Calculation method for far-field space weighted phase of phased-array antenna array element

Abstract

The invention discloses a method for calculating a far-field space weighted phase of an array element of a phased-array antenna, and the method comprises the steps: taking a signal transmitted from a far-field virtual target and a signal transmitted from a far-field actual target as signals parallel to an array plane normal of the phased-array antenna for the signal synthesis of the phased-array antenna; a central array element is used as a reference point, and for an actual target and a virtual target which meet far-field conditions, the wave path difference of signals transmitted by the far-field actual target and / or the far-field virtual target reaching the central array element of the phased-array antenna and any array element except the central array element is calculated, so that the equivalent space weighted phase of the any array element is obtained. The method is simple, reliable and convenient to implement, and can meet the requirement for beam forming of a phased-array antenna system in engineering practice.

Description

Technical Field

[0001] The present invention relates to the technical field of phased array antennas, and in particular to a method for calculating a far-field spatial weighted phase of a phased array antenna element. Background Art

[0002] Digital multi-beam spherical phased array antennas have the technical advantages of using multi-beam working mode and full airspace coverage to track and control multiple space targets at the same time. In recent years, they have received increasing attention in the research of new antennas and have become a hot area in the research of new antennas.

[0003] A key technical problem in the design of digital multi-beam spherical phased array antennas is how to complete digital beamforming. The premise of digital beamforming of digital multi-beam phased array antennas is that the phases of each channel of the antenna must be consistent. Therefore, it is necessary to calculate the spatial weighted phase of each element antenna, and then form a beam synthesis signal by summing the phase compensation of the corresponding element channel signals. For planar phased array antennas, a technical solution often used in engineering practice is to use the equivalent parallel waves of far-field targets to calculate the spatial weighted phase by calculating the spatial path difference of the antenna elements. However, for spherical phased array antennas, since it is necessary to consider the influence of the curved surface of the antenna array, the calculation formula for the spatial path difference of the antenna elements is relatively complicated and very cumbersome in actual use. Summary of the invention

[0004] In view of this, in view of the need to calculate the spatial weighted phase of each element antenna when a spherical phased array antenna system performs beamforming on a far-field spatial target, the present invention proposes a method for calculating the far-field spatial weighted phase of a spherical phased array antenna, aiming to provide a simple, reliable and easy-to-implement method for calculating the spatial weighted phase of a spherical phased array antenna element. This method does not require any external equipment, and is convenient for designing a spherical phased array antenna system that meets the index requirements in engineering practice.

[0005] The present invention discloses a method for calculating the far-field spatial weighted phase of a phased array antenna element, which comprises:

[0006] For the signal synthesis of the phased array antenna, the signal emitted from the far-field virtual target and the signal emitted from the far-field actual target are both regarded as signals parallel to the array normal of the phased array antenna; that is, taking the central array element as the reference point, for the actual target and virtual target that meet the far-field conditions, the equivalent spatial weighted phase of the arbitrary array element is obtained by calculating the path difference between the signal emitted by the far-field actual target and / or the far-field virtual target and reaching the central array element of the phased array antenna and any array element other than the central array element.

[0007] Further, when the phased array antenna is a planar phased array, if the difference between the first distance difference and the second distance difference is less than a specified multiple of the wavelength of a signal emitted by a far-field virtual target or a far-field virtual target, the signal emitted from the far-field virtual target and the signal emitted from the far-field actual target are regarded as signals parallel to the normal of the array surface of the planar phased array antenna; the first distance difference is: the distance difference between the signal emitted by the far-field virtual target reaching the central array element and the first array element, and the second distance difference is: the distance difference between the signal emitted from the far-field actual target reaching the central array element and the first array element; the first array element is the array element with the longest distance from the center point of the array surface in the planar phased array antenna; the center point of the array surface is the center point of the central array element.

