Wave position design method and system based on space-based early warning radar

Abstract

This invention provides a wavefront design method and system based on a space-based early warning radar, including acquiring the system scanning time, radar range-azimuth ground coverage range, beam coverage overlap rate, radar azimuth beam center, and radar initial wavefront near-end down-view angle; determining the 3-dB elevation main lobe beamwidth of the current wavefront based on the near-end down-view angle value of the current range wavefront; determining the far-end down-view angle value of the current wavefront based on the beam center calculation result of the current range wavefront; iteratively updating the near-end down-view angle of the next range wavefront to the near-end down-view angle of the current wavefront, and outputting all range wavefront division results; sequentially calculating the 3-dB azimuth main lobe beamwidth based on the near-end spatial cone angle of each azimuth wavefront, sequentially updating the beam center and far-end down-view angle of the azimuth wavefront, iteratively processing until the azimuth-ground distance meets the given azimuth coverage requirements; and finally outputting the wavefront design calculation results that meet the range-azimuth coverage requirements and the required dwell time for each wavefront.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of a spaceborne radar wave position design method, in particular to a wave position design method and system based on a space-based early warning radar. BACKGROUND

[0002] The space-based early warning radar system has the advantages of all-weather, all-day, large range and high precision detection, and has been widely applied and developed in remote early warning, target monitoring and other scenes. For the early warning radar system working in search mode, the radar scanning wave position and the beam dwell time on each wave position need to be set in advance to realize effective coverage of the observation space, therefore, a reasonable wave position design scheme is an important prerequisite for the space-based early warning radar system to realize effective target detection. The traditional wave position coverage design method calculates the main lobe width of the radar beam through the size of the radar antenna to realize two-dimensional beam coverage in range-azimuth. This method greatly reduces the utilization rate of radar energy resources because it does not consider the characteristics of the change of the radar beam width with the beam scanning. In addition, further considering the change characteristics of the radar beam width, a scheme of dividing the wave position by using the changing main lobe width of the beam is further proposed, thereby effectively improving the utilization rate of the radar beam resources. However, the above-mentioned methods do not consider the echo receiving window time boundary problem of the radar in a wave position, so it is difficult to ensure that the distance dimension non-fuzzy interval in a wave position can cover the entire pitch wave position.

[0003] Therefore, it is necessary to propose a new scheme to improve the above technical problems. SUMMARY

[0004] In view of the defects in the prior art, the purpose of the present application is to provide a wave position design method and system based on a space-based early warning radar.

[0005] According to the wave position design method based on a space-based early warning radar provided by the present application, the method comprises the following steps:

[0006] Step S1: acquiring the scanning time of the radar system, the radar range-azimuth ground coverage range, the beam coverage overlap rate, the radar azimuth beam center and the initial distance wave position near-downward angle of the radar;

[0007] Step S2: determining the 3-dB main lobe beam width of the current distance wave position according to the value of the near-downward angle of the current distance wave position, judging whether distance ambiguity occurs within the current main lobe beam width, if distance ambiguity occurs, calculating the downward angle beam center of the current distance wave position according to the pulse repetition time, if there is no distance ambiguity, calculating the value of the downward angle beam center of the current distance wave position according to the 3-dB main lobe beam width;

[0008] Step S3: calculating the far-downward angle value of the current distance wave position according to the calculation result of the beam center of the current distance wave position;

[0009] Step S4: Based on the beam coverage overlap rate and the coverage distance of the current range position, calculate the near-end downward angle of the next range position as the near-end downward angle of the current position, and iterate until the beam coverage range exceeds the given distance coverage requirement to obtain the range position division result.

[0010] Step S5: Traverse different range positions, calculate the 3-dB azimuth main lobe beamwidth according to the near-end spatial cone angle of each azimuth position, update the beam center and far-end downward angle of the azimuth position in turn, and iterate until the azimuth distance meets the given azimuth coverage requirements.

[0011] Step S6: Output the wave position design calculation results that meet the range-azimuth coverage requirements and the required dwell time for each wave position.

[0012] Preferably, in step S2, the 3-dB main lobe beamwidth is obtained by a one-dimensional search using the near-end downward angle of the current range position and the radar transmit / receive pattern.

