Conformal phased array plane near-field calibration diagnosis method and system

Abstract

The invention provides a conformal phased array plane near-field calibration diagnosis method and system. The method comprises the following steps: calculating a plane wave spectrum of an antenna generation field according to near-field measurement data of a conformal phased array to be diagnosed; reducing according to the plane spectrum of the antenna generation field to obtain an aperture surface magnetic field component of the conformal phased array to be diagnosed; calculating an aperture plane tangential magnetic field of the conformal phased array to be diagnosed according to the aperture plane magnetic field component; and normalizing the tangential magnetic field of the aperture surface of the whole to-be-diagnosed conformal phased array, and calibrating and diagnosing by using the normalized tangential magnetic field of the aperture surface. According to the technical scheme, the technical problem that in the prior art, an existing near-field calibration diagnosis method cannot be applied to a conformal phased array is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of phased array antenna testing, and particularly relates to a conformal phased array planar near-field calibration diagnosis method and system. BACKGROUND

[0002] Calibration and diagnosis of a phased array antenna is a key link in an antenna testing process and is also a complex technical problem, and plays an important role in development and debugging of the phased array antenna.

[0003] Antenna measurement is generally divided into near-field measurement and far-field measurement. Compared with an antenna far-field testing system, a near-field testing system has been widely applied in phased array testing fields due to small occupied area, low construction cost, high automation degree and convenient operation. The biggest difference between the near-field measurement and the far-field measurement is that a sampling region of the near-field measurement is located in a radiation near-field region, and a directional diagram of the antenna in the radiation near-field region has not been completely unfolded, main lobe information and side lobe information are mixed into a complex envelope, and therefore sampling data obtained by the near-field measurement cannot be directly used, and a usable far-field directional diagram needs to be obtained through complex near-far-field conversion operation.

[0004] Antenna near-field diagnosis is a near-field detection method for phased array antenna units developed on the basis of the near-field measurement method. The number of units of the phased array antenna is large, and each unit needs to be tested for its quality and performance. The most direct method is to test each unit in turn, but this method has large workload and is not suitable for conformal antenna arrays.

[0005] A conformal antenna array refers to an antenna array in which antenna units are arranged according to a specific curved surface, which is different from a general antenna array arranged according to a plane. Compared with a planar phased array, a conformal phased array generally has a more complex structure, and a theory and technology are more difficult and relatively immature, but the conformal phased array also has corresponding advantages: a carrier conformal design can expand an aperture of the array and save space inside the carrier; and the conformal phased array can have a wider scanning range than the planar phased array. A basic principle of the antenna near-field diagnosis is to inversely deduce a distribution of an antenna aperture field or an excitation current of each radiation unit of the antenna by measuring a distribution of a near-field of the antenna, so as to judge a position where the aperture field or the excitation current is distorted and a corresponding radiation unit, and to achieve a diagnosis purpose of the antenna.

[0006] A basic principle of the antenna near-field diagnosis is to inversely deduce a distribution of an antenna aperture field or an excitation current of each radiation unit of the antenna by measuring a distribution of a near-field of the antenna, so as to judge a position where the aperture field or the excitation current is distorted and a corresponding radiation unit, and to achieve a diagnosis purpose of the antenna. For the near-field antenna diagnosis, currently, there are mainly three methods of a spectrum method, a directional diagram multiplication method and a numerical method.

[0007] The early diagnosis of the antenna array by using the near-field antenna data is mainly the wave spectrum method, a wave spectrum domain function is obtained by transforming the measured near-field data, the wave spectrum domain function is backward transformed to obtain the field on the aperture plane of the antenna, and the working state of the antenna array unit is judged by the amplitude and phase of the field.

[0008] The pattern multiplication method is a method for diagnosing the antenna array unit based on the pattern multiplication theorem, and this method needs to measure the far-field pattern of the antenna to obtain the array factor of the antenna array. However, for a conformal array, the radiation direction of the unit is not always forward, and the far-field pattern of the unit cannot be obtained by multiplying the far-field pattern function of the unit by the array factor.

[0009] The numerical method has two paths, one is the matrix method, and the other is the use of artificial intelligence. The matrix method is to solve the linear matrix related to the array element excitation and the field at the measurement point to achieve the purpose of diagnosing the antenna to be measured. Generally, it is only suitable for small-scale arrays. When the scale of the array increases, the matrix solution may not converge or the calculation time may be too long. By using artificial intelligence, the relationship between the array excitation and the measured field is learned by means of the emerging powerful artificial intelligence algorithm, so as to achieve the purpose of diagnosing the antenna unit. The diagnosis accuracy of this method is strongly related to the data model and the training set, and the general applicability is not good.

