A ship model ontology RCS test system and method under a complex external field environment

Abstract

The application discloses a ship model body RCS test system and method under a complex external field environment, which comprises an RCS system, a rotating table, a ship model and a test auxiliary assembly. The RCS system comprises a vector network analyzer, a wideband radio frequency processing unit, a power amplifier, a radio frequency transceiving antenna, a radio frequency cable, a test control and processing analysis system. The rotating table is a platform with controllable rotating precision and a weight greater than or equal to the weight of the ship model, and a foam support structure is arranged on the rotating table. The ship model is arranged on the foam support structure, and a center point of a rotating table surface and a position where a geometric center of the ship model is located coincide. The test auxiliary assembly comprises a low-scattering metal plane shielding screen. The RCS system, the rotating table, the ship model and the test auxiliary assembly are arranged in a test site according to test requirements. The test system provided by the application can realize the ship model body RCS test under the complex external field environment, and fills the blank of the ship model body RCS test method under the complex external field environment.

Description

Technical Field

[0001] This invention belongs to the field of ship electromagnetic scattering characteristic testing and measurement, specifically involving a ship model RCS test system and method under complex external environment. Background Technology

[0002] Ships are large, complex platforms with multiple scales, exhibiting both ultra-large wavelength hull and superstructure configurations, as well as intricate local configurations and processes with complex shapes at multiple scales. This involves hundreds of structural components. For research on radar stealth design and related electromagnetic scattering characteristics of ships, efficient and accurate on-board RCS tests and measurements are required for diverse schemes and states of the main hull, superstructure, masts, electronic equipment, and deck electrical / attachment / mechanical components. This is to meet the following quantitative analysis needs: verifying the confidence level of simulation predictions of the ship's overall radar stealth performance; evaluating the radar stealth effects of different stealth design schemes and control measures; studying the RCS values ​​of various structural components and their impact mechanism on the overall ship's RCS; and deriving the low-detectability performance achievable by the ship's overall RCS index under actual operating conditions. Due to the structural characteristics of ship platforms, it is impossible to conduct full-scale RCS tests of the entire ship and its various local structures during the engineering design and preliminary research stages. Therefore, conducting on-board RCS tests on ship models under scaled-down conditions becomes a practical approach to solving these problems.

[0003] Target RCS testing under ideal conditions originates from the testing and evaluation of the high stealth performance of airborne targets. It aims to conduct tests in a far-field environment where the target's electromagnetic scattering echo is significantly higher than the background clutter echo. This is to accurately extract the target's electromagnetic scattering echo under conditions where the incident electromagnetic beam uniformly covers the target. The main testing environments include compacted fields and open flat-field environments. Compacted fields utilize precise plane wave calibration and background scattering absorption within a high-performance microwave anechoic chamber to create ultra-low background clutter far-field RCS testing conditions in a confined space, placing high demands on site and system design and construction. Open flat-field testing conditions utilize far-field testing distances of over a kilometer to create far-field RCS testing conditions. Standardized methods such as high-precision flat ground design, high-elevation isolation of the target and ground coupling scattering suppression, and strict control of environmental clutter around the site are used to achieve accurate measurement of the target's electromagnetic scattering echo. This is mainly suitable for accurate RCS testing of low-profile targets such as aircraft with a length of less than 30 meters. In the field of ship radar stealth design and related electromagnetic scattering characteristics research, RCS tests of ship models are conducted under iterative conditions with multiple schemes and states. Test subjects include scaled-down ship models, scaled-down models of parts of the superstructure, scaled-down or full-size models of components and equipment, etc. The testing process is highly exploratory and research-oriented, unlike RCS performance evaluation under ideal testing conditions. When relevant research institutions lack microwave anechoic chambers with compressed fields and open horizontal testing environments, relying solely on these ideal testing environments presents numerous practical problems, such as ship model transportation, information exchange, data analysis, on-site rectification, and schedule control. How to conduct efficient and accurate on-site RCS tests of ship models in relatively complex ordinary environments has become a critical issue that urgently needs to be addressed in the field of ship radar stealth design and electromagnetic scattering characteristics research.

