A source-stirred reverberation chamber based on a mechanically variable multi-polarization array antenna and a stirring method

Abstract

This invention discloses a source stirring reverberation chamber and stirring method based on a mechanically variable frequency multi-polarized array antenna, belonging to the field of electromagnetic compatibility testing technology. The source stirring reverberation chamber based on the mechanically variable frequency multi-polarized array antenna includes a shielded shell, a transceiver system, and a control system. The shielded shell contains a closed test space. The transceiver system, including test antennas, is installed within the test space. The test antennas include at least two transmitting antennas and at least two receiving antennas. The same number of transmitting antennas are provided on three side walls, and each side wall has a receiving antenna that is centrally symmetrical with respect to the transmitting antennas about its geometric center. The control system is signal-connected to the transceiver system. According to a preset source stirring field control algorithm, the control system calculates and controls the amplitude and phase of the transmitting antenna feed signal, enabling the synthesis of a uniformly distributed random field within the test space, thus improving the electric field uniformity index in the low-frequency test area.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic compatibility testing technology, and in particular to a source stirring reverberation chamber and stirring method based on a mechanically variable frequency multipolar array antenna. Background Technology

[0002] Electromagnetic compatibility (EMC) testing is used to verify the immunity of electronic products in complex electromagnetic environments. Reverberation chambers, as an alternative to anechoic chambers, utilize high-quality metal shielded cavities and internal stirring devices to create a statistically uniform, isotropic, and randomly polarized electromagnetic environment within the test area. Because reverberation chambers can generate extremely high field strengths with relatively low input power, they are widely used in radiation susceptibility testing, and related testing standards such as IEC 61000-4-21 have been widely adopted.

[0003] In related technologies, reverberation chamber field uniformity is mainly achieved through mechanical stirring and source stirring. Mechanical stirring alters the boundary conditions of the chamber by rotating a mechanical stirrer, thereby changing the electromagnetic mode distribution within the chamber. However, mechanical stirring technology faces severe physical bottlenecks in the low-frequency range (especially 30MHz to 80MHz). First, mechanical stirring has insufficient boundary disturbance capability: according to reverberation chamber theory, the efficiency of the stirrer depends on its electrical size relative to the wavelength. At 30MHz, the electromagnetic wave wavelength is as long as 10 meters. Limited by the chamber space, the size of the mechanical stirrer is usually difficult to make sufficiently large, for example, exceeding half the wavelength. Therefore, in the low-frequency range, the disturbance of boundary conditions by the mechanical stirrer is extremely weak, resulting in insufficient independent sampling samples and difficulty in meeting the standard deviation requirements for field uniformity. Second, the minimum usable frequency is limited: the decrease in mechanical stirring efficiency directly leads to a higher minimum usable frequency for the reverberation chamber, limiting its application in the VHF band.

[0004] To address the aforementioned issues, related technologies employ source stirring to improve low-frequency performance, i.e., increasing the number of independent samples by altering the position or state of the transmitting source. However, current source stirring techniques mostly involve simple position switching or random feeding, lacking phase coordination between antenna elements. This incoherent excitation method cannot utilize the wavefront synthesis principle of array antennas to actively shape the intracavity field distribution, thus failing to fundamentally eliminate low-frequency standing wave dark regions. Summary of the Invention

[0005] The purpose of this invention is to provide a source stirring reverberation chamber and stirring method based on a mechanically variable frequency multipolar array antenna, which can be used to actively control the spatial distribution of electromagnetic field and improve the electric field uniformity index in the test area in the low frequency band.

[0006] This invention is achieved using the following technical solution:

[0007] On one hand, the present invention provides a source stirring reverberation chamber based on a mechanically variable frequency multipolar array antenna, comprising:

[0008] A shielding housing having an enclosed test space, the test space being constructed as a cuboid structure;

[0009] A transceiver system, comprising a test antenna disposed on three adjacent sidewalls of the test space to form an array, the test antenna comprising at least two transmitting antennas and at least two receiving antennas, the three sidewalls having the same number of transmitting antennas, and each sidewall having a receiving antenna that is centrally symmetrical with respect to the transmitting antennas thereon about the geometric center of the sidewall;

[0010] A control system is connected to the transceiver system by signal. The control system is adapted to calculate and control the amplitude and phase of the transmitting antenna feed signal according to a preset source-field control algorithm, so as to synthesize a uniformly distributed random field in the test space.

