A method and system for fitting the radiation pattern of a planar sparse array antenna

Abstract

The present invention relates to the field of array antenna integrated technology, and discloses a method and system for fitting the directional pattern of a planar sparse array antenna. The method comprises the following steps: obtaining the excitation phase distribution matrix and excitation amplitude of each antenna unit at each scanning angle; obtaining the actual gain of the planar sparse array antenna at each scanning angle according to the excitation phase distribution matrix and the excitation amplitude; obtaining the array key parameters of the planar sparse array antenna according to the actual gain; the half-power beam width draws the directional pattern at each scanning angle according to the actual gain of the planar sparse array antenna at each scanning angle; and outputs the key data of the array. The receiving and transmitting sum and difference directional patterns of the set scanning angle can be quickly fitted, thereby improving the efficiency of the preliminary design evaluation of the array antenna, and the fitting result is given in the form of actual gain, which can effectively evaluate the actual gain of the antenna.

Description

Technical Field

[0001] The present invention relates to the field of array antenna integration technology, and in particular to a method and system for fitting a directional pattern of a planar sparsely distributed array antenna. Background Art

[0002] Since full-wave simulation of antenna arrays is extremely time-consuming, in order to quickly complete array evaluation, a common method is to first complete the simulation of the unit field in the array through full-wave simulation software, and then perform full-array pattern fitting based on the simulation results of the unit field in the array. This method can save a lot of simulation time and shorten the design cycle, but it still has the following shortcomings: First, it can only fit the full array, and cannot fit the missing corner array or sparse array; second, the fitting result is a normalized pattern, and the actual gain of the array cannot be obtained; third, only the antenna normal pattern can be observed, and weighted and pattern scanning is not supported, and the scanning deterioration phenomenon that may occur after the array is sparsely distributed cannot be evaluated; fourth, only the sum pattern can be observed, and the difference pattern is not supported, and the evaluation of the array is not comprehensive.

[0003] In view of this, this application is hereby filed. Summary of the invention

[0004] The present invention proposes a method and system for fitting the directional pattern of a planar sparse array antenna, which solves the deficiencies in the above-mentioned prior art and is achieved through the following technical solutions:

[0005] In a first aspect, a method for fitting a planar sparse array antenna pattern is provided, comprising the following steps: obtaining an excitation phase distribution matrix and an excitation amplitude of each antenna unit at each scanning angle; obtaining the actual gain of the planar sparse array antenna at each scanning angle based on the excitation phase distribution matrix and the excitation amplitude of each antenna unit at each scanning angle; obtaining array key parameters of the planar sparse array antenna based on the actual gain of the planar sparse array antenna at each scanning angle; the array key parameters include: maximum actual gain, sidelobe level value, half-power beam width, scanning drop data and difference beam zero depth at a specified scanning angle; drawing the pattern at each scanning angle based on the actual gain of the planar sparse array antenna at each scanning angle; and outputting the array key data.

[0006] Furthermore, the excitation phase distribution matrix includes: a sum pattern excitation phase distribution matrix and a difference pattern excitation phase distribution matrix; obtaining the excitation phase distribution matrix includes the following steps: obtaining the sum pattern excitation phase distribution matrix when the array is full; if the array scanning direction is horizontal scanning, the sum pattern excitation phase distribution matrix is ​​divided into a left sub-matrix and a right sub-matrix, and the phase of each element of one of the left sub-matrix and the right sub-matrix is ​​added by 180° to obtain a new sub-matrix, and the new sub-matrix is ​​re-spliced ​​with the other sub-matrix to obtain a difference pattern excitation phase distribution matrix; if the array scanning direction is pitch scanning, the sum pattern excitation phase distribution matrix is ​​divided into an upper sub-matrix and a lower sub-matrix, and the phase of each element of one of the upper sub-matrix and the lower sub-matrix is ​​added by 180° to obtain a new sub-matrix, and the new sub-matrix is ​​re-spliced ​​with the other sub-matrix to obtain the excitation phase distribution matrix of the difference pattern.

[0007] Furthermore, the excitation amplitude = the number of excitation amplitudes in the x-axis direction × the excitation amplitude in the y-axis direction; obtaining the excitation amplitude includes the following steps: obtaining the sidelobe level value when the planar sparse array antenna is weighted in the x-axis direction and the sidelobe level value when the planar sparse array antenna is weighted in the y-axis direction; according to the sidelobe level value when weighted in the x-axis direction and the number of antenna units in each row of the planar sparse array antenna, using the Taylor weighting method to obtain the excitation amplitude of each antenna unit of the planar sparse array antenna in the x-axis direction; according to the sidelobe level value when weighted in the y-axis direction and the number of antenna units in each column of the planar sparse array antenna, using the Taylor weighting method to obtain the excitation amplitude of each antenna unit of the planar sparse array antenna in the y-axis direction; for each antenna unit, multiplying the excitation amplitude in the x-axis direction by the excitation amplitude on the y-axis.