[0010] In summary, the existing near-field calibration method can only invert the aperture field distribution of a planar array antenna. For a conformal phased array with an arbitrary curved surface, if the traditional planar field back-propagation method is used, the amplitude and phase information of the conformal phased array on the aperture plane cannot be accurately restored, and the near-field calibration and fault unit diagnosis of the conformal phased array cannot be realized. Therefore, it is of great significance to study the planar near-field calibration and diagnosis method of the conformal phased array to realize the accurate restoration of the amplitude and phase data of the phased array aperture field. SUMMARY

[0011] The present application provides a conformal phased array planar near-field calibration diagnosis method and system, which can solve the technical problem that the existing near-field calibration diagnosis method in the prior art cannot be applied to the conformal phased array.

[0012] According to an aspect of the present application, a conformal phased array planar near-field calibration diagnosis method is provided, the method comprising:

[0013] calculating the planar spectrum of the antenna generated field according to the near-field measurement data of the conformal phased array to be diagnosed;

[0014] restoring the aperture plane magnetic field component of the conformal phased array to be diagnosed according to the planar spectrum of the antenna generated field;

[0015] calculating the aperture plane tangential magnetic field of the conformal phased array to be diagnosed according to the aperture plane magnetic field component.

[0016] The aperture plane tangential magnetic field of the entire conformal phased array to be diagnosed is normalized, and the normalized aperture plane tangential magnetic field is used for calibration and diagnosis.

[0017] Further, the plane wave spectrum of the antenna generated field is calculated according to the near-field measurement data of the conformal phased array to be diagnosed by the following formula:

[0018]

[0019]

[0020] In the above formula, A x , A y , A z denote the spectrum function in the antenna coordinate system components on the x, y, z axes, a 11 , a 12 , a 21 , a 22 , I x , I y are intermediate quantities, A x , A y , A z denote the spectrum function in the probe coordinate system components on the x', y', z' axes, A" x″ , A" y″ , A" z″ denote the spectrum function in the probe coordinate system components on the x'', y'', z'' axes, k denotes the wave number, k x , k y , k z denote the wave number vector components on the x, y, z axes, F(B x ) denotes the two-dimensional Fourier inverse transform of the near-field measurement data measured when the probe main electric field polarization is oriented along the x direction, F(B y ) denotes the two-dimensional Fourier inverse transform of the near-field measurement data measured when the probe main electric field polarization is oriented along the y direction, θ' denotes the angle between the wave number vector and the z' axis, denotes the angle between the wave number vector and the x' axis, θ'' denotes the angle between the wave number vector and the z'' axis, denotes the angle between the wave number vector and the x'' axis, f E denotes the E-plane normalized far-field pattern function of the probe, fH H represents the H-plane normalized far-field pattern function of the probe.

[0021] Further, the aperture plane magnetic field component of the conformal phased array to be diagnosed is:

[0022]

[0023] In the above formula, H x , H y , H z represents the aperture plane magnetic field component of the conformal phased array to be diagnosed, ω represents the frequency, μ represents the vacuum magnetic permeability constant, j represents the complex number, and (x, y, z) represents the coordinate point on the z=f(x, y) of the conformal phased array to be diagnosed.

[0024] Further, the aperture plane tangential magnetic field of the conformal phased array to be diagnosed is:

[0025]

[0026] In the above formula, represents the aperture plane tangential magnetic field, represents the magnetic field on the z=f(x, y) of the conformal phased array to be diagnosed, represents the tangential component at each uniform grid point of the conformal phased array to be diagnosed z=f(x, y), represents the unit vector in the antenna coordinate system in turn.

[0027] Further, the normalization processing of the aperture plane tangential magnetic field of the entire conformal phased array to be diagnosed includes:

[0028] According to the edge effect proximity of the conformal phased array to be diagnosed, the array elements are classified into multiple groups;

[0029] First, the in-group normalization processing is performed on each group of array elements respectively;

[0030] Then, the overall normalization processing of the entire conformal phased array to be diagnosed is performed according to the results of each group of normalization processing.

[0031] According to another aspect of the present application, a conformal phased array plane near-field calibration diagnosis system is provided, which includes an antenna generated field plane wave spectrum calculation unit, an aperture plane magnetic field component calculation unit, an aperture plane tangential magnetic field calculation unit, a normalization processing unit and a calibration diagnosis unit;

[0032] The antenna generated field plane wave spectrum calculation unit is used to calculate the plane wave spectrum of the antenna generated field according to the near-field measurement data of the conformal phased array to be diagnosed;

[0033] The aperture plane magnetic field component calculation unit is used to restore the aperture plane magnetic field component of the conformal phased array to be diagnosed according to the plane wave spectrum of the antenna generated field.

[0034] The aperture plane tangential magnetic field calculation unit is configured to calculate the aperture plane tangential magnetic field of the conformal phased array to be diagnosed according to the aperture plane magnetic field component;

[0035] The normalization processing unit is configured to perform normalization processing on the aperture plane tangential magnetic field of the entire conformal phased array to be diagnosed;

[0036] The calibration diagnosis unit is configured to perform calibration and diagnosis by using the normalized aperture plane tangential magnetic field.

