A method for evaluating the influence of target radar wave stealth defects

Abstract

A target radar wave stealth defect influence evaluation method, comprising: performing radar imaging on a stealth target in an initial state, obtaining a reference image of the stealth target, and obtaining a reference RCS of the target through inversion calculation; modifying the obtained local radar image result according to the corresponding region position of the obtained target reference image to obtain an evaluation image of the target; performing RCS inversion calculation on the obtained evaluation image; comparing the reference RCS obtained through inversion calculation of the reference image with the RCS result obtained through inversion calculation of the evaluation image to obtain a quantitative result of the RCS change of the target, and evaluating the influence of the radar wave stealth defect of the target. The present application can quantitatively evaluate the change of the stealth performance of the equipment in use at any time, and has the advantages of short evaluation time, low cost and small difficulty, and provides strong support for the evaluation of the tactical performance of the equipment and the maintenance of the stealth performance.

Description

Technical Field

[0001] This invention relates to the field of radar wave stealth of equipment, and specifically to a method for assessing the impact of target radar wave stealth defects. Background Technology

[0002] In the context of modern high-tech warfare, the stealth performance of equipment, especially radar stealth, has received high attention from militaries worldwide, and stealth has become one of the fundamental attributes of military equipment. Radar stealth technology targets the root cause of radar threats by altering the equipment's physical field to improve its stealth performance, reducing the likelihood of detection by the enemy and the probability of being hit by precision-guided weapons, thus becoming an effective and fundamental method to enhance the combat survivability of equipment. However, the stealth performance of equipment inevitably changes with use. For example, stealth materials, structural steps, and gaps on stealth aircraft or ships may maintain a good condition after the equipment leaves the factory or undergoes major repairs, but after a period of use, or even after a single takeoff / landing, these changes can lead to a deterioration in the overall stealth performance of the equipment.

[0003] The radar cross section (RCS) is an indicator characterizing radar stealth performance. RCS is an imaginary area of ​​a target, related to its geometric and physical parameters (such as size, shape, material, and structure), as well as the parameters of the incident radar wave (such as frequency, polarization, and waveform), and the target's attitude angle relative to the radar. Testing methods for obtaining accurate RCS of equipment generally require large, specialized measurement sites, which are costly to build, complex to operate, and demand highly skilled personnel, making them difficult to promote and unsuitable for widespread implementation.

[0004] To ensure the radar stealth performance of equipment, it is necessary to quantitatively assess the deterioration of the radar stealth performance of in-service equipment. However, accurate measurement of the radar cross-section (RCS) of equipment is costly and difficult. Therefore, providing an economical and usable method for evaluating the radar stealth performance of actual equipment has become a pressing issue that needs to be addressed by existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide an economical and usable method for evaluating the radar stealth performance of targets. This method can assess the radar stealth performance of in-service equipment, quantify the deterioration of stealth performance by quantitatively comparing it with the initial state, and provide support for equipment tactical performance evaluation and stealth maintenance.

[0006] To achieve this objective, the present invention adopts the following technical solution.

[0007] A method for assessing the impact of target radar wave stealth defects includes the following steps:

[0008] Target baseline data acquisition step S110:

[0009] Radar imaging is performed on the stealth target in its initial state to obtain the reference image of the stealth target. The reference image of the target is then inverted to obtain the reference RCS of the target.

[0010] Defect area measurement and imaging step S120:

[0011] Local radar imaging and localization are performed on areas of the target that may have defects. If there are multiple areas, local radar imaging and localization are performed on each area separately.

[0012] Defect area correction step S130:

[0013] The local radar image obtained in step S120 is used to correct the target reference image obtained in step S110 according to the corresponding area location to obtain the target evaluation image.

[0014] Target evaluation inversion calculation step S140:

[0015] RCS inversion calculation is performed on the obtained evaluation image;

[0016] Stealth performance evaluation step S150:

[0017] By comparing the baseline RCS obtained from the reference image inversion with the RCS obtained from the evaluation image inversion, quantitative results of the target RCS change are obtained, and the impact of the target's radar wave stealth defect is evaluated.

