Near-field simulation device for any electromagnetic scene

Abstract

The invention discloses a near-field simulation device for any electromagnetic scene, and belongs to the technical field of electromagnetic testing and simulation. The device is mainly composed of a target field, a near-field comprehensive method and a near-field comprehensive phased array plane. By optimizing the unit excitation weighting of the phased array aperture array plane, the integration of any target field can be realized on the near-field integration plane, and the phased array aperture array plane needs to be arranged according to the highest spatial frequency of the target field. If the highest spatial frequency of the target field is relatively small and the distance between the phased array aperture array plane units is required to be relatively large, the phased array aperture array plane can be a planar array; if the highest spatial frequency of the target field is large, the distance between the phased array aperture array plane units is required to be small, and the space field angle of the phased array plane is required to be large, the phased array aperture array plane needs to be a cylindrical array or a spherical array. According to the invention, near-field simulation of any electromagnetic scene can be realized, and the system has the advantages of compact system, materialization of electromagnetic environment simulation and high fidelity, and can be applied to physical electromagnetic environment simulation in the fields of radar target scenes, communication channel scenes and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic testing and simulation, and specifically relates to a near-field simulation device for arbitrary electromagnetic scenes, which is mainly used for near-field simulation of arbitrary electromagnetic environments in scenes such as missile-target rendezvous, automobile radar, and communication channels. Background Art

[0002] In the fields of missile-target rendezvous, automotive radar, communication channels, etc., radar and target, base station and terminal interact not only in the traditional far field, but also in the near field. The near field interaction is more complex and can be seen as the synthesis of far field plane waves from multiple different directions and with different amplitudes and phases. Existing electromagnetic environment simulation devices mostly use RF injection simulation, which requires different clusters and different time delays to synthesize the complex electromagnetic environment to be simulated in the far field. It usually requires a large amount of equipment and a sufficiently large experimental environment, and the simulation results are not realistic and have poor accuracy. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a near-field simulation device for arbitrary electromagnetic scenes. Based on the principle of aperture near-field transmission, according to the highest spatial frequency of the target field and the physical size of the aperture array unit, a suitable array layout is determined to achieve near-field synthesis of any target field, and by optimizing the unit excitation weighting of the aperture array, any complex electromagnetic environment target field (electromagnetic environment to be simulated) can be synthesized in the near-field area of ​​the aperture array.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A near-field simulation device for any electromagnetic scene, comprising a target field setting unit, a phased array aperture selection unit, and a near-field comprehensive result generation module, wherein:

[0006] The target field setting unit is used to provide any electromagnetic environment, including a single-direction far-field plane wave, and any complex near-field electromagnetic wave formed by the superposition of multiple plane waves of different directions, amplitudes, and initial phases;

[0007] 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 target field amplitude and phase distribution;

[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] Furthermore, the phased array aperture selection unit includes at least one of a phased array with controllable amplitude and phase, a phased array with controllable phase only, and a programmable metasurface reflection array or transmission array with controllable phase only.

[0010] Further, the calculating of the target field spatial frequency of any electromagnetic environment given by the target field setting unit and the selecting of 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 a plane aperture array is selected; 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 space angle is large, then a cylindrical aperture array or a spherical aperture array is selected.

[0011] Furthermore, 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:

[0012] (1)

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

[0014] The cell spacing of a cylindrical or spherical array is determined by the highest mode order of the target field:

[0015] (2)

[0016] in, are the unit spacing of the array elements in spherical and cylindrical coordinates, M max is the highest mode order of the target field;

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

[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 accuracy;

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

[0021] (4)

[0022] Where R is the radius of the cylindrical array or 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 spatial frequency of the target field:

[0024] (5)

[0025] In the formula, are the maximum aperture angles in azimuth and elevation respectively.

[0026] Furthermore, the geometric distribution of the near-field comprehensive surface is consistent with that of the target field.

[0027] Furthermore, the aperture optimization algorithm includes any one of an intersection algorithm, a genetic algorithm, and an intelligent optimization algorithm.

[0028] The beneficial effects of the present invention are:

[0029] Existing electromagnetic environment simulation devices mostly use radio frequency injection simulation, and the target field simulation results are not realistic. The present invention can simulate the target field of any complex electromagnetic environment, and has the advantages of physical and realistic target field simulation results and a more compact system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the principle of a near-field simulation device for arbitrary electromagnetic scenes according to the present invention;

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

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

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

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

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

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

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

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

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

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

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

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

[0043] The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0044] like Figure 1 As shown, the present invention provides a near-field simulation device for an arbitrary electromagnetic scene, including a target field setting unit, a phased array aperture selection unit, and a near-field comprehensive result generation module.