[0037] The technical scheme of the present application provides a conformal phased array plane near-field calibration diagnosis method and system, which is improved from the traditional plane wave spectrum diagnosis algorithm. Different from the traditional plane wave spectrum diagnosis algorithm which directly uses the fast Fourier transform (FFT) method, the present application replaces the spatial coordinate variable Z with an equation composed of spatial coordinate variables X and Y determined by the surface equation of the conformal surface, and substitutes it into the summation formula for calculating the aperture plane magnetic field, so as to calculate the aperture plane magnetic field of the antenna to be measured. As a result, the plane wave spectrum diagnosis algorithm can also be applied to the conformal antenna array, and it is no longer required that the units of the antenna array to be measured are all on the same plane. In addition, the present application inherits the advantages of the wave spectrum method, so that it has a wide range of application and can achieve diagnosis for the units of the conformal antenna array with any curved surface within a certain range. Furthermore, due to the limited sampling range and the more dispersed radiation of the conformal antenna array, the edge effect of the array diagnosis result is stronger when the plane wave spectrum diagnosis is used, which is manifested as that the diagnosis amplitude of the edge units is obviously lower than that of the middle units. The present application compensates for the edge effect by performing normalization processing on the aperture plane tangential magnetic field of the array, so that it is more suitable for the diagnosis of the conformal antenna array, and performs better in the conformal curved surface antenna array with a large angle. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings included are part of the specification and illustrate embodiments of the present application and, together with the written description, serve to explain the principles behind the application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0039] Figure 1 Fig. 1 shows a flowchart of the conformal phased array plane near-field calibration diagnosis method provided by the specific embodiments of the present application;

[0040] Figure 2 Fig. 2 shows a schematic diagram of the alignment of the probe coordinate system and the antenna coordinate system according to the specific embodiments of the present application;

[0041] Figure 3A diagram showing that the probe coordinate system and the antenna coordinate system are orthogonal is shown according to a specific embodiment of the present application;

[0042] Figure 4 A diagram showing grouping of a cylindrical conformal array is shown according to a specific embodiment of the present application;

[0043] Figure 5 A diagram showing grouping of a spherical conformal array is shown according to a specific embodiment of the present application;

[0044] Figure 6 A diagram showing amplitude diagnosis of a conformal curved surface being a spherical surface with a radius of 900 mm is shown according to a specific embodiment of the present application;

[0045] Figure 7 A diagram showing phase diagnosis of a conformal curved surface being a spherical surface with a radius of 900 mm is shown according to a specific embodiment of the present application;

[0046] Figure 8 A diagram showing amplitude diagnosis of a conformal curved surface being a spherical surface with a radius of 1200 mm is shown according to a specific embodiment of the present application;

[0047] Figure 9 A diagram showing phase diagnosis of a conformal curved surface being a spherical surface with a radius of 1200 mm is shown according to a specific embodiment of the present application;

[0048] Figure 10 A diagram showing amplitude diagnosis of a conformal curved surface being a cylindrical surface is shown according to a specific embodiment of the present application;

[0049] Figure 11 A diagram showing phase amplitude diagnosis of a conformal curved surface being a cylindrical surface is shown according to a specific embodiment of the present application;

[0050] Figure 12 A diagram showing amplitude diagnosis of no edge effect compensation is shown according to a specific embodiment of the present application;

[0051] Figure 13 A diagram showing amplitude diagnosis of edge effect compensation is shown according to a specific embodiment of the present application;

[0052] Figure 14 A diagram showing amplitude diagnosis of a conformal antenna array with an abnormal unit is shown according to a specific embodiment of the present application. DETAILED DESCRIPTION

[0053] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other in the case of no conflict. The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The description of the at least one example embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0054] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a reference to the presence of a feature, step, operation, device, component and / or combinations thereof.

[0055] Unless specifically stated otherwise, the relative arrangements of the components and steps, numerical expressions, and values shown in the embodiments are not meant to limit the scope of the present application. At the same time, it should be understood that the sizes of the various parts shown in the drawings are not drawn in proportion. The techniques, methods and devices known to those skilled in the relevant art can not be discussed in detail, but should be considered as part of the authorized description. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0056] For a conformal antenna array, the pattern multiplication method is not applicable, and the numerical method can solve the problem, but it is only for a specific conformal antenna array, so the present application considers using the wave spectrum method. The traditional plane wave spectrum method diagnoses the antenna unit by using fast Fourier transform (FFT), which can efficiently and quickly obtain the field of the antenna aperture, and then achieve the purpose of diagnosis. However, in principle, the traditional plane wave spectrum diagnosis algorithm requires the antenna array elements to be on the same plane. When the diagnosis object becomes a conformal antenna array, the antenna array elements are no longer arranged on a plane, and the traditional plane wave spectrum diagnosis algorithm is no longer applicable.

