A multi-beam forming method with adaptive beam width using tilted array

Abstract

The present invention proposes a method for forming multi-beams with adaptive beam widths of tilted arrays, which uses azimuth multi-beam pitch scanning to traverse and search the spatial coverage range, and makes matching compensation for the pitch pointing angle according to the vertical beam width of the pitch pointing direction of the lateral multi-beam; the horizontal beam width of each beam in the horizontal direction of the same pitch layer is kept the same as the horizontal beam width of the azimuth method beam of the layer through the Taylor window coefficient widening method. The present invention makes full use of the spatial resources of the phased array to receive multiple beams at different pitch angles, and only performs beam widening in the horizontal dimension. Under the premise of meeting the spatial coverage requirements of the geodetic coordinate system, the directional pattern distortion of the side beam is reduced as much as possible, thereby improving the direction finding accuracy of the array.

Description

Technical Field

[0001] The invention relates to an active phased array system, and in particular to a method for forming multi-beams with adaptive beam width of tilted arrays. Background Art

[0002] According to the actual application scenarios of the antenna array, and in order to reduce the impact of multipath effects, the phased array system often adopts an inclined installation fastening method. In the phased array system that receives signals in an azimuth multi-beam pitch scanning mode, the airspace coverage range remains unchanged, and the change of the installation tilt angle will require the multi-beam arrangement of the array to be readjusted and optimized. The traditional adjustment method is often achieved only by changing the original two-dimensional width of each beam. For the side beams in extreme positions such as high pitch and high azimuth, excessive broadening will cause distortion of the beam pattern, seriously affecting the direction finding accuracy. At the same time, due to the coordinate system transformation caused by the tilt angle, the beam originally close to the azimuth boundary may have exceeded the effective range of the scanning airspace under high pitch pointing, resulting in a waste of system beam resources. Therefore, the ability to realize the adaptive arrangement and formation method of receiving multiple beams according to the pitch scanning pointing is of great significance to improving the working efficiency and system measurement accuracy of the array system, and is also the key and difficulty for the normal operation of the array system under tilted placement conditions. Summary of the invention

[0003] The purpose of the present invention is to provide a multi-beam forming method with tilted array and adaptive beam width.

[0004] The technical solution to achieve the purpose of the present invention is: a method for forming multi-beams with adaptive beam width of tilted arrays, which uses azimuth multi-beam pitch scanning to traverse and search the spatial coverage range, and matches and compensates the pitch pointing angle according to the vertical beam width of the pitch pointing of the lateral multi-beam; for the horizontal beam width of each beam in the horizontal direction of the same pitch layer, the Taylor window coefficient widening method is used to keep it the same as the horizontal beam width of the beam in the azimuth method of the layer.

[0005] Furthermore, matching compensation is performed on the elevation pointing angle according to the vertical beam width of the elevation pointing direction of the lateral multi-beam, and the specific method is as follows:

[0006] Calculate the longitudinal beam width of the beam at the elevation scan position. The specific formula is:

[0007]

[0008] where θ BW_V is the longitudinal width of the beam, k is the coefficient, λ is the signal wavelength, L V is the vertical aperture of the array, is the beam elevation angle in the array coordinate system;

[0009] The longitudinal beam width of the beam at the elevation scanning position is used as the actual longitudinal beam width value of the direction finding compensation to perform elevation direction finding error compensation.

[0010] Furthermore, the direction finding compensation adopts a two-beam amplitude comparison direction finding method.

[0011] Furthermore, the horizontal beam width of each beam in the horizontal direction of the same pitch layer is kept the same as the horizontal beam width of the beam in the azimuth direction of the layer by using the Taylor window coefficient widening method. The specific method is:

[0012] Calculate the upper and lower limits of the azimuth of the scanning pitch layer edge beam in the array coordinate system;

[0013] The number of beams of the array is combined and arranged at equal intervals in azimuth to obtain the azimuth beam spacing value of each beam in the elevation layer;

[0014] By using the Taylor window coefficient method and substituting different beam pointing angles, the lateral beam width of the multi-beams in this layer is adjusted to the horizontal beam width of the azimuth phase phase of this layer.