[0004] Currently, the main domestic and international technologies for testing electromagnetic scattering characteristics using general-purpose facilities and systems are still lacking in RCS testing methods, which mainly involve calibration accuracy, combined electromagnetic scattering tests of targets and the environment, and RCS testing methods for ship models with certain environmental universality. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a ship model RCS testing system and method for complex external environments, enabling the testing and verification of the accuracy of ship electromagnetic scattering characteristic simulation calculations, the verification of the feasibility of schemes in the ship radar wave stealth design stage, and the simulation test analysis of factors affecting ship electromagnetic scattering characteristics.

[0006] The objective of this invention is achieved through the following technical solution: a ship model RCS test system for complex outdoor environments, comprising: an RCS system, a rotary table, a ship model, and test auxiliary components.

[0007] The RCS system includes a vector network analyzer, a broadband RF processing unit, a power amplifier, an RF transceiver antenna, RF cables, and a test, control, processing, and analysis system.

[0008] The rotary table is a platform with controllable rotational precision and a load-bearing capacity greater than or equal to the weight of the ship model. A foam support structure is installed on the rotary table.

[0009] The ship model is set on a foam support structure, and the center point of the rotating platform coincides with the geometric center of the ship model.

[0010] The testing auxiliary components include a low-scattering metallic planar shielding screen.

[0011] The RCS system, rotary table, ship model, and test auxiliary components were set up in the test site according to the test requirements.

[0012] In the RCS system, the receiving antenna of the RF transceiver antenna is connected in sequence to the low-noise amplifier, the broadband RF processing unit, and the vector network analyzer via RF cables; the transmitting antenna of the RF transceiver antenna is connected in sequence to the power amplifier, the broadband RF processing unit, and the vector network analyzer via RF cables; the vector network analyzer transmits data to the test control and processing analysis system via a GPIB / LAN interface, and the test control and processing analysis system is connected to the rotary table via a cable to control the rotation of the rotary table.

[0013] Preferably, the RF transceiver antenna and its front-end components of the RCS system are located near the edge of the test site. Along the direction from the RF transceiver antenna to the ship model, the distance from the geometric center of the ship model to its near edge of the test site is greater than or equal to twice its total length.

[0014] Preferably, the shortest test distance required from the RF transceiver antenna to the geometric center of the ship model satisfies the following relationship:

[0015]

[0016] Where R is the shortest test distance required from the transmitting and receiving antenna to the ship model, L is the total length of the ship model, and θ is the half-power beamwidth of the transmitting and receiving antenna.

[0017] Preferably, the rotation angle accuracy of the rotary table meets the following requirement:

[0018]

[0019] Where Δφ is the turntable rotation angle accuracy required for lateral resolution, L is the total length of the ship model, c is the speed of light, and f is the test frequency.

[0020] Preferably, the vertical distance between the bottom surface of the ship model and the ground is greater than or equal to 1.5 times the total height of the ship model, and the exposed surface of the rotating platform is covered with wave-absorbing wedge material.

[0021] Preferably, the width of the shielding screen is greater than or equal to 1.5 times the diameter of the rotating platform, and the height of the shielding screen is lower than the bottom surface of the ship model.

[0022] In addition to providing a ship model RCS testing system for complex outdoor environments, this invention further provides a method for conducting ship model RCS testing using the aforementioned system, comprising the following steps:

[0023] Step 1: Construct far-field simulation conditions based on beam uniformity coverage:

[0024] Step 1.1: Measure the maximum length, width and height of the ship model as the total length, total width and total height. Survey the test site environment. Under the condition of no obvious obstacles and a relatively flat open ground, determine the longitudinal and transverse range of the site.