[0008] Furthermore, the Taylor weighted method is used to obtain the excitation amplitude of each antenna unit in the planar sparse array antenna in the x-axis direction, including the following steps: for each antenna unit, using the first model to convert the sidelobe level value when weighted in the x-axis direction into a linear value of the sidelobe level in the x-axis direction, according to the linear value of the sidelobe level in the x-axis direction, using the second model to obtain the number of zero sidelobes when the sidelobes are weighted, and according to the zero sidelobe number, using the third model to obtain the excitation amplitude in the x-axis direction.

[0009] Furthermore, the Taylor weighted method is used to obtain the excitation amplitude of each antenna unit in the planar sparse array antenna in the y-axis direction, including the following steps: for each antenna unit, using the first model to convert the sidelobe level value when weighted in the y-axis direction into a linear value of the sidelobe level in the y-axis direction, according to the linear value of the sidelobe level in the y-axis direction, using the second model to obtain the number of zero sidelobes when the sidelobes are weighted, and according to the zero sidelobe number, using the third model to obtain the excitation amplitude in the y-axis direction.

[0010] Furthermore, the expression of the first model is: 1); in formula (1), R0 represents the linear value of the sidelobe level, and SLL represents the weighted sidelobe level value; the expression of the second model is: (2); In formula (2), represents the number of zero side lobes, int represents rounding, arccosh represents the inverse hyperbolic cosine function, and R0_x represents the linear value of the desired side lobe level; the expression of the third model is: (3), (4), (5), (6); In formula (3) to formula (6), Indicates n The excitation amplitude of each antenna element, represents the Taylor space factor, N Indicates the number of antenna units when the array is fully deployed. d represents the spacing between antenna elements, m Indicates m Antenna units, represents the lobe broadening factor, A Represents a constant calculated from the sidelobe level.

[0011] Furthermore, the actual gain of the planar sparse array antenna at each scanning angle is obtained, including the following steps: using a planar array pattern model to obtain a full array pattern; multiplying the sparse array by the full array pattern to obtain a normalized sparse array pattern; according to the Taylor spatial factor, using a fourth model to obtain the weighted aperture efficiency of the array; according to the sparse array, the ideal gain of the array is obtained; the actual gain of the pattern of the unit in the array is obtained; the unit in the array is the antenna unit located at the center of the planar sparse array antenna; according to the actual gain of the pattern of the unit in the array, the normalized sparse array pattern, the weighted aperture efficiency and the ideal gain of the array, the actual gain of the planar sparse array antenna is obtained.

[0012] Furthermore, the expression of the planar array pattern model is: ; In formula (7) to formula (9), represents the actual gain of the planar sparse array antenna, θ and φ represent the scanning direction, express x The directional pattern of the linear array composed of all antenna units in the axial direction, Represents the directional pattern of the linear array composed of all antenna units on the y-axis, N x express x The number of antenna elements in the axial direction, I xm express x The excitation amplitude of each antenna unit in the axial direction, express x The excitation phase of each antenna element in the axial direction, N y express y The number of antenna elements in the axial direction, I yn express y Axial excitation amplitude for each antenna element, express y The excitation phase of each antenna unit in the axial direction; the expression of the fourth model is: (10); In formula (10), represents aperture efficiency; the ideal gain of the array = 10·log N (11); The actual gain of the planar sparse array antenna ≈ the actual gain of the radiation pattern of the elements in the array + the ideal gain of the array + the weighted aperture efficiency of the array + the normalized sparse array radiation pattern.