[0057] To solve this problem, according to the specific embodiments of the present application, a conformal phased array plane near-field calibration diagnosis method is provided, the basic idea of which is to firstly perform two-dimensional Fourier transform on the near-field data to obtain the wave number spectrum of the far field, then perform probe compensation, and then restore the aperture field distribution of the antenna by using inverse Fourier transform. The method has the advantages of high efficiency calculation by using fast Fourier transform (FFT), and thus has strong engineering practicability and can be widely applied. As shown in FIG. 1, the method specifically comprises the following steps: Figure 1

[0058] S1, calculating the plane wave spectrum of the antenna generated field according to the near-field measurement data of the conformal phased array to be diagnosed;

[0059] The wave spectrum is a function for representing electromagnetic waves in space by superposition of multiple regular ideal electromagnetic waves in different directions, and the plane wave spectrum is to regard the electromagnetic waves in space as superposition of multiple ideal plane electromagnetic waves in different directions.

[0060] S2, restoring the aperture magnetic field component of the conformal phased array to be diagnosed according to the plane wave spectrum of the antenna generated field;

[0061] Specifically, the spatial coordinate variable Z is replaced by an equation composed of spatial coordinate variables X and Y determined by the surface equation of the conformal surface, and the equation is substituted into the summation formula for calculating the aperture magnetic field, so as to calculate the aperture magnetic field of the antenna to be measured.

[0062] S3, calculating the aperture tangential magnetic field of the conformal phased array to be diagnosed according to the aperture magnetic field component;

[0063] S4, performing normalization processing on the aperture tangential magnetic field of the entire conformal phased array to be diagnosed, and performing calibration and diagnosis by using the normalized aperture tangential magnetic field.

[0064] ​With the configuration, a conformal phased array plane near-field calibration diagnosis method is provided, which is improved from a traditional plane wave spectrum diagnosis algorithm, and is different from the traditional plane wave spectrum diagnosis algorithm which directly uses a fast Fourier transform (FFT) method, the method replaces a spatial coordinate variable Z with an equation composed of spatial coordinate variables X and Y determined by a surface equation of a conformal surface, and substitutes the equation into a summation formula for calculating a magnetic field on an aperture plane, so as to calculate the magnetic field on the aperture plane of the antenna to be measured, so that the plane wave spectrum diagnosis algorithm can also be applied to the conformal antenna array, and the units of the antenna to be measured are no longer required to be on the same plane, and the advantages of the wave spectrum method are inherited, so that the method has universality and can achieve diagnosis on units of a conformal antenna array with any curved surface within a certain range. In addition, due to the limited sampling range and the more dispersed radiation of the conformal antenna array, when the plane wave spectrum diagnosis is used, the edge effect of the diagnosis result of the array plane is stronger, that is, the diagnosis amplitude of the edge units is obviously lower than that of the middle units, the method compensates for the edge effect by normalizing the tangential magnetic field on the aperture plane, so that the method is more suitable for diagnosis of the conformal antenna array, and the method performs better when the conformal curved surface antenna array has a large angle. Compared with the prior art, the technical scheme of the present application can solve the technical problem that the existing near-field calibration diagnosis method cannot be applied to the conformal phased array in the prior art.

[0065] Further, in the embodiment of the present application, the process of S1 for calculating the plane wave spectrum is as follows:

[0066] Suppose that the signal (near-field measurement data) measured when the probe main electric field polarization is oriented along the x direction and scanned on the z=d (d is a constant, indicating the probe acquisition plane) plane is B x (x,y,d), and the signal (near-field measurement data) measured when the probe main electric field polarization is oriented along the y direction and scanned on the z=d plane is B y (x,y,d), then the coupling formula of the plane near-field antenna measurement can be obtained as follows:

[0067]

[0068] In the formula, k represents a wave number, k z represents a wave number vector along the Z-axis direction, that is, the wave number vector in the z-axis, represents a wave spectrum function in the antenna coordinate system, represents a wave spectrum function in the probe coordinate system when the antenna and the probe coordinate are aligned, represents a wave spectrum function in the probe coordinate system when the antenna and the probe coordinate are orthogonal, F[B x (x,y,d)] and F[B y (x,y,d) and B x (x,y,d) and B ya two-dimensional Fourier inverse transform of (x, y, d), i.e.

[0069]

[0070] In the above formula, j represents a complex number, k x represents a wave number vector propagating along the x-axis direction, i.e. a wave number vector with a component on the x-axis, k y represents a wave number vector propagating along the y-axis direction, i.e. a wave number vector with a component on the y-axis.

[0071] When the x, y reference vectors of the probe coordinate system and the antenna coordinate system are coplanar Figure 2 or differ by 90 degrees Figure 3 , the antenna coordinate system and the probe coordinate system have the following relationship:

[0072]

[0073] denote the unit vectors in the antenna coordinate system, respectively, denote the unit vectors in the probe coordinate system when the antenna coordinate system and the probe coordinate system are aligned, respectively, denote the unit vectors in the probe coordinate system when the antenna coordinate system and the probe coordinate system are orthogonal.

