Deformation measurement method, compensation method and system for main reflector of parabolic antenna

Abstract

The present invention discloses a method for measuring the deformation of the main reflector of a parabola antenna, a method for compensating for the deformation and a system thereof. The measuring method comprises: obtaining the intensity measurement value of the radiation signal on a set area, the set area being a lower hemisphere with the focus of the main reflector of the parabola antenna as the center, and the set area being located below the feed source of the parabola antenna. The deformation δ(x, y) on the main reflector of the parabola antenna is calculated according to #imgabs0#, wherein #imgabs1#A0(x, y) is the intensity distribution of the radiation signal on the set area when the main reflector of the parabola antenna is not deformed, A(x, y) is the intensity measurement value of the radiation signal on the set area, R is the radius of the hemisphere, d(x, y) is the distance between the hemisphere and the main reflector surface of the parabola antenna on the reflected light path, F is the focal length of the main reflector, and x and y are the horizontal and vertical coordinates of the point (x, y) on the hemisphere projected on the aperture surface of the parabola antenna. The present invention has the advantages of small scanning area, no interference from feed source factors, and no problem of difficulty in separating double reflector deformation data in measurement data.

Description

Technical Field

[0001] The invention relates to the field of deformation detection of a main reflector surface of a parabola antenna, and in particular to a deformation measurement method and compensation method of the main reflector surface of a parabola antenna, as well as a measurement system and a compensation system. Background Art

[0002] During millimeter-wave radio observations, the surface accuracy of the main reflector of a parabolic antenna or Gregorian antenna directly determines its own performance and observation efficiency. In order to ensure that it can achieve sufficient resolution during high-frequency observations above 100 GHz, the root mean square deformation of the main reflector must be less than 0.2 mm. The surface errors of large-aperture reflectors mainly come from mechanical errors such as machining and assembly, and system errors caused by gravity, temperature, wind loads, and other dynamic loads. Due to its huge size and weight, the surface deformation of the reflector caused by the above factors on the 100-meter QTT antenna varies greatly in different postures and climates, seriously affecting the observation efficiency.

[0003] In order to make real-time corrections to the antenna surface shape errors, large radio telescopes at home and abroad, such as TM-65m (Tianma Radio Telescope, Shanghai Astronomical Observatory), GBT-110m (Green Bank Telescope, National Astronomical Observatory of the United States), and Effelsberg-100m (Effelsberg Telescope, European Astronomical Observatory) generally install active surface systems under the main reflector to compensate and correct the measured deformation of the antenna reflector in real time. At present, the active surface technology used for the correction of the main reflector of the telescope is quite mature, but there are still many deficiencies in the theory and technology of rapid surface shape measurement.

[0004] For real-time surface shape measurement of large radio telescopes, the most widely studied and applied methods are based on their electrical properties, among which radio holography is the most popular. Holographic measurement methods include phase coherence method and phase recovery method. The theoretical basis of the phase coherence method is the two-dimensional Fourier transform relationship between the far-field complex radiation pattern of the antenna and the aperture surface field distribution. This method requires the measurement of the amplitude and phase of the far field, and the lack of a suitable artificial high-frequency source at different elevation angles means that it can only work at a specific elevation angle; the phase recovery method does not require the far-field phase, but requires multiple measurements of the amplitude of the antenna focus and defocus radiation pattern. Among them, the out-of-focus holographic measurement technology (OOF) requires a small dynamic movement range of the antenna posture, which can meet the measurement at all elevation angles. However, its poor signal-to-noise ratio leads to low surface shape recovery accuracy.

