Array antenna radiation near-field prediction method based on polarization vector synthesis

Abstract

The invention discloses an array antenna radiation near-field prediction method based on polarization vector synthesis, and the method comprises the following steps: 1) constructing a unit characteristic representation matrix for antenna units of an array antenna; 2) constructing an array configuration description matrix of the array antenna according to the unit characteristic representation matrix; 3) setting parameters of array frequency, radiation power and radiation efficiency; 4) projecting the source polarization vector from the unit local coordinate system to the array global coordinate system; 5) calculating the projection of the source polarization vector at the field point according to the position of the field observation point; 6) decomposing the projection of the source polarization vector at the field point, and calculating a horizontal polarization coefficient and a vertical polarization coefficient; and 7) calculating a horizontal polarization field, a vertical polarization field and a total field at the field point. Compared with a full-wave method, the method has the advantage that the array antenna radiation near-field prediction calculation efficiency is higher by adopting the radiation field analysis calculation model based on polarization vector synthesis.

Description

Technical Field

[0001] The present invention relates to an array antenna radiation field prediction technology, and in particular to an array antenna radiation near field prediction method based on polarization vector synthesis. Background Art

[0002] Array antennas are composed of many antenna units and have the advantage of high directivity compared to traditional single antennas. Array antennas offset the radiation beam by controlling the feeding phase of the antenna elements and achieve beam scanning through electrical control. They have fast beam scanning capabilities that are far superior to traditional mechanical scanning array antennas.

[0003] At present, the application of array antennas mainly focuses on far-field radiation characteristics. However, with the increase in application scenarios, the near-field characteristics of array antennas have gradually become a research hotspot. For the near-field analysis of array antennas, full-wave simulation methods are often used, such as HFSS, FEKO, CST and other full-wave simulation software, which are based on numerical algorithms such as the method of moments and the finite difference method, and can provide better calculation accuracy. However, since modern array antennas are mostly characterized by large electrical size, multi-scale space, and material diversity, full-wave analysis will consume huge computing resources and computing time.

[0004] In the case of full-wave simulation limitations, the near-field analysis formula based on the superposition principle is currently commonly used. On the one hand, this is a scalar field strength synthesis formula, which cannot provide polarization information, especially longitudinal polarization information; on the other hand, it does not consider the influence of coupling between units. Unlike the far field, the near field of the array antenna has nonlinear spatial position factors between different array elements, and the beam from each array element to the observation point cannot be processed in parallel; the near-field antenna needs to accurately consider the nonlinear spatial position factors of each point when designing. The calculation of near-field information cannot use a fixed phase center. During the superposition of the radiation field, the phase center continues to shift with the antenna unit. At the same time, the near-field beamforming dimension will also change from the far-field (θ, φ) to (x, y, z), and the polarization will become a three-dimensional vector polarization (e x ,e y ,e z ). There is obvious longitudinal polarization in the near-field space. The conventional scalar field synthesis formula based on the superposition principle is obviously not applicable enough, especially in scenarios involving near-field focus scanning and polarization control. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for predicting the near field of radiation of an array antenna based on polarization vector synthesis in view of the defects in the prior art.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a method for predicting the near field of radiation of an array antenna based on polarization vector synthesis, comprising the following steps:

[0007] 1) For the antenna elements of the array antenna, a unit characteristic representation matrix is ​​constructed; the details are as follows:

[0008] For antenna unit n, construct a 3*5 matrix A n , whose structure is

[0009]

[0010] in, It is a spatial rotation matrix, which is used to represent the orientation information of the unit in the unit's local coordinate system;

[0011] are the position coordinates of the antenna unit, calculated according to the geometric array method;

[0012] Amp is the excitation amplitude of the array element, Pha is the phase of the array element; Elt is the type index of the directional pattern;

[0013] 2) constructing an array configuration description matrix of the array antenna according to the unit characteristic characterization matrix;

[0014] For an array antenna consisting of K elements, construct a 3*5*K matrix B;