[0025] Step 1.2: Arrange the test system's RF transceiver antenna and the ship model on the longitudinal axis of the site to maximize the distance between the RF transceiver antenna and the ship model;

[0026] Step 1.3: Adjust the half-power beamwidth of the RF transceiver antenna and the transmit power of the test system to ensure that the incident electromagnetic beam can uniformly cover the ship model while effectively receiving the electromagnetic scattered echo from the ship model.

[0027] Step 2: Strong coupling scattering shielding between the ship model and the erection area

[0028] Step 2.1: Adjust the center point of the turntable to coincide with the geometric center of the ship model, and set up a foam support structure on the turntable to support the ship model;

[0029] Step 2.2: On the longitudinal axis between the RF transceiver antenna and the ship model, arrange a low-scattering metal planar shield at the same height as the bottom surface of the ship model. Use the optical bouncing ray analysis method to track and evaluate the area where the ship model and the ground undergo multiple scattering, so that the distance between the low-scattering metal planar shield and the ship model is greater than the area of ​​multiple scattering mentioned above.

[0030] Step 3: Identification of longitudinal and transverse discrete sources of environmental scattering and RCS reconstruction

[0031] Step 3.1: Construct an RCS test system based on a linear frequency sweeping system. The normal of the aperture surface of the radio frequency transceiver antenna is parallel to the ground, and the height of the aperture center is the same as the height of the geometric center of the ship model.

[0032] Step 3.2: Set the test parameters of the test system, including center frequency, transmit pulse width, bandwidth, and pulse repetition period;

[0033] Step 3.3: Place a standard sphere and a ship model on the foam support structure one after the other. With the radio frequency transceiver antenna fixed, rotate the turntable to test the electromagnetic scattering characteristics of the standard sphere and the ship model in different directions using high-resolution imaging. The location of the electromagnetic scattering source of the standard sphere and the ship model and its corresponding relative amplitude of echo energy are displayed by a two-dimensional color scale diagram with adjustable echo energy dynamic range.

[0034] Step 3.4: By analyzing the vertical and horizontal positional distribution of the scattering resolution units in the two-dimensional color scale diagram, the regions where the electromagnetic scattering sources corresponding to the standard sphere and the ship model are located are extracted. The total scattering field is obtained by vector superposition of the scattering fields of each resolution unit.

[0035] Step 3.5: Based on the standard sphere theoretical RCS value, the RCS of the ship model is generated by comparing the total scattering field data of the standard sphere and the ship model.

[0036] Preferably, in step 3.2, the center frequency is selected as the RCS test frequency required for the test, the distance corresponding to half of the transmitted pulse width is not less than 1.5 times the maximum radial dimension of the target, the radial resolution corresponding to the test bandwidth is not greater than 1 / 5 of the minimum radial dimension of the ship model, the distance corresponding to the pulse repetition period is twice the test distance, and not less than the distance from the RF transceiver antenna to the geometric center of the ship model.

[0037] Preferably, in step 3.4, the total scattered field can be expressed as:

[0038]

[0039] Among them, R n Let k be the one-way distance from the nth structural unit to the sensor, and k be the free space wavenumber, k = 2πf / c. Let be the scattering field of the nth resolution unit.

[0040] Preferably, in step 3.5, the relative calibration method is used to process the total scattering field data of the standard sphere and the ship model using the following formula:

[0041]

[0042] Where, σ T For the RCS of the ship model, σ S For the RCS of a standard ball, The total scattered field of the ship model The total scattering field of a standard sphere.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] This invention provides a ship model RCS testing system and method for complex external environments, addressing the challenges of achieving suitable far-field conditions and eliminating clutter scattering interference in such environments. The invention solves the following problems:

[0045] (1) Solve the problem of simulating the uniformity of incident electromagnetic waves in the ship model area under the condition of unobstructed line of sight and short distance;

[0046] (2) Under the condition that it is impossible to achieve multiple scattering isolation between the target and the ground through high elevation, solve the coupling scattering shielding problem between the ship model and the erection area;

[0047] (3) Under the condition that there are interference scattering sources around the test site, solve the problem of electromagnetic scattering echo identification of ship model under interference stray echo.