[0018] Optionally, in steps S110 and S120, radar imaging is radar imaging of the target at various angles, at certain angles, or at a fixed angle.

[0019] The center frequency of the radar imaging band is a commonly used radar frequency band, or an optional frequency selected within the entire microwave frequency band.

[0020] The radar imaging uses either SAR or ISAR mode. The same imaging mode can be used in different steps, or different imaging modes can be used. The imaging mode used is determined according to the characteristics of the target.

[0021] The radar imaging can be performed in the near field or the far field.

[0022] Optionally, in steps S110 and S120,

[0023] Imaging options include two-dimensional or three-dimensional imaging.

[0024] The resolution of radar imaging is determined as needed, thereby determining the bandwidth and aperture angle of the imaging test;

[0025] The signal system used for radar imaging is a broadband signal, employing pulse compression signals with frequency stepping or linear sweep frequency signals.

[0026] Optionally, during radar imaging in steps S110 and S120,

[0027] If imaging tests are not performed under conditions that meet the requirements of the far field, the near field effect can be corrected using a far field correction method.

[0028] Optionally, in step S130, the radar imaging results of the defect area measured in step 120 are used to replace the corresponding position results of the reference image obtained in step S110, or the corresponding position results in the reference image are modified according to the radar imaging results of the defect area measured in step S120.

[0029] Optionally, the replacement and modification may involve simultaneously replacing or modifying the local images of all defective regions in the reference image, or replacing or modifying only the local images of one or several defective regions.

[0030] Optionally, before RCS inversion imaging, the radar imaging results can be modified by using scattering source editing technology to eliminate the influence of background or other irrelevant targets, thereby improving the effectiveness and accuracy of RCS inversion.

[0031] Optionally, in step S150, the quantitative result of the RCS change is a comparison of the RCS of the reference image inversion and the RCS of one or more defective regions at a certain frequency point, an comparison of the mean of a certain angle range, or a comparison of the results after smoothing according to certain rules, or a comparison after processing the data using other numerical methods.

[0032] Optionally, in step S110, a reference two-dimensional image of the target in the X-band is measured using the I SAR mode. The center frequency is selected as 10 GHz, and the resolution is set to 15 cm. According to the relationship between resolution, bandwidth, and aperture angle, the resolution is set as δ, the imaging bandwidth B = c / 2δ, where c is the speed of light; the aperture angle Θ = λ / 2δ, where λ is the center frequency of radar imaging. The measurement bandwidth is 1 GHz, and the azimuth aperture angle is approximately 5.73°. The test signal is selected as a frequency-stepped signal with 801 frequency step points. The imaging results at each position within a forward ±5° range at 1° intervals are obtained. The reference RCS results at 10 GHz within a forward ±5° range at 0.25° intervals are obtained by inverting the imaging results.

[0033] In step S120, SAR imaging results of two regions on the target are obtained using SAR method. The center frequency and resolution are the same as the reference image. Imaging results at each position within a 1° interval in the forward ±5° range of the two regions are obtained respectively.

[0034] Optionally, in step S140, the evaluation RCS results at 10 GHz with an interval of 0.25° within a forward ±5° range are obtained by inverting the imaging results of each modified reference image;

[0035] In step S150, based on the baseline RCS results and the evaluation RCS results with an interval of 0.25° within a range of ±5°, the mean value of 1° sliding window within a range of ±5° is calculated, and the position is compared angle by angle.