[0005] In addition, although the traditional near-field measurement method has the advantages of high signal-to-noise ratio and high surface recovery accuracy, its near-field beacon distance and height are fixed, which makes it impossible to measure at full pitch angles. The near-field single-surface amplitude scanning method based on the rope parallel mechanism only needs to measure the antenna near-field amplitude and can achieve measurement at full pitch angles. However, this method still has shortcomings such as large scanning area, susceptibility to interference from feed source factors, and difficulty in separating the accuracy of double reflection surfaces. Summary of the invention

[0006] The purpose of the present invention is to provide a near-field measurement method and a measurement system for the deformation of the main reflector of a parabolic antenna, as well as a compensation method and a compensation system based on the measurement method, which have the advantages of a small scanning area, no interference from feed source factors, and no problem of difficulty in separating the deformation data of the double reflectors in the measurement data.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A method for measuring deformation of a main reflector surface of a parabolic antenna, comprising:

[0009] Obtaining a strength measurement value of a radiation signal in a set area, wherein the set area is a lower hemisphere with a focus of a main reflection surface of the parabola antenna as the center, and the set area is located below a feed source of the parabola antenna;

[0010] according to Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, where A0(x,y) is the intensity distribution of the radiation signal in the set area when the main reflection surface of the parabolic antenna is not deformed, A(x,y) is the intensity measurement value of the radiation signal in the set area, R is the radius of the hemisphere, d(x,y) is the distance between the hemisphere and the main reflection surface of the parabolic antenna on the path of the reflected light passing through the point (x,y) on the hemisphere, F is the focal length of the main reflection surface, x and y are the horizontal and vertical coordinates of the point (x,y) on the hemisphere projected on the aperture surface of the parabolic antenna.

[0011] Optionally, the basis Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, including:

[0012] according to The finite difference-Gaussian iteration method is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna.

[0013] Optionally, the basis Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, including:

[0014] according to The neural network model is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna.

[0015] Optionally, the parabolic antenna is a Gregorian or Cassegrain antenna.

[0016] A second aspect of the present invention provides a method for compensating deformation of a main reflector surface of a parabolic antenna, comprising:

[0017] Determine the deformation of the main reflecting surface of the parabolic antenna by using the main reflecting surface deformation measurement method of the parabolic antenna provided by the first aspect of the present invention;

[0018] According to the deformation of the main reflecting surface of the parabola antenna, the deformation of the main reflecting surface of the parabola antenna is compensated.

[0019] A third aspect of the present invention provides a main reflector deformation measurement system for a parabolic antenna, comprising:

[0020] An intensity measurement value acquisition module is used to acquire the intensity measurement value of the radiation signal in a set area, wherein the set area is a lower hemisphere with the focus of the main reflection surface of the parabola antenna as the sphere center, and the set area is located below the parabola antenna feed source;

[0021] Deformation calculation module, used to calculate Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, where A0(x,y) is the intensity distribution of the radiation signal in the set area when the main reflection surface of the parabolic antenna is not deformed, A(x,y) is the intensity measurement value of the radiation signal in the set area, R is the radius of the hemisphere, d(x,y) is the distance between the hemisphere and the main reflection surface of the parabolic antenna on the path of the reflected light passing through the point (x,y) on the hemisphere, F is the focal length of the main reflection surface, x and y are the horizontal and vertical coordinates of the point (x,y) on the hemisphere projected on the aperture surface of the parabolic antenna.

[0022] Optionally, the deformation calculation module specifically includes:

[0023] Deformation calculation unit, used to calculate The finite difference-Gaussian iteration method is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna.

[0024] Optionally, the deformation calculation module specifically includes:

[0025] Deformation calculation unit, used to calculate The neural network model is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna.

[0026] Optionally, the parabolic antenna is a Gregorian or Cassegrain antenna.

[0027] The fourth aspect of the present invention provides a main reflector deformation compensation system for a parabolic antenna, comprising: a deformation compensation module and the main reflector deformation measurement system for the parabolic antenna provided by the third aspect of the present invention, wherein the deformation compensation module is used to compensate for the deformation of the main reflector of the parabolic antenna according to the deformation of the main reflector of the parabolic antenna.