[0008] Furthermore, assuming that the target is on the normal line passing through the center point O of the plane phased array antenna, a coordinate system is established with the center point O of the plane phased array antenna as the center point, the line from the first array element to the center point O of the plane as the x-axis, and the normal line passing through the center point O of the plane phased array antenna as the y-axis; in this coordinate system, the coordinates of the space target A are set to (0, y A ), the coordinates of the center point O of the plane array are (0,0), and the coordinates of the first array element are (x 1 ,0); Assume that the space target A meets the far-field condition for the planar phased array antenna, and arbitrarily create a target B that meets the far-field condition on the y-axis, and set its coordinates to (0,y B ) The first array element is the array element with the longest distance from the center point of the array surface in the phased array antenna;

[0009] If the distance y between the space target A and the center point O of the array A The distance between the space target A and the first array element is L 1A The distance difference ΔL 1A If the following formula is satisfied, the space target A is considered to meet the far-field condition:

[0010]

[0011] If the distance y between the virtual target B and the center point O of the array B The distance between the virtual target B and the first array element is L 1B The distance difference ΔL 1B If the following formula is satisfied, the virtual target B is considered to meet the far-field condition:

[0012]

[0013] Furthermore, when the phased array antenna is a spherical phased array, a virtual target that meets the far field condition is selected from the far field, and the coordinate value of the virtual target in the spherical phased array coordinate system is calculated; according to the distance from the central array element of the spherical phased array to the virtual target, and the distance from the coordinates of any array element on the spherical phased array to the virtual target, the path difference from the central array element to any array element is obtained; and according to the path difference, the equivalent spatial weighted phase of any array element is obtained.

[0014] Furthermore, when the phased array antenna is a spherical phased array, when the distance from the space target to the center of the spherical phased array is greater than When , the space target meets the far field condition; where r is the radius of the spherical phased array, f A is the maximum frequency of the phased array receiving signal, c is the speed of light; the first array element is the array element in the spherical phased array antenna whose distance from the center point of the array surface is the array surface radius.

[0015] Further, the calculating of the coordinate value of the virtual target in the spherical phased array coordinate system includes:

[0016] A three-dimensional coordinate system with the center of the sphere as the origin is established in the spherical phased array antenna. The azimuth angle of the space target that meets the far-field condition in the coordinate system of the spherical array is The pitch angle is The array element on the array plane corresponding to the azimuth angle and the pitch angle is defined as the central array element C and its coordinates in the coordinate system of the spherical array are (x C ,y C ,z C ), the coordinate value (x B ,y B ,z B ):

[0017]

[0018] Furthermore, the distance from the central array element of the spherical phased array to the virtual target is calculated according to the following formula:

[0019] The distance L from the center element C to the virtual target B CB :

[0020]

[0021] Furthermore, the distance from the coordinates of any array element on the spherical phased array to the virtual target is calculated according to the following formula:

[0022] Any coordinate on the spherical phased array is (x 1 ,y 1 ,z 1 ) to the virtual target B 1B:

[0023]

[0024] Furthermore, the path difference from the central array element to any array element is obtained by the following method:

[0025] Let any coordinate be (x 1 ,y 1 ,z 1 ) is at point D on the array surface, and a plane α tangent to the spherical surface of the spherical phased array antenna is drawn through point C where the central array element is located, and the intersection of plane α and line segment DB is set to be E; the length of line segment BE is approximately equal to the length of line segment BC, and line segment DE is the coordinate (x 1 ,y 1 ,z 1 ) and the central element C. 1C =L 1B -L CB .

[0026] Further, obtaining the equivalent spatial weighted phase of any array element according to the path difference includes:

[0027] According to the following formula, calculate any coordinate (x 1 ,y 1 ,z 1 ) of the array element's equivalent spatial weighted phase Δφ 1C :

[0028]

[0029] Where c is the speed of light, f A is the maximum frequency of the phased array antenna, () 取小数 To perform decimal operations.

[0030] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0031] 1. Solve the problem of calculating the spatial weighted phase of the phased array antenna elements to the far-field target. According to the characteristics of the far-field conditions of the space target, the present invention proposes a method of using a virtual far-field space target to calculate the spatial weighted phase of each element antenna of the phased array antenna to the space target. The method is simple, reliable and easy to implement, and can meet the needs of beam synthesis of phased array antenna systems in engineering practice. This method can be used to design a phased array antenna system that meets the index requirements in engineering practice, solving a key problem in the design of digital multi-beam phased array antenna systems.