[0011] In this scheme, the test space is constructed as a cuboid structure, and the test antennas are arranged in an array on three adjacent sidewalls of the test space. The test antennas include at least two transmitting antennas and at least two receiving antennas. The same number of transmitting antennas are arranged on each of the three sidewalls, and each sidewall has a receiving antenna that is centrally symmetrical with respect to the transmitting antennas about its geometric center. By adjusting the excitation state of the transmitting antennas according to a preset source-stirring field control algorithm, the uniformity of the electric field distribution within the test space can be optimized. Using multi-polarized test antennas distributed on the three orthogonal sidewalls, combined with a source-stirring field control algorithm based on a theoretical model, rich field modes can be generated using the array synthesis principle. This approach eliminates the reliance on mechanical stirrers and, through the coordinated excitation and weighting coefficient optimization of the test antenna array, enables active control of the electromagnetic field spatial distribution. It overcomes the problem of insufficient boundary condition perturbation capability caused by the electrical size limitations of mechanical stirrers in the low-frequency band, improving the electric field uniformity index of the test area in the low-frequency band.

[0012] Optionally, the shortest straight-line distance between the radiating structure of the test antenna and the adjacent sidewall is not less than λ / 4, where λ is the wavelength corresponding to the set lowest frequency.

[0013] Optionally, the polarization direction of the transmitting antenna is perpendicular to its sidewall, and the polarization direction of the receiving antenna is perpendicular to its sidewall.

[0014] Optionally, the transceiver system further includes a transmitter connected to the transmitting antenna, and the receiving antenna connected to a matched load.

[0015] Optionally, the test antenna located on each of the sidewalls includes two transmitting antennas and two receiving antennas.

[0016] Optionally, the length of the test antenna is adjustable, and the control system is adapted to adjust the length of the test antenna according to the current test frequency. The adjustment method is: L=c / 4f, where L is the length of the test antenna, f is the current test frequency, and c is the speed of light.

[0017] Optionally, both the transmitting antenna and the receiving antenna are telescopic monopole antennas.

[0018] In this design, the source stirring reverberation chamber includes a shielded enclosure containing a closed test space. A transceiver system is installed within the test space, adapted to input interfering electromagnetic waves and to receive and measure the electric field strength at different locations within the test space. The transceiver system includes a test antenna with an adjustable length. The transceiver system is signal-connected to a control system, which adjusts the antenna length to a quarter wavelength according to the current test frequency. By changing the antenna length, it is ensured that the antenna remains in a resonant state across a wide frequency band from 30MHz to 80MHz, thus maintaining a low VSWR, avoiding impedance mismatch at low frequencies, and improving the efficiency of transmitter energy injection into the reverberation chamber.

[0019] On the other hand, this application provides a stirring method for a source stirring reverberation chamber based on a mechanically variable frequency multipolar array antenna as described in the first aspect, the method comprising the following steps:

[0020] S1, Construct a mapping model between the complex excitation parameters of the transmitting antenna and the electric field distribution in the test space;

[0021] S2 defines a uniformity metric function to characterize the degree of deviation of the electric field distribution in the test space from the target average field strength.

[0022] S3, Based on the uniformity metric function, the source mixing field control problem is modeled as a constrained optimization problem;

[0023] S4, Solve the optimization problem to obtain the optimal complex excitation parameters;

[0024] S5, the optimal complex excitation parameters are converted into control signals for the transmitting antenna and driven to be executed so that the electric field uniformity in the test space reaches the optimal level.

[0025] Optionally, the mapping model between the complex excitation parameters of the transmitting antenna and the electric field distribution in the test space is expressed as:

[0026] ,

[0027] In the formula, For electric field distribution, This refers to the number of transmitting antennas in the array antenna. For the first Complex excitation parameters of each transmitting antenna, For the first The generalized Green's function corresponding to each transmitting antenna For the location of the field, ω is the angular frequency.

[0028] Optionally, the uniformity metric function is defined to characterize the degree of deviation of the electric field distribution in the test space from the target average field strength. The uniformity metric function is expressed as follows:

[0029] ,

[0030] In the formula, It is a uniformity measurement function. For the test area, These are the weighting coefficients. yes The electric field strength at the location, The target average field strength, Let the order of the moment constraint be denoted by .

[0031] The source mixing field control problem is modeled as a constrained optimization problem based on the uniformity metric function, as follows:

[0032] ,

[0033] The constraints are:

[0034] ,

[0035] ,

[0036] ,

[0037] In the formula, These are weighting coefficients. For regularization parameters, The k-th order statistical moment of the electric field distribution is represented. For the corresponding set of statistical indicator constraints, This represents the feasible region for the transmitter's complex excitation parameters.

[0038] Optionally, the optimization problem can be solved using a numerical optimization algorithm.