[0028] According to the specific embodiment provided by the present invention, the present invention discloses the following technical effects: the deformation measurement method, compensation method, measurement system and compensation system of the main reflector of the parabolic antenna provided by the present invention are based on the relationship between the intensity of the radiation signal on the lower hemisphere below the parabolic antenna feed source and the deformation of the main reflector of the parabolic antenna with the focus of the main reflector of the parabolic antenna as the sphere center under the signal receiving state, and the deformation of the main reflector of the parabolic antenna is determined by measuring the intensity of the radiation signal on the lower hemisphere. Since the measurement area used in the above method is located below the parabolic antenna feed source, the measured data is only affected by the deformation of the main reflector of the parabolic antenna, so there is no problem in the prior art that it is difficult to separate the double reflector deformation data in the measurement data. On the other hand, since the measurement area is located below the parabolic antenna feed source, the measurement signal is only a receiving signal, so it will not be interfered by the feed source factor. Moreover, the radius of the hemispherical measurement area of ​​the present invention can be selected according to actual needs, and the hemispherical measurement area can be smaller than the scanning area in the traditional near-field measurement method. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 (a) is a schematic diagram of the Gregorian antenna structure in an embodiment of the present invention, Figure 1 (b) is a cross-sectional view of the main reflective surface of the antenna in an embodiment of the present invention, Figure 1 (c) is a front view of the main reflective surface of the antenna in an embodiment of the present invention;

[0031] Figure 2 A schematic flow chart of a method for measuring deformation of a main reflector surface of a parabolic antenna provided by an embodiment of the present invention;

[0032] Figure 3 A location diagram of a measurement area in an embodiment of the present invention;

[0033] Figure 4 It is a flow chart of an implementation method of an antenna profile measurement method based on close-range near-field hemispherical amplitude scanning in an embodiment of the present invention;

[0034] Figure 5 Schematic diagram of phase matching principle in an embodiment of the present invention;

[0035] Figure 6 Schematic diagram of a hemispherical amplitude scanning area in an embodiment of the present invention;

[0036] Figure 7 A schematic structural diagram of a system for measuring deformation of a main reflector surface of a parabolic antenna provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The purpose of the present invention is to provide a near-field measurement method and a measurement system for the deformation of the main reflector of a parabolic antenna, as well as a compensation method and a compensation system based on the measurement method, which have the advantages of a small scanning area, no interference from feed source factors, and no problem of difficulty in separating the deformation data of the double reflectors in the measurement data.

[0039] In order to facilitate the understanding of the present invention, the basic structure of the parabolic antenna and its active surface system are briefly introduced by taking the Gregorian antenna as an example.

[0040] The basic structure of the Gregorian antenna is as follows Figure 1 (a) is shown. The main body of the Gregorian antenna consists of three parts: the main reflector 2, the sub-reflector 3 and the feed source 4, which together constitute the core part of the Gregorian antenna. Among them, the main reflector 2 is supported by the parabolic steel structure surface 1, but it is not directly fixed to the steel structure surface. Figure 1 As shown in the cross-sectional view of (b), the main reflector is indirectly connected to the steel structure surface through a set of actuators. The actuator is a precision linear motor that can make absolute position control according to program instructions. Figure 1(c) As shown in the front view, unlike the steel frame structure surface 1 which is fixed and processed in an integrated manner, the main reflector 2 is not in an integral form, but is composed of many aluminum reflector panels. Different panels share the same corner points, and a precision actuator is installed at each corner point. The sub-reflector 3 of the standard Gregorian antenna is an integrally formed rotating ellipsoid surface, which is directly fixed to the steel structure surface through a steel structure. Therefore, the surface shape of the sub-surface changes as a whole with its own posture. By adjusting the length of the sub-surface support frame, the position and posture of the sub-reflector 3 can be controlled macroscopically. Under the sub-reflector 3 are the antenna feed 3 and the receiver system, which are used to collect radio waves from a certain direction in the universe. The core part of the above-mentioned antenna is installed as a whole on the base 6, and the two are connected by a posture adjustment joint 5 with two degrees of freedom, so that the antenna can achieve high-precision movement at two angles of pointing and pitch.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Example 1

[0043] See also Figure 2 This embodiment provides a method for measuring the deformation of the main reflector of a parabolic antenna, where the parabolic antenna may be a Gregorian antenna, a Cassegrain antenna, or the like. The method comprises the following steps:

[0044] Step 101: Obtain the intensity measurement value of the radiation signal in a set area, wherein the set area is a lower hemisphere with the focus of the main reflection surface of the parabola antenna as the sphere center, and the set area is located below the parabola antenna feed source, see Figure 3 .

