Special-shaped array radar angle measurement compensation method

Abstract

The invention belongs to the technical field of phased array radar detection, and particularly relates to a special-shaped array radar angle measurement compensation method, which performs sum-difference gain and beam pointing deflection angle compensation aiming at the asymmetric characteristic of a special-shaped array on the basis of a traditional sum-difference angle measurement method. The angle measurement error caused by gain and equivalent phase center offset during asymmetric antenna array plane angle measurement is compensated, the angle measurement error correction of the special-shaped array radar is realized, and the angle measurement precision of the special-shaped array radar is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of phased array radar detection, and specifically relates to an angle measurement compensation method for a special-shaped array radar. Background Art

[0002] Since the birth of radar, its technological achievements have played an increasingly important role in production and life. Phased array radar has the advantages of simultaneous multi-function, multi-target tracking, long range, high data rate, high adaptability and high reliability. Its emergence has met the requirements for high-performance radar systems to a certain extent. However, phased array radar still has many shortcomings, such as limited angle measurement accuracy, beam scanning range, and inability to form and transmit multiple beams at the same time.

[0003] Angle measurement is a major task of radar detection. In current practical engineering, the commonly used angle measurement forms of active phased array radars usually include amplitude comparison angle measurement, phase comparison angle measurement, and interferometric angle measurement. In modern active phased array radars, single pulse phase comparison angle measurement is the most commonly used form. The most basic element of single pulse phase comparison angle measurement is to use two antenna arrays to form corresponding sum and difference beams for phase comparison angle measurement. This method usually requires that the two antenna arrays have equivalent phase centers that are symmetrical and equal in size. It is a symmetrical array radar, otherwise it will affect the angle measurement accuracy of the radar. In engineering practice, due to the limitations of array conditions, it is sometimes impossible to make the two antenna arrays equal in size and symmetrical in equivalent phase center. The equivalent phase center connection line of the half array has an angle with the reference coordinate axis of the array azimuth and elevation angle. For a special-shaped array radar, if direct single pulse phase comparison angle measurement is performed, it will cause angle measurement information error. In view of this, this application is proposed. Summary of the invention

[0004] The purpose of this application is to provide a method for compensating the angle measurement of a shaped array radar. Based on theoretical analysis, by introducing gain compensation and beam center deviation compensation, the sum and difference angle detection errors and the slope of the angle detection curve are corrected, and the angle measurement error caused by the gain and phase center offset during the angle measurement of the asymmetric antenna array is compensated, thereby realizing the correction of the angle measurement error of the shaped array radar and improving the accuracy of the angle measurement of the shaped array radar.

[0005] The technical solution of this application is:

[0006] A method for angle measurement compensation of a special-shaped array radar, comprising:

[0007] Step 1: Detect the received signals E1 and E2 of the two antenna arrays, calculate the sum and difference single pulse phase comparison

[0008] Step 2: Compare the phase with the sum and difference single pulses Calculate the angle Δθ that the beam points away from the beam center:

[0009]

[0010] in,

[0011] λ is the wavelength;

[0012] D′ is the length of the equivalent phase center of the two antenna arrays;

[0013] θ0 is the beam pointing angle;

[0014] α is the relative rotation angle between the angle-detection coordinate system of the two antenna arrays of the special-shaped array radar and the angle-detection coordinate system of the two antenna arrays of the symmetric array radar;

[0015] To obtain the sum and difference single pulse phase comparison The imaginary part of

[0016] Step 3: Calculate the target pointing angle θ1 based on the beam pointing angle θ0, which is the deviation of the beam pointing from the beam center angle Δθ.

[0017] According to at least one embodiment of the present application, in the above-mentioned shaped array radar angle measurement compensation method, in step 1, the received signals E1 and E2 of the two antenna array surfaces are detected, and the sum difference single pulse phase comparison is calculated. Specifically:

[0018]

[0019] According to at least one embodiment of the present application, in the above-mentioned shaped array radar angle measurement compensation method, step 2 further includes extracting the slope k′ of the sum and difference angle measurement and discrimination curve:

[0020]

[0021] According to at least one embodiment of the present application, in the above-mentioned angle measurement compensation method of the shaped array radar, in step 2, the angle error correction coefficient μ is 1.

[0022] According to at least one embodiment of the present application, in the above-mentioned shaped array radar angle measurement compensation method, in step three, based on the beam pointing deviation from the beam center angle Δθ and the beam pointing angle θ0, the target pointing angle θ1 is calculated, specifically θ1=θ0+Δθ.