[0015] 3) Set the array frequency, radiation power, and radiation efficiency parameters;

[0016] 4) Project the source polarization vector from the unit local coordinate system to the array global coordinate system;

[0017] For a linearly polarized antenna, the polarization vector of element n on the aperture plane is e, which is set as a unit vector along the x-axis. Then its coordinate in the local coordinate system of the element is u e =(1,0,0), the origin of the local coordinate system is u o =(0;0;0);

[0018] Then the unit n source polarization vector is projected from the unit local coordinate system to the array global coordinate system

[0019]

[0020] u og is the origin of the array global coordinate system, u eg is the unit vector along the x-axis in the array global coordinate system;

[0021] 5) According to the position of the field observation point, calculate the projection of the source polarization vector at the field point;

[0022] 5.1) Construct polarization rotation matrix;

[0023] Assume that the spherical coordinate position of the field observation point in the global coordinate system is Then the polarization rotation matrix is:

[0024]

[0025] Among them, Prot is the polarization rotation matrix, Ptra is the translation matrix, ZR represents rotation around the z-axis, and YR represents rotation around the y-axis;

[0026]

[0027] 5.2) According to the position of the field observation point, the polarization rotation matrix is ​​used to obtain the projection of the source polarization vector at the field point;

[0028]

[0029] Among them, inv is the matrix inversion operation, u f is the projected vector, u of is the source point coordinate after projection, u ef is the endpoint coordinate after projection;

[0030] 6) Decompose the projection of the source polarization vector at the field point and calculate the horizontal polarization coefficient and the vertical polarization coefficient;

[0031] For a linearly polarized antenna unit, since the electric field polarization vector is assumed to be along the x-axis, the horizontal polarization component corresponds to the vector u f The y component of the vertical polarization component corresponds to the vector u f The z component of

[0032] 7) According to the projection decomposition results, calculate the horizontal polarization field, vertical polarization field and total field at the field point; the process is as follows:

[0033] 7.1) The projection of the calculated field point in the local coordinate system at the unit antenna n is:

[0034]

[0035] in, is the Cartesian coordinate of the projection of the field point in the local coordinate system at the element antenna n;

[0036] Convert Cartesian coordinates to spherical coordinates in,

[0037]

[0038] 7.2) According to the unit pattern data, determine The corresponding power pattern gain value g is calculated based on the power pattern gain value. The pattern weighting factor of the unit n at the field point is expressed as:

[0039] eleAmp=10^(g / 20)

[0040] eleAmp is the directional pattern weighting factor of unit n;

[0041] 7.3) The vertical and horizontal polarization fields generated by antenna element n at the field point are

[0042]

[0043] Among them, Evpn and Ehpn are the vertical polarization field and the horizontal polarization field; Amp is the excitation amplitude of the unit, eleAmp is the directional pattern weighting factor; |VP| and |HP| are the absolute values ​​of the vertical and horizontal polarization coefficients respectively; PhaVPt and PhaHPt are the phases of the vertical field and the horizontal field, as expressed by the following formula:

[0044]

[0045] Where k is the wave number, k*r loc is the phase brought by spatial path propagation, Pha is the unit excitation phase; PhaVP and PhaHP are the correction phases representing the positive and negative directions of vertical polarization and horizontal polarization; they are expressed as follows:

[0046]

[0047] The above is the field generated by unit n;

[0048] 7.4) For an array antenna with K elements, the polarization field is

[0049]

[0050] The total field is:

[0051] Among them, Evp is the vertical polarization field of the array antenna, and Ehp is the horizontal polarization field of the array antenna.

[0052] According to the above scheme, the Elt directional pattern type is an isolated directional pattern.