[0045] Step 102: According to Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, where A0(x,y) is the intensity distribution of the radiation signal in the set area when the main reflection surface of the parabolic antenna is not deformed, A(x,y) is the intensity measurement value of the radiation signal in the set area, R is the radius of the hemisphere, d(x,y) is the distance between the hemisphere and the main reflection surface of the parabolic antenna on the path of the reflected light passing through the point (x,y) on the hemisphere, F is the focal length of the main reflection surface, x and y are the horizontal and vertical coordinates of the point (x,y) on the hemisphere projected on the aperture surface of the parabolic antenna.

[0046] The above measurement method provided by the present invention is performed when the antenna is in a normal receiving state. At this time, the signal from the outer space satellite radiation source or the far-field artificial beacon can be regarded as a plane wave incident, which makes the measurement method provided by the present invention applicable to a wider range of working conditions. Therefore, the selection of the signal source during measurement only needs to meet the far-field condition.

[0047] For further information, see Figure 4 , the specific operation process of the present invention can be as follows:

[0048] Step 1: Set up a plane wave radiation source.

[0049] Step 2: Spherical field amplitude scanning and sampling.

[0050] Determine the intensity distribution of the radiation signal on the close-range near-field hemispherical surface below the Gregorian antenna sub-reflector (or below the parabolic antenna feed source). The scanning area is the lower hemisphere of the sphere with the main surface focus as the sphere center and R as the radius.

[0051] Step 3: Establish amplitude-deformation relationship.

[0052] The process of establishing the relationship between the near-field spherical amplitude distribution and the deformation of the main reflector surface is mainly divided into three steps:

[0053] a): The curvature matrix distribution of the antenna main reflector is expressed by the Weingarten map in differential geometry [a].

[0054] See also Figure 4 and Figure 5 First, define the antenna to be The coordinate system is a cylindrical coordinate system, and the surface function of the main reflection surface is defined as the following formula (1):

[0055]

[0056] in is the deformation distribution function on the main reflector, then any point on the main reflector of the antenna can be expressed as According to the Weingarten mapping theory, the curvature matrix of point Z can be expressed as formula (2):

[0057]

[0058] in, is the first basic quantity of the surface, Represents the surface shape function of r and The first-order partial derivative of .

[0059]

[0060] is the second fundamental quantity of the surface, Represents the surface shape function of r and The second-order partial derivative of .

[0061] After simplifying equations (1) and (2), we can obtain that the elements in the curvature matrix of any point on the main reflection surface can be approximately expressed as:

[0062]

[0063] b): Substitute the curvature matrix [a] obtained in a) into formula (4) and derive the main curvature distribution of the reflected wavefront at each point on the main reflection surface by the phase matching method.

[0064] like Figure 5 As shown, the phase matching relationship of the incident and reflected wavefront on the curved surface is as follows: (Note: the superscripts i and r are incident and reflected respectively, and T is transposition)

[0065] [a]cosγ i +K i T Q i (P0)K i = -[a]cosγ r +K r T Q r (P0)K r (4)

[0066] Where [a] is the curvature matrix of the reflection surface, γ i is the incident angle, γ r is the reflection angle, Q i (P0) is the incident wavefront curvature matrix, Q r (P0) is the reflected wavefront curvature matrix, is the orthogonal transformation matrix from the local coordinate system of the incident wavefront near the reflection point to the local coordinate system of the antenna surface near the reflection point, is the transformation matrix from the local coordinate system of the antenna surface near the reflection point to the local coordinate system of the reflected wavefront near the reflection point.