[0023] This application has at least the following beneficial technical effects:

[0024] A method for angle measurement compensation of a shaped array radar is provided. On the basis of the traditional sum and difference angle measurement method, sum and difference gain and beam pointing angle compensation are performed according to the asymmetric characteristics of the shaped array, so as to compensate for the angle measurement error caused by gain and phase center offset when measuring the angle of the asymmetric antenna array surface, realize the angle measurement error correction of the shaped array radar, and improve the angle measurement accuracy of the shaped array radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of single pulse angle measurement of a symmetrical array radar array provided in an embodiment of the present application;

[0026] Figure 2 A schematic diagram of asymmetric array single pulse angle measurement of a special-shaped array radar provided in an embodiment of the present application;

[0027] Figure 3 A schematic diagram of a shaped array radar antenna surface provided in an embodiment of the present application;

[0028] Figure 4 A schematic diagram of the sum and difference beams of the shaped array radar provided in an embodiment of the present application when gain is not compensated;

[0029] Figure 5 The sum and difference beam patterns of the shaped array radar provided in the embodiment of the present application when the gain is not compensated;

[0030] Figure 6 A comparison diagram of the sum and / or elevation difference beam directions of the shaped array radar after gain compensation provided in an embodiment of the present application;

[0031] Figure 7 A comparison diagram of the front and rear pitch angle detection curves of the compensation gain of the heterogeneous array radar provided in an embodiment of the present application.

[0032] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be construed as limitations on the present application. DETAILED DESCRIPTION

[0033] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0034] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application shall have the usual meanings understood by those of ordinary skill in the art to which this application belongs. The words used in the description of this application to indicate orientation are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application indicates that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0035] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0036] Symmetrical array radars are arranged symmetrically on both sides, such as Figure 1 As shown, the equivalent phase centers of the two antenna arrays are O1 and O2, and the distance between them is D. For the convenience of solving the angle, the line connecting the equivalent phase centers of the two antenna arrays is usually parallel to or coincides with one of the coordinate axes of the angle detection coordinate system. The beam pointing angle is θ0, the target pointing angle is θ1, and the angle of the beam pointing deviation from the beam center is Δθ. The phase differences of the incoming waves reaching the two antenna arrays in the beam pointing and target directions are The phase difference in these two directions is The angle-detection coordinate system is the XO1Y coordinate system.

[0037] The two sides of the heterogeneous array radar are asymmetric, such as Figure 2 As shown, the gain ratio of the two antenna arrays is m times, the gain of the first antenna array is mE, the gain of the second antenna array is E, the equivalent phase centers of the first antenna array and the second antenna array are O1 and O′2 respectively, the length of O1O′2 is D′, the coordinate system X′O1Y′ is an angle discrimination coordinate system with O1O′2 as one of the coordinate axes, the coordinate system XO1Y is the final angle discrimination coordinate system, the relative rotation angle of the two coordinate systems is α, and the phase differences of the incoming waves reaching the two antenna arrays in the beam pointing and target directions are respectively The phase difference in these two directions is

[0038] In order to perform correct sum and difference angle measurement for a special-shaped array radar, it is necessary to perform gain compensation on the antenna array surface to keep the gains of the antenna array surfaces participating in the sum and difference angle measurement equal. The gain of one of the antenna array surfaces can be used as a reference to perform gain correction on the received signal of the other antenna array surface so that the gain ratio of the two antenna array surfaces is 1. In addition to gain compensation for the two antenna array surfaces, the offset of the azimuth and elevation centers will also produce beam pointing deviation angles, which also need to be compensated. For this reason, the present application provides a method for angle measurement compensation for a special-shaped array radar.

[0039] Step 1: Detect the received signals E1 and E2 of the two antenna arrays, calculate the sum and difference single pulse phase comparison

[0040] S ∑ is the sum wave signal, S ∑=E1+E2……(1)

[0041] S Δ is the difference signal, S Δ =E1-E2……(2)

[0042] For the digitized antenna array, before performing digital sum and difference, the gain of one antenna array is used as the reference to directly correct the gain multiple of the other antenna array signal after sampling and quantization. Then the received signals of the two antenna arrays can be expressed as:

[0043]

[0044] E2=E……(4)

[0045] The sum and difference beam signals can be expressed as:

[0046]

[0047]

[0048] Combining equations (5) and (6), we can get the phase comparison of the sum and difference single pulses:

[0049]

[0050] Taking the imaginary part of formula (5), we have:

[0051]

[0052]

[0053] Further transformation yields:

[0054]

[0055] Step 2: Compare the phase with the sum and difference single pulses Calculate the angle Δθ that the beam pointing deviates from the beam center, as well as the slope k′ of the sum and difference angle measurement and discrimination curves.