[0013] Preferably, based on the 3-dB main lobe beamwidth of the current range position, the expression for calculating the angle of view below the beam center at the current range position is:

[0014] (1)

[0015] In the formula, This represents the near-downward angle of the k-th range wave position. This represents the near-end slant range of k range wave positions. This represents the 3-dB main lobe beamwidth at the k-th range position. This represents the far-end slant range corresponding to the 3-dB main lobe beamwidth at the k-th range position. At the speed of light, The pulse repetition time, For the radar platform height, Represents the Earth's radius. It is an inverse cosine function. Represents the absolute value symbol.

[0016] Preferably, the expression for calculating the far-end downward viewing angle of the current distance wave position is:

[0017] (2)

[0018] In the formula, The far-end downward angle is the k-th distance wave position.

[0019] Preferably, the expression for calculating the near-end downward angle of the next range position in step S4 is:

[0020] (3)

[0021] In the formula, For the (k+1)th range position, the near-side downward angle is... The near-end slant range of the (k+1)th range wave position;

[0022] The expression for calculating the near-end slant range of the (k+1)th range wave position is:

[0023] (4)

[0024] In the formula, Let be the near-slope range of the (k+1)th range position. The geocentric angle corresponding to the line connecting the near-end beam illumination point of the (k+1)th range position and the sub-satellite point;

[0025] The expression for calculating the geocentric subtended angle corresponding to the line connecting the near-end beam illumination point and the nadir point at the (k+1)th range position is:

[0026] (5)

[0027] In the formula, This refers to the radar wave coverage overlap rate. The near-end distance to the ground for the k-th range wave position. The distance to the ground at the far end of the k-th distance wave position.

[0028] This invention also provides a wavelet design system based on space-based early warning radar, the system comprising the following modules:

[0029] Module M1: Acquires radar system scan time, radar range-azimuth ground coverage, beam coverage overlap rate, radar azimuth beam center, and radar initial range position near-end downward angle of view;

[0030] Module M2: Determines the 3-dB main lobe beamwidth of the current range position based on the near-end downward angle value of the current range position, and determines whether range ambiguity occurs within the current main lobe beamwidth. If range ambiguity occurs, the downward angle beamcenter of the current range position is calculated based on the pulse repetition time. If there is no range ambiguity, the downward angle beamcenter value of the current range position is calculated based on the 3-dB main lobe beamwidth.

[0031] Module M3: Calculates the far-end downward angle value of the current range position based on the beam center calculation result of the current range position;

[0032] Module M4: Based on the beam coverage overlap rate and the coverage distance of the current range position, calculate the near-end downward angle of the next range position as the near-end downward angle of the current position, and iterate until the beam coverage range exceeds the given range distance coverage requirement to obtain the range position division result.

[0033] Module M5: Traverse different range positions, calculate the 3-dB azimuth main lobe beamwidth according to the near-end spatial cone angle of each azimuth position, update the beam center and far-end downward angle of the azimuth position in turn, and iterate until the azimuth distance meets the given azimuth coverage requirements.

[0034] Module M6: Outputs the wavefront design calculation results that meet the range-azimuth coverage requirements and the dwell time required for each wavefront.

[0035] Preferably, the 3-dB main lobe beamwidth in module M2 is obtained by a one-dimensional search using the near-end downward angle of the current range position and the radar transmit / receive pattern.

[0036] Preferably, based on the 3-dB main lobe beamwidth of the current range position, the expression for calculating the angle of view below the beam center at the current range position is:

[0037] (1)

[0038] In the formula, This represents the near-downward angle of the k-th range wave position. This represents the near-end slant range of k range wave positions. This represents the 3-dB main lobe beamwidth at the k-th range position. This represents the far-end slant range corresponding to the 3-dB main lobe beamwidth at the k-th range position. At the speed of light, The pulse repetition time, For the radar platform height, Represents the Earth's radius. It is an inverse cosine function. Represents the absolute value symbol.

[0039] Preferably, the expression for calculating the far-end downward viewing angle of the current distance wave position is:

[0040] (2)

[0041] In the formula, The far-end downward angle is the k-th distance wave position.