[0067] Combined with Fermat's law (the incident angle γ i Equal to the reflection angle γ r ), we can get the curvature matrix of the reflected wavefront at a point after the plane wave is incident on the main reflection surface of the antenna:

[0068]

[0069] The elements are Q 12 =2a 12 , Q 21 =2a 21 , Q22 = -2cosγa 22 , the cosine of the angle of incidence and the angle of reflection are

[0070] According to the principal curvature of a point on the surface as the eigenvalue of its curvature matrix, the two principal curvatures of the reflected wavefront of the antenna after the plane wave is incident on the main reflection surface are distributed as follows:

[0071]

[0072] c) The principal curvature of the reflected wavefront obtained in b) is Substituting into formula (7), the relationship between the hemispherical scanning amplitude and the surface deformation of the main reflection surface is obtained through geometric optics approximation (ie, formula (9)).

[0073] The geometric optics method is a high-frequency approximate method for studying the antenna radiation field, such as Figure 6 As shown, the complex amplitude of the electric field at a point P on the above hemispherical measurement area can be expressed by the complex amplitude of point M on the main reflection surface as follows:

[0074]

[0075] Among them, R1 and R2 are the principal curvature radii of the wavefront of the light reflected from point M, d is the distance between point P and point M, j is a unit imaginary number, and k=ω / v=2π / λ is the propagation constant of light.

[0076] According to formula (6) and formula (7), when the main reflector has no deformation and has deformation, the amplitude of P can be expressed as:

[0077]

[0078] According to formula (6) and formula (8), after simplification, the relationship between the hemispherical scanning amplitude and the deformation of the main reflector surface of the antenna is obtained as follows:

[0079]

[0080] According to formula (9), let in is the ratio of the ideal electric field intensity distribution to the electric field intensity obtained by the actual scanning sampling of the above hemispherical area. The Poisson equation can be finally obtained:

[0081] Δδ=F AG (10)

[0082] The calculated matrix F AG Substitute Δδ=F AG , we use numerical algorithm to solve δ, is the effect of the Laplace operator on the deformation.

[0083] Step 4: Solve the surface deformation of the main reflector.

[0084] Substitute the collected hemispherical amplitude data A into the formula Get the amplitude ratio F A Where A0 is the amplitude distribution of the radiation signal on the set hemispherical surface when the main reflector of the antenna under test is not deformed (this value can be obtained through simulation and calculation). A Substitution Calculate the matrix F AG . Where F is the focal length of the main reflector, d = F + zR is the distance between the hemispherical surface and the main reflector surface on the reflected light path, R is the radius of the hemispherical surface, δ(x, y) is the deformation of the main reflector to be measured, x and y are the horizontal and vertical coordinates of a point on the main reflector projected on the aperture surface, and z is the height of the point (with the vertex of the parabola as the zero point). Then, the process of solving the deformation is completely transformed into solving a standard Poisson equation, that is By solving this equation, the deformation of the main reflector surface of the parabolic antenna is obtained.

[0085] As an implementation method of this embodiment, the deformation can be solved using the finite difference-Gaussian iteration method: first, the convolution of the Laplace operator in the Poisson equation on the deformation to be solved is converted into a matrix multiplication form according to the difference format, and then the Gaussian iteration method is used to solve it. When there are many amplitude sampling points in the hemispherical scanning area, the equivalent difference matrix of the Laplace operator needs to be sparse to avoid the problem of long solution time.

[0086] The amplitude-deformation equation of formula (9) can be transformed into the standard Poisson equation, where the Laplace operator's action on the deformation Δδ can be approximated as the convolution δ*L of the Laplace operator L on the deformation with third-order accuracy, where

[0087] According to the finite difference method, the third-order accurate Laplace operator L is first expanded into a matrix T whose number of elements is equivalent to the number of amplitude sampling points, and then the amplitude-deformation equation of formula (9) is converted into the finite difference format:

[0088]

[0089] Where b is a discrete matrix The transformed column vector, δ'(x,y) is the column vector transformed by the discrete deformation matrix δ(x,y).