[0013] Further, obtaining the sidelobe level value of the planar sparse array antenna includes the following steps: from multiple actual gains of the planar sparse array antenna at multiple scanning angles, searching for the maximum gain value within the range of ±1° of the specified scanning angle to obtain the maximum actual gain; deriving the actual gain of the planar sparse array antenna at each scanning angle to obtain the maximum scanning angle corresponding to the point where the derivative result is 0; obtaining the scanning range corresponding to the maximum scanning angle; within the scanning range, setting the actual gain of the planar sparse array antenna at each scanning angle to 0 to obtain a new actual gain of the planar sparse array antenna at each scanning angle; obtaining the maximum value of the new actual gain; sidelobe level value = maximum actual gain - maximum value of the new actual gain; obtaining the half-power beam width of the planar sparse array antenna includes the following steps: from multiple actual gains of the planar sparse array antenna at multiple scanning angles, searching for the maximum gain value within the range of ±1° of the specified scanning angle to obtain the maximum actual gain; subtracting the maximum actual gain by 3 to obtain the corrected maximum actual gain; searching from multiple actual gains of the planar sparse array antenna at multiple scanning angles Find the actual gain with the smallest difference between the maximum actual gain and the corrected actual gain to obtain the target gain data; obtain the maximum scanning angle corresponding to the target gain data; obtain the angle difference between the maximum scanning angle and the specified scanning angle; the half-power beam width = 2× the angle difference; obtain the scanning descent data of the planar sparse array antenna, including the following steps: obtain the actual gain of the planar sparse array antenna at the specified scanning angle; obtain the actual gain of the planar sparse array antenna when the scanning angle is 0°; scanning descent data = actual gain when the scanning angle is 0° - actual gain at the specified scanning angle; obtain the difference beam zero depth of the planar sparse array antenna at the specified scanning angle, including the following steps: obtain the actual gain of the planar sparse array antenna at the specified scanning angle; obtain the maximum value of the azimuth difference far-field pattern data of the planar sparse array antenna at the specified scanning angle; obtain the maximum value in the elevation difference far-field pattern data of the planar sparse array antenna at the specified scanning angle; the difference beam zero depth at the specified scanning angle = the maximum value in the difference pattern data at the specified scanning angle - the actual gain at the specified scanning angle.

[0014] In a second aspect, a system for fitting the radiation pattern of a planar sparse array antenna is provided, comprising: a first data acquisition module, used to obtain the excitation phase distribution matrix and excitation amplitude of each antenna unit at each scanning angle; a second data acquisition module, used to obtain the actual gain of the planar sparse array antenna at each scanning angle according to the excitation phase distribution matrix and excitation amplitude of each antenna unit at each scanning angle; a third data acquisition module, used to obtain the array key parameters of the planar sparse array antenna according to the actual gain of the planar sparse array antenna at each scanning angle; the array key parameters include: maximum actual gain, sidelobe level value, half-power beam width, scanning drop data and difference beam zero depth at a specified scanning angle; a radiation pattern drawing module, used to draw the radiation pattern at each scanning angle according to the actual gain of the planar sparse array antenna at each scanning angle; and output the array key data.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0016] 1. This application can fit the actual gain and difference patterns of multiple scanning directions of a planar sparse array antenna, and supports sidelobe weighting, providing a reliable basis for array antenna design. It can improve the efficiency of the preliminary design evaluation of the array antenna, and the fitting results are given in the form of actual gain, which can effectively evaluate the actual gain of the antenna.

[0017] 2. This application can quickly complete the evaluation of sparse arrays, and quickly output the directional diagram and key parameter list required for array evaluation, where the directional diagram includes the sum and difference directional diagrams of each scanning direction in units of actual gain, and the key parameter list lists the gain, sidelobe level, and half-power beamwidth parameters of each scanning direction. It can more comprehensively and accurately evaluate the array sparse effect, greatly improving the efficiency and accuracy of the early evaluation of sparse arrays. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 An example diagram of the arrangement rules of sparse array antenna units provided in an embodiment of the present invention;

[0020] Figure 2 The actual gain pattern provided by the embodiment of the present invention;

[0021] Figure 3Horizontal and directional diagrams at various scanning angles provided by an embodiment of the present invention;

[0022] Figure 4 The horizontal difference pattern at each scanning angle provided by the embodiment of the present invention;

[0023] Figure 5 The key index graph of the array calculated according to the embodiment of the present invention; DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0025] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known structures, circuits, materials, or methods are not specifically described.

[0026] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0028] Embodiment: A first aspect provides a method for fitting a planar sparse array antenna pattern, comprising the following steps:

[0029] Step 1: Call the electromagnetic simulation software to simulate the actual gain data of the array unit located at the center of the planar sparse array, and import the calculation results into the MATLAB workspace.

[0030] Step 2: Read the user-defined planar sparse array related parameters.

[0031] The parameters related to the planar sparse array include: antenna unit arrangement rules, sidelobe level requirements and scanning angle. Among them, the antenna unit arrangement rules are as follows: Figure 1 As shown, it is a 20×20 sparse array. Figure 1 The position of the numerical value indicates the position of the antenna unit in the array. When the value at the position of the numerical value is equal to 0, it indicates that there is no antenna unit at that position; when it is 1, it indicates that there is an antenna unit at that position.

[0032] The relevant parameters of the planar sparse array are specifically: the x-axis spacing of the array elements, the y-axis spacing of the array elements, the number of array elements in the x-axis direction when the rectangular array is fully arranged, the number of array elements in the y-axis direction when the rectangular array is fully arranged, the scanning frequency, the scanning angle in the φ direction during beam scanning, the maximum scanning angle in the θ direction during beam scanning, the scanning angle interval in the θ direction during beam scanning, the phase random error factor of the excitation of each antenna unit, the sidelobe level value when weighted in the x-axis direction, the sidelobe level value when weighted in the y-axis direction, and the amplitude random error factor of the excitation of each antenna unit.