[0074] The wave number vector is expanded in the probe coordinate system under the two corresponding conditions as follows:

[0075]

[0076]

[0077] where θ' represents the angle between the wave number vector and the z' axis, represents the angle between the wave number vector and the x' axis, θ" represents the angle between the wave number vector and the z" axis, represents the angle between the wave number vector and the x" axis, and sin*, cos* are the sine and cosine functions of the corresponding angles, respectively.

[0078] It can be obtained that:

[0079]

[0080] i.e. there are

[0081]

[0082] With the above correspondence, the wave spectrum function in the probe coordinate system in (1) can be converted to the following form:

[0083]

[0084] Similarly, the wave spectrum function in (2) can be converted to the following form:

[0085]

[0086] wherein, denotes a unit vector with an angle of θ' to the z-axis, denotes a unit vector with an angle of θ' to the x-axis, denotes a unit vector with an angle of θ' to the y-axis, θ′ denotes the scalar component of the wave spectrum vector function A' on the unit vector θ', denotes the scalar component of the wave spectrum vector function A" on the unit vector θ", θ″ denotes the scalar component of the wave spectrum vector function A'" on the unit vector θ", denotes the scalar component of the wave spectrum vector function A"" on the unit vector θ", denotes the scalar component of the wave spectrum vector function A"" on the unit vector θ", denotes the scalar component of the wave spectrum vector function A"" on the unit vector θ". denotes the scalar component of the wave spectrum vector function A"" on the unit vector θ". denotes the scalar component of the wave spectrum vector function A"" on the unit vector θ". denotes the scalar component of the wave spectrum vector function A"" on the unit vector θ". denotes the scalar component of the wave spectrum vector function A"" on the unit vector θ".

[0087] Substituting (13) and (14) into (1) and (2) and combining them with (5) and (6), we have:

[0088]

[0089] wherein, A x , A y , A z denote the components of the wave spectrum function in the antenna coordinate system on the x, y, z axes, respectively, A x ", A y ", A z " denote the components of the wave spectrum function in the probe coordinate system on the x', y', z' axes, respectively, when the antenna and probe coordinates are aligned, A x″ ", A y″ ", A z″ denote the components of the wave spectrum function in the probe coordinate system on the x", y", z" axes, respectively, when the antenna and probe coordinates are orthogonal, F(B x ), F(B y ) are F[B x (x, y, d)] and F[B y ​​The short hand of (x, y, d) is used.

[0090] Substitute the above two equations into the equation (12), we have

[0091]

[0092] From equation (13), we have The relationship between and is

[0093]

[0094] A z = -A' θ′ sin θ' (20)

[0095] Since

[0096]

[0097] In the above two equations, f E represents the E-plane normalized far-field pattern function of the probe, f H represents the H-plane normalized far-field pattern function of the probe, are the elevation-plane and the horizontal-plane normalized far-field pattern functions of the probe, respectively.

[0098] So we have

[0099]

[0100] Substitute the above two equations into equations (18), (19), (20), we have

[0101]

[0102] Similarly, we have

[0103]

[0104]

[0105] Equation (17) can be written as

[0106]

[0107] where the coefficients a 11 , a 12 , a 21 , a 22 , I x , I y have the following expressions:

[0108] ​​

[0109] Thus, A can be solved from equation (31) x and A y , and then A is solved z , and the plane wave spectrum is obtained

[0110] For the planar array antenna, the steps of calculating the antenna magnetic field are as follows:

[0111] The tangential component of the planar near field is calculated, and the values at each element position on the aperture plane of the array antenna are extracted. It can be foreseen from the electromagnetic field boundary conditions that for the planar array antenna, the sampling values of the tangential magnetic field on the aperture plane represent the relative amplitude and phase distribution between the array elements.

[0112] The tangential component of the electric field on the z=h plane is obtained from the planar wave expansion of the field generated by the antenna as follows:

[0113]

[0114] is the tangential component of the electric field on the z=h plane, is the wave spectrum function corresponding to the tangential electric field, and h is the preset height of the calculated electric field plane.

[0115] Therefore, the tangential component of the electric field on the z=h plane at each uniform grid point is:

[0116]

[0117] In the formula:

[0118]

[0119] is the discretized form of the tangential electric field, is the discretized wave spectrum function corresponding thereto, Δx and Δy are the minimum distances of the discrete points on the x and y axes, respectively, pΔx and qΔy are the distances of the discrete points from the origin on the x and y axes, respectively, N and M are the numbers of discrete points on the x and y axes, respectively, π is the circular constant, n and m are the sequence numbers of the discrete points on the x and y axes in summation, and Δk x , Δk y is the discretization of the wave number vector on the x and y axes, and its expression is

[0120] Similarly, the magnetic field on the z=h plane is:

[0121]

[0122] ​is the magnetic field in the z=h plane, ω represents frequency, μ represents the vacuum permeability constant, and its value is 4π×10 -7 .