[0090] According to δ (k+1) =D -1 (L+U)δ (k) +D -1b performs k+1 iterations to obtain the deformation of the antenna main reflector within the effective accuracy. (k+1) and δ (k) are the deformations obtained by the k+1th and kth solutions, respectively, D=diag(a 11 ,a 22 ,…a nn ) is a diagonal matrix obtained by taking only the diagonal elements of the T matrix, Negate each element of the lower triangular matrix of the T matrix. The upper triangular matrix of the T matrix is ​​negative, a 11 ,a 12 ,…,a nn are the elements of each row and column of matrix T. Since there are many sampling points of the hemispherical amplitude, in this embodiment, the number of sampling points reaches 66049, when solving the Gaussian iterative solution, the T matrix needs to be converted into a sparse matrix for iteration, that is, the 0 elements in the matrix are removed, so that the solution time is greatly shortened.

[0091] As an implementation method of this embodiment, a fully connected layer neural network method can be used to solve the hemispherical amplitude-deformation equation. The main steps include:

[0092] First, the network input data is preprocessed, mainly including F A and coordinates x and y so that they are within the same order of magnitude.

[0093] Set the neural network structure and parameters of the fully connected layer, mainly including network width, network depth, and learning rate.

[0094] Constructing loss function Make it a neural network optimization target.

[0095] According to the causes and characteristics of the deformation of the main reflector surface, in this embodiment, it is set to 0 at the boundary (circular boundary of the rotating parabola) to construct a tentative solution for the deformation of the main reflector surface. in, is the two-dimensional Cartesian coordinate vector of the antenna, For a feed-forward neural network with n inputs and a single output, Tune the parameters for the neural network, is the boundary function of the antenna aperture surface, The boundary conditions are met, and the F function is 0 at the boundary. The optimization problem is solved by adjusting the weights and biases of the neural network in the function. It can be noted that through the form of the trial solution construction, no matter the neural network The output of is any value, the trial solution will always satisfy the boundary conditions of the spherical field amplitude-deformation equation. Therefore, the original optimization problem with constraints has been transformed into an unconstrained optimization problem.

[0096] According to the characteristics of the sigmoid activation function of the neural network, the first-order and second-order partial derivatives of the network input can be expressed by the function itself. The derivative of coordinates x and y can be expressed as:

[0097]

[0098] Where σ is the sigmoid activation function, W (input layer to hidden layer) and V (hidden layer to output layer) are both weight tensors in the neural network parameters, and the subscripts [0] and [1] respectively represent the first input (i.e., x) and second input (i.e., y) parts of the tensor.

[0099] Preferably, for the above optimization goal, the Adam optimization algorithm can be used to continuously train the fully connected layer neural network to optimize the network parameters so that the above trial solution The deformation is continuously converged toward the main reflection surface, and finally a deformation distribution within an effective accuracy is obtained.

[0100] The core of the antenna main reflector surface shape measurement method of the present invention is to scan and sample the signal amplitude in the hemispherical area, solve the deformation according to the spherical near-field amplitude-deformation equation derived by the present invention, and preferably adopt the numerical solution method of finite difference-Gaussian iteration method and neural network method.

[0101] Compared with the prior art, the present invention has the following beneficial effects:

[0102] 1. The measurement method provided by the present invention can greatly reduce the near-field scanning area, thereby greatly shortening the effective scanning time. Furthermore, the measurement method of the present invention can perform quasi-real-time measurement of the deformation of the main reflector caused by real-time factors such as wind load, temperature, and posture.

[0103] 2. The present invention only needs to use a single electrical index and a single measurement, that is, only the signal amplitude of the above-mentioned hemispherical surface area needs to be scanned. Compared with the phase measurement, the amplitude scanning requires simpler equipment, is convenient to implement, and takes less time.