[0048] The experimental system and method provided by this invention solve the problem of accurate RCS testing of ship models in complex environments, even without a standard RCS testing environment. This provides a reliable and efficient experimental analysis tool for extensive iterative research on ship stealth design optimization and target characteristic control. The ship model RCS testing method provided by this invention is not only applicable to the study of electromagnetic scattering characteristics of multi-scale scaled models of the entire ship, but also to the RCS testing of scaled models, full-scale models, and physical objects of various ship local structures, equipment, and components. Furthermore, it can be extended to other equipment, demonstrating significant versatility and universality. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the construction of a ship model RCS test system under a complex outdoor environment according to an embodiment of the present invention;

[0050] Figure 2 This is a flowchart of a ship model RCS test method under a complex external environment according to an embodiment of the present invention;

[0051] Figure 3 This is a side view of the ship model in an embodiment of the present invention;

[0052] Figure 4 This is a front view of the ship model in an embodiment of the present invention;

[0053] Figure 5 This is a schematic diagram of the half-power beamwidth of the transceiver antenna in the elevation direction in an embodiment of the present invention;

[0054] Figure 6 This is a schematic diagram of the half-power beamwidth in the azimuth direction of the transceiver antenna in an embodiment of the present invention;

[0055] Figure 7 This is a schematic diagram of the arrangement of the rotary table and the ship model in an embodiment of the present invention;

[0056] Figure 8 This is a schematic diagram of the arrangement of low-scattering metal planar shielding screens and the suppression of coupled scattering in an embodiment of the present invention;

[0057] Figure 9 This is a two-dimensional high-resolution imaging test result of the electromagnetic scattering characteristics of a standard sphere in an embodiment of the present invention;

[0058] Figure 10 This is a two-dimensional high-resolution imaging test result of the electromagnetic scattering characteristics of the tested ship model in an embodiment of the present invention;

[0059] Figure 11 This is a schematic diagram of scattering source interception and echo energy reconstruction in a two-dimensional color scale diagram in an embodiment of the present invention;

[0060] Figure 12 This is a schematic diagram comparing the RCS of the ship model generated in this embodiment of the invention with the RCS pattern curve test results of the same ship model under horizontal incident conditions. Detailed Implementation

[0061] 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.

[0062] like Figure 1 As shown, the technical solution of the present invention provides a ship model RCS test system for complex outdoor environments, including: an RCS system, a rotary table, a ship model, and test auxiliary components.

[0063] The RCS system includes a vector network analyzer, a broadband RF processing unit, a power amplifier, an RF transceiver antenna, RF cables, and a test, control, processing, and analysis system.

[0064] The rotary table is a platform with controllable rotational precision and a load-bearing capacity greater than or equal to the weight of the ship model. A foam support structure is installed on the rotary table.

[0065] The ship model is set on a foam support structure, and the center point of the rotating platform coincides with the geometric center of the ship model.

[0066] The testing auxiliary components include a low-scattering metallic planar shielding screen.

[0067] The RCS system, rotary table, ship model, and test auxiliary components were set up in the test site according to the test requirements.

[0068] In the RCS system, the receiving antenna of the RF transceiver antenna is connected in sequence to the low-noise amplifier, the broadband RF processing unit, and the vector network analyzer via RF cables; the transmitting antenna of the RF transceiver antenna is connected in sequence to the power amplifier, the broadband RF processing unit, and the vector network analyzer via RF cables; the vector network analyzer transmits data to the test control and processing analysis system via a GPIB / LAN interface, and the test control and processing analysis system is connected to the rotary table via a cable to control the rotation of the rotary table.

