analyzer is connected to each receiving antenna.

[0016] 3. A reverberation chamber stirring method based on a phased array antenna

[0017] S1: Set up a phase-stirred reverberation chamber and a test system for the phase-stirred reverberation chamber;

[0018] S2: Determine the number of samples for phase scanning. Use the control device to perform phase control on the phased array antenna. The phased array antenna emits signals in the reverberation chamber box, and use the monitoring device to obtain field strength data. The field strength data refers to the field strength component values at 8 vertices of the area under test when the phase difference of the phased array antenna is fixed. Among them, using the control device to perform phase control on the phased array antenna is specifically to set different values of the phase difference between the antenna elements in the phased array antenna through a digital phase shifter, so that the beam pointing angle of the phased array antenna changes.

[0019] S3: Calculate and obtain the number of independent samples among the number of samples for phase scanning. Select several samples from the independent samples to calculate the field uniformity of the test area 8. If the field uniformity of the test area 8 does not meet the test conditions, adjust the control signal of the phased array antenna until the field uniformity of the test area 8 meets the test conditions. Among them, the method for calculating the field uniformity is the method described in the IEC61000-4-21 standard. The test conditions are specifically the IEC 61000-4-21 standard values.

[0020] In S2, the specific process of using the control device to perform phase control on the phased array antenna is to set different values of the phase difference between adjacent antenna elements in the phased array antenna through a digital phase shifter, so as to change the beam pointing angle of the phased array antenna.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The operation process of the present invention is carried out entirely in the reverberation chamber. It is simple, convenient, and has a low cost, and can quickly and efficiently realize the testing of various devices.

[0023] The method proposed by the present invention uses the method of phased array beam scanning, which can replace the mechanical stirring device. By changing the input phase difference of the phased array antenna, the gain beam is scanned, so as to achieve the stirring effect and meet the field strength uniformity requirements in the test area of the reverberation chamber.

[0024] In actual testing, compared with the traditional testing method, the present invention can greatly improve the testing efficiency, simplify the cavity structure, reduce the size of the reverberation chamber cavity, increase the volume of the test area of the reverberation chamber, and reduce the testing cost of the reverberation chamber. Description of the Drawings

[0025] Figure 1 It is the antenna unit structure diagram in Embodiment 1 of the present invention.

[0026] Figure 2 It is the schematic diagram of the phase stirring reverberation chamber testing device in Embodiment 1 of the present invention.

[0027] Figure 3 It is the calculation result of the correlation coefficient in Embodiment 1 of the present invention.

[0028] Figure 4 It is the calculation result of the field strength uniformity of the reverberation chamber in Embodiment 1 of the present invention.

[0029] Figure 5 It is the schematic diagram of the phase stirring reverberation chamber testing device in Embodiment 2 of the present invention.

[0030] Figure 6 It is the MIMO channel K-factor CDF distribution diagram in Embodiment 2 of the present invention.

[0031] In the figure: 1. director, 2. antenna patch, 3. feed line, 4. ground plane, 5. dielectric substrate, 6. receiving antenna, 7. vector network analyzer, 8. test area, 9. reverberation chamber cavity, 10. array antenna, 11. phase shifter, 12. signal generator, 13. computer, 14. power amplifier, 15. electric field probe. DETAILED DESCRIPTION

[0032] The specific implementation method of the present invention is described below with reference to the accompanying drawings and examples, but the present invention is not limited to this embodiment.

[0033] Embodiment 1

[0034] The present invention proposes a phase-stirred reverberation chamber, such as Figure 1 As shown, the phase-stirred reverberation chamber includes a phased array antenna, and the phased array antenna is placed in the reverberation chamber cavity 9. The test area 8 in the reverberation chamber cavity 9 is arranged at intervals from the phased array antenna, and the test area 8 is used to place the device to be tested. The test area 8 is spaced more than λ / 4 from the inner wall of the reverberation chamber and the phased array antenna, where λ is the wavelength corresponding to the lowest available frequency of the reverberation chamber.

[0035] The phased array antenna includes an array antenna 10 and a phase shifter 11. The antenna array needs to have good directivity, very low return loss and a wide frequency band. The array antenna 10 includes n antenna units arranged in an array, n≥4, each antenna unit is connected to the phase shifter 11, and the phase shifter 11 is a digital phase shifter of several bits. The antenna units correspond to the number of bits of the digital phase shifter one by one. Each antenna unit can independently control the phase to achieve dynamic scanning of the beam. The phase shifter 11 is connected to the signal generator 12 through a power amplifier 14.