[0123] And:

[0124]

[0125] Therefore, the tangential magnetic field in the z=h plane is:

[0126]

[0127] Therefore, the tangential magnetic field in the z=h plane is: is replaced by and respectively, the tangential component H x (pΔx,qΔy,h) of the magnetic field at each uniform grid point in the z=h plane can be obtained. y (pΔx,qΔy,h) can be obtained.

[0128] If h=0 is taken, the tangential electric field and the tangential magnetic field on the aperture plane of the array antenna can be obtained, and then the values thereof at the positions of each radiating element can be extracted. According to the electromagnetic field boundary condition, the current distribution or the magnetic current distribution on each element can be respectively replaced by the tangential magnetic field or the tangential electric field at the position of each element.

[0129] For a conformal array antenna, i.e. a conformal phased array to be diagnosed, the magnetic field calculation step S2 is:

[0130] According to the plane wave expansion formula of the field generated by the antenna, the tangential component of the electric field on the z=f(x,y) curved surface is:

[0131]

[0132] is the tangential component of the electric field on the curved surface z=f(x,y), is the corresponding wave spectrum function, k x ,k y ,k z are the x, y, and z direction components of the wave number vector .

[0133] Therefore, the component of the electric field at each uniform grid point on the z=f(x,y) curved surface is:

[0134]

[0135] is the discretization form of the tangential electric field x component, This is its corresponding discretized spectral function. Δx and Δy are the minimum spacing between discrete points on the x and y axes, respectively. Then pΔx and qΔy are the distances of the discrete points from the origin on the x and y axes, respectively. N and M are the number of discrete points on the x and y axes, respectively. π is pi. When n and m are summed, the index of the discrete point on the x and y axes is Δk. x ,Δk y The discretization of the wavenumber vector components along the x and y axes is expressed as follows:

[0136] Similarly, the magnetic field component H on the surface z = f(x,y) x H y H z for:

[0137]

[0138] It is the magnetic field on the surface z = f(x,y), where ω is the frequency and μ is the free permeability constant, with a value of 4π × 10⁻⁶. -7 .

[0139]

[0140] Therefore, the magnetic field components on the surface z = f(x,y) are:

[0141]

[0142] Therefore, in equations (46), (47), and (48) Replace them respectively The magnetic field components H at each uniform grid point on the z = f(x,y) surface can then be obtained. x (pΔx,qΔy,z), H y (pΔx,qΔy,z) and H z (pΔx,qΔy,z).

[0143] Further, step S3 calculates the tangential components at each uniform grid point of the surface z = f(x,y) according to the following formula.

[0144]

[0145] In the above formula, Indicates the tangential magnetic field of the aperture surface. This represents the magnetic field on the conformal phased array z = f(x,y) to be diagnosed. This represents the tangential component at each uniform grid point of the conformal phased array z = f(x,y) to be diagnosed. (x, y, z) represents a coordinate point on the z=f(x, y) conformal phased array to be diagnosed.

[0146] According to the electromagnetic field boundary condition, the current distribution or the magnetic current distribution on each unit can be respectively replaced by the tangential magnetic field or the tangential electric field at the position of each unit.

[0147] Further, in step S4, when the amplitude and phase data of the antenna unit to be measured are represented by the amplitude and phase of the tangential magnetic field, if the original data is directly used for diagnosis, the diagnosis accuracy is difficult to meet the requirements, because the unit radiation of the conformal array changes with the conformal surface. This means that the radiation energy of the conformal array is more dispersed, and the energy covered by the same scanning surface is relatively less, which will result in stronger edge effect of the diagnosis result and affect the diagnosis accuracy.

[0148] In order to weaken the edge effect in the diagnosis result, when the diagnosis result is normalized, the array units are divided into groups according to the edge effect similarity of the conformal phased array to be diagnosed; the in-group normalization processing is performed on each group of array units respectively; and the overall normalization processing of the entire conformal phased array to be diagnosed is performed according to the results after the normalization processing of each group.

[0149] As shown in Figure 4 and Figure 5 , in actual application, the interpolation method is used to obtain the magnetic field data corresponding to each antenna array unit to be measured, and the amplitude and phase of the magnetic field data correspond to the diagnosis amplitude and phase of each antenna array unit to be measured. According to the arrangement characteristics of the conformal array, the units with similar edge effects are grouped, for example, each row and each column is separately grouped, the in-group normalization is performed first, and then the overall normalization of the antenna aperture surface is performed, that is, the amplitude data of the units in each row and each column are normalized separately, and then the rows and columns are integrated together for the normalization of the entire array surface. The normalized amplitude is used as the diagnosis result of the amplitude. In this way, the influence of the edge effect on the diagnosis result is eliminated as much as possible in the group, thereby reducing the influence of the edge effect on the diagnosis result.