[0036] In summary, this invention provides an economical and usable method for assessing the impact of target radar wave stealth defects. It can quantitatively assess changes in the stealth performance of equipment in use at any time, and the assessment is quick, cost-effective, and easy, providing strong support for equipment tactical performance assessment and stealth maintenance. Attached Figure Description

[0037] Figure 1 This is a flowchart of a target radar wave stealth defect impact assessment method according to the present invention. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0039] The main features of this invention are: performing radar imaging on a stealth target in its initial state, inverting to obtain the target's baseline RCS, and comparing it with the RCS inverted from the imaging results of the stealth defect state, thereby obtaining a quantitative assessment result of the deterioration of the equipment's radar wave stealth performance. The stealth defect state imaging results can replace or modify the baseline image pixel by pixel according to the corresponding region of the local radar imaging results, and then invert the modified image to obtain a quantitative result of the impact of the local area's deterioration on the overall stealth performance of the target. Radar imaging can be performed in the near field or far field, and the near field effect can be corrected using far field correction methods. The imaging results can eliminate the influence of the background or other irrelevant targets through scattering source editing technology.

[0040] For details, see Figure 1 The flowchart of the target radar wave stealth defect impact assessment method according to the present invention is shown, including the following steps.

[0041] Target baseline data acquisition step S110:

[0042] Radar imaging is performed on the stealth target in its initial state to obtain the reference image of the stealth target. The reference image of the target is then inverted to obtain the reference RCS of the target.

[0043] Defect area measurement and imaging step S120:

[0044] Local radar imaging and localization are performed on areas of the target that may have defects. If there are multiple areas, local radar imaging and localization are performed on each area separately.

[0045] Defect area correction step S130:

[0046] The local radar image obtained in step S120 is used to correct the target reference image obtained in step S110 according to the corresponding area location to obtain the target evaluation image.

[0047] Target evaluation inversion calculation step S140:

[0048] RCS inversion calculation is performed on the obtained evaluation image;

[0049] Stealth performance evaluation step S150:

[0050] By comparing the baseline RCS obtained from the reference image inversion with the RCS obtained from the evaluation image inversion, quantitative results of the target RCS change are obtained, and the impact of the target's radar wave stealth defect is evaluated.

[0051] In steps S110 and S120, radar imaging is radar imaging of the target at various angles, at certain angles, or at a fixed angle.

[0052] The center frequency of the radar imaging band is either a commonly used radar frequency band or an optional frequency selected within the entire microwave frequency band.

[0053] The radar imaging uses either SAR or ISAR mode. The same imaging mode can be used in different steps, or different imaging modes can be used. The imaging mode used is determined according to the characteristics of the target.

[0054] The radar imaging can be performed in either the near-field or far-field conditions. When imaging tests are not performed under far-field conditions, near-field effects can be corrected using a far-field correction method.

[0055] The imaging options are two-dimensional or three-dimensional imaging.

[0056] The resolution of radar imaging is determined as needed, thereby determining the bandwidth and aperture angle of the imaging test.

[0057] The signal system used for radar imaging is a broadband signal, which can be a pulse compression signal such as a frequency-stepped or linearly swept frequency signal, or other types of broadband signals.

[0058] In step S130, the corresponding position result of the reference image obtained in step S110 is replaced by the radar imaging result of the defect area obtained in step 120, or the corresponding position result in the reference image is modified according to the radar imaging result of the defect area obtained in step S120.

[0059] The replacement and modification can be performed simultaneously on all local images of defective regions in the reference image, or it can be performed on only one or a few local images of defective regions.

[0060] Before RCS inversion imaging, radar imaging results can be modified by using scattering source editing techniques to eliminate the influence of background or other irrelevant targets, thereby improving the effectiveness and accuracy of RCS inversion.

[0061] In step S150, the quantitative result of RCS change is a comparison of the inverted RCS of the reference image and the corrected RCS of one or more defect regions at a certain frequency point, an comparison of the mean values ​​within a certain angle range, or a comparison of the results after smoothing according to certain rules. Alternatively, other numerical methods can be used to process the data before comparison. This invention is not limited to these methods; any comparison of the RCS of the two images is acceptable.