[0036] In the phased array antenna, the phase differences between different antenna units are the same. The beam pointing angle of the phased array antenna is adjusted by changing the value of the phase difference between the antenna units so that the field intensity distribution in the test area 8 meets the test conditions.

[0037] Exemplarily, the control terminal may be a computer, and the phase shifter is controlled by the computer to change the phase difference of the array antenna within a certain range to perform beam scanning.

[0038] Specifically, the implementation process of this embodiment is as follows:

[0039] S1. Design and debug the required antenna array;

[0040] Exemplarily, the antenna unit used in this embodiment is a Vivaldi antenna, such as Figure 2 (a) and Figure 2 As shown in (b), it includes a director 1, an antenna patch 2, a feed line 3, a ground plane 4 and a dielectric substrate 5.

[0041] Exemplarily, a 1×8 linear array is adopted in this embodiment, which has good directivity, low loss, and low back radiation characteristics in the range of 8-12 GHz, and the VSWR in the frequency band is <1.8.

[0042] S2. Determine the number of samples for phase scanning. Use a phased array antenna to transmit signals in the reverberation chamber box and perform phase scanning to obtain field strength data.

[0043] Exemplarily, an electric field probe 15 is used in this embodiment to collect field strength data.

[0044] S3. Calculate the number of independent samples. Select an appropriate number of samples to calculate the field uniformity and compare it with the IEC 61000-4-21 standard value.

[0045] The method for calculating the number of independent samples is the total number of samples divided by the number of steps that make the sample displacement correlation coefficient less than the threshold. The IEC 61000-4-21 standard stipulates that this threshold is 0.3678 (e / 1).

[0046] Exemplarily, to increase the stirred samples, 50 frequency samples within a 20 MHz bandwidth are introduced in this embodiment for mixing and stirring. The calculation results of the displacement correlation coefficients between the phase samples and the frequency samples are as shown in Figure 3 (a) of Figure 3 (b) of. Therefore, the number of independent samples of the phase samples and the frequency samples in this embodiment are 6 and 25 respectively, totaling 150.

[0047] Exemplarily, 150 independent samples are selected at equal intervals among all the samples. For the field uniformity, that is, the three directions of the eight vertices of the area to be measured, calculate the standard deviation of the electric field intensity. The calculation results of the field uniformity are as shown in Figure 4 shown. The red line is the IEC61000-4-21 standard value. Obviously, in this embodiment, the field strength uniformity result values of the standard deviation of the electric field intensity are mostly much smaller than the required threshold of 3 dB line, meeting the field strength uniformity requirements, and can be applied to the design and production of the source-stirred reverberation chamber, which has practical value for the actual testing of the reverberation chamber and electromagnetic compatibility.

[0048] Embodiment 2

[0049] The present invention also proposes a test system for a phase-stirred reverberation chamber, as shown in Figure 5 shown. The test system includes a phase-stirred reverberation chamber, a control device, and a monitoring device. The control device is a computer 13. The control device is connected to the phased array antenna of the phase-stirred reverberation chamber, and the monitoring device is connected to the control device. The monitoring device is used to collect the field strength in the test area 8 of the phase-stirred reverberation chamber, and the control device is used to generate control signals for the phased array antenna (i.e., adjust the phase of each antenna unit through a phase shifter).

[0050] The monitoring device includes a receiving antenna 6 and a vector network analyzer 7. A plurality of receiving antennas 6 are placed in the test area 8 of the phase-stirred reverberation chamber, and the vector network analyzer 7 is placed outside the phase-stirred reverberation chamber and the vector network analyzer 7 is connected to each receiving antenna 6.

[0051] The phase-stirred reverberation chamber test system is an exemplary refinement scheme of the first embodiment and is used for performing multi-input multi-output (MIMO) over-the-air (OTA) tests in the reverberation chamber. This embodiment uses the same reverberation chamber as the first embodiment, except that the electric field probes in the test area are replaced with a plurality of receiving antennas. These receiving antennas are placed at different positions and point in different directions, and are jointly connected to the vector network analyzer with the transmitting antenna. The stirring efficiency and MIMO performance in the reverberation chamber are represented by the parameters between the transmitting antenna and the receiving antenna.

[0052] Exemplarily, this embodiment uses a 2×4 MIMO channel, that is, two groups of four-element phased array antennas form the transmitting module, and four horn antennas form the receiving module. The phased array antenna uses the same Vivaldi antenna as the first embodiment.

[0053] Specifically, the implementation process of this embodiment is to repeat the process of the first embodiment several times until the S21 parameter of each channel is measured. If the number of ports of the vector network analyzer is insufficient, a radio frequency switch can be used to change the input and output channels.

