An arbitrary electromagnetic scenario near-field simulation apparatus

Abstract

The application discloses a kind of arbitrary electromagnetic scene near-field simulation device, belong to electromagnetic test and simulation technical field.The device is mainly by target field, near-field synthesis method and near-field synthesis phased array face composition.Through the unit excitation weighting of optimization phased array aperture array, the synthesis of arbitrary target field can be realized in near-field synthesis surface, wherein phased array aperture array needs to be laid out according to the highest spatial frequency of target field.If the highest spatial frequency of target field is smaller, it requires that the unit spacing of phased array aperture array is larger, then phased array aperture array can be plane array;If the highest spatial frequency of target field is larger, it requires that the unit spacing of phased array aperture array is smaller and the space angle of phased array surface is larger, then phased array aperture array needs to be cylindrical array or spherical array.The application can realize the near-field simulation of arbitrary electromagnetic scene, has the advantages of compact system, electromagnetic environment simulation materialization, and high fidelity, can be applied to radar target scene, communication channel scene and other fields electromagnetic environment simulation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electromagnetic test and simulation, and particularly relates to an arbitrary electromagnetic scene near-field simulation device, which is mainly applied to near-field simulation of an arbitrary electromagnetic environment in scenarios such as missile-target encounter, automobile radar and communication channel. BACKGROUND

[0002] In the fields of missile-target encounter, automobile radar and communication channel, radars and targets, base stations and terminals not only interact in the traditional far-field region, but also interact in the near-field region, and the near-field interaction is more complex, which can be regarded as a synthesis of multiple far-field plane waves from different directions and with different amplitudes and phases. Existing electromagnetic environment simulation devices mostly simulate through radio frequency injection, and different clusters and different time delays are needed to synthesize a complex electromagnetic environment to be simulated in the far-field region, which usually requires a large number of devices and a large experimental environment, and the simulation result is not real and has poor precision. SUMMARY

[0003] To solve the above technical problems, the present application provides an arbitrary electromagnetic scene near-field simulation device. Based on the aperture near-field transmission principle, the highest spatial frequency of a target field and the physical size of an aperture array element are determined to determine a suitable array layout, so as to realize near-field synthesis of an arbitrary target field. By optimizing the element excitation weighting of the aperture array, an arbitrary complex electromagnetic environment target field (an electromagnetic environment to be simulated) can be synthesized in the aperture array near-field region.

[0004] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0005] An arbitrary electromagnetic scene near-field simulation device, the device comprising a target field setting unit, a phased array aperture array selection unit and a near-field synthesis result generation module, wherein,

[0006] The target field setting unit is used to give an arbitrary electromagnetic environment, including a single-direction far-field plane wave and an arbitrary complex near-field electromagnetic wave formed by superposition of multiple different-direction, amplitude and initial-phase plane waves;

[0007] The phased array aperture array selection unit calculates the target field spatial frequency of the arbitrary electromagnetic environment given by the target field setting unit, selects a corresponding phased array aperture array, and synthesizes a radiation field consistent with the amplitude and phase distribution of the target field;

[0008] The near-field synthesis result generation module is used to perform aperture optimization on the synthesized radiation field based on an aperture optimization algorithm to obtain a final near-field synthesis surface.

[0009] Further, the phased array aperture array selection unit comprises at least one of a phased array with controllable amplitude and phase, a phased array with only controllable phase, a programmable super surface reflection array with only controllable phase or a transmission array.

[0010] Further, the calculation of the target field space frequency of any electromagnetic environment given by the target field setting unit, the selection of the corresponding phased array aperture array includes: if the target field highest space frequency is small, the aperture array unit spacing is required to be large, then the planar aperture array is selected; if the target field highest space frequency is large, the aperture array unit spacing is required to be small and the phased array space angle is required to be large, then the cylindrical aperture array or the spherical aperture array is selected.