[0042] Preferably, the expression for calculating the near-end downward angle of the next range wave position in module M4 is:

[0043] (3)

[0044] In the formula, For the (k+1)th range position, the near-side downward angle is... The near-end slant range of the (k+1)th range wave position;

[0045] The expression for calculating the near-end slant range of the (k+1)th range wave position is:

[0046] (4)

[0047] In the formula, Let be the near-slope range of the (k+1)th range position. The geocentric angle corresponding to the line connecting the near-end beam illumination point of the (k+1)th range position and the sub-satellite point;

[0048] The expression for calculating the geocentric subtended angle corresponding to the line connecting the near-end beam illumination point and the nadir point at the (k+1)th range position is:

[0049] (5)

[0050] In the formula, This refers to the radar wave coverage overlap rate. The near-end distance to the ground for the k-th range wave position. The distance to the ground at the far end of the k-th distance wave position.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] This invention proposes a wave position design method based on a space-based early warning radar system. This method considers the characteristics of radar beam changes with the illumination area, and combines the relationship between the radar elevation main lobe beam illumination width and range ambiguity to realize range wave position division processing in different cases. Thus, it completes the two-dimensional wave position design under a given range-azimuth coverage requirement and obtains the final wave position dwell time, further improving the radar beam resource utilization rate. Attached Figure Description

[0053] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0054] Figure 1 This is a flowchart of the space-based early warning radar wave position design method provided in the embodiments of the present invention;

[0055] Figure 2 This is the beam design result of the present invention after implementation in a space-based early warning radar system. Figure 1 ;

[0056] Figure 3This is the beam design result of the present invention after implementation in a space-based early warning radar system. Figure 2 . Detailed Implementation

[0057] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0058] Example 1

[0059] According to the present invention, a wave position design method based on a space-based early warning radar includes the following steps:

[0060] Step S1: Obtain the radar system scanning time, radar range-azimuth ground coverage, beam coverage overlap rate, radar azimuth beam center, and radar initial range position near-end downward angle.

[0061] Step S2: Determine the 3-dB main lobe beamwidth of the current range position based on the near-end downward angle value of the current range position. Determine whether range ambiguity occurs within the current main lobe beamwidth. If range ambiguity occurs, calculate the downward angle beamcenter of the current range position based on the pulse repetition time. If there is no range ambiguity, calculate the downward angle beamcenter value of the current range position based on the 3-dB main lobe beamwidth.

[0062] The 3-dB main lobe beamwidth is obtained by a one-dimensional search using the near-end downward angle of the current range position and the radar transmit / receive pattern.

[0063] Based on the 3-dB main lobe beamwidth of the current range position, the expression for calculating the downward angle of view at the beam center of the current range position is as follows:

[0064] (1)

[0065] In the formula, This represents the near-downward angle of the k-th range wave position. This represents the near-end slant range of k range wave positions. This represents the 3-dB main lobe beamwidth at the k-th range position. This represents the far-end slant range corresponding to the 3-dB main lobe beamwidth at the k-th range position. At the speed of light, The pulse repetition time, For the radar platform height, Represents the Earth's radius. It is an inverse cosine function. Represents the absolute value symbol.

[0066] The expression for calculating the far-end downward angle of the current distance wave position is:

[0067] (2)

[0068] In the formula, The far-end downward angle is the k-th distance wave position.

[0069] Step S3: Calculate the far-end downward angle value of the current range position based on the beam center calculation result of the current range position.

[0070] Step S4: Based on the beam coverage overlap rate and the coverage distance of the current range position, calculate the near-end downward angle of the next range position as the near-end downward angle of the current position, and iterate until the beam coverage range exceeds the given distance coverage requirement to obtain the range position division result.

[0071] The expression for calculating the near-angle of the next range wavefront is:

[0072] (3)

[0073] In the formula, For the (k+1)th range position, the near-side downward angle is... It is the near-end slant range of the (k+1)th range wave position.

[0074] The expression for calculating the near-end slant range of the (k+1)th range wave position is:

[0075] (4)

[0076] In the formula, Let be the near-slope range of the (k+1)th range position. The geocentric angle corresponding to the line connecting the near-end beam illumination point of the (k+1)th range position and the sub-satellite point.

[0077] The expression for calculating the geocentric subtended angle corresponding to the line connecting the near-end beam illumination point and the nadir point at the (k+1)th range position is:

[0078] (5)

[0079] In the formula, This refers to the radar wave coverage overlap rate. The near-end distance to the ground for the k-th range wave position. The distance to the ground at the far end of the k-th distance wave position.

[0080] Step S5: Traverse different range positions, calculate the 3-dB azimuth main lobe beamwidth according to the near-end spatial cone angle of each azimuth position, update the beam center and far-end downward angle of the azimuth position in turn, and iterate until the azimuth distance meets the given azimuth coverage requirements.