[0039] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: This invention utilizes multi-polarized test antennas distributed on three orthogonal sidewalls, combined with a source-stirring field control algorithm based on a theoretical model, to generate rich field modes using array synthesis principles. This approach eliminates the reliance on mechanical stirrers, and through the coordinated excitation and weighting coefficient optimization of the test antenna array, it enables active control of the spatial distribution of the electromagnetic field; it overcomes the problem of insufficient boundary condition perturbation capability caused by the electrical size limitations of mechanical stirrers in the low-frequency band, and improves the electric field uniformity index of the test area in the low-frequency band. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments or related technologies of this disclosure, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the overall structure of the source stirring reverberation chamber based on a mechanically variable frequency multipolar array antenna provided in Embodiment 1 of the present invention;

[0042] Figure 2 This is a schematic flowchart of the stirring method for the source stirring reverberation chamber based on a mechanically variable frequency multipolar array antenna provided in Embodiment 4 of the present invention.

[0043] Figure 3 This is a simulation diagram of the uniformity of the x-polarization field in the test space provided in Embodiment 4 of the present invention;

[0044] Figure 4 This is a simulation diagram of the uniformity of the y-polarization field in the test space provided in Embodiment 4 of the present invention;

[0045] Figure 5 This is a simulation diagram of the uniformity of the z-polarization field in the test space provided in Embodiment 4 of the present invention;

[0046] Figure 6 This is a simulation diagram of the uniformity of the fully polarized field in the test space provided in Embodiment 4 of the present invention.

[0047] Explanation of reference numerals in the attached diagram: 1-Shielding housing; 2-Transmitting antenna; 3-Receiving antenna. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure / invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0049] Example 1

[0050] This embodiment 1 introduces a source stirring reverberation chamber based on a mechanically variable frequency multipolar array antenna, referencing... Figure 1 The source stirring reverberation chamber based on a mechanically variable frequency multipolar array antenna in this embodiment includes: a shielded housing 1, a transceiver system, and a control system. The shielded housing 1 contains a closed test space, which is constructed as a cuboid. A transceiver system is installed within the test space, adapted to input interfering electromagnetic waves into the test space and to receive and measure the electric field strength at different locations within the test space. Specifically, the transceiver system includes test antennas, which are arranged in an array on three adjacent sidewalls of the test space. Further, the test antennas include at least two transmitting antennas 2 and at least two receiving antennas 3. The same number of transmitting antennas are provided on the three sidewalls, and each sidewall has a receiving antenna that is centrally symmetrical with respect to the transmitting antennas about the geometric center of the sidewall. It should be noted that the number of receiving antennas 3 on each sidewall may be greater than the number of transmitting antennas 2. Besides the receiving antennas 3 that are centrally symmetrical with respect to the transmitting antennas 2 about the geometric center of the sidewall, the remaining receiving antennas 3 can be located at positions where more energy is received. In addition, it should be noted that the transmitting antenna 2 located on the same side wall should not be centrally symmetrical about the geometric center of the side wall.

[0051] Furthermore, the control system is connected to the transceiver system. The control system calculates and controls the amplitude and phase of the feed signal of the transmitting antenna 2 according to the preset source field control algorithm, so as to synthesize a uniformly distributed random field in the test space.

[0052] In some embodiments, the shortest straight-line distance between the radiating structure of the test antenna and the adjacent sidewall is not less than λ / 4, where λ is the wavelength corresponding to the set lowest frequency. This arrangement avoids the electric field zeros of low-order resonant modes in the test space, ensures sufficient space decorrelation between the test antennas, and is beneficial for uniform field synthesis.

[0053] By utilizing multi-polarized test antennas distributed on three orthogonal sidewalls and combining them with a source-stirring field control algorithm based on a theoretical model, rich field modes can be generated using the array synthesis principle. This approach eliminates the reliance on mechanical stirrers and, through the coordinated excitation of the test antenna array and optimization of weighting coefficients, enables active control of the spatial distribution of the electromagnetic field. It overcomes the problem of insufficient boundary condition perturbation capability caused by the electrical size limitations of mechanical stirrers in the low-frequency band, thus improving the electric field uniformity index of the test area in the low-frequency band.