[0150] The innovation of the present application is embodied in that it can effectively diagnose different types of conformal surfaces and different conformal surface radii. The following is a simulation of diagnosing conformal antenna arrays under different conditions. It is assumed that the units of an 8x8 antenna array to be measured are excited in phase and uniformly. In the ideal case, the diagnosis result should be that the amplitudes and phases of all units are equal. When the conformal surface of the antenna array to be measured is a spherical surface with different radii (900mm and 1200mm), the amplitude and phase diagnosis results are as shown in Figures 6 to 9 , and when the conformal surface of the antenna array to be measured is a cylindrical surface with a radius of 900mm, the amplitude and phase diagnosis results are as shown in Figure 10 and Figure 11As shown, the x, y coordinates of the amplitude diagnosis and phase diagnosis graph represent the corresponding unit, and the z coordinate represents the amplitude and phase diagnosis result corresponding to the coordinate.

[0151] The second innovation of the present application is that when the normalization step is not performed, the edge effect of the amplitude diagnosis result will significantly deteriorate the amplitude diagnosis result. Taking an 8x8 conformal antenna array with equal phase and equal amplitude excitation as an example, the conformal antenna array is on a cylindrical surface with a radius of 1200 mm. When no compensation is performed, the amplitude diagnosis graph shown in Figure 12 is obtained, and when compensation is performed, the amplitude diagnosis graph shown in Figure 13 is obtained. It can be seen that the edge compensation of the normalization processing significantly improves the amplitude diagnosis result, so that the amplitude diagnosis result is closer to the true situation. When there is no edge compensation, the amplitude diagnosis effect of the algorithm fluctuates too much at the edge, which makes the overall diagnosis result worse.

[0152] In the actual diagnosis process, first, the plane near-field measurement of the forward radiation of the antenna array to be measured in a certain angle domain is performed in the near-field antenna test system, and the near-field measurement data of different polarizations is obtained. Then, the measurement data is substituted into the algorithm, and the information related to the conformal antenna array to be measured is input, and the operation is performed to obtain the amplitude diagnosis graph and the phase diagnosis graph of the conformal antenna array to be measured. When all the units of the conformal antenna array to be measured work normally, the diagnosis result is similar to Figure 6 , Figure 8 , Figure 10 and Figure 13 When a unit of the conformal antenna array to be measured works abnormally, the amplitude diagnosis may be as shown in Figure 14 , and the diagnosis amplitude of the abnormal unit corresponding to the coordinate is significantly lower than that of the normally working unit, so as to achieve the diagnosis purpose.

[0153] According to another aspect of the present application, a conformal phased array plane near-field calibration diagnosis system is provided, which comprises an antenna generated field plane wave spectrum calculation unit, an aperture plane magnetic field component calculation unit, an aperture plane tangential magnetic field calculation unit, a normalization processing unit and a calibration diagnosis unit.

[0154] The antenna generated field plane wave spectrum calculation unit is used to calculate the plane wave spectrum of the antenna generated field according to the near-field measurement data of the conformal phased array to be diagnosed.

[0155] The aperture plane magnetic field component calculation unit is used to restore the aperture plane magnetic field component of the conformal phased array to be diagnosed according to the plane wave spectrum of the antenna generated field.

[0156] The aperture plane tangential magnetic field calculation unit is used to calculate the aperture plane tangential magnetic field of the conformal phased array to be diagnosed according to the aperture plane magnetic field component.

[0157] The normalization processing unit is used to perform normalization processing on the aperture plane tangential magnetic field of the entire conformal phased array to be diagnosed.

[0158] The calibration diagnosis unit is used for calibration and diagnosis by using the normalized aperture plane tangential magnetic field.

[0159] In summary, the present application provides a conformal phased array plane near-field calibration diagnosis method and system, which is improved from the traditional plane wave spectrum diagnosis algorithm, and is different from the traditional plane wave spectrum diagnosis algorithm directly using the fast Fourier transform (FFT) method. In the present application, the spatial coordinate variable Z is replaced by an equation composed of spatial coordinate variables X and Y determined by the surface equation of the conformal surface, which is substituted into the summation formula for calculating the aperture plane magnetic field to obtain the aperture plane magnetic field of the antenna under test. As a result, the plane wave spectrum diagnosis algorithm can also be applied to the conformal antenna array, and it is no longer required that the units of the antenna array under test are all in the same plane, and the advantages of the wave spectrum method are inherited, so that the present application has universality and can achieve diagnosis for the units of the conformal antenna array with any curved surface within a certain range. In addition, due to the limited sampling range and the more dispersed radiation of the conformal antenna array, the edge effect of the array diagnosis result is stronger when the plane wave spectrum diagnosis is used, which is manifested as that the diagnosis amplitude of the edge units is significantly lower than that of the middle units. The present application compensates for the edge effect by normalizing the aperture plane tangential magnetic field of the array, so that it is more suitable for the diagnosis of the conformal antenna array, and performs better in the conformal curved surface antenna array with a large angle. Compared with the prior art, the technical scheme of the present application can solve the technical problem that the existing near-field calibration diagnosis method cannot be applied to the conformal phased array in the prior art.