[0011] Further, when the planar aperture array is selected, according to the sampling theorem, the unit interval is determined by the highest space frequency of the target field:

[0012] (1)

[0013] wherein, is the unit interval, k max is the highest space frequency of the target field;

[0014] The unit interval of the cylindrical or spherical array is determined by the highest mode order of the target field:

[0015] (2)

[0016] wherein, is the unit interval of the array element in the spherical, cylindrical coordinate, M max is the highest mode order of the target field;

[0017] The highest mode order depends on the physical size of the target field:

[0018] (3)

[0019] In the formula, r t is the minimum radiation sphere radius surrounding the target field, k is the wave number in free space, and M0 is the mode order margin value related to the accuracy;

[0020] Then the unit interval in the rectangular coordinate system is represented as:

[0021] (4)

[0022] In the formula, R is the radius value of the cylindrical array or the spherical array;

[0023] The aperture angle range of the cylindrical or spherical array is adjusted by the following formula to ensure that the array synthesis result covers the highest space frequency of the target field:

[0024] (5)

[0025] In the formula, is the maximum aperture angle in the azimuth and elevation directions, respectively.

[0026] Further, the near-field comprehensive surface geometry distribution is consistent with the target field surface.

[0027] Further, the caliber optimization algorithm comprises any one of intersection algorithm, genetic algorithm and intelligent optimization algorithm.

[0028] The present application has the following advantages:

[0029] The existing electromagnetic environment simulation device is simulated through radio frequency injection, and the target field simulation result is not real. The present application can simulate the target field of any complex electromagnetic environment, and has the advantages of real object, higher reality and more compact system. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Fig. 1 is a schematic diagram of the principle of the present application;

[0031] Figure 2 Fig. 2 is the amplitude and phase distribution diagram of the first target field;

[0032] Figure 3 Fig. 3 is the angular spectrum distribution diagram of the first target field;

[0033] Figure 4 Fig. 4 is the near-field comprehensive result diagram of the first target field;

[0034] Figure 5 Fig. 5 is the near-field comprehensive error diagram of the first target field;

[0035] Figure 6 Fig. 6 is the amplitude and phase distribution diagram of the second target field;

[0036] Figure 7 Fig. 7 is the angular spectrum distribution diagram of the second target field;

[0037] Figure 8 Fig. 8 is the near-field comprehensive result diagram of the second target field;

[0038] Figure 9 Fig. 9 is the near-field comprehensive error diagram of the second target field;

[0039] Figure 10 Fig. 10 is the amplitude and phase distribution diagram of the third target field;

[0040] Figure 11 Fig. 11 is the angular spectrum distribution diagram of the third target field;

[0041] Figure 12 Fig. 12 is the near-field comprehensive result diagram of the third target field;

[0042] Figure 13 Fig. 13 is the near-field comprehensive error diagram of the third target field. DETAILED DESCRIPTION

[0043] The application is further illustrated below with reference to the accompanying drawings and specific embodiments.

[0044] As Figure 1 shown, the application provides an arbitrary electromagnetic scene near-field simulation device, comprising a target field setting unit, a phased array aperture array surface selection unit, and a near-field synthesis result generation module.

[0045] The target field setting unit is used to set an arbitrary electromagnetic environment, including but not limited to a single-direction far-field plane wave, an arbitrary complex near-field electromagnetic wave formed by superposition of multiple different-direction, amplitude, and initial-phase plane waves, and a geometrically distributed array including but not limited to a plane, a cylinder, and a sphere. Numericalization of the target field is achieved by using an electromagnetic calculation method, full-wave simulation method is used for electrically small-size targets, and a ray tracing method is used for electrically large-size targets.

[0046] The phased array aperture array surface selection unit has various forms, including but not limited to a phased array with controllable amplitude and phase, a phased array with controllable phase only, a programmable metasurface reflection array or transmission array with controllable phase only; the layout thereof is determined according to the highest spatial frequency of the target field setting unit to avoid contradiction between the required unit spacing of the highest spatial frequency of the target field and the actual physical size of the unit aperture, and the specific principle is as follows:

[0047] For a planar aperture array, according to the sampling theorem, the unit spacing is determined by the highest spatial frequency of the target field:

[0048] (1)

[0049] wherein, is the unit spacing of the array element, k max is the highest spatial frequency of the target field.

[0050] If the highest spatial frequency of the target field is small, the required unit spacing is large, and the synthesis of the target field can be achieved by using a planar array.

[0051] If the highest spatial frequency of the target field is large, the unit spacing satisfying the sampling theorem may be smaller than the target unit aperture size, and there is a possibility of unit interference. If the unit spacing is forcibly increased, the near-field synthesis result will be spatially frequency-spectrally aliasing, and the synthesis of the target field cannot be achieved by using a planar array. At this time, for the synthesis of the target field with a high spatial frequency, a cylindrical or spherical aperture array can be used for synthesis. The unit spacing of the cylindrical or spherical array is mainly determined by the highest mode order M max of the target field:

[0052] (2)

[0053] wherein, are the unit spacings of the array elements in the spherical and cylindrical coordinates, respectively, and Mmax The highest mode order of the target field.