[0053] According to the above scheme, in step 4), for the linearly polarized antenna, the polarization vector of unit n on the aperture plane is e, which is set as a unit vector along the x-axis, and its coordinate in the unit local coordinate system is u e =(1,0,0), the origin of the local coordinate system is u o =(0;0;0);

[0054] Then the unit n source polarization vector is projected from the unit local coordinate system to the array global coordinate system

[0055]

[0056] uog is the coordinate of the origin of the local coordinate system in the global coordinate system after projection transformation, u eg is the coordinate of the source unit vector in global coordinates after projection transformation;

[0057] According to the above scheme, in step 5), the details are as follows:

[0058] 5.1) Construct polarization rotation matrix;

[0059] Assume that the spherical coordinate position of the field observation point in the global coordinate system is Then the polarization rotation matrix is:

[0060]

[0061] Among them, Prot is the polarization rotation matrix, Ptra is the translation matrix, ZR represents rotation around the z-axis, and YR represents rotation around the y-axis;

[0062]

[0063]

[0064] 5.2) According to the position of the field observation point, the polarization rotation matrix is ​​used to obtain the projection of the source polarization vector at the field point;

[0065]

[0066] Among them, inv is the matrix inversion operation, u f is the projected vector, u of is the source point coordinate after projection, u ef are the endpoint coordinates after projection.

[0067] According to the above scheme, the Elt directional pattern type is an isolated directional pattern.

[0068] According to the above scheme, in step 7.3), the mutual coupling effect compensation correction is performed for the antenna unit n according to the following formula;

[0069]

[0070] Among them, s nm is the array S parameter model, which can be obtained through full-wave simulation software simulation or actual test, and m and n are unit numbers.

[0071] The beneficial effects produced by the present invention are:

[0072] 1. The present invention adopts a radiation field analytical calculation model based on polarization vector synthesis, which has higher calculation efficiency than the full-wave method;

[0073] 2. The present invention can effectively calculate the polarization field generated by the source polarization vector at the field point by constructing a polarization rotation matrix. Compared with the commonly used scalar field synthesis formula, it fully considers the contribution of each polarization component to the near field, and can not only obtain the near-field total radiation field information, but also obtain each polarization field, polarization field phase, axial ratio and other useful information.

[0074] 3. The present invention uses the array S parameter matrix to correct the excitation, and while ensuring the calculation speed, the calculated radiation field also includes a certain mutual coupling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0076] Figure 1 is a method flow chart of an embodiment of the present invention;

[0077] Figure 2 is a schematic diagram of transformation between the global coordinate system and the unit local coordinate system according to an embodiment of the present invention; Figure 3 is a schematic diagram of radiation characteristics of a horn antenna unit according to an embodiment of the present invention;

[0078] Figure 4 is a schematic diagram of normal radiation field distribution according to an embodiment of the present invention;

[0079] Figure 5 is a schematic diagram of using directional pattern data to characterize the spatial radiation characteristics of a unit antenna according to an embodiment of the present invention;

[0080] Figure 6 is a schematic diagram of near-field calculation results obtained based on the method of the present invention in an embodiment of the present invention;

[0081] Figure 7 It is a schematic diagram of near-field calculation results obtained based on the method of the present invention in an embodiment of the present invention. DETAILED DESCRIPTION

[0082] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0083] like Figure 1 As shown, a method for predicting the near field of radiation of an array antenna based on polarization vector synthesis includes the following steps:

[0084] 1) For the antenna elements of the array antenna, a unit characteristic representation matrix is ​​constructed; the details are as follows:

[0085] For antenna unit n, construct a 3*5 matrix A n , whose structure is

[0086]

[0087] in, It is a spatial rotation matrix, which is used to represent the orientation information of the unit in the unit's local coordinate system;

[0088] The spatial rotation matrix can be obtained by rotating the global coordinate system around the axis. According to the order of the rotation transformation around the axis, if we rotate α around the x-axis first, then β around the y-axis, and finally γ around the z-axis, then

[0089] rot=XR*YR*ZR

[0090] in

[0091]

[0092]

[0093] When the order of the transformations around the axes changes, the order of the rotation matrix multiplications must also change accordingly;

[0094] are the position coordinates of the antenna unit, calculated according to the geometric array method;

[0095] Amp is the excitation amplitude of the array element, Pha is the phase of the array element; Elt is the type index of the directional pattern; Elt directional pattern types can be divided into two categories: isolated directional pattern and active directional pattern, which can be represented by 'sl' and 'at' respectively; isolated directional pattern corresponds to the directional pattern data in a single antenna environment, which does not include the array mutual coupling effect. Active directional pattern corresponds to the directional pattern data of the unit in an array environment, which includes the array mutual coupling effect.