[0081] Step S6: Output the wave position design calculation results that meet the range-azimuth coverage requirements and the required dwell time for each wave position.

[0082] The present invention also provides a wave position design system based on space-based early warning radar. The wave position design system based on space-based early warning radar can be implemented by executing the process steps of the wave position design method based on space-based early warning radar. That is, those skilled in the art can understand the wave position design method based on space-based early warning radar as a preferred embodiment of the wave position design system based on space-based early warning radar.

[0083] Example 2

[0084] This invention also provides a wavelet design system based on space-based early warning radar, the system comprising the following modules:

[0085] Module M1: Acquires radar system scan time, radar range-azimuth ground coverage, beam coverage overlap rate, radar azimuth beam center, and radar initial range position near-end downward angle.

[0086] Module M2: Determines the 3-dB main lobe beamwidth of the current range position based on the near-end downward angle value of the current range position, and determines whether range ambiguity occurs within the current main lobe beamwidth. If range ambiguity occurs, the downward angle beamcenter of the current range position is calculated based on the pulse repetition time. If there is no range ambiguity, the downward angle beamcenter value of the current range position is calculated based on the 3-dB main lobe beamwidth.

[0087] The 3-dB main lobe beamwidth is obtained by a one-dimensional search using the near-end downward angle of the current range position and the radar transmit / receive pattern.

[0088] Based on the 3-dB main lobe beamwidth of the current range position, the expression for calculating the downward angle of view at the beam center of the current range position is as follows:

[0089] (1)

[0090] In the formula, This represents the near-downward angle of the k-th range wave position. This represents the near-end slant range of k range wave positions. This represents the 3-dB main lobe beamwidth at the k-th range position. This represents the far-end slant range corresponding to the 3-dB main lobe beamwidth at the k-th range position. At the speed of light, The pulse repetition time, For the radar platform height, Represents the Earth's radius. It is an inverse cosine function. Represents the absolute value symbol.

[0091] The expression for calculating the far-end downward angle of the current distance wave position is:

[0092] (2)

[0093] In the formula, The far-end downward angle is the k-th distance wave position.

[0094] Module M3: Calculates the far-end downward angle value of the current range position based on the beam center calculation result of the current range position.

[0095] Module M4: Based on the beam coverage overlap rate and the coverage distance of the current range position, calculate the near-end downward angle of the next range position as the near-end downward angle of the current position, and iterate until the beam coverage range exceeds the given distance coverage requirement to obtain the range position division result.

[0096] The expression for calculating the near-angle of the next range wavefront is:

[0097] (3)

[0098] In the formula, For the (k+1)th range position, the near-side downward angle is... It is the near-end slant range of the (k+1)th range wave position.

[0099] The expression for calculating the near-end slant range of the (k+1)th range wave position is:

[0100] (4)

[0101] In the formula, Let be the near-slope range of the (k+1)th range position. The geocentric angle corresponding to the line connecting the near-end beam illumination point of the (k+1)th range position and the sub-satellite point.

[0102] The expression for calculating the geocentric subtended angle corresponding to the line connecting the near-end beam illumination point and the nadir point at the (k+1)th range position is:

[0103] (5)

[0104] In the formula, This refers to the radar wave coverage overlap rate. The near-end distance to the ground for the k-th range wave position. The distance to the ground at the far end of the k-th distance wave position.

[0105] Module M5: Traverse different range positions, calculate the 3-dB azimuth main lobe beamwidth according to the near-end spatial cone angle of each azimuth position, update the beam center and far-end downward angle of the azimuth position in turn, and iterate until the azimuth distance meets the given azimuth coverage requirements.

[0106] Module M6: Outputs the wavefront design calculation results that meet the range-azimuth coverage requirements and the dwell time required for each wavefront.

[0107] Example 3

[0108] The purpose of this invention is to overcome the shortcomings of existing technologies that do not consider the relationship between the unambiguous range of radar and the beam position coverage area, resulting in insufficient utilization of radar beam resources, and to provide a beam position design method based on a space-based early warning radar system.