[0032] 2. Simple implementation, less resource occupation, and reduced system design cost. The present invention does not require complex circuits, and the implementation method is relatively simple. The present invention only uses the original equipment of the system without adding additional equipment, and realizes the multi-level comparison method channel phase consistency detection function of the system through software algorithms, which is convenient for automatic operation and reduces the system design cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0034] Figure 1 It is a schematic diagram of the far-field target decision conditions of the phased array antenna.

[0035] Figure 2 It is a schematic diagram of the calculation of the path difference of a traditional phased array antenna for a far-field target.

[0036] Figure 3 It is a schematic diagram of the phased array antenna using the virtual target method for the target that meets the far-field conditions.

[0037] Figure 4 It is a schematic diagram of the spherical phased array antenna receiving signals from far-field targets.

[0038] Figure 5 It is a schematic diagram of the equivalent spatial weighted phase calculation of a spherical phased array antenna using a virtual target for a far-field target. DETAILED DESCRIPTION

[0039] The present invention is further described in conjunction with the accompanying drawings and embodiments, and the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present invention.

[0040] Traditionally, digital multi-beam phased array antenna systems generally use the equivalent parallel wave method to calculate the spatial path difference of antenna elements, and thereby calculate the spatial weighted phase of each element antenna for the far-field space target. This method of calculating the spatial path difference requires calculating the incoming wave angle for each element separately. For curved phased array antennas, it is also necessary to consider the influence of the antenna's array surface curvature on the element's incoming wave angle, so the calculation is very cumbersome. According to the characteristics of the far-field conditions of the space target, this application proposes a method of using a virtual far-field space target to calculate the spatial weighted phase of each element antenna of a spherical phased array antenna for the space target. This method is simple, reliable and easy to implement, and can meet the needs of beam synthesis of spherical phased array antenna systems in engineering practice. This method can be used to design a spherical phased array antenna system that meets the index requirements in engineering practice.

[0041] The present invention provides an embodiment of a method for calculating a far-field spatially weighted phase of a phased array antenna element, comprising:

[0042] For the signal synthesis of the phased array antenna, the signal emitted from the far-field virtual target and the signal emitted from the far-field actual target are both regarded as signals parallel to the array normal of the phased array antenna; that is, taking the central array element as the reference point, for the actual target and virtual target that meet the far-field conditions, the equivalent spatial weighted phase of the arbitrary array element is obtained by calculating the path difference between the signal emitted by the far-field actual target and / or the far-field virtual target and reaching the central array element of the phased array antenna and any array element other than the central array element.

[0043] In one embodiment of the present application, when the phased array antenna is a planar phased array, if the difference between the first distance difference and the second distance difference is less than a specified multiple of the wavelength of a signal emitted by a far-field virtual target or a far-field virtual target, the signal emitted from the far-field virtual target and the signal emitted from the far-field actual target are regarded as signals parallel to the normal of the array surface of the planar phased array antenna; the first distance difference is: the distance difference between the signal emitted by the far-field virtual target reaching the center array element and the first array element, and the second distance difference is: the distance difference between the signal emitted from the far-field actual target reaching the center array element and the first array element; the first array element is the array element with the longest distance from the center point of the array surface in the planar phased array antenna; the center point of the array surface is the center point of the central array element.

[0044] In one embodiment of the present application, assuming that the target is on the normal line passing through the center point O of the plane phased array antenna, a coordinate system is established with the center point O of the plane phased array antenna as the center point, the line connecting the first array element to the center point O of the plane as the x-axis, and the normal line passing through the center point O of the plane phased array antenna as the y-axis; in this coordinate system, the coordinates of the space target A are set to (0, y A ), the coordinates of the center point O of the plane array are (0,0), and the coordinates of the first array element are (x1 ,0); Assume that the space target A meets the far-field condition for the planar phased array antenna, and arbitrarily create a target B that meets the far-field condition on the y-axis, and set its coordinates to (0,y B ) The first array element is the array element with the longest distance from the center point of the array surface in the phased array antenna;