[0062] In one specific embodiment

[0063] In step S110, a reference two-dimensional image of the target in the X-band is obtained using the I SAR mode, with a center frequency of 10 GHz and a resolution of 15 cm. Based on the relationship between resolution, bandwidth, and aperture angle, the resolution is set to δ, the imaging bandwidth B = c / 2δ, where c is the speed of light, and the aperture angle Θ = λ / 2δ, where λ is the center frequency of the radar imaging. This yields a measurement bandwidth of 1 GHz and an azimuth aperture angle of approximately 5.73°. The test signal is selected as a frequency-stepped signal with 801 frequency step points. Imaging results are obtained at various positions within a forward ±5° range at 1° intervals. The reference RCS results at 10 GHz are then obtained by inverting these imaging results within a forward ±5° range at 0.25° intervals.

[0064] In step S120, SAR imaging results of two regions on the target are obtained using SAR method. The center frequency and resolution are the same as the reference image. Imaging results at each position within a 1° interval in the forward ±5° range of the two regions are obtained respectively.

[0065] In step S140, the evaluation RCS results at 10 GHz with an interval of 0.25° within a forward ±5° range are obtained by inverting the imaging results of each modified reference image.

[0066] In step S150, based on the baseline RCS results and the evaluation RCS results with an interval of 0.25° within a range of ±5°, the mean value of 1° sliding window within a range of ±5° is calculated, and the position is compared angle by angle.

[0067] Example 1:

[0068] In this embodiment, the test target is a UAV target with a maximum dimension of 5m. Two locations with possible defects are selected at the leading edges of the two wings. It is necessary to evaluate the RCS variation of the average value of 1° sliding window within a range of ±5° of pitch angle (0°, i.e., horizontal direction) at 10GHz.

[0069] First, ISAR imaging tests were conducted on the UAV target under factory conditions. The center frequency of the imaging test was 10 GHz, the frequency step signal was used, the test resolution was set to 15 cm, the bandwidth was determined to be 1 GHz, and the horizontal aperture angle was approximately 5.73°. Imaging results were obtained at various positions within a forward ±5° range and at 1° intervals. The baseline RCS results at 10 GHz with a forward ±5° range and an interval of 0.25° were obtained by inverting the imaging results at various positions within a forward ±5° range and at 1° intervals. Furthermore, the baseline results were obtained at 10 GHz with a pitch angle of 0° and a 1° sliding window mean within a range of ±5° of the nose direction azimuth angle.

[0070] After a period of use, SAR imaging was performed on two potentially defective areas. The test conditions, including center frequency, signal type and parameters, resolution, bandwidth, elevation angle, and azimuth aperture angle, were consistent with the benchmark results. SAR imaging results of the defective areas were obtained under the same angular conditions as the benchmark image.

[0071] The image corresponding to the reference image is corrected based on the SAR imaging results of the defect area to ensure consistency between the original reference image and the SAR imaging results of the defect area, thus obtaining the evaluation image. RCS inversion is performed on the evaluation image to obtain inversion results consistent with the reference image inversion conditions, thereby obtaining an evaluation result consistent with the reference image conditions. The reference results and evaluation results are compared point-by-point to obtain an assessment of the impact of the target's radar wave stealth defect.

[0072] In summary, this invention provides an economical and usable method for assessing the impact of target radar wave stealth defects. It can quantitatively assess changes in the stealth performance of equipment in use at any time, and the assessment is quick, cost-effective, and easy, providing strong support for equipment tactical performance assessment and stealth maintenance.

[0073] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A method for assessing the impact of target radar wave stealth defects, characterized in that, Includes the following steps: Target baseline data acquisition step S110: Radar imaging is performed on the stealth target in its initial state to obtain the reference image of the stealth target. The reference image of the target is then inverted to obtain the reference RCS of the target. Defect area measurement and imaging step S120: Local radar imaging and localization are performed on areas of the target that may have defects. If there are multiple areas, local radar imaging and localization are performed on each area separately. Defect area correction step S130: The local radar image obtained in step S120 is used to correct the target reference image obtained in step S110 according to the corresponding area location to obtain the target evaluation image. Target evaluation inversion calculation step S140: RCS inversion calculation is performed on the obtained evaluation image; Stealth performance evaluation step S150: By comparing the baseline RCS obtained from the reference image inversion with the RCS obtained from the evaluation image inversion, quantitative results of the target RCS change are obtained, and the impact of the target's radar wave stealth defect is evaluated.