[0033] In this embodiment, dx represents the x-axis spacing of array elements, in mm; dy represents the y-axis spacing of array elements, in mm; Nx represents the number of array elements in the x-axis direction when the rectangular array is fully arranged, Ny represents the number of array elements in the y-axis direction when the rectangular array is fully arranged, Freq represents the scanning frequency, in GHz; phi represents the φ direction scanning when beam scanning is performed, and the angle unit is degree; theta represents the maximum scanning angle in the θ direction when beam scanning is performed, in degree; delta_theta represents the scanning angle interval in the θ direction when beam scanning is performed, in degree; K_phase represents the phase random error factor of the excitation of each antenna unit, SLL_x represents the sidelobe level value when weighting is performed in the x-axis direction, in dB; SLL_y represents the sidelobe level value when weighting is performed in the y-axis direction, in dB; K_mag represents the amplitude random error factor of the excitation of each antenna unit.

[0034] Step 3: Calculate the excitation phase distribution matrix and excitation amplitude of each antenna unit in the planar sparse array antenna at each scanning angle.

[0035] Among them, the excitation phase distribution matrix includes the sum pattern excitation phase distribution matrix and the difference pattern excitation phase distribution matrix, and the excitation amplitude includes the sum pattern excitation amplitude and the difference pattern excitation amplitude. For example, in step 2, when the beam scanning is performed, the maximum scanning angle in the θ direction is customized to 60 degrees, and the scanning angle interval in the θ direction is customized to 10 degrees when the beam scanning is performed, then the scanning angles of the antenna include: -60°, -50°, -40°, -30°, -20°, -10°, 0°, 10°, 20°, 30°, 40°, 50° and 60°.

[0036] Furthermore, the method for calculating the excitation phase distribution matrix of each antenna unit in the planar sparse array antenna at each scanning angle is:

[0037] Step 3.1.1: Based on the planar array pattern function calculation formula, calculate the sum pattern excitation phase distribution matrix when the array is full.

[0038] Step 3.1.2: Check the array scanning direction. If the array scanning direction is horizontal scanning, the sum pattern excitation phase distribution matrix is ​​divided into a left sub-matrix and a right sub-matrix, and the phase of each element of one of the left and right sub-matrices is added by 180° to obtain a new sub-matrix, and the new sub-matrix is ​​reconnected with the other sub-matrix to obtain the difference pattern excitation phase distribution matrix; if the array scanning direction is elevation scanning, the sum pattern excitation phase distribution matrix is ​​divided into an upper sub-matrix and a lower sub-matrix, and the phase of each element of one of the upper and lower sub-matrixes is added by 180° to obtain a new sub-matrix, and the new sub-matrix is ​​reconnected with the other sub-matrix to obtain the difference pattern excitation phase distribution matrix.

[0039] Furthermore, the method for calculating the excitation amplitude of each antenna unit in the planar sparse array antenna at each scanning angle is: based on the sidelobe level value in the sparse array related parameters described in step 2 and the number of antenna units in each row in the array, weighted calculation of the excitation amplitude of each antenna unit in the row arrangement.

[0040] It should be noted that the sidelobe level value described in this step specifically refers to the sidelobe level value SLL_x when weighted in the x-axis direction and the sidelobe level value SLL_y when weighted in the y-axis direction. In addition, the array amplitude weighting method can use Taylor weighting, Chebyshev weighting, Fourier transform and other methods to achieve amplitude weighting.

[0041] Taking Taylor weighting as an example, the method of calculating the excitation amplitude of each antenna unit in the row arrangement using Taylor weighting method is:

[0042] S1: Convert the user-defined sidelobe level value SLL_x when weighted in the x-axis direction and the sidelobe level value SLL_y when weighted in the y-axis direction into linear values.

[0043] The expression of the conversion model used to convert the weighted sidelobe level value into the sidelobe level linear value is: (1); In formula (1), R0 represents the linear value of the sidelobe level, and SLL represents the sidelobe level value when weighted. Substituting SLL_x and SLL_y into formula (1) respectively, R0_x and R0_y can be calculated. Among them, R0_x represents the linear value of the sidelobe level on the x-axis, and R0_y represents the linear value of the sidelobe level on the y-axis.

[0044] S2: Substitute the linear value of the sidelobe level R0_x on the x-axis and the linear value of the sidelobe level R0_y on the y-axis calculated by S1 into the following formula (2) to calculate the number of zero sidelobes when the sidelobes are weighted.