[0054] The highest mode order is M max Depending on the physical size of the target field:

[0055] (3)

[0056] In the formula, r t is the minimum radiation sphere radius surrounding the target field, k is the wave number in free space, M0 is the mode order margin value related to the accuracy, and according to experience, M0=10 can guarantee most applications.

[0057] Then the unit interval in the rectangular coordinate system can be expressed as:

[0058] (4)

[0059] In the formula, R is the radius value of the cylindrical aperture array surface or the spherical aperture array surface.

[0060] Therefore, the radius value of the cylindrical array / spherical array is adjusted, so that the unit interval does not interfere under the premise of satisfying the sampling theorem. In addition, the aperture angle range of the cylindrical / spherical array surface can be adjusted by the following formula to ensure that the array surface synthesis result covers the highest spatial frequency of the target field.

[0061] (5)

[0062] In the formula, k max is the highest spatial frequency of the target field, k is the wave number in free space, is the maximum aperture angle in the azimuth direction and the elevation direction, respectively.

[0063] The near-field synthesis result generation module is located in the near-field area of the aperture array surface, and performs aperture array surface optimization on the selected aperture array surface, which is not limited to the intersection algorithm, genetic algorithm, intelligent optimization algorithm, etc. The synthesis of any target field can be realized on the near-field synthesis surface, and the geometric distribution is consistent with the target field surface.

[0064] Embodiment:

[0065] The following describes the specific implementation of the present application by synthesizing target fields with different amplitude and phase distributions and a working frequency of 10 GHz by using waveguide arrays. The waveguide unit uses an X-band standard waveguide, and the aperture size is 22.9 mm 10.2 mm.

[0066] First, the first target field shown in Figure 2 is synthesized, and the geometric distribution form is a plane, 210 mm 210 mm, as shown in Figure 3From the target field angular spectrum distribution, we know that its highest spatial frequency is less than k / 2. To integrate the target field, according to formula (1), the unit spacing can be greater than λ (30 mm). Therefore, the aperture array adopts a plane with equal spacing to prevent the units from interfering. 16. The waveguide planar array with a unit spacing of 30 mm synthesizes the target field. The distance between the near-field synthesis surface and the aperture array surface is 900 mm. The near-field synthesis results are as follows: Figure 4 As shown, Figure 2 By comparison, the near-field synthesis results are almost consistent with the target field amplitude and phase distribution. The near-field synthesis error is as follows: Figure 5 As shown in the figure, except for the large error at the edge of the target field, the comprehensive error in the rest of the area is very small. This is mainly due to the existence of an effective angular region in the plane near-field comprehensive aperture truncation.

[0067] Then for example Figure 6 The second target field is integrated, and its geometric distribution is a plane, 210 mm 210 mm, by Figure 7 From the target field angular spectrum distribution, it can be seen that its highest spatial frequency is about 0.8k in azimuth and less than k / 2 in elevation. In order to synthesize the target field through a planar array, according to formula (1), the unit spacing in azimuth must be less than 22 mm, which is smaller than the unit aperture size. Considering dual polarization, the use of a planar array layout will inevitably lead to interference between units in azimuth. If the unit spacing is forcibly increased, the near-field synthesis result spectrum will be aliased. In summary, it cannot be achieved through a planar array. Figure 6 The synthesis of the second target field shown in FIG. According to the present invention, the second target field can be synthesized by a cylindrical array. According to equations (2) to (3), the azimuth unit spacing is 4°. To avoid interference between the azimuth units, according to equation (4), the cylindrical radius is selected to be 500 mm, and the unit azimuth spacing is approximately 35 mm. Finally, in order to achieve coverage of the target field spatial frequency, the azimuth aperture angle is 60° according to equation (5). The pitch unit spacing can be greater than λ (30 mm) due to the high spatial frequency, and 16 units are selected in the pitch direction. The near-field synthesis surface is located at the origin of the cylindrical coordinates, and finally 31 The near-field synthesis results of the 16-cylinder array are as follows: Figure 8 As shown, the azimuth unit spacing is 6°, the elevation unit spacing is 30 mm, and the near-field comprehensive error is as follows: Figure 9 As shown, the combined error is very small.