2. The evaluation method according to claim 1, characterized in that, In steps S110 and S120, radar imaging is radar imaging of the target at various angles, at certain angles, or at a fixed angle. The center frequency of the radar imaging band is a commonly used radar frequency band, or an optional frequency selected within the entire microwave frequency band. The radar imaging uses either SAR or ISAR mode. The same imaging mode can be used in different steps, or different imaging modes can be used. The imaging mode used is determined according to the characteristics of the target. The radar imaging can be performed in either the near or far field.

3. The evaluation method according to claim 2, characterized in that, In steps S110 and S120, Imaging options include two-dimensional or three-dimensional imaging. The resolution of radar imaging is determined as needed, thereby determining the bandwidth and aperture angle of the imaging test; The signal system used for radar imaging is a broadband signal, employing pulse compression signals with frequency stepping or linear sweep frequency signals.

4. The evaluation method according to claim 2, characterized in that, During radar imaging in steps S110 and S120, If imaging tests are not performed under conditions that meet the requirements of the far field, the near field effect can be corrected using a far field correction method.

5. The evaluation method according to claim 1, characterized in that, In step S130, the corresponding position result of the reference image obtained in step S110 is replaced by the radar imaging result of the defect area obtained in step 120, or the corresponding position result in the reference image is modified according to the radar imaging result of the defect area obtained in step S120.

6. The evaluation method according to claim 5, characterized in that, The replacement and modification involves simultaneously replacing or modifying the local images of all defective regions in the reference image, or replacing or modifying only the local images of one or several defective regions.

7. The evaluation method according to claim 4, characterized in that, Before RCS inversion imaging, radar imaging results can be used to eliminate the influence of background or other irrelevant targets through scattering source editing technology, thereby improving the effectiveness and accuracy of RCS inversion.

8. The evaluation method according to claim 1, characterized in that, In step S150, the quantitative result of RCS change is a comparison of the RCS of the reference image inversion and the RCS of one or more defective regions at a certain frequency point, an comparison of the mean of a certain angle range, or a comparison of the results after smoothing according to certain rules, or a comparison after processing the data using other numerical methods.

9. The evaluation method according to claim 1, characterized in that, In step S110, the ISAR mode is used to measure the reference two-dimensional image of the target in the X-band. The center frequency is selected as 10 GHz, and the resolution is set to 15 cm. According to the relationship between resolution, bandwidth and aperture angle, the resolution is set as δ, the imaging bandwidth B = c / 2δ, where c is the speed of light; the aperture angle Θ = λ / 2δ, where λ is the center frequency of radar imaging. The measurement bandwidth is 1 GHz, and the azimuth aperture angle is about 5.73°. The test signal is selected as a frequency stepping signal with 801 frequency stepping points. The imaging results at each position within a forward ±5° range at 1° intervals are obtained. The reference RCS results at 10 GHz within a forward ±5° range at 0.25° intervals are obtained by inverting the imaging results. In step S120, SAR imaging results of two regions on the target are obtained using SAR method. The center frequency and resolution are the same as the reference image. Imaging results at each position within a 1° interval in the forward ±5° range of the two regions are obtained respectively.

10. The evaluation method according to claim 9, characterized in that, In step S140, the evaluation RCS results at 10 GHz with an interval of 0.25° within a forward ±5° range are obtained by inverting the imaging results of each modified reference image; In step S150, based on the baseline RCS results and the evaluation RCS results with an interval of 0.25° within a range of ±5°, the mean value of 1° sliding window within a range of ±5° is calculated, and the position is compared angle by angle.

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