[0104] 3. The present invention is applicable to a wider range of working conditions. It can perform detection at full pitch angles, and when the radio telescope is in a normal receiving state, the measurement method of the present invention can be applied. At this time, whether the signal comes from an outer space satellite radiation source or a far-field artificial beacon, it can be regarded as a plane wave incident, so that the collected amplitude signal can be completely free from the influence of feed source noise.

[0105] 4. The present invention can get rid of the influence of the antenna sub-reflector and only accurately measure the deformation of the main reflector. For Gregorian antennas, most of the existing measurement technologies based on antenna electrical performance can only measure the comprehensive influence of the deformation of the dual reflectors on the antenna observation efficiency. When the antenna posture and working conditions change, the measurement results often change. Although the deformation of the sub-surface is smaller than that of the main surface, its influence on the overall observation efficiency of the antenna cannot be ignored.

[0106] Example 2

[0107] This embodiment provides a method for compensating for the deformation of the main reflector surface of a parabola antenna. The method adopts the main reflector surface deformation measurement method of the parabola antenna provided in Example 1 to determine the deformation of the main reflector surface of the parabola antenna; then, based on the deformation of the main reflector surface of the parabola antenna, the deformation of the main reflector surface of the parabola antenna is compensated.

[0108] Example 3

[0109] See also Figure 7 This embodiment provides a main reflector deformation measurement system for a parabolic antenna, the system comprising:

[0110] The intensity measurement value acquisition module 701 is used to obtain the intensity measurement value of the radiation signal in a set area, wherein the set area is a lower hemisphere with the focus of the main reflection surface of the parabola antenna as the sphere center, and the set area is located below the parabola antenna feed source;

[0111] The deformation calculation module 702 is used to calculate the deformation according to Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, where A0(x,y) is the intensity distribution of the radiation signal in the set area when the main reflection surface of the parabolic antenna is not deformed, A(x,y) is the intensity measurement value of the radiation signal in the set area, R is the radius of the hemisphere, d(x,y) is the distance between the hemisphere and the main reflection surface of the parabolic antenna on the path of the reflected light passing through the point (x,y) on the hemisphere, F is the focal length of the main reflection surface, x and y are the horizontal and vertical coordinates of the point (x,y) on the hemisphere projected on the aperture surface of the parabolic antenna.

[0112] The deformation calculation module 702 specifically includes:

[0113] Deformation calculation unit, used to calculate The finite difference-Gaussian iteration method is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, or to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna according to The neural network model is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna.

[0114] Example 4

[0115] This embodiment provides a main reflector deformation compensation system for a parabolic antenna, the system comprising: a deformation compensation module and the main reflector deformation measurement system for the parabolic antenna provided in Example 3, wherein the deformation compensation module is used to compensate for the deformation of the main reflector of the parabolic antenna according to the deformation of the main reflector of the parabolic antenna.

[0116] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0117] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for measuring deformation of the main reflector surface of a parabolic antenna, characterized in that: include: Obtaining a strength measurement value of a radiation signal in a set area, wherein the set area is a lower hemisphere with a focus of a main reflection surface of the parabola antenna as the center, and the set area is located below a feed source of the parabola antenna; according to Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, where A0(x, y) is the intensity distribution of the radiation signal in the set area when the main reflection surface of the parabola antenna is not deformed, A(x, y) is the intensity measurement value of the radiation signal in the set area, R is the radius of the hemisphere, d(x, y) is the distance between the hemisphere and the main reflection surface of the parabola antenna on the path of the reflected light passing through the point (x, y) on the hemisphere, F is the focal length of the main reflection surface, x and y are the horizontal and vertical coordinates of the point (x, y) on the hemisphere projected on the aperture surface of the parabola antenna; Steps of the method for measuring the deformation of the main reflector of a parabolic antenna: Step 1: Set up a plane wave radiation source; Step 2: Scan and sample the spherical field amplitude to determine the intensity distribution of the radiation signal on the near-field hemispherical surface below the Gregorian antenna sub-reflector or below the parabolic antenna feed; Step 3: Establish amplitude deformation relationship; The curvature matrix distribution of the antenna's main reflector is expressed by Weingarten mapping in differential geometry; According to the curvature matrix distribution, the main curvature distribution of the reflected wavefront at each point on the main reflection surface is derived by the phase matching method; According to the distribution of principal curvature, the relationship between the hemispherical scanning amplitude and the deformation of the principal reflective surface is obtained through geometric optics approximation. Step 4: Solve the surface deformation of the main reflector.