[0045] If the distance y between the space target A and the center point O of the array A The distance between the space target A and the first array element is L 1A The distance difference ΔL 1A If the following formula is satisfied, the space target A is considered to meet the far-field condition:

[0046]

[0047] If the distance y between the virtual target B and the center point O of the array B The distance between the virtual target B and the first array element is L 1B The distance difference ΔL 1B If the following formula is satisfied, the virtual target B is considered to meet the far-field condition:

[0048]

[0049] In one embodiment of the present application, when the phased array antenna is a spherical phased array, a virtual target that meets the far field condition is selected from the far field, and the coordinate value of the virtual target in the spherical phased array coordinate system is calculated; based on the distance from the central array element of the spherical phased array to the virtual target, and the distance from the coordinates of any array element on the spherical phased array to the virtual target, the path difference from the central array element to any array element is obtained; and based on the path difference, the equivalent spatial weighted phase of the any array element is obtained.

[0050] In one embodiment of the present application, when the phased array antenna is a spherical phased array, when the distance between the space target and the center of the spherical phased array is greater than When , the space target meets the far field condition; where r is the radius of the spherical phased array, f A is the maximum frequency of the phased array receiving signal, c is the speed of light; the first array element is the array element in the spherical phased array antenna whose distance from the center point of the array surface is the array surface radius.

[0051] In one embodiment of the present application, the step of calculating the coordinate value of the virtual target in the spherical phased array coordinate system includes:

[0052] A three-dimensional coordinate system with the center of the sphere as the origin is established in the spherical phased array antenna. The azimuth angle of the space target that meets the far-field condition in the coordinate system of the spherical array is The pitch angle is The array element on the array plane corresponding to the azimuth angle and the pitch angle is defined as the central array element C and its coordinates in the coordinate system of the spherical array are (x C ,y C ,z C ), the coordinate value (x B ,y B ,z B ):

[0053]

[0054] In one embodiment of the present application, the distance from the central element of the spherical phased array to the virtual target is calculated according to the following formula:

[0055] The distance L from the center element C to the virtual target B CB :

[0056]

[0057] In one embodiment of the present application, the distance from the coordinates of any array element on the spherical phased array to the virtual target is calculated according to the following formula:

[0058] Any coordinate on the spherical phased array is (x 1 ,y 1 ,z 1 ) to the virtual target B 1B :

[0059]

[0060] In one embodiment of the present application, the path difference from the central array element to any array element is obtained by the following method:

[0061] Let any coordinate be (x 1 ,y 1 ,z 1 ) is at point D on the array surface, and a plane α tangent to the spherical surface of the spherical phased array antenna is drawn through point C where the central array element is located, and the intersection of plane α and line segment DB is set to be E; the length of line segment BE is approximately equal to the length of line segment BC, and line segment DE is the coordinate (x 1 ,y 1 ,z 1 ) and the central element C. 1C =L 1B -L CB .

[0062] In one embodiment of the present application, obtaining the equivalent spatial weighted phase of any array element according to the path difference includes:

[0063] According to the following formula, calculate any coordinate (x 1 ,y 1 ,z 1 ) of the array element's equivalent spatial weighted phase Δφ 1C :

[0064]

[0065] Where c is the speed of light, f A is the maximum frequency of the phased array antenna, () 取小数 To perform decimal operations.

[0066] For ease of understanding, the present invention provides a more specific embodiment:

[0067] See also Figure 1 , using a planar phased array antenna to illustrate how to determine whether a space target meets the far-field condition for a phased array antenna in engineering. First, assume that the target is on the normal line passing through the center point O of the planar phased array antenna, such as Figure 1 As shown in the figure, the center point O of the plane phased array antenna is taken as the center point, the line connecting the edge array element 1 with the longest distance from the center point O of the plane phased array antenna to the center point O of the plane phased array antenna is taken as the x-axis, and the normal line passing through the center point O of the plane phased array antenna is taken as the y-axis. In this coordinate system, the coordinates of the space target A are (0, y A ), the coordinates of the center point O of the plane array are (0,0), and the coordinates of the edge element 1 are (x 1 ,0). At this time, the distance between the space target A and the center point O of the array is L 1O , the distance between space target A and edge element 1 is L 1A . Let L 1A With L OA The distance difference is ΔL 1A , calculate the distance difference ΔL 1A The algorithm is as follows:

[0068]

[0069] It can be seen that as the distance of space target A increases, L 1A With L OA The difference between ΔL 1A The judgment condition for the far-field condition of space target A is that when the distance difference ΔL 1A When the distance difference is reduced to the point where it does not affect the signal synthesis of the center array element O and the edge array element 1, the far-field condition is met. In engineering implementation, the far-field condition is generally taken as: the distance difference is less than or equal to 1% of the signal wavelength. Based on this condition, formula (1) can be used to determine whether the space target meets the far-field condition. For example, the phased array antenna array radius is 2 meters, and the received signal frequency is f A =3·109 Hz, from which 1% of the signal wavelength can be obtained as: Meters, where c is the speed of light. Apply formula (1) and substitute x 1 =2, we get:

[0070]

[0071] That is, when the distance between target A and the phased array antenna is greater than or equal to two kilometers, the far-field condition is met. When the space target meets the far-field condition for the phased array antenna, the signal transmitted by the space target can be regarded as a parallel wave signal for the phased array antenna.

[0072] See also Figure 2 , using a planar phased array to illustrate how to calculate the weighted phase of a far-field space target to a phased array antenna element through the traditional path difference, such as Figure 2 As shown in the figure, the far-field space target A, the center point O of the planar phased array antenna, and the array element 1 form a plane. Let the angle between the path r0 of the signal from the target A to the center array element O and the line connecting the array element 1 to the array element O be θ 1 , the angle is the signal incident angle of target A relative to array element 1. Since space target A meets the far-field condition for the planar phased array antenna, the path r0 is parallel to the path r1 of the signal from space target A to array element 1. A straight line s is made perpendicular to r0 through the center point O of the planar array. This straight line s is also perpendicular to r1. Let the intersection of straight line s and r1 be B.

[0073] according to Figure 1 According to the analysis in the previous section, the distances from the far-field target A to the center array element O and to point B are approximately equal, so the path difference of the edge array element 1 is the distance ΔL from point B to array element 1. 1 The coordinates of array element 1 and the signal incident angle θ can be used to 1 To calculate the path difference: ΔL 1 =x 1 sinθ 1 , and finally through the wave path difference ΔL 1 To calculate the spatial weighted phase of edge element 1.

[0074] The complexity of this traditional method of solving the array element path difference lies in the signal incident angle θ 1 Each array element on the array plane is variable, and each array element needs to be calculated separately according to the projection method, which brings great complexity. In this regard, an improved method for solving the weighted phase of the array element of the virtual far-field target is proposed.

[0075] See also Figure 3, or use the planar phased array to illustrate how to calculate the weighted phase of the far-field space target to the phased array antenna element by the method of virtual far-field target. Or first assume that the target is on the normal line passing through the center point O of the planar phased array antenna, such as Figure 3 As shown in the figure, the center point O of the plane phased array antenna is taken as the center point, the line connecting the edge array element 1 with the longest distance from the center point O of the plane phased array antenna to the center point O of the plane phased array antenna is taken as the x-axis, and the normal line passing through the center point O of the plane phased array antenna is taken as the y-axis. In this coordinate system, the coordinates of the space target A are (0, y A ), the coordinates of the center point O of the plane array are (0,0), and the coordinates of the edge element 1 are (x 1 ,0). Assume that the space target A meets the far-field condition for the planar phased array antenna. In this case, a target B that meets the far-field condition is arbitrarily virtualized on the normal y-axis passing through the center of the array surface O where the space target A is located, and its coordinates are set to (0,y B ).

[0076] Since the space target A meets the far-field condition for the planar phased array antenna, according to formula (1): Similarly, for the virtual target B that meets the far-field condition, the following can be obtained: Therefore, we can get:

[0077] |ΔL 1A -ΔL 1B |<1% of signal wavelength(2)

[0078] Therefore, for the signal synthesis of the phased array antenna, the signal emitted from the far-field virtual target B and the signal emitted from the far-field target A can be regarded as signals parallel to the array surface normal. That is, taking the central array element as the reference point, the equivalent spatial weighted phase of the array element can be obtained by calculating the path difference of the array element for a virtual target B that meets the far-field condition.