[0045] (2); In formula (2), Represents the number of zero sidelobes, int represents rounding, arccosh is the inverse hyperbolic cosine function, and R0_x represents the linear value of the expected sidelobe level.

[0046] S3: Calculate the excitation amplitude of each antenna unit in the x-axis direction according to equations (3) to (6) and the excitation amplitude of each antenna element in the y-axis direction .

[0047] (3),

[0048] (4),

[0049] (5),

[0050] (6).

[0051] In formula (3) to formula (6), Indicates n The excitation amplitude of each antenna element, represents the Taylor space factor, N Indicates the number of antenna units when the array is fully deployed. d represents the spacing between antenna elements, m Indicates m Antenna units, represents the lobe broadening factor, A Represents a constant calculated from the sidelobe level.

[0052] S4: Multiply the excitation amplitude in the x-axis direction by the excitation amplitude in the y-axis direction.

[0053] For the antenna element at (m,n) in a rectangular array, the excitation amplitude is .

[0054] Step 4: Based on the excitation phase and sidelobe weighting coefficient data of the sum and difference patterns at different scanning angles of each antenna unit calculated in step 3, the actual gain pattern of the array at different scanning angles is calculated.

[0055] The specific steps include:

[0056] Step 4.1: Use the planar array pattern model to obtain the full array pattern.

[0057] The expression of the planar array pattern model is: ; In formula (7) to formula (9), represents the actual gain of the planar sparse array antenna, θ and φ represent the scanning direction, express x The directional pattern of the linear array composed of all antenna units in the axial direction, Represents the directional pattern of the linear array composed of all antenna units on the y-axis, N x express x The number of antenna elements in the axial direction, I xm express x The excitation amplitude of each antenna unit in the axial direction, express x The excitation phase of each antenna element in the axial direction, N y express y The number of antenna elements in the axial direction, I yn express y Axial excitation amplitude for each antenna element, express y The excitation phase of each antenna element along the axis.

[0058] Step 4.2: Multiply the sparse array with the full array pattern calculated in step 4.1 to obtain a normalized sparse array pattern.

[0059] Step 4.3: Based on the spatial factor calculated in step 3 , calculate the array weighted aperture efficiency η.

[0060] (10); In formula (10), Indicates aperture efficiency.

[0061] Step 4.4: Calculate the ideal gain of the array based on the sparse array.

[0062] Array ideal gain = 10·log N (11). In formula (11), N represents the number of antenna units contained in the planar sparse array.

[0063] Step 4.5: Based on the actual gain data of the array unit pattern derived in step 1, the array ideal gain, the array weighted aperture efficiency and the normalized sparse array pattern data, the actual gain pattern of the array is calculated.

[0064] The actual gain pattern of the array = the actual gain of the array unit pattern derived by the full-wave simulation software + the ideal gain of the array + the aperture efficiency of the array after weighting + the normalized sparse array pattern. The addition here means the addition of matrices of the same dimension.

[0065] Figure 2 The actual gain pattern calculated in step 4 is shown as follows: Figure 1 The 3D far-field radiation pattern in spherical coordinates formed by the array is given in the form of actual antenna gain in dBi. Figure 3 The actual gain pattern calculated in step 4 is shown as follows: Figure 1 The horizontal direction and directional diagram at each scanning angle when the array is transmitting, where the horizontal axis is the theta angle in spherical coordinates and the vertical axis is the actual gain of the antenna. Figure 3 The antenna scanning decline at different scanning angles can be intuitively seen in the figure. Figure 4 The actual gain pattern calculated in step 4 is shown as follows: Figure 1 The horizontal difference pattern at each scanning angle when the array is transmitting, where the abscissa is the theta angle in spherical coordinates and the ordinate is the actual gain of the antenna. Figure 4 The zero depth of the antenna under different scanning angles can be intuitively seen.

[0066] Step 5: Calculate the key parameters of the array based on the actual gain pattern data of the array at different scanning angles calculated in step 4, including the maximum achieved gain, sidelobe level, half-power beamwidth, zero depth and scanning drop data. Specifically including:

[0067] Step 5 is specifically as follows: according to the parameters in step 3 and step 3, traverse step 3 and step 4, respectively calculate the actual gain at different scanning angles, and calculate the maximum achieved gain, sidelobe level, half-power beam width, zero depth and scanning drop data of the array according to the calculated array actual gain pattern. Before traversal, first calculate the scanning angle matrix according to the set scanning angle range and scanning interval, determine the number of traversals according to the length of the scanning angle matrix, take the nth element in the scanning angle matrix and bring it into the rectangular plane array factor function for the nth traversal, and calculate the sum and difference pattern excitation phase distribution matrix when the array is full.