[0015] Furthermore, assuming that the installation angle of the tilted array is α, the elevation and azimuth of the beam in the geodetic coordinate system are pointed to Convert to the corresponding position in the array coordinate system The specific formula is:

[0016]

[0017] A tilted array adaptive beam width multi-beam forming system realizes tilted array adaptive beam width multi-beam forming based on the tilted array adaptive beam width multi-beam forming method.

[0018] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, based on the tilted array adaptive beam width multi-beam forming method, the tilted array adaptive beam width multi-beam forming is realized.

[0019] A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, based on the tilted array adaptive beam width multi-beam forming method, the tilted array adaptive beam width multi-beam forming is realized.

[0020] Compared with the prior art, the present invention has the following significant advantages: 1) the spatial resources of the phased array for receiving multiple beams at different elevation angles are fully utilized, and beam broadening is performed only in the horizontal dimension. The distortion of the directional pattern of the side beam is reduced as much as possible while meeting the spatial coverage requirements of the geodetic coordinate system, thereby improving the direction-finding accuracy of the array; 2) the beam interval is compressed during high-elevation angle scanning through an equidistant arrangement, so that the gain at the lowest point of the overlapping directional patterns between adjacent beams is improved, thereby optimizing the signal sensitivity of the array. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the corresponding relationship diagram between the two-dimensional beam width (3dB attenuation) of the phased array and the beam pointing direction;

[0022] Figure 2 This is the Taylor window coefficient broadening diagram of the transverse beamwidth of multiple beams at the same pitch layer;

[0023] Figure 3 It is a schematic diagram of the spatial coverage of the geodetic coordinate system and the wave position distribution of the corresponding front coordinate system;

[0024] Figure 4 This is a diagram of the equal-interval arrangement of multiple beams in the same pitch layer;

[0025] Figure 5 This is the control flow chart of the array adaptive multi-beamforming system. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0027] The present invention discloses a method for forming multi-beams with adaptive beam width of tilted arrays. The method combines the characteristic that the pitch beam width widens as the pitch angle increases during the pitch scanning of the receiving beam to realize the compensation of the direction finding error in the equally spaced pitch angle scanning mode, thereby improving the pitch direction finding accuracy without changing the vertical beam width of each pitch layer. For the simultaneous multi-beam arrangement of the same pitch layer, the Taylor window coefficient widening method is used to adjust the horizontal width of the beams in different azimuths to the same state as the horizontal beam width at the azimuth normal phase (horizontal center) of the layer. The beam spacing at the azimuth of the same pitch layer is obtained by dividing the actually required range in the array coordinate system by the number of beams. Finally, the above-mentioned pitch compensation value, Taylor window widening coefficient and beam spacing are used as inputs of the system wave control module and the DBF digital beam synthesis module to control the array to complete the corresponding multi-beam synthesis.

[0028] In the process of receiving beam forming of the two-dimensional phased array, the formulas of the two-dimensional beam width (taking 3dB attenuation as an example) are respectively as follows:

[0029]

[0030] where θ BW_H is the beam width in the horizontal dimension of the beam, θ BW_V is the beam width in the vertical direction of the beam, k is the coefficient, which is 0.886 when the beam width is 3dB, λ is the signal wavelength, L H is the horizontal aperture of the array, L V is the vertical aperture of the array, θ AZ is the beam azimuth (in the front coordinate system), is the beam pitch angle. From the formula, we can see that the horizontal width of the beam increases with the increase of the beam azimuth angle, and the vertical width of the beam increases with the increase of the beam pitch angle. The corresponding relationship between the beam width (3dB attenuation) and the beam pointing is as follows: Figure 1 In the present invention, when the phased array adopts the working mode of scanning multiple beams in azimuth and elevation dimensions at the same time, the increase of the elevation beam width is used to optimize the direction finding accuracy through the error compensation method, and no special adjustment is made to the longitudinal beam width itself. The increase of the transverse beam width is synthesized through the Taylor window coefficient broadening method, and the transverse widths of the beams pointing in different azimuths of the same layer are adjusted to be consistent, such as Figure 2 shown.

[0031] The design principle and workflow of the tilted array adaptive beam width multi-beam forming method of the present invention are specifically introduced below.