[0069] like Figure 2 As shown, in addition to providing a ship model RCS testing system for complex outdoor environments, the present invention further provides a method for conducting ship model RCS testing using the above system, including the following steps:

[0070] Step 1: Construct far-field simulation conditions based on beam uniformity coverage:

[0071] Step 1.1: Measure the maximum length, width and height of the ship model as the total length, total width and total height. Survey the test site environment. Under the condition of no obvious obstacles and a relatively flat open ground, determine the longitudinal and transverse range of the site.

[0072] Step 1.2: Arrange the test system's RF transceiver antenna and the ship model on the longitudinal axis of the site. To maximize the distance between the transceiver antenna and the ship model under test, the test system's RF transceiver antenna and its front-end components should be as close as possible to the edge of the site. Along the direction from the transceiver antenna to the ship model under test, the distance from the geometric center of the ship model under test to its near edge of the site should be greater than or equal to twice its total length.

[0073] Step 1.3: Adjust the half-power beamwidth of the RF transceiver antenna and the transmit power of the test system to ensure that the incident electromagnetic beam can uniformly cover the ship model while effectively receiving the electromagnetic scattered echo from the ship model.

[0074] Step 2: Strong coupling scattering shielding between the ship model and the erection area

[0075] Step 2.1: Use a rotary table with controllable rotational accuracy and a load-bearing capacity greater than or equal to the weight of the model being tested. The center point of the rotary table surface coincides with the location of the geometric center of the ship model being tested, which has been determined. The ship model being tested is supported on the rotary table by a foam support structure. The vertical distance from the bottom surface of the ship model to the ground is not less than 1.5 times the total height of the model. Wave-absorbing wedge material is laid on the exposed rotary table surface.

[0076] Step 2.2: On the longitudinal axis between the RF transceiver antenna and the ship model, arrange a low-scattering metal planar shield at the same height as the bottom surface of the ship model. Use the optical bouncing ray analysis method to track and evaluate the area where the ship model and the ground cause multiple scattering. Ensure that the distance between the low-scattering metal planar shield and the ship model under test is greater than the aforementioned area of ​​multiple scattering. The width of the low-scattering metal planar shield is greater than or equal to 1.5 times the diameter of the turntable, and the height of the shield is slightly lower than the bottom surface of the model. This is to achieve sufficient shielding of electromagnetic waves incident on the turntable and supporting structure while ensuring that the ship model is fully irradiated by the incident electromagnetic waves.

[0077] Step 3: Identification of longitudinal and transverse discrete sources of environmental scattering and RCS reconstruction

[0078] Step 3.1: Construct an RCS test system based on a linear frequency sweeping system. The normal of the aperture surface of the radio frequency transceiver antenna is parallel to the ground, and the height of the aperture center is the same as the height of the geometric center of the ship model.

[0079] Step 3.2: Set the test parameters of the test system, including center frequency, transmit pulse width, bandwidth, and pulse repetition period. The center frequency is the RCS test frequency required for the test. The distance corresponding to half of the transmit pulse width is not less than 1.5 times the maximum radial dimension of the target. The radial resolution corresponding to the test bandwidth is not greater than 1 / 5 of the minimum radial dimension of the ship model under test. Half of the distance corresponding to the pulse repetition period is the test distance, which is not less than the distance from the transmitting and receiving antenna to the geometric center of the ship model under test.

[0080] Step 3.3: Place a standard sphere and a ship model on the foam support structure one after the other. The projections of the geometric centers of both on the ground coincide with the projections of the turntable center on the ground. With the radio frequency transceiver antenna fixed, rotate the turntable to test the electromagnetic scattering characteristics of the standard sphere and the ship model in different orientations using high-resolution imaging. The location of the electromagnetic scattering source of the standard sphere and the ship model and its corresponding relative amplitude of echo energy are displayed by an adjustable two-dimensional color scale diagram with dynamic range of echo energy.

[0081] Step 3.4: By analyzing the vertical and horizontal positional distribution of the scattering resolution units in the two-dimensional color scale diagram, the regions where the electromagnetic scattering sources corresponding to the standard sphere and the ship model are located are extracted. The total scattering field is obtained by vector superposition of the scattering fields of each resolution unit.