[0160] For the purposes of the description hereinafter, spatially relative terms, such as "above", "below", "up", "down", "between", "within", "left", "right", "rear", "front", "upper", "lower", "horizontal", "vertical", "above", "below", "on", "under", "in", "out", "right", "left", "forward", "backward", "upward", "downward", "up", "down", "front", "back", "side", "under" and the like, can be used to describe the relative position of one element or features to another as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device in the figures is inverted, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device in the figures is inverted, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0161] In addition, it should be noted that the use of "first", "second", and the like words to qualify parts is only for the convenience of distinguishing the corresponding parts, and the above words have no special meaning unless otherwise stated, and therefore cannot be understood as limiting the scope of protection of the present application.

[0162] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A conformal phased array planar near-field calibration and diagnostic method, characterized by, The method comprises: calculating a plane wave spectrum of an antenna-generated field according to near-field measurement data of a conformal phased array to be diagnosed; deriving a magnetic field component on an aperture plane of the conformal phased array to be diagnosed according to the plane wave spectrum of the antenna-generated field; calculating a tangential magnetic field on the aperture plane of the conformal phased array to be diagnosed according to the magnetic field component on the aperture plane; performing normalization processing on the tangential magnetic field on the aperture plane of the entire conformal phased array to be diagnosed, and performing calibration and diagnosis by using the normalized tangential magnetic field on the aperture plane.

2. The method of claim 1, wherein, The plane wave spectrum of the antenna-generated field is calculated according to the near-field measurement data of the conformal phased array to be diagnosed by the following formula: In the above equations, A x , A y , A z denote the spectral function in the antenna coordinate system , a 11 , a 12 , a 21 , a 22 , I x , I y are intermediate quantities, A x , A y , A z denote the spectral function in the probe coordinate system when the antenna and probe coordinates are aligned , A x″ , A y″ , A z″ denote the spectral function in the probe coordinate system when the antenna and probe coordinates are orthogonal , k x , k y , k z denote the wave number vector , F(B x ) denotes the two-dimensional Fourier inverse transform of the near-field measurement data measured when the probe main electric field polarization is oriented along the x direction, F(B y ) denotes the two-dimensional Fourier inverse transform of the near-field measurement data measured when the probe main electric field polarization is oriented along the y direction, θ' denotes the angle of the wave number vector with the z' axis, denotes the angle of the wave number vector with the x' axis, θ" denotes the angle of the wave number vector with the z" axis, denotes the angle of the wave number vector with the x" axis, f E denotes the E-plane normalized far-field pattern function of the probe, f H denotes the H-plane normalized far-field pattern function of the probe.

3. The method of claim 2, wherein, The magnetic field component on the aperture plane of the conformal phased array to be diagnosed is: In the above formula, H x , H y , H z represents the aperture plane magnetic field component of the conformal phased array to be diagnosed, ω represents the frequency, μ represents the vacuum permeability constant, j represents the complex number, (x, y, z) represents the coordinate point on the z=f(x, y) of the conformal phased array to be diagnosed.

4. The method of claim 3, wherein, The tangential magnetic field on the aperture plane of the conformal phased array to be diagnosed is: In the above formula, denotes the aperture tangential magnetic field, denotes the magnetic field on the conformal phased array to be diagnosed z=f(x,y), denotes the tangential component at each uniform grid point of the conformal phased array to be diagnosed z=f(x,y), denotes the unit vector in the antenna coordinate system in turn.

5. The method of claim 4, wherein, The normalization processing on the tangential magnetic field on the aperture plane of the entire conformal phased array to be diagnosed comprises: grouping the array elements into multiple groups according to the edge effect similarity of the conformal phased array to be diagnosed; performing in-group normalization processing on each group of array elements respectively; performing overall normalization processing on the entire conformal phased array to be diagnosed according to the results of the normalization processing on each group.

6. A conformal phased array planar near-field calibration and diagnostic system, characterized by, The system comprises an antenna-generated field plane wave spectrum calculation unit, a magnetic field component on an aperture plane calculation unit, a tangential magnetic field on an aperture plane calculation unit, a normalization processing unit and a calibration and diagnosis unit; The antenna-generated field plane wave spectrum calculation unit is configured to calculate a plane wave spectrum of an antenna-generated field according to near-field measurement data of a conformal phased array to be diagnosed; The magnetic field component on an aperture plane calculation unit is configured to derive a magnetic field component on an aperture plane of the conformal phased array to be diagnosed according to the plane wave spectrum of the antenna-generated field; The tangential magnetic field on an aperture plane calculation unit is configured to calculate a tangential magnetic field on the aperture plane of the conformal phased array to be diagnosed according to the magnetic field component on the aperture plane; The normalization processing unit is configured to perform normalization processing on the tangential magnetic field on the aperture plane of the entire conformal phased array to be diagnosed; The calibration and diagnosis unit is configured to perform calibration and diagnosis by using the normalized tangential magnetic field on the aperture plane.

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