[0109] This embodiment provides a wavelet design method based on space-based early warning radar, including the following steps:

[0110] 1) Obtain the radar system scanning time, radar range-azimuth ground coverage, beam coverage overlap rate, radar azimuth beam center, and radar initial range position near-end downward angle of view;

[0111] 2) Determine the 3-dB main lobe beamwidth of the current range position based on the near-end downward angle value of the current range position, and determine whether range ambiguity occurs within the current main lobe beamwidth. If range ambiguity occurs, calculate the downward angle beamcenter of the current range position based on the pulse repetition time. If there is no range ambiguity, calculate the downward angle beamcenter value of the current range position based on the 3-dB main lobe beamwidth.

[0112] 3) Calculate the far-end downward angle value of the current range position based on the beam center calculation result of the current range position;

[0113] 4) Based on the beam coverage overlap rate and the coverage distance of the current range position, calculate the near-end downward angle of the next range position as the near-end downward angle of the current position, and iterate until the beam coverage range exceeds the given range distance coverage requirement to obtain the range position division result.

[0114] 5) Traverse different range positions, calculate the 3-dB azimuth main lobe beamwidth according to the near-end spatial cone angle of each azimuth position, update the beam center and far-end downward angle of the azimuth position in turn, and iterate until the azimuth distance meets the given azimuth coverage requirements.

[0115] 6) The final output is the wave position design result that meets the range-azimuth coverage requirements and the dwell time required for each wave position.

[0116] The specific method for obtaining the 3-dB main lobe beamwidth in step 2) is to use the near-end downward angle of the current range position and combine it with the radar transmit and receive pattern to obtain it through a one-dimensional search.

[0117] Based on the 3-dB main lobe beamwidth of the current range position, the expression for calculating the downward angle of view at the beam center of the current range position is as follows:

[0118] (1)

[0119] In the formula, This represents the near-downward angle of the k-th distance wave position. This represents the near-end slant range of k range wave positions. This represents the 3-dB main lobe beamwidth at the k-th range position. This represents the far-end slant range corresponding to the 3-dB main lobe beamwidth at the k-th range position. At the speed of light, The pulse repetition time, For the radar platform height, Represents the Earth's radius. It is an inverse cosine function. Represents the absolute value symbol.

[0120] The expression for calculating the far-end downward angle of the current range position mentioned in step 3) is:

[0121] (2)

[0122] In the formula, The far-end downward angle is the k-th distance wave position.

[0123] The expression for calculating the near-end downward angle of the next range wave position in step 4) is as follows:

[0124] (3)

[0125] In the formula, For the (k+1)th range position, the near-side downward angle is... It is the near-end slant range of the (k+1)th range wave position.

[0126] The expression for calculating the near-end slant range of the (k+1)th range wave position is:

[0127] (4)

[0128] In the formula, Let be the near-slope range of the (k+1)th range position. The geocentric angle corresponding to the line connecting the near-end beam illumination point of the (k+1)th range position and the sub-satellite point.

[0129] The expression for calculating the geocentric subtended angle corresponding to the line connecting the near-end beam illumination point and the nadir point at the (k+1)th range position is:

[0130] (5)

[0131] In the formula, This refers to the radar wave coverage overlap rate. The near-end distance to the ground for the k-th range wave position. Let be the far-end distance to the ground for the k-th range position. Iteratively calculate the near-end downward angle, beam center, and far-end downward angle for each range position until the distance to the ground covered by all range positions meets the requirements, thus obtaining the range position division result.

[0132] The method for dividing azimuth positions at different distance positions in step 5) specifically involves iterating through each distance position and iteratively calculating the near-end azimuth angle, azimuth beam center, and far-end azimuth angle of the azimuth position using the azimuth 3-dB beam main lobe width, until the azimuth position meets the ground distance coverage requirements.

[0133] Step 6) Output the final wave position design result and output the final wave position dwell time according to the given radar scan time.

[0134] The specific implementation steps of the wave position design method based on space-based early warning radar in this embodiment are described below.

[0135] All implementation steps in this embodiment are performed on the MATLAB 2018b simulation platform.