[0056] The beam points upward, and the phase difference between the two antenna arrays is:

[0057]

[0058] λ is the wavelength;

[0059] In the target direction, the phase difference between the two antenna arrays is:

[0060]

[0061] Then the phase difference in the two directions is:

[0062]

[0063] Can be further transformed into:

[0064]

[0065]

[0066] Since Δθ is very small, sin(Δθ)≈Δθ, we can get:

[0067]

[0068] The beam is pointed at an angle β with the Y axis in the angle-detection coordinate system X′O1Y′, and we have:

[0069] β=θ0-α……(15)

[0070] The angle of the beam pointing away from the beam center:

[0071]

[0072]

[0073] Combining equations (9) and (16), we have:

[0074]

[0075] make Then μ is called the angle error correction coefficient;

[0076] m is a value close to 1. When calculating, m can be taken as 1. At this time, the angle error correction coefficient μ=1, and:

[0077]

[0078] At this time, the slope of the sum and difference angle measurement and angle discrimination curve is:

[0079]

[0080] Step 3: Calculate the target pointing angle θ1 based on the beam pointing angle θ0, which is the deviation of the beam pointing from the beam center angle Δθ.

[0081] θ1=θ0+Δθ, and obtain the actual pointing angle of the target in the desired angle-detecting coordinate system X′O1Y′.

[0082] by Figure 3Taking the heterogeneous array shown in the figure as an example, the azimuth difference is formed according to the subarray [1+2+5+6]-subarray [3+4+7+8], and the elevation difference is formed according to the subarray [5+6+7+8]-subarray [1+2+3+4]. The size of the array elements on both sides of the azimuth difference is consistent, and the size ratio of the subarrays on both sides of the elevation difference is m. Before gain compensation, the simulation is directly performed by digital sum and difference, and the sum, azimuth and elevation beams formed are as follows Figure 4-5 As shown in the figure, without gain compensation, the azimuth difference zero depth reaches 45.5dB due to the similar scale of the azimuth beam subarrays. When the elevation beam is formed, the elevation difference zero depth is only 22dB due to the unequal scale of the upper and lower subarrays. The zero depth of the elevation difference beam is poor, which seriously affects the elevation angle measurement accuracy.

[0083] When forming a digital elevation beam, the subarray gain is compensated according to the gain ratio m to form an elevation beam, such as Figure 6 As shown, the pitch difference zero depth is 48.7dB, and the pitch difference zero depth is improved by 25.8dB.

[0084] like Figure 7 As shown in FIG. 1 , the slope of the angle detection curve is different before and after the asymmetric array gain compensation. Even if gain compensation is performed, the angle detection slope needs to be corrected according to formula (19) to correctly calculate the target deflection angle. Otherwise, it will cause angle measurement errors and reduce the target tracking angle accuracy.

[0085] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A method for angle measurement compensation of a shaped array radar, characterized in that: include: Step 1: Detect the received signals E1 and E2 of the two antenna arrays, calculate the sum and difference single pulse phase comparison Step 2: Compare the phase with the sum and difference single pulses Calculate the angle Δθ that the beam pointing deviates from the beam center: in, λ is the wavelength; D ′ is the length of the equivalent phase center of the two antenna arrays; θ0 is the beam pointing angle; α is the relative rotation angle between the angle-detection coordinate system of the two antenna arrays of the special-shaped array radar and the angle-detection coordinate system of the two antenna arrays of the symmetric array radar; To obtain the sum and difference single pulse phase comparison The imaginary part of Step 3: Calculate the target pointing angle θ1 based on the beam pointing angle θ0, which is the deviation of the beam pointing from the beam center angle Δθ.

2. The angle measurement compensation method of the shaped array radar according to claim 1, characterized in that: In step 1, the received signals E1 and E2 of the two antenna arrays are detected, and the sum and difference single pulses are calculated. Specifically:

3. The angle measurement compensation method of the shaped array radar according to claim 1, characterized in that: Step 2 also includes extracting the slope k of the angle determination curve ′ :

4. The angle measurement compensation method of the shaped array radar according to claim 1, characterized in that: In step 2, the angle detection error correction coefficient μ is set to 1.

5. The angle measurement compensation method of the shaped array radar according to claim 1, characterized in that: In step three, the target pointing angle θ1 is calculated according to the beam pointing angle θ0, which is the beam pointing angle Δθ deviating from the beam center, and is specifically θ1=θ0+Δθ.

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