[0079] See also Figure 4 , the spherical phased array antenna can also be used to determine whether the space target meets the far-field condition for the spherical phased array antenna according to the judgment condition given by formula (1). Here, it is necessary to replace x in formula (1) with 1 Substitute for the radius r of the spherical phased array antenna. The minimum distance threshold min for the target to meet the far field condition can be calculated 远场 for:

[0080]

[0081] Where r is the radius of the spherical phased array, f A is the maximum frequency of the phased array receiving signal, and c is the speed of light.

[0082] like Figure 4 As shown, when the space target meets the far-field condition, the signal of the far-field target can be regarded as a parallel wave signal.

[0083] See also Figure 5 For space targets that meet far-field conditions, the spherical phased array antenna can also use the virtual far-field target method to calculate the equivalent spatial weighted phase of each array element on the array plane. Figure 5 As shown, a three-dimensional coordinate system with the center of the sphere as the origin is established in the spherical phased array antenna. The azimuth angle of the space target that meets the far-field condition in the coordinate system of the spherical array is The pitch angle is The array element on the array plane corresponding to the azimuth angle and the elevation angle is defined as the central array element C and its coordinate in the coordinate system of the spherical array is (x C ,y c ,z c The minimum distance threshold min of the far-field condition of the spherical phased array antenna can be calculated according to formula (3): 远场 , and take the distance L from the virtual target B to the center of the spherical phased array antenna B Satisfy the far-field condition, that is, L B >min 远场 Therefore, the coordinate value (x B ,y B ,z B ):

[0084]

[0085] And the distance L from the center array element C to the virtual target B is obtained according to the following algorithm: CB :

[0086]

[0087] And any coordinate on the spherical phased array is (x 1 ,y 1 ,z 1 ) from element 1 to virtual target B 1B :

[0088]

[0089] Assume that array element 1 is at point D on the array surface, and draw a plane α tangent to the spherical surface of the spherical phased array antenna through point C where the center array element is located, and assume that the intersection of plane α and line segment DB is E. According to the conclusion analyzed in formula (2), it can be obtained that: the length of line segment BE is approximately equal to the length of line segment BC, and line segment DE is the path difference between array element 1 and center array element C. Thus, the path difference ΔL between array element 1 and center array element C can be obtained1C It can be calculated as follows:

[0090] ΔL 1C =L 1B -L CB (7)

[0091] After obtaining the path difference ΔL of array element 1 1C After that, the equivalent spatial weighted phase Δφ of array element 1 can be calculated according to the following algorithm: 1C :

[0092]

[0093] Here c is the speed of light, f A is the maximum frequency of the phased array antenna, () 取小数 To perform decimal operations.

[0094] The method given here to calculate the equivalent spatial weighted phase of the phased array antenna element by virtual far-field targets is not only applicable to planar phased arrays and spherical phased array antennas, but also to other types of curved phased array antennas. And this method is not only applicable to far-field space targets, but also to near-field targets with known position information.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for calculating the far-field spatial weighted phase of a phased array antenna element, characterized in that: include: For the signal synthesis of the phased array antenna, the signal emitted from the far-field virtual target and the signal emitted from the far-field actual target are both regarded as signals parallel to the array normal of the phased array antenna; that is, taking the central array element as the reference point, for the actual target and virtual target that meet the far-field conditions, the equivalent spatial weighted phase of the arbitrary array element is obtained by calculating the path difference between the signal emitted by the far-field actual target and / or the far-field virtual target and reaching the central array element of the phased array antenna and any array element other than the central array element.

2. The method according to claim 1, characterized in that When the phased array antenna is a planar phased array, if the difference between the first distance difference and the second distance difference is less than the far-field virtual target or the specified multiple of the wavelength of the signal emitted by the far-field virtual target, the signal emitted from the far-field virtual target and the signal emitted from the far-field actual target are regarded as signals parallel to the normal of the array surface of the planar phased array antenna; the first distance difference is: the distance difference between the signal emitted by the far-field virtual target reaching the central array element and the first array element, and the second distance difference is: the distance difference between the signal emitted from the far-field actual target reaching the central array element and the first array element; the first array element is the array element with the longest distance from the center point of the array surface in the planar phased array antenna; the center point of the array surface is the center point of the central array element.