[0096] For large arrays, extracting the active pattern of antenna elements one by one consumes a lot of computing time and resources. The present invention uses isolated patterns and then corrects the excitation using array port S parameters to compensate for the mutual coupling effect.

[0097] 2) constructing an array configuration description matrix of the array antenna according to the unit characteristic characterization matrix;

[0098] The unit characteristic matrix is ​​a 3*5 matrix A n , for an array antenna consisting of K units, construct a 3*5*K matrix B;

[0099] The entire array spatial orientation, position, excitation distribution, unit information, etc. are all in matrix B. By modifying matrix B, the configuration parameters of the array simulation can be modified.

[0100] 3) Set the array frequency, radiation power, and radiation efficiency parameters;

[0101] 4) Project the source polarization vector from the unit local coordinate system to the array global coordinate system, such as Figure 2 ;

[0102] For a linearly polarized antenna, the polarization vector of element n on the aperture plane is e, which is set as a unit vector along the x-axis. Then its coordinate in the local coordinate system of the element is u e =(1,0,0), the origin of the local coordinate system is u o =(0;0;0);

[0103] Then the unit n source polarization vector is projected from the unit local coordinate system to the array global coordinate system

[0104]

[0105] u og is the origin of the array global coordinate system, u eg is the unit vector along the x-axis in the array global coordinate system;

[0106] 5) According to the position of the field observation point, calculate the projection of the source polarization vector at the field point;

[0107] 5.1) Construct polarization rotation matrix;

[0108] Assume that the spherical coordinate position of the field observation point in the global coordinate system is Then the polarization rotation matrix is:

[0109]

[0110] Among them, Prot is the polarization rotation matrix, Ptra is the translation matrix, ZR represents rotation around the z-axis, and YR represents rotation around the y-axis;

[0111]

[0112] 5.2) According to the position of the field observation point, the polarization rotation matrix is ​​used to obtain the projection of the source polarization vector at the field point;

[0113]

[0114] Among them, inv is the matrix inversion operation, u f is the projected vector, u of For ef for

[0115] 6) Decompose the projection of the source polarization vector at the field point and calculate the horizontal polarization coefficient and the vertical polarization coefficient;

[0116] For a linearly polarized antenna unit, since the electric field polarization vector is assumed to be along the x-axis, the horizontal polarization component corresponds to the vector uf The y component of the vertical polarization component corresponds to the vector u f The z component of

[0117] For a linearly polarized antenna unit, since the electric field polarization vector is assumed to be along the x-axis, the horizontal polarization component corresponds to the vector u f The y component of the vertical polarization component corresponds to the vector u f The z component of .

[0118]

[0119] VPc and HPc are the horizontal and vertical polarization coefficients, respectively;

[0120]

[0121] Tc is the total polarization coefficient;

[0122] Furthermore, the horizontal and vertical polarization coefficients are normalized to obtain VP and HP, where VP and HP are the values ​​of the vertical and horizontal polarization coefficients, respectively;

[0123]

[0124] For circularly polarized antennas,

[0125] 7) According to the projection decomposition, calculate the horizontal polarization field, vertical polarization field and total field at the field point;

[0126] 7.1) The projection of the calculated field point in the local coordinate system at the unit antenna n is:

[0127]

[0128] in, is the Cartesian coordinate of the projection of the field point in the local coordinate system at the element antenna n;

[0129] Convert Cartesian coordinates to spherical coordinates in,

[0130]

[0131] 7.2) According to the unit pattern data, determine The corresponding power pattern gain value g is calculated based on the power pattern gain value. The pattern weighting factor of the unit n at the field point is expressed as:

[0132] eleAmp=10^(g / 20)

[0133] eleAmp is the directional pattern weighting factor of unit n;

[0134] It should be noted that, since the data exported by the simulation software or the test data itself is sometimes unable to find the corresponding gain at different field points, it is necessary to interpolate the exported gain pattern. The interpolation method adopts the existing method and will not be described here.