[0136] like Figure 1 As shown, the implementation steps of this embodiment include:

[0137] S1: Input the parameters for the space-based early warning radar wave position design, including: radar system scanning time. Radar range-azimuth ground coverage is 200km, beam coverage overlap rate The radar azimuth beam center is set to 90° and the radar initial range beam near-end downward angle is set to... =20°, where ;

[0138] S2: Calculate the 3-dB pitch main lobe beamwidth at the k-th range position. ;

[0139] S3: Using the 3-dB pitch main lobe beamwidth from the previous step, determine the downward angle of the beam center at the k-th distance position according to formula (1). ;

[0140] S4: Using the beam center downward angle from the previous step, calculate the far-end downward angle at the k-th distance beam position according to formula (2). ;

[0141] S5: The near-end downward angle based on the calculated k-th range wave position. Pitch beam center Far-end downward view Calculate the near-end downward angle of the (k+1)th range wave position, and perform the following sub-steps in sequence:

[0142] S51: Calculate the geocentric angle corresponding to the line connecting the near-end beam illumination point and the nadir point of the (k+1)th range position according to formula (5). ;

[0143] S52: Utilizing the geocentric angle from the previous step The near-end slant range of the (k+1)th range wave position is calculated according to formula (4). ;

[0144] S52: Utilize the proximal slope distance from the previous step The near-downward angle of the (k+1)th range wave position is calculated according to formula (3). .

[0145] make Iteratively calculate and update the k-th range position until the range-to-ground coverage requirement is met;

[0146] S6: Iterate through the range positions one by one, and calculate the near-end azimuth angle, azimuth beam center and far-end azimuth angle of the azimuth position using the azimuth 3-dB main lobe width, until the azimuth position meets the ground distance coverage requirements.

[0147] S7: Output the final wave position design result and output the final wave position dwell time according to the given radar scan time.

[0148] The beam design results of the space-based early warning radar system obtained according to the present invention are as follows: Figure 2 As shown. Among them, Figures 2 to 3Comparison of target output SCNR curves obtained by designing wave positions for radar near-end and far-end observations using the method provided in this invention is presented. The results show that, using the method provided in this invention, in near-end radar observation, dividing the elevation wave position using a 3-dB main lobe ensures that the moving target is always within the main lobe of the beam. In far-end radar observation, dividing the elevation wave position using PRT time ensures that the radar can receive all echo data within a single wave position, ultimately achieving full utilization of radar energy resources.

[0149] Those skilled in the art can understand this embodiment as a more specific description of Embodiment 1 and Embodiment 2.

[0150] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0151] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A wavefront design method based on space-based early warning radar, characterized in that, The method includes the following steps: Step S1: Obtain the radar system scanning time, radar range-azimuth ground coverage, beam coverage overlap rate, radar azimuth beam center, and radar initial range position near-end downward angle. Step S2: Determine the 3-dB main lobe beamwidth of the current range position based on the near-end downward angle value of the current range position, and determine whether range ambiguity occurs within the current main lobe beamwidth. If range ambiguity occurs, calculate the downward angle beam center of the current range position based on the pulse repetition time. If there is no range ambiguity, calculate the downward angle beam center value of the current range position based on the 3-dB main lobe beamwidth. Step S3: Calculate the far-end downward angle value of the current range position based on the beam center calculation result of the current range position; Step S4: Based on the beam coverage overlap rate and the coverage distance of the current range position, calculate the near-end downward angle of the next range position as the near-end downward angle of the current position, and iterate until the beam coverage range exceeds the given distance coverage requirement to obtain the range position division result. Step S5: Traverse different range positions, calculate the 3-dB azimuth main lobe beamwidth according to the near-end spatial cone angle of each azimuth position, update the beam center and far-end downward angle of the azimuth position in turn, and iterate until the azimuth distance meets the given azimuth coverage requirements. Step S6: Output the wave position design calculation results that meet the range-azimuth coverage requirements and the required dwell time for each wave position.

2. The wave position design method based on space-based early warning radar according to claim 1, characterized in that, In step S2, the 3-dB main lobe beamwidth is obtained by using the near-end downward angle of the current range position and combining it with the radar transmit / receive pattern through a one-dimensional search.

3. The wave position design method based on space-based early warning radar according to claim 2, characterized in that, Based on the 3-dB main lobe beamwidth of the current range position, the expression for calculating the downward angle of view at the beam center of the current range position is as follows: （1） In the formula, This represents the near-downward angle of the k-th distance wave position. This represents the near-end slant range of k range wave positions. This represents the 3-dB main lobe beamwidth at the k-th range position. This represents the far-end slant range corresponding to the 3-dB main lobe beamwidth at the k-th range position. At the speed of light, The pulse repetition time, For the radar platform height, Represents the Earth's radius. It is an inverse cosine function. Represents the absolute value symbol.