3. The method according to claim 2, characterized in that Assuming that the target is on the normal line passing through the center point O of the plane phased array antenna, a coordinate system is established with the center point O of the plane phased array antenna as the center point, the line from the first array element to the center point O of the plane as the x-axis, and the normal line passing through the center point O of the plane phased array antenna as the y-axis. In this coordinate system, the coordinates of the space target A are set to (0, y A ), the coordinates of the center point O of the plane array are (0,0), and the coordinates of the first array element are (x1,0); suppose that the space target A meets the far-field condition for the plane phased array antenna, and arbitrarily create a target B that meets the far-field condition on the y-axis, and set its coordinates to (0,y B ) The first array element is the array element with the longest distance from the center point of the array surface in the phased array antenna; If the distance y between the space target A and the center point O of the array A The distance between the space target A and the first array element is L 1A The distance difference ΔL 1A If the following formula is satisfied, the space target A is considered to meet the far-field condition: If the distance y between the virtual target B and the center point O of the array B The distance between the virtual target B and the first array element is L 1B The distance difference ΔL 1B If the following formula is satisfied, the virtual target B is considered to meet the far-field condition:

4. The method according to claim 1, characterized in that: When the phased array antenna is a spherical phased array, a virtual target that meets the far field condition is selected from the far field, and the coordinate value of the virtual target in the spherical phased array coordinate system is calculated; according to the distance from the central array element of the spherical phased array to the virtual target, and the distance from the coordinates of any array element on the spherical phased array to the virtual target, the path difference from the central array element to any array element is obtained; according to the path difference, the equivalent spatial weighted phase of any array element is obtained.

5. The method according to claim 4, characterized in that When the phased array antenna is a spherical phased array, when the distance between the space target and the center of the spherical phased array is greater than When , the space target meets the far field condition; where r is the radius of the spherical phased array, f A is the maximum frequency of the phased array receiving signal, c is the speed of light; the first array element is the array element in the spherical phased array antenna whose distance from the center point of the array surface is the array surface radius.

6. The method according to claim 4, characterized in that The step of calculating the coordinate value of the virtual target in the spherical phased array coordinate system includes: A three-dimensional coordinate system with the center of the sphere as the origin is established in the spherical phased array antenna. The azimuth angle of the space target that meets the far-field condition in the coordinate system of the spherical array is The pitch angle is The array element on the array plane corresponding to the azimuth angle and the pitch angle is defined as the central array element C and its coordinates in the coordinate system of the spherical array are (x C ,y C ,z C ), the coordinate value (x B ,y B ,z B ):

7. The method according to claim 6, characterized in that The distance from the central element of the spherical phased array to the virtual target is calculated according to the following formula: The distance L from the center element C to the virtual target B CB :

8. The method according to claim 7, characterized in that The distance from the coordinates of any array element on the spherical phased array to the virtual target is calculated according to the following formula: The distance L from any element with coordinates (x1, y1, z1) on the spherical phased array to the virtual target B 1B :

9. The method according to claim 7, characterized in that: The path difference from the central array element to any array element is obtained by the following method: Assume that an array element with arbitrary coordinates (x1, y1, z1) is at point D on the array surface, and draw a plane α tangent to the spherical surface of the spherical phased array antenna through point C where the central array element is located, and let the intersection of plane α and line segment DB be E; the length of line segment BE is approximately equal to the length of line segment BC, and line segment DE is the path difference ΔL between the array element with coordinates (x1, y1, z1) and the central array element C 1C =L 1B -L CB .

10. The method according to claim 9, characterized in that The step of obtaining the equivalent spatial weighted phase of any array element according to the wave path difference comprises: The equivalent spatial weighted phase Δφ of an array element with arbitrary coordinates (x1, y1, z1) is calculated according to the following formula: 1C : Where c is the speed of light, f A is the maximum frequency of the phased array antenna, () 取小数 To perform decimal operations.

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