[0032] 1) Assume that the installation angle of the tilted array is α, and according to the coordinate system conversion formula, the elevation and azimuth of the beam in the geodetic coordinate system are pointed to Convert to the corresponding position in the array coordinate system As shown in formula (2).

[0033]

[0034] Since this method does not change the longitudinal width of the scanning beam, it is necessary to calculate the pitch angle by The difference between the longitudinal beam width of the actual beam at the elevation angle and the longitudinal beam width of the beam in the normal phase of the array is calculated using equation (1), and this is used as a conditional parameter for direction finding compensation (commonly used in the two-beam amplitude comparison direction finding method). Since the frequency and elevation position of the beam are different, the direction finding compensation value will also change accordingly, that is, adaptive beamforming compensation is achieved.

[0035] 2) When the multi-beam scan reaches a certain elevation angle in the geodetic coordinate system When the spatial domain coverage requirement of the geodetic coordinate system is combined, the upper and lower limits of the azimuth of the edge beam of this layer are calculated according to formula (2). Assume that the azimuth spatial domain coverage required in the geodetic coordinate system is ±θ' max, then the azimuth coverage after conversion to the array coordinate system is like Figure 3 .

[0036] 3) The number of multi-beams scanned by the system is arranged at equal intervals in the array azimuth space calculated in step 3). Assuming the number of beams in each layer is n, the interval between adjacent beams is like Figure 4 (a). As can be seen from the figure, after the coordinate system transformation, the horizontal multi-beams of the same elevation layer in the geodetic coordinate system have a slight difference in elevation in the array coordinate system, forming an arc. When arranging the multi-beams on the array, if the elevation pointing remains unchanged, the longitudinal beam width of the instantaneous scan should be able to cover this arc to ensure the accuracy of direction finding.

[0037] 4) According to the azimuth interval determined in step 3), the transverse beam width of each beam in the pitch layer is adjusted to the same state as the transverse beam width of the azimuth normal phase beam of the layer by the Taylor window coefficient method, such as Figure 4 (b).

[0038] 5) Input the scanning beam pitch pointing, pitch direction finding compensation, Taylor window coefficient, multi-beam spacing and other parameters into the system beam control module and DBF digital beam synthesis module to complete the adaptive beam forming. The overall flow chart is as follows: Figure 5 .

[0039] 6) When the array scans to the next elevation position, steps 1) to 5) are repeated to achieve complete adaptive beam width multi-beam arrangement and formation.

[0040] The present invention also proposes a tilted array adaptive beam width multi-beam forming system, which realizes tilted array adaptive beam width multi-beam forming based on the tilted array adaptive beam width multi-beam forming method.

[0041] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, based on the tilted array adaptive beam width multi-beam forming method, the tilted array adaptive beam width multi-beam forming is realized.

[0042] A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, based on the tilted array adaptive beam width multi-beam forming method, the tilted array adaptive beam width multi-beam forming is realized.

[0043] The present invention reasonably utilizes the directional pattern characteristics of the beam itself, reduces the directional pattern distortion of the side beam through a close arrangement design concept while meeting the spatial domain requirements of the array, improves the direction finding accuracy of the array, and optimizes the signal sensitivity of the array.

[0044] Example

[0045] In order to verify the effectiveness of the scheme of the present invention, the following experiment was carried out.

[0046] In this embodiment, the phased array operating frequency is 6 GHz, the array aperture is 1 m×1 m, the system spatial domain coverage range is -10° to 55° in elevation and -30° to 30° in azimuth in the geodetic coordinate system, the array installation angle is 10°, and the number of multi-beams per layer is 30. When the array receives a signal, when the elevation scan is directed to 50°, the beamforming method of the present invention is applied, and the process is as follows.

[0047] 1) According to formula (1), the longitudinal beam width (3 dB attenuation) of the beam at the elevation is calculated to be 3.31°. This value is used as the actual longitudinal beam width value of the elevation two-beam amplitude comparison heading measurement to compensate for the elevation heading measurement error.