[0068] The method for calculating the sidelobe level value of the planar sparse array antenna is:

[0069] S1: From multiple actual gains of the planar sparse array antenna at multiple scanning angles, find the maximum gain within the range of ±1° of the specified scanning angle to obtain the maximum actual gain.

[0070] S2: Derivative the actual gain of the planar sparse array antenna at each scanning angle, and find the maximum scanning angle corresponding to the point where the derivative result is 0.

[0071] S3: Obtain a scanning range corresponding to the maximum scanning angle; within the scanning range, set the actual gain of the planar sparse array antenna at each scanning angle to 0, and obtain a new actual gain of the planar sparse array antenna at each scanning angle.

[0072] S4: Find the maximum value among the new actual gains

[0073] S5: Subtract the maximum value of the new actual gain from the maximum actual gain to obtain the sidelobe level value.

[0074] Furthermore, the method for calculating the half-power beamwidth of the planar sparse array antenna is:

[0075] S1: From multiple actual gains of the planar sparse array antenna at multiple scanning angles, find the maximum gain within the range of ±1° of the specified scanning angle to obtain the maximum actual gain, and subtract 3 from the maximum actual gain to obtain the corrected maximum actual gain.

[0076] S2: From multiple actual gains of the planar sparse array antenna at multiple scanning angles, find the actual gain with the smallest difference from the corrected maximum actual gain, obtain the target gain data, and calculate the maximum scanning angle in the θ scanning direction corresponding to the target gain data when performing beam scanning.

[0077] S3: Calculate the angle difference between the maximum scanning angle described in S2 and the specified scanning angle, then the half-power beam width = 2× the angle difference.

[0078] Furthermore, the method for calculating the scanning descent data of the planar sparse array antenna is:

[0079] S1: Find the actual gain of a planar sparse array antenna at a specified scan angle.

[0080] S2: Obtain the actual gain of the planar sparse array antenna when the scanning angle is 0°.

[0081] S3: Calculate the scan down data. Scan down data = actual gain when the scan angle is 0° - actual gain at the specified scan angle.

[0082] For example: when calculating the scanning drop at θ=15°, first find the gain at θ=0° in the actual gain pattern of the array, and then find the gain at θ=15°. The scanning drop at θ=15° = the gain at θ=0° in the actual gain pattern of the array - the gain at θ=15° in the actual gain pattern of the array. Similarly, the scanning drop corresponding to other scanning angles can be calculated.

[0083] Furthermore, the method for calculating the difference beam null depth of the planar sparse array antenna at a specified scanning angle is:

[0084] S1: Get the actual gain of the planar sparse array antenna at a specified scanning angle.

[0085] For example, the maximum scanning angle in the θ direction during beam scanning in step 2 is set to 45 degrees, and the scanning angle interval in the θ direction during beam scanning is set to 10 degrees. In this step, the actual gain corresponding to the θ scanning angles (-45°, -30°, -15°, 0°, 15°, 30°, and 45°) is obtained.

[0086] S2: Find the maximum value of the azimuth difference far-field pattern data of the planar sparse array antenna at the specified scanning angle, and find the maximum value of the elevation difference far-field pattern data of the planar sparse array antenna at the specified scanning angle.

[0087] S3: Calculate the difference beam zero depth at the specified scanning angle. The difference beam zero depth at the specified scanning angle = the maximum value in the difference pattern data at the specified scanning angle - the actual gain at the specified scanning angle.

[0088] For example, when calculating the zero depth of θ=15°, find the maximum value in the calculated array actual gain pattern difference pattern data of θ=15°, and then find the corresponding dB value when θ=15°. The zero depth of the difference pattern of θ=15° = the maximum value of the difference pattern - the corresponding dB value when 15°. Similarly, the zero depth corresponding to other scanning angles can be calculated.

[0089] Figure 5The actual gain pattern calculated in step 5 is shown, specifically based on Figure 1 The key indicator results of the antenna array are obtained by calculating the array formation and radiation pattern, including the half-power beamwidth, antenna gain and sidelobe level at different scanning angles.

[0090] Step 6: Call the drawing function to output the directional diagrams at different scanning angles and output the key parameters of the array.

[0091] The output method includes but is not limited to outputting to Excel, and can also be output in other forms, such as printing directly on the screen, and outputting to a txt file, etc. The data exported as described in step 1 is the actual gain data of the unit pattern in the array, which includes the influence of the antenna radiation efficiency and return loss on the antenna gain, and the result is closer to the actual radiation of the antenna. The sparse array in step 2 is used to define the array surface sparse rules, which is customized by the user. Taking a 20×20 planar array as an example, 0 in the matrix indicates that the antenna unit is sparse, and 1 indicates that the antenna unit is retained. The user can arbitrarily sparse the array according to the actual situation.