[0135] 7.3) The vertical and horizontal polarization fields generated by antenna element n at the field point are

[0136]

[0137] Among them, Evpn and Ehpn are the vertical polarization field and the horizontal polarization field; Amp is the excitation amplitude of the unit, eleAmp is the directional pattern weighting factor; |VP| and |HP| are the absolute values ​​of the vertical and horizontal polarization coefficients respectively; PhaVPt and PhaHPt are the phases of the vertical field and the horizontal field, as expressed by the following formula:

[0138]

[0139] Where k is the wave number, k*r loc is the phase brought by spatial path propagation, Pha is the unit excitation phase; PhaVP and PhaHP are the correction phases representing the positive and negative directions of vertical polarization and horizontal polarization; they are expressed as follows:

[0140]

[0141] The above is the field generated by unit n;

[0142] For antenna unit n, the mutual coupling effect compensation correction is performed as follows:

[0143]

[0144] Among them, s nm The S-parameter model of the array port for simulation and measurement;

[0145] 7.4) For an array antenna with K elements, the polarization field is

[0146]

[0147] The total field is:

[0148] Among them, Evp is the vertical polarization field of the array antenna, and Ehp is the horizontal polarization field of the array antenna. Specific embodiment:

[0150] (1) Taking an 8*8 horn antenna as an example, the unit radiation characteristics are as follows Figure 3 Now it is necessary to study its near-field radiation characteristics under focused phase feeding.

[0151] (2) When the focused phase is fed (the focus point is (0,0,1.2)) and each unit is fed with 1W, the normal radiation field distribution obtained by the FEKO full-wave simulation software is as follows Figure 4 As shown. It can be seen that through the focus phase design, the array achieves electromagnetic wave coherence in the near field area, generating a strong electromagnetic environment with a maximum field strength of 1901V / m (65.4dBV / m);

[0152] (3) Figure 5 , derive the unit pattern data as the radiation model of the unit antenna. Then arrange the array, construct the array description matrix, rotate the projection, calculate each polarization field, etc.

[0153] (4) Figure 6 The near-field calculation results are obtained based on the present invention. It can be seen that compared with the full-wave simulation, the electric field distribution has good consistency, the maximum field strength is 1996V / m (66dBV / m), and the result deviation is 0.6dB.

[0154] (5) Figure 7 Based on the calculation results of the transverse polarization near field obtained by the present invention, it can be seen that, limited by the size of the antenna aperture, the antenna unit spacing is greater than 1 wavelength at this time, and the focused near field will show grating lobe results similar to the far field.