[0048] 2) According to formula (2), the upper and lower limits of the azimuth of the pitch layer side beam are calculated. After conversion to the array coordinate system, the value is -25.3° to 25.3°. The schematic diagram is shown in Figure 3 .

[0049] 3) The number of multi-beams scanned by the system is arranged at equal intervals in the array azimuth space calculated in step 3), and the interval between adjacent beams is 1.7°, as shown in the schematic diagram. Figure 4 (a) Calculation shows that after the coordinate system transformation, the pitch conversion fluctuation of the scanning layer is about 1°, which meets the coverage requirements of the longitudinal beam width.

[0050] 4) According to formula (2), the system parameters are substituted into the horizontal beam width of the normal phase beam in the elevation direction, which is 2.5°. By using the Taylor window coefficient method, the pointing data of beams in different azimuth directions are substituted into the horizontal beam width of the multi-beams in this layer is adjusted to 2.5°, as shown in Figure 4 (b) as shown.

[0051] 5) Input the scanning beam pitch pointing, pitch direction finding compensation, Taylor window coefficient, multi-beam spacing and other parameters into the system beam control module and DBF digital beam synthesis module to complete the adaptive beam forming. The overall flow chart is as follows: Figure 5 .

[0052] 6) When the array scans to the next elevation position, steps 1) to 5) are repeated to achieve complete adaptive beam width multi-beam arrangement and formation.

[0053] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for multi-beam forming with an inclined array and adaptive beam width, characterized in that: The azimuth multi-beam elevation scanning method is used to traverse and search the airspace coverage range, and the elevation pointing angle is matched and compensated according to the vertical beamwidth of the elevation pointing direction of the lateral multi-beam. The Taylor window coefficient widening method is used to keep the horizontal beamwidth of each beam in the horizontal direction of the same elevation layer the same as the horizontal beamwidth of the beam in the azimuth method of the layer. The horizontal beam width of each beam in the horizontal direction of the same pitch layer is kept the same as the horizontal beam width of the beam in the azimuth method of the layer by using the Taylor window coefficient widening method. The specific method is: Calculate the upper and lower limits of the azimuth of the scanning pitch layer edge beam in the array coordinate system; The number of beams of the array is combined and arranged at equal intervals in azimuth to obtain the azimuth beam spacing value of each beam in the elevation layer; By using the Taylor window coefficient method and substituting different beam pointing angles, the lateral beam width of the multi-beams in this layer is adjusted to the horizontal beam width of the azimuth phase phase of this layer.

2. The method for multi-beam forming with adaptive beam width by tilting the array according to claim 1, characterized in that: The pitch pointing angle is matched and compensated according to the vertical beam width of the pitch pointing direction of the lateral multi-beam. The specific method is as follows: Calculate the longitudinal beam width of the beam at the elevation scan position. The specific formula is: where θ BW_V is the longitudinal width of the beam, k is the coefficient, λ is the signal wavelength, L V is the vertical aperture of the array, is the beam elevation angle in the array coordinate system; The longitudinal beam width of the beam at the elevation scanning position is used as the actual longitudinal beam width value of the direction finding compensation to perform elevation direction finding error compensation.

3. The method for multi-beam forming with tilted array and adaptive beam width according to claim 2, characterized in that: The direction finding compensation adopts a two-beam amplitude comparison direction finding method.

4. The method for multi-beam forming with tilted array and adaptive beam width according to claim 2 or 3, characterized in that: Assume that the installation angle of the tilted array is α, and point the elevation and azimuth of the beam in the geodetic coordinate system to Convert to the corresponding position in the array coordinate system The specific formula is:

5. A tilted array adaptive beam width multi-beam forming system, characterized in that: Based on the method for multi-beam forming with adaptive beam width of tilted array as described in any one of claims 1 to 4, multi-beam forming with adaptive beam width of tilted array is realized.

6. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for adaptive beam width multi-beam forming with a tilted array is based on the method for adaptive beam width multi-beam forming with a tilted array as described in any one of claims 1 to 4 to implement adaptive beam width multi-beam forming with a tilted array.

7. A computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, based on the tilted array adaptive beam width multi-beam forming method according to any one of claims 1 to 4, the tilted array adaptive beam width multi-beam forming is implemented.

Images