2. The method for measuring deformation of the main reflector surface of a parabolic antenna according to claim 1, characterized in that: The basis Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, including: according to The finite difference-Gaussian iteration method is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna.

3. The method for measuring deformation of the main reflector surface of a parabolic antenna according to claim 1, characterized in that: The basis Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, including: according to The neural network model is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna.

4. The method for measuring deformation of the main reflector surface of a parabolic antenna according to claim 1, characterized in that: The parabolic antenna is a Gregorian or Cassegrain antenna.

5. A method for compensating deformation of the main reflector of a parabolic antenna, characterized in that: include: Determine the deformation of the main reflector surface of the parabolic antenna by using the main reflector surface deformation measurement method of the parabolic antenna according to any one of claims 1 to 4; According to the deformation of the main reflecting surface of the parabola antenna, the deformation of the main reflecting surface of the parabola antenna is compensated.

6. A parabolic antenna main reflector deformation measurement system, characterized in that: include: An intensity measurement value acquisition module is used to acquire the intensity measurement value of the radiation signal in a set area, wherein the set area is a lower hemisphere with the focus of the main reflection surface of the parabola antenna as the sphere center, and the set area is located below the parabola antenna feed source; Deformation calculation module, used to calculate Calculate the deformation δ(x,y) on the main reflector of the parabolic antenna, where A0(x, y) is the intensity distribution of the radiation signal in the set area when the main reflection surface of the parabola antenna is not deformed, A(x, y) is the intensity measurement value of the radiation signal in the set area, R is the radius of the hemisphere, d(x, y) is the distance between the hemisphere and the main reflection surface of the parabola antenna on the path of the reflected light passing through the point (x, y) on the hemisphere, F is the focal length of the main reflection surface, x and y are the horizontal and vertical coordinates of the point (x, y) on the hemisphere projected on the aperture surface of the parabola antenna; Steps of the method for measuring the deformation of the main reflector of a parabolic antenna: Step 1: Set up a plane wave radiation source; Step 2: Scan and sample the spherical field amplitude to determine the intensity distribution of the radiation signal on the near-field hemispherical surface below the Gregorian antenna sub-reflector or below the parabolic antenna feed; Step 3: Establish amplitude deformation relationship; The curvature matrix distribution of the antenna's main reflector is expressed by Weingarten mapping in differential geometry; According to the curvature matrix distribution, the main curvature distribution of the reflected wavefront at each point on the main reflection surface is derived by the phase matching method; According to the distribution of principal curvature, the relationship between the hemispherical scanning amplitude and the deformation of the principal reflective surface is obtained through geometric optics approximation. Step 4: Solve the surface deformation of the main reflector.

7. The main reflector deformation measurement system of a parabolic antenna according to claim 6, characterized in that: The deformation calculation module specifically includes: Deformation calculation unit, used to calculate The finite difference-Gaussian iteration method is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna.

8. The main reflector deformation measurement system of a parabolic antenna according to claim 6, characterized in that: The deformation calculation module specifically includes: Deformation calculation unit, used to calculate The neural network model is used to calculate the deformation δ(x,y) on the main reflector of the parabolic antenna.

9. The main reflector deformation measurement system of a parabolic antenna according to claim 6, characterized in that: The parabolic antenna is a Gregorian or Cassegrain antenna.

10. A main reflector deformation compensation system for a parabolic antenna, characterized in that: include: A deformation compensation module and a main reflector deformation measurement system for a parabolic antenna as described in any one of claims 6 to 9, wherein the deformation compensation module is used to compensate for the deformation of the main reflector of the parabolic antenna according to the deformation of the main reflector of the parabolic antenna.

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