[0054] Example 2

[0055] Based on the same inventive concept as Embodiment 1, Embodiment 2 provides an example for a test frequency band of 30MHz to 80MHz. In this embodiment, the shielding housing 1 is a metal wall structure, and the shielding housing 1 has a cubic shielded test space with dimensions of 10m × 10m × 10m. (Reference) Figure 1 To achieve effective multipath and multipolarization excitation in the low-frequency band, test antennas are arranged on three mutually perpendicular sidewalls of the shielded housing 1—the rear wall, left sidewall, and bottom wall—to form an antenna array. Each sidewall's test antenna includes two transmitting antennas 2 and two receiving antennas 3. Furthermore, the polarization direction of the transmitting antennas 2 is perpendicular to the sidewall they are located on. Each transmitting antenna 2 is connected to an independent transmitter, and multiple transmitting antennas 2 constitute a coherent excitation array capable of wavefront synthesis. The polarization direction of the receiving antennas 3 is perpendicular to the sidewall they are located on, and each receiving antenna 3 is connected to a matching load to absorb some reflected energy and improve the multipath transmission environment within the cavity.

[0056] In this embodiment, the distances of the two transmitting antennas 2 and the two receiving antennas 3 from the adjacent sidewalls are all 3 meters. In the test frequency band of 30MHz to 80MHz, the corresponding wavelength range is 0.9375m-2.5m, thus ensuring sufficient space for decorrelation between the test antennas, which is beneficial for uniform field synthesis.

[0057] Example 3

[0058] In existing technologies, reverberation chambers typically use broadband log-periodic antennas or biconical antennas as the transmitter. However, within the confined space of a reverberation chamber, due to strong cavity reflections and mutual coupling effects, broadband antennas often suffer from severe impedance mismatch at low frequencies, resulting in extremely high voltage standing wave ratios (VSWRs). This causes most of the power to be reflected back to the transmitter, not only reducing energy injection efficiency and forcing the test system to be equipped with extremely expensive high-power amplifiers, but also easily damaging the RF front-end equipment.

[0059] To address the aforementioned issues, in this embodiment 3, the length of the test antenna is adjustable. The control system is adapted to adjust the length of the test antenna to one-quarter of the wavelength according to the current test frequency. That is, L = c / 4f, where L is the length of the test antenna, f is the current test frequency, and c is the speed of light. For example:

[0060] When the test frequency is 30MHz, the length of each test antenna is extended to approximately 2.5 meters.

[0061] When the test frequency is 80MHz, the length of each test antenna is reduced to approximately 0.9375 meters.

[0062] By changing the length of the test antenna, it is ensured that the test antenna can always be in a resonant state in the low-frequency range, thereby maintaining a low VSWR of the test antenna, avoiding impedance mismatch in the low-frequency range, and improving the efficiency of transmitter energy injection into the reverberation chamber.

[0063] In some embodiments, both the transmitting antenna 2 and the receiving antenna 3 are length-adjustable telescopic monopole antennas, and the monopole antennas are driven to extend and retract by a servo motor. The control system is connected to the servo motor and is used to control the servo motor to drive the monopole antenna to extend and retract. During testing, the control system controls the servo motor to drive the monopole antenna to extend and retract so that its physical length follows the quarter-wavelength resonance principle.

[0064] Example 4

[0065] This embodiment 4 provides a stirring method for the source stirring reverberation chamber of a mechanically frequency-converting multi-polarized array antenna, based on the source stirring reverberation chamber of the mechanically frequency-converting multi-polarized array antenna in embodiment 1. (See reference...) Figure 2 The method includes the following steps:

[0066] S1, construct a mapping model between the complex excitation parameters of transmitting antenna 2 and the electric field distribution in the test space, the formula is:

[0067] ,

[0068] In the formula, For electric field distribution, This refers to the number of transmitting antennas in the array antenna. For the first Complex excitation parameters of each transmitting antenna, For the first The generalized Green's function corresponding to each transmitting antenna For the location of the field, ω is the angular frequency.

[0069] S2, Define the uniformity measurement function The formula is used to characterize the degree of deviation of the electric field distribution in the test space from the target average field strength:

[0070] ,

[0071] In the formula, It is a uniformity measurement function. This is the test area, the region within the test space. These are weighting coefficients. For the location of the field, yes The electric field strength at the location, The target average field strength, It is the order of the moment constraint;

[0072] S3, Based on the uniformity metric function, the source mixing plant regulation problem is modeled as a constrained optimization problem, expressed as:

[0073] ,

[0074] The constraints are:

[0075] ,

[0076] ,

[0077] ,

[0078] In the formula, These are weighting coefficients. For regularization parameters, The k-th order statistical moment of the electric field distribution is represented. For the corresponding set of statistical indicator constraints, This represents the feasible region for the transmitter's complex excitation parameters.

[0079] The problem of electric field uniformity control is modeled as a constrained optimization problem, and a regularization parameter is introduced to balance field uniformity with power cost.