[0155] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for predicting near-field radiation of an array antenna based on polarization vector synthesis, characterized in that: The following steps are involved: 1) For the antenna elements of the array antenna, a unit characteristic representation matrix is ​​constructed; the details are as follows: For antenna unit n, construct a 3*5 matrix A n , whose structure is in, It is a spatial rotation matrix, which is used to represent the orientation information of the unit in the unit's local coordinate system; are the position coordinates of the antenna unit, calculated according to the geometric array method; Amp is the excitation amplitude of the array element, Pha is the phase of the array element; Elt is the type index of the directional pattern; 2) constructing an array configuration description matrix of the array antenna according to the unit characteristic characterization matrix; 3) Set the array frequency, radiation power, and radiation efficiency parameters; 4) Project the source polarization vector from the unit local coordinate system to the array global coordinate system; 5) According to the position of the field observation point, calculate the projection of the source polarization vector at the field point; 6) Decompose the projection of the source polarization vector at the field point and calculate the horizontal polarization coefficient and the vertical polarization coefficient; For a linearly polarized antenna unit, assuming that the electric field polarization vector is along the x-axis, the horizontal polarization component corresponds to the projection vector u of the source polarization vector at the field point. f The y component of the vertical polarization component corresponds to the projection vector u of the source polarization vector at the field point f The z component of Among them, VPc and HPc are the horizontal and vertical polarization coefficients respectively; 7) According to the projection decomposition results, calculate the horizontal polarization field, vertical polarization field and total field at the field point; the process is as follows: 7.1) The projection of the calculated field point in the local coordinate system at the unit antenna n is: in, is the Cartesian coordinate of the projection of the field point in the local coordinate system at the element antenna n; Convert Cartesian coordinates to spherical coordinates in, 7.2) According to the unit pattern data, determine The corresponding power pattern gain value g is calculated based on the power pattern gain value. The pattern weighting factor of the unit n at the field point is expressed as: eleAmp=10^(g / 20) eleAmp is the directional pattern weighting factor of unit n; 7.3) The vertical and horizontal polarization fields generated by antenna element n at the field point are Among them, Evpn and Ehpn are the vertical polarization field and the horizontal polarization field; Amp is the excitation amplitude of the unit, eleAmp is the directional pattern weighting factor; |VP| and |HP| are the absolute values ​​of the vertical and horizontal polarization coefficients respectively; PhaVPt and PhaHPt are the phases of the vertical field and the horizontal field, as expressed by the following formula: Where k is the wave number, k*r loc is the phase brought by spatial path propagation, Pha is the unit excitation phase; PhaVP and PhaHP are the correction phases representing the positive and negative directions of vertical polarization and horizontal polarization; they are expressed as follows: The above is the field generated by unit n; 7.4) For an array antenna with K elements, the polarization field is The total field is: Among them, Evp is the vertical polarization field of the array antenna, and Ehp is the horizontal polarization field of the array antenna.

2. The method for predicting the near field of radiation of an array antenna based on polarization vector synthesis according to claim 1, characterized in that: In the step 4), For a linearly polarized antenna, the polarization vector of element n on the aperture plane is e, which is set as a unit vector along the x-axis. Then its coordinate in the local coordinate system of the element is u e =(1,0,0), the origin of the local coordinate system is u o =(0;0;0); Then the unit n source polarization vector is projected from the unit local coordinate system to the array global coordinate system u og is the coordinate of the origin of the local coordinate system in the global coordinate system after projection transformation, u eg is the coordinate of the source unit vector in global coordinates after projection transformation.

3. The method for predicting the near field of radiation of an array antenna based on polarization vector synthesis according to claim 1, characterized in that: In the step 5), the details are as follows: 5.1) Construct polarization rotation matrix; Assume that the spherical coordinate position of the field observation point in the global coordinate system is Then the polarization rotation matrix is: Among them, Prot is the polarization rotation matrix, Ptra is the translation matrix, ZR represents rotation around the z-axis, and YR represents rotation around the y-axis; 5.2) According to the position of the field observation point, the polarization rotation matrix is ​​used to obtain the projection of the source polarization vector at the field point; Among them, inv is the matrix inversion operation, u f is the projected vector, u of is the source point coordinate after projection, u ef are the endpoint coordinates after projection.

4. The method for predicting the near field of radiation of an array antenna based on polarization vector synthesis according to claim 1, characterized in that: The Elt pattern type is an isolated pattern.

5. The method for predicting the near field of radiation of an array antenna based on polarization vector synthesis according to claim 4, characterized in that: In the step 7.3), for the antenna unit n, the mutual coupling effect compensation correction is performed according to the following formula; Among them, s nm is the array S parameter model, m, n are the unit numbers.

6. An electronic device, characterized in that: include: one or more processors; as well as a storage device for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors are caused to execute the method according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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