4. The wave position design method based on space-based early warning radar according to claim 3, characterized in that, The expression for calculating the far-end downward viewing angle of the current distance wave position is: （2） In the formula, The far-end downward angle is the k-th distance wave position.

5. The wave position design method based on space-based early warning radar according to claim 3, characterized in that, The expression for calculating the near-side downward angle of the next range position in step S4 is as follows: （3） In the formula, For the (k+1)th range position, the near-side downward angle is... The near-end slant range of the (k+1)th range wave position; The expression for calculating the near-end slant range of the (k+1)th range wave position is: （4） In the formula, Let be the near-slope range of the (k+1)th range position. The geocentric angle corresponding to the line connecting the near-end beam illumination point of the (k+1)th range position and the sub-satellite point; The expression for calculating the geocentric subtended angle corresponding to the line connecting the near-end beam illumination point and the nadir point at the (k+1)th range position is: （5） In the formula, This refers to the radar wave coverage overlap rate. The near-end distance to the ground for the k-th range wave position. The distance to the ground at the far end of the k-th distance wave position.

6. A wavefront design system based on space-based early warning radar, characterized in that, The system includes the following modules: Module M1: Acquires radar system scan time, radar range-azimuth ground coverage, beam coverage overlap rate, radar azimuth beam center, and radar initial range position near-end downward angle of view; Module M2: Determines the 3-dB main lobe beamwidth of the current range position based on the near-end downward angle value of the current range position, and determines whether range ambiguity occurs within the current main lobe beamwidth. If range ambiguity occurs, the downward angle beamcenter of the current range position is calculated based on the pulse repetition time. If there is no range ambiguity, the downward angle beamcenter value of the current range position is calculated based on the 3-dB main lobe beamwidth. Module M3: Calculates the far-end downward angle value of the current range position based on the beam center calculation result of the current range position; Module M4: Based on the beam coverage overlap rate and the coverage distance of the current range position, calculate the near-end downward angle of the next range position as the near-end downward angle of the current position, and iterate until the beam coverage range exceeds the given range distance coverage requirement to obtain the range position division result. Module M5: Traverse different range positions, calculate the 3-dB azimuth main lobe beamwidth according to the near-end spatial cone angle of each azimuth position, update the beam center and far-end downward angle of the azimuth position in turn, and iterate until the azimuth distance meets the given azimuth coverage requirements. Module M6: Outputs the wavefront design calculation results that meet the range-azimuth coverage requirements and the dwell time required for each wavefront.

7. The wave position design system based on space-based early warning radar according to claim 6, characterized in that, The 3-dB main lobe beamwidth in module M2 is obtained by a one-dimensional search using the near-end downward angle of the current range position and the radar transmit / receive pattern.

8. The wave position design system based on space-based early warning radar according to claim 7, characterized in that, Based on the 3-dB main lobe beamwidth of the current range position, the expression for calculating the downward angle of view at the beam center of the current range position is as follows: （1） In the formula, This represents the near-downward angle of the k-th distance wave position. This represents the near-end slant range of k range wave positions. This represents the 3-dB main lobe beamwidth at the k-th range position. This represents the far-end slant range corresponding to the 3-dB main lobe beamwidth at the k-th range position. At the speed of light, The pulse repetition time, For the radar platform height, Represents the Earth's radius. It is an inverse cosine function. Represents the absolute value symbol.

9. The wave position design system based on space-based early warning radar according to claim 8, characterized in that, The expression for calculating the far-end downward viewing angle of the current distance wave position is: （2） In the formula, The far-end downward angle is the k-th distance wave position.

10. The wavefront design system based on space-based early warning radar according to claim 8, characterized in that, The expression for calculating the near-side downward angle of view of the next range position in module M4 is as follows: （3） In the formula, For the (k+1)th range position, the near-side downward angle is... The near-end slant range of the (k+1)th range wave position; The expression for calculating the near-end slant range of the (k+1)th range wave position is: （4） In the formula, Let be the near-slope range of the (k+1)th range position. The geocentric angle corresponding to the line connecting the near-end beam illumination point of the (k+1)th range position and the sub-satellite point; The expression for calculating the geocentric subtended angle corresponding to the line connecting the near-end beam illumination point and the nadir point at the (k+1)th range position is: （5） In the formula, This refers to the radar wave coverage overlap rate. The near-end distance to the ground for the k-th range wave position. The distance to the ground at the far end of the k-th distance wave position.

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