[0068] Then for example Figure 10 The third target field shown is integrated, and its geometric distribution form is a plane, 210 mm 210 mm, by Figure 11The target field angle spectrum distribution can be known that the highest spatial frequency azimuth and elevation are both about 0.8k, to synthesize the target field by a planar array, according to formula (1), the element interval needs to be less than 22mm, which is less than the element aperture size, using planar array layout will inevitably lead to element interference, if the element interval is forcibly increased, it will lead to the near-field synthesis result spectrum aliasing, in summary, it cannot be realized by a planar array Figure 10 The synthesis of the third target field shown in FIG. 3. According to the present application, the third target field can be synthesized by a spherical array, according to formula (2)~formula (3), the azimuth element interval is 4°, to avoid element interference, according to formula (4), the spherical radius is selected as 500mm, the element interval is about 35mm, finally, to realize the coverage of the target field spatial frequency, through formula (5), the azimuth and elevation aperture angle is 60°. The near-field synthesis plane is located at the cylindrical coordinate origin, the final 31 The near-field synthesis result of the spherical array of 31 is shown in FIG. 4. Figure 12 Compared with FIG. 3, the near-field synthesis result is almost consistent with the target field amplitude distribution, the near-field synthesis error is shown in FIG. 5. Figure 10 The synthesis error is very small. Figure 13

[0069] In summary, the device proposed by the present application can realize near-field simulation of any electromagnetic scene.

[0070] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application, it should be understood that the above-described is only a specific embodiment of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.​

Claims

1. A near-field simulation device for arbitrary electromagnetic scenes, characterized in that: The device includes a target field setting unit, a phased array aperture selection unit, and a near-field comprehensive result generation module, wherein: The target field setting unit is used to provide an arbitrary electromagnetic environment, including a single-direction far-field plane wave and an arbitrary complex near-field electromagnetic wave formed by the superposition of multiple plane waves of different directions, amplitudes, and initial phases; The phased array aperture selection unit calculates the target field spatial frequency of any electromagnetic environment given by the target field setting unit, selects the corresponding phased array aperture, and synthesizes a radiation field consistent with the amplitude and phase distribution of the target field; The near-field synthesis result generation module is used to perform aperture optimization on the synthesized radiation field based on the aperture optimization algorithm to obtain the final near-field synthesis surface; The calculating of the target field spatial frequency of the arbitrary electromagnetic environment given by the target field setting unit and selecting the corresponding phased array aperture array include: if the highest spatial frequency of the target field is small and the aperture array unit spacing is required to be large, then selecting a planar aperture array; if the highest spatial frequency of the target field is large and the aperture array unit spacing is required to be small and the phased array spatial angle is large, then selecting a cylindrical aperture array or a spherical aperture array; When a planar aperture array is selected, the unit spacing is determined by the highest spatial frequency of the target field according to the sampling theorem: (1) in, is the unit interval, k max is the highest spatial frequency of the target field; The element spacing of a cylindrical or spherical array is determined by the highest mode order of the target field: (2) in, are the unit spacing of the array elements in spherical and cylindrical coordinates respectively, M max is the highest mode order of the target field; The highest mode order depends on the physical size of the field of interest: (3) Where, r t is the minimum radiation sphere radius surrounding the target field, k is the wave number in free space, M 0 is the mode order margin value related to accuracy; Then the unit interval in the rectangular coordinate system is expressed as: (4) Where R is the radius of the cylindrical array or spherical array; The aperture angle range of the cylindrical or spherical array is adjusted by the following formula to ensure that the array synthesis result covers the highest spatial frequency of the target field: (5) Where, are the maximum aperture angles in azimuth and elevation, respectively.

2. The near-field simulation device for any electromagnetic scene according to claim 1, characterized in that: The phased array aperture selection unit includes at least one of a phased array with controllable amplitude and phase, a phased array with controllable only phase, a programmable metasurface reflection array or a transmission array with controllable only phase.

3. The near-field simulation device for any electromagnetic scene according to claim 1, characterized in that: The geometric distribution of the near-field comprehensive surface is consistent with that of the target scene.

4. The near-field simulation device for arbitrary electromagnetic scenes according to claim 1, characterized in that: The aperture optimization algorithm includes any one of an intersection algorithm, a genetic algorithm, and an intelligent optimization algorithm.

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