[0080] S4. The optimization problem is solved using a numerical optimization algorithm to obtain the optimal complex excitation parameters.

[0081] S5 converts the optimal complex excitation parameters into control signals for transmitting antenna 2 and drives its execution so that the electric field uniformity in the test space reaches the optimal level.

[0082] refer to Figure 3 The figure shows the simulation results of the x-polarization field uniformity in the test space based on the method of this embodiment. The standard deviation is less than 4dB in the range of 30MHz to 80MHz.

[0083] refer to Figure 4The figure shows the simulation results of the y-polarization field uniformity in the test space based on the method of this embodiment. The standard deviation is less than 4dB in the range of 30MHz to 80MHz.

[0084] refer to Figure 5 The figure shows the simulation results of the z-polarization field uniformity in the test space based on the method of this embodiment. The standard deviation is less than 4dB in the range of 30MHz to 80MHz.

[0085] refer to Figure 6 The figure shows the simulation results of the uniformity of the fully polarized field in the test space based on the method of this embodiment. The standard deviation is less than 4dB in the range of 30MHz to 80MHz.

[0086] This embodiment eliminates the need for mechanical stirring. Through the coordinated excitation of the transmitting antenna 2 and the optimization of the weighting coefficients, it achieves active control over the spatial distribution of the electromagnetic field. It overcomes the problem of insufficient boundary condition disturbance capability caused by the electrical size limitation of mechanical stirrers in the low-frequency band and improves the electric field uniformity index of the test area in the low-frequency band.

[0087] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present disclosure / the present invention, and these improvements and modifications should also be considered within the scope of protection of the present disclosure / the present invention.

Claims

1. A stirring method for a source stirring reverberation chamber based on a mechanically frequency-converted multi-polarized array antenna, wherein the source stirring reverberation chamber based on the mechanically frequency-converted multi-polarized array antenna comprises: A shielding housing having an enclosed test space, the test space being constructed as a cuboid structure; A transceiver system, comprising a test antenna arranged in an array on three adjacent sidewalls of a test space, the test antenna including at least two transmitting antennas and at least two receiving antennas, the same number of transmitting antennas on the three sidewalls, and a receiving antenna on each sidewall that is centrally symmetrical with respect to the transmitting antennas about the geometric center of the sidewall, both the transmitting and receiving antennas being telescopic monopole antennas; and a control system connected to the transceiver system, the control system being adapted to calculate and control the amplitude and phase of the transmitting antenna feed signal according to a preset source-field control algorithm to synthesize a uniformly distributed random field within the test space, characterized by comprising the following steps: S1, Construct a mapping model between the complex excitation parameters of the transmitting antenna and the electric field distribution in the test space; S2 defines a uniformity metric function to characterize the degree of deviation of the electric field distribution in the test space from the target average field strength. S3, Based on the uniformity metric function, the source mixing field control problem is modeled as a constrained optimization problem; S4, Solve the optimization problem to obtain the optimal complex excitation parameters; S5, the optimal complex excitation parameters are converted into control signals for the transmitting antenna and driven to be executed so that the electric field uniformity in the test space reaches the optimal level.

2. The stirring method for the source stirring reverberation chamber based on a mechanically variable frequency multi-polarized array antenna according to claim 1, characterized in that, The mapping model between the complex excitation parameters of the transmitting antenna and the electric field distribution in the test space is expressed as: ， In the formula, For electric field distribution, This refers to the number of transmitting antennas in the array antenna. For the first Complex excitation parameters of each transmitting antenna, For the first The generalized Green's function corresponding to each transmitting antenna For the location of the field, ω is the angular frequency.

3. The stirring method for the source stirring reverberation chamber based on a mechanically variable frequency multi-polarized array antenna according to claim 2, characterized in that, The defined uniformity metric function characterizes the degree of deviation of the electric field distribution within the test space from the target average field strength. The uniformity metric function is expressed as follows: ， In the formula, It is a uniformity measurement function. For the test area, These are the weighting coefficients. yes The electric field strength at the location, The target average field strength, Let the order of the moment constraint be denoted by . The source mixing field control problem is modeled as a constrained optimization problem based on the uniformity metric function, as follows: ， The constraints are: ， ， ， In the formula, These are weighting coefficients. For regularization parameters, The k-th order statistical moment of the electric field distribution is represented. For the corresponding set of statistical indicator constraints, This represents the feasible region for the transmitter's complex excitation parameters.

4. The stirring method for the source stirring reverberation chamber based on a mechanically variable frequency multi-polarized array antenna according to claim 3, characterized in that, The optimization problem is solved using a numerical optimization algorithm.

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