[0054] Exemplarily, the cumulative distribution function (CDF) of the K factor of the 2×4 MIMO channel is as Figure 6 shown. The results show that the stirring efficiency of the reverberation chamber is good (the smaller the K factor value, the better the stirring efficiency), and the values between different channels are not very different, indicating that the reverberation chamber has good spatial uniformity and isotropy, is suitable for performing MIMO OTA tests, and has the advantages of faster test speed and smaller occupied space.

[0055] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0056] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0057] In addition, any combination can be made among various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should equally be regarded as the content disclosed by the present invention.

Claims

1. A phase-stirred reverberation chamber, characterized in that, It includes a phased array antenna. A phased array antenna is placed inside a reverberation chamber cavity (9). A test area (8) inside the reverberation chamber cavity (9) is arranged at an interval from the phased array antenna. The test area (8) is used to place a device under test; The test area (8) is spaced more than λ / 4 from the inner wall of the reverberation chamber and the phased array antenna, where λ is the wavelength corresponding to the lowest available frequency of the reverberation chamber; In the phased array antenna, the phase difference between adjacent antenna elements is the same. By changing the value of the phase difference between the antenna elements, the beam pointing angle of the phased array antenna is adjusted so that the field strength distribution in the test area (8) meets the test conditions.

2. The phase stirring reverberation chamber according to claim 1, wherein The phased array antenna includes an array antenna (10) and a phase shifter (11). The array antenna (10) includes n antenna elements arranged in an array, n≥4, and each antenna element is connected to the phase shifter (11).

3. A test system for a phase-stirred reverberation chamber, characterized in that, The test system includes a phase-stirred reverberation chamber, a control device, and a monitoring device. The control device is connected to the phased array antenna of the phase-stirred reverberation chamber. The monitoring device is connected to the control device. The monitoring device is used to collect the field strength in the test area (8) of the phase-stirred reverberation chamber, and the control device is used to generate a control signal for adjusting the phase difference of the phased array antenna; A phase-stirred reverberation chamber includes a phased array antenna. A phased array antenna is placed inside a reverberation chamber cavity (9). A test area (8) inside the reverberation chamber cavity (9) is arranged at an interval from the phased array antenna. The test area (8) is used to place a device under test; The test area (8) is spaced more than λ / 4 from the inner wall of the reverberation chamber and the phased array antenna, where λ is the wavelength corresponding to the lowest available frequency of the reverberation chamber; In the phased array antenna, the phase difference between adjacent antenna elements is the same. By changing the value of the phase difference between the antenna elements, the beam pointing angle of the phased array antenna is adjusted so that the field strength distribution in the test area (8) meets the test conditions.

4. The test system of a phase stirring reverberation chamber according to claim 3, characterized in that, The monitoring device includes a receiving antenna (6) and a vector network analyzer (7). A plurality of receiving antennas (6) are placed in the test area (8) of the phase-stirred reverberation chamber. The vector network analyzer (7) is placed outside the phase-stirred reverberation chamber and the vector network analyzer (7) is connected to each receiving antenna (6).

5. A reverberation chamber stirring method based on a phased array antenna, characterized in that, It includes the following steps: S1: Build a phase-stirred reverberation chamber and the test system of the phase-stirred reverberation chamber; A phase-stirred reverberation chamber includes a phased array antenna. A phased array antenna is placed inside a reverberation chamber cavity (9). A test area (8) inside the reverberation chamber cavity (9) is arranged at an interval from the phased array antenna. The test area (8) is used to place a device under test; The test area (8) is spaced more than λ / 4 from the inner wall of the reverberation chamber and the phased array antenna, where λ is the wavelength corresponding to the lowest available frequency of the reverberation chamber; In the phased array antenna, the phase difference between adjacent antenna elements is the same. By changing the value of the phase difference between the antenna elements, the beam pointing angle of the phased array antenna is adjusted so that the field strength distribution in the test area (8) meets the test conditions; S2: Determine the number of samples for phase scanning. Use the control device to perform phase control on the phased array antenna. The phased array antenna emits signals and scans in the reverberation chamber box, and use the monitoring device to collect field strength data; S3: Calculate and obtain the number of independent samples among the number of samples of phase scanning, select several samples from the number of independent samples to calculate the field uniformity of the test area (8). If the field uniformity of the test area (8) does not meet the test conditions, adjust the control signal of the phased array antenna until the field uniformity of the test area (8) meets the test conditions.

6. A reverberation chamber stirring method based on a phased array antenna according to claim 5, characterized in that In the above S2, the specific method of using the control device to perform phase control on the phased array antenna is to set different values of the phase difference between adjacent antenna elements in the phased array antenna through a digital phase shifter, so as to change the beam pointing angle of the phased array antenna.

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