[0045] The target field setting unit is used to set any electromagnetic environment, including but not limited to single-direction far-field plane waves, any complex near-field electromagnetic waves formed by the superposition of multiple plane waves of different directions, amplitudes, and initial phases, and various geometric distributions, including but not limited to planes, cylinders, and spheres. The target field is digitized using electromagnetic calculation methods, and the full-wave simulation method is used for electrically small-sized targets, and the ray tracing method is used for electrically large-sized targets;

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

[0047] When the unit layout is 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] in, is the array element spacing, k max is the highest spatial frequency of the target field.

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

[0051] If the highest spatial frequency of the target field is large, the unit spacing that satisfies 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 spatial spectrum of the near-field synthesis result will be aliased, and the target field cannot be synthesized through the plane array. At this time, for the synthesis of the target field with a higher spatial frequency, it can be achieved through the cylindrical or spherical aperture array. The unit spacing of the cylindrical or spherical array is mainly determined by the highest mode order M of the target field. max Sure:

[0052] (2)

[0053] in, are the unit spacing of the array elements in spherical and cylindrical coordinates, Mmax is the highest mode order of the target field.

[0054] The highest mode order is M max Depends 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, and M0 is the mode order margin value related to accuracy. 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] Where R is the radius of the cylindrical aperture array or the spherical aperture array.

[0060] Therefore, by adjusting the radius of the cylindrical / spherical array, it is possible to ensure that there is no interference between units while satisfying the sampling theorem. In addition, the aperture angle range of the cylindrical / spherical array can be adjusted by the following formula to ensure that the array 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 free space wave number, are the maximum aperture angles in azimuth and elevation respectively.

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

[0064] Example:

[0065] The following is a specific embodiment of the present invention, using a target field with different amplitude and phase distributions at a waveguide array integrated operating frequency of 10 GHz. The waveguide unit uses an X-band standard waveguide with an aperture size of 22.9 mm. 10.2 mm.

[0066] First, Figure 2 The first target field shown is integrated, and its geometric distribution form is a plane, 210 mm 210 mm, by Figure 3From the target field angular spectrum distribution, it can be seen that the 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, which is mainly due to the existence of an effective angular domain in the plane near-field comprehensive aperture truncation;

[0067] Then for example Figure 6 The second target field shown is integrated, and its geometric distribution form 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 integrate 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 the 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, 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 higher spatial frequency, and 16 units are selected in the pitch direction. The near-field synthesis plane 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: Fig. 9 As shown, the combined error is very small.

[0068] Then for example Fig.10 The third target field shown is integrated, and its geometric distribution form is a plane, 210 mm 210 mm, by Fig.11From the target field angular spectrum distribution, it can be seen that the highest spatial frequency in both azimuth and elevation is about 0.8k. To integrate the target field through a planar array, according to formula (1), the unit spacing must be less than 22 mm, which is smaller than the unit aperture size. The use of a planar array layout will inevitably lead to unit interference. If the unit spacing is forcibly increased, the near-field integrated result spectrum will be aliased. In summary, it cannot be achieved through a planar array. Fig.10 The synthesis of the third target field shown in FIG. According to the present invention, the third target field can be synthesized by a spherical array. According to equations (2) to (3), the azimuth unit spacing is 4°. To avoid unit interference, according to equation (4), the spherical radius is selected to be 500 mm, and the unit spacing is about 35 mm. Finally, in order to achieve coverage of the target field spatial frequency, the azimuth and elevation aperture angles are obtained to be 60° through equation (5). The near-field synthesis plane is located at the origin of the cylindrical coordinates. Finally, 31 The near-field comprehensive results of the spherical array of 31 are as follows Fig.12 As shown, Fig.10 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: Fig.13 As shown, the combined error is very small.

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

[0070] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A near-field simulation device for any electromagnetic scene, characterized in that: The device comprises 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 any electromagnetic environment, including a single-direction far-field plane wave, and any 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 target field amplitude and phase distribution; 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.

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 phase only, and a programmable metasurface reflection array or transmission array with controllable phase only.

3. The near-field simulation device for any electromagnetic scene according to claim 1, characterized in that: The calculating of the target field spatial frequency of any electromagnetic environment given by the target field setting unit and the selecting of the corresponding phased array aperture array surface include: if the highest spatial frequency of the target field is small and the aperture array surface unit spacing is required to be large, then a plane aperture array surface is selected; if the highest spatial frequency of the target field is large and the aperture array surface unit spacing is required to be small and the phased array surface spatial angle is large, then a cylindrical aperture array surface or a spherical aperture array surface is selected.

4. The near-field simulation device for any electromagnetic scene according to claim 3, characterized in that: 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 cell 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, 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) 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 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) In the formula, are the maximum aperture angles in azimuth and elevation respectively.

5. 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.

6. The near-field simulation device for any electromagnetic scene 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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