[0092] A second aspect of the present embodiment provides a system for fitting a planar sparse array antenna pattern, characterized by comprising:

[0093] A first data acquisition module is used to obtain an excitation phase distribution matrix and an excitation amplitude of each antenna unit at each scanning angle;

[0094] A second data acquisition module is used to obtain the actual gain of the planar sparse array antenna at each scanning angle according to the excitation phase distribution matrix and excitation amplitude of each antenna unit at each scanning angle;

[0095] A third data acquisition module is used to obtain the array key parameters of the planar sparse array antenna according to the actual gain of the planar sparse array antenna at each scanning angle; the array key parameters include: maximum actual gain, sidelobe level value, half-power beam width, scanning drop data and difference beam zero depth at a specified scanning angle;

[0096] The pattern drawing module is used to draw the pattern at each scanning angle according to the actual gain of the planar sparse array antenna at each scanning angle; and output the array key data.

[0097] The specific implementation methods 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 implementation method of the present invention and is not intended to limit the scope of protection of 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 method for fitting a planar sparse array antenna pattern, characterized in that: The following steps are involved: Obtain the excitation phase distribution matrix and excitation amplitude of each antenna unit at each scanning angle; Obtaining the actual gain of the planar sparse array antenna at each scanning angle according to the excitation phase distribution matrix and excitation amplitude of each antenna unit at each scanning angle; According to the actual gain of the planar sparse array antenna at each scanning angle, the key array parameters of the planar sparse array antenna are obtained; The key parameters of the array include: maximum actual gain, sidelobe level value, half-power beam width, scanning drop data and difference beam zero depth at a specified scanning angle; According to the actual gain of the planar sparse array antenna at each scanning angle, draw the directional diagram at each scanning angle; output the key parameters of the array; The excitation phase distribution matrix includes: a sum pattern excitation phase distribution matrix and a difference pattern excitation phase distribution matrix; Acquiring the excitation phase distribution matrix includes the following steps: acquiring the sum pattern excitation phase distribution matrix when the array is full; if the array scanning direction is horizontal scanning, dividing the sum pattern excitation phase distribution matrix into a left sub-matrix and a right sub-matrix, adding 180° to the phase of each element of one of the left sub-matrix and the right sub-matrix to obtain a new sub-matrix, and reconnecting the new sub-matrix with the other sub-matrix to obtain a difference pattern excitation phase distribution matrix; if the array scanning direction is pitch scanning, dividing the sum pattern excitation phase distribution matrix into an upper sub-matrix and a lower sub-matrix, adding 180° to the phase of each element of one of the upper sub-matrix and the lower sub-matrix to obtain a new sub-matrix, and reconnecting the new sub-matrix with the other sub-matrix to obtain an excitation phase distribution matrix of the difference pattern; The excitation amplitude = the excitation amplitude of the sum pattern × the excitation amplitude of the difference pattern; Obtaining the excitation amplitude includes the following steps: obtaining the sidelobe level value when the planar sparse array antenna is weighted in the x-axis direction and the sidelobe level value when the planar sparse array antenna is weighted in the y-axis direction; according to the sidelobe level value when weighted in the x-axis direction and the number of antenna units in each row of the planar sparse array antenna, using the Taylor weighting method to obtain the excitation amplitude of each antenna unit of the planar sparse array antenna in the x-axis direction; according to the sidelobe level value when weighted in the y-axis direction and the number of antenna units in each column of the planar sparse array antenna, using the Taylor weighting method to obtain the excitation amplitude of each antenna unit of the planar sparse array antenna in the y-axis direction; for each antenna unit, multiplying the excitation amplitude in the x-axis direction by the excitation amplitude in the y-axis direction; The Taylor weighting method is used to obtain the excitation amplitude of each antenna unit of the planar sparse array antenna in the x-axis direction, including the following steps: for each antenna unit, using a first model to convert the sidelobe level value when weighted in the x-axis direction into a linear value of the sidelobe level in the x-axis direction, using a second model to obtain the number of zero side lobes when the side lobes are weighted according to the linear value of the sidelobe level in the x-axis direction, and using a third model to obtain the excitation amplitude in the x-axis direction according to the zero sidelobe number; The Taylor weighted method is used to obtain the excitation amplitude of each antenna unit of the planar sparse array antenna in the y-axis direction, comprising the following steps: for each antenna unit, using the first model to convert the sidelobe level value when weighted in the y-axis direction into a linear value of the sidelobe level in the y-axis direction, according to the linear value of the sidelobe level in the y-axis direction, using the second model to obtain the number of zero side lobes when the side lobes are weighted, and according to the zero sidelobe number, using the third model to obtain the excitation amplitude in the y-axis direction; The expression of the first model is: (1); In formula (1), R0 represents the linear value of the sidelobe level, and SLL represents the weighted sidelobe level value; The expression of the second model is: (2); In formula (2), Represents the number of zero side lobes, int represents rounding, arccosh represents the inverse hyperbolic cosine function, and R0_x represents the linear value of the expected side lobe level; The expression of the third model is: （3）， （4）， (5), (6); In formula (3) to formula (6), Indicates n The excitation amplitude of each antenna element is represents the Taylor space factor, N Indicates the number of antenna units when the array is fully deployed. d represents the spacing between antenna elements, m Indicates m Antenna units, represents the lobe broadening factor, A represents the constant calculated from the sidelobe level; Obtaining the actual gain of the planar sparse array antenna at each scanning angle comprises the following steps: Use the planar array pattern model to obtain the full array pattern; Multiplying the sparse array with the full array pattern to obtain a normalized sparse array pattern; According to the Taylor spatial factor, the fourth model is used to obtain the weighted aperture efficiency of the array; Obtaining an ideal gain of an array according to the sparse array; Obtaining an actual gain of a directional pattern of a unit in an array; the unit in an array is an antenna unit located at the center of the planar sparse array antenna; Obtaining the actual gain of the planar sparse array antenna according to the actual gain of the directional pattern of the array unit, the normalized sparse array directional pattern, the weighted aperture efficiency and the ideal gain of the array; The expression of the planar array pattern model is: ; In formula (7) to formula (9), represents the actual gain of the planar sparse array antenna, θ and φ represent the scanning direction, express x The directional pattern of the linear array composed of all antenna units in the axial direction, Represents the directional pattern of the linear array composed of all antenna units on the y-axis, N x express x The number of antenna elements in the axial direction, I xm express x The excitation amplitude of each antenna unit in the axial direction, express x The excitation phase of each antenna element in the axial direction, N y express y The number of antenna elements in the axial direction, I yn express y Axial excitation amplitude for each antenna element, express y The excitation phase of each antenna unit in the axial direction; the expression of the fourth model is: ; In formula (10), Indicates aperture efficiency; The ideal gain of the array = 10·log N (11); The actual gain of the planar sparse array antenna is equal to the actual gain of the pattern of the array elements + the ideal gain of the array + the array gain. Weighted aperture efficiency + normalized sparse array pattern.

2. The method for fitting the directional pattern of a planar sparse array antenna according to claim 1, characterized in that: Obtaining the sidelobe level value of the planar sparse array antenna comprises the following steps: searching for the maximum gain value within the range of ±1° of a specified scanning angle from a plurality of actual gains of the planar sparse array antenna at a plurality of scanning angles to obtain the maximum actual gain; derivatizing the actual gain of the planar sparse array antenna at each scanning angle to obtain the maximum scanning angle corresponding to the point where the derivation result is 0; obtaining the scanning range corresponding to the maximum scanning angle; within the scanning range, setting the actual gain of the planar sparse array antenna at each scanning angle to 0 to obtain a new actual gain of the planar sparse array antenna at each scanning angle; obtaining the maximum value of the new actual gains; sidelobe level value = maximum actual gain - maximum value of the new actual gains; Obtaining the half-power beam width of the planar sparse array antenna comprises the following steps: from a plurality of actual gains of the planar sparse array antenna at a plurality of scanning angles, searching for the maximum gain value within the range of ±1° of a specified scanning angle to obtain the maximum actual gain; subtracting 3 from the maximum actual gain to obtain a corrected maximum actual gain; from a plurality of actual gains of the planar sparse array antenna at a plurality of scanning angles, searching for the actual gain with the smallest difference from the corrected maximum actual gain to obtain target gain data; obtaining the maximum scanning angle corresponding to the target gain data; obtaining the angle difference between the maximum scanning angle and the specified scanning angle; the half-power beam width=2×the angle difference; Obtaining the scanning descent data of the planar sparse array antenna comprises the following steps: obtaining the actual gain of the planar sparse array antenna at the specified scanning angle; obtaining the actual gain of the planar sparse array antenna when the scanning angle is 0°; scanning descent data = actual gain when the scanning angle is 0° - actual gain at the specified scanning angle; Obtaining the difference beam zero depth of the planar sparse array antenna at a specified scanning angle comprises the following steps: obtaining the actual gain of the planar sparse array antenna at the specified scanning angle; obtaining the maximum value of the azimuth difference far-field pattern data of the planar sparse array antenna at the specified scanning angle; obtaining the maximum value of the elevation difference far-field pattern data of the planar sparse array antenna at the specified scanning angle; the azimuth / elevation difference beam zero depth at the specified scanning angle = the maximum value of the azimuth / elevation difference pattern data at the specified scanning angle - the actual gain at the specified scanning angle.

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