[0082] Step 3.5: Based on the standard sphere theoretical RCS value, the RCS of the ship model is generated by comparing the total scattering field data of the standard sphere and the ship model.

[0083] The following specific example further illustrates the RCS testing system and method for ship model bodies under complex outdoor environments provided in this invention:

[0084] First, a ship model is created. In this embodiment, the ship model is as follows: Figures 3 to 4 As shown, the maximum values ​​of the overall length, width, and height of the ship model under test were measured and recorded as total length L = 7.7m, total width W = 0.98m, and total height H = 1.0m. The test site environment was surveyed, and under the conditions of no obvious obstacles and relatively flat open ground, a rectangular area with longitudinal and transverse dimensions of 65m and 50m respectively was determined for the RCS test.

[0085] The RF transceiver antenna and its front-end components of the RCS test system and the ship model under test are arranged on the longitudinal axis of the site. Taking the system transmit power required for a signal-to-noise ratio of not less than 10dB under the site environment with a -5.5dBsm calibration sphere as a reference, the distance between the RF transceiver antenna of the test system and the ship model under test is set to 43m. There are no significant spurious echo interference sources within 15m of the geometric center of the ship model under test from the far end of the site.

[0086] Calculate the shortest test distance required from the RF transceiver antenna to the geometric center of the ship model according to equation (1):

[0087]

[0088] Where R is the shortest test distance required from the transmitting and receiving antenna to the ship model, L is the total length of the ship model, and θ is the half-power beamwidth of the transmitting and receiving antenna. Figures 5 to 6 As shown, in this embodiment, a transceiver antenna with θ = 30° is selected, which can completely cover the ship model under test at a distance of 43m, and achieve power uniformity of the incident beam in the area of ​​the ship model under test within 3dB.

[0089] like Figure 7 As shown, a rotary table with a diameter of 4m is prepared, which has controllable rotational accuracy and a load capacity greater than or equal to the weight of the ship model being tested. The rotation angle accuracy of the rotary table is determined according to equation (2):

[0090]

[0091] Where Δφ is the required rotation angle accuracy of the turntable for lateral resolution, L is the total length of the ship model, c is the speed of light, and f is the test frequency. When the maximum test frequency is 15GHz, Δφ = 0.01°. The ship model under test is supported by a foam structure on the turntable, and the vertical distance between the bottom surface of the ship model and the ground is 1.5m. Wave-absorbing wedge material is laid on the exposed surface of the turntable.

[0092] A low-scattering metallic planar shield with a height of 1.3m and tilted at 45° is placed along the longitudinal axis between the RF transceiver antenna and the ship model under test. A schematic diagram of the arrangement of the low-scattering metallic planar shield and coupling scattering suppression is shown below. Figure 8As shown, the width of the shielding screen is 6m. The boundary of the area where the tested ship model and the ground scatter multiple times is determined to be about 10m from the center of the turntable by the optical bouncing ray analysis method. Based on this distance, the low-scattering metal planar shielding screen is placed more than 10m in front of the center of the turntable, actually about 12m. At this time, the distance between the low-scattering metal planar shielding screen and the transmitting and receiving antenna is about 31m.

[0093] The RCS test system is constructed based on the linear frequency sweeping system, including a vector network analyzer, power amplifier, transceiver antenna, RF cable, test control and processing analysis software, etc. The RF transceiver antenna is 2m above the ground, and the aperture plane normal is parallel to the ground.

[0094] In this embodiment, the experimental system parameters are set as follows: the center frequency of the experimental system is 15 GHz, the transmit pulse width T' ≥ 1.5 × 2L / c = 0.07 μs, taken as 0.1 μs, and the bandwidth B = c / 2I. r =750MHz, in this embodiment, 2GHz is selected, at which point the radial resolution I r The value is 0.075m, which is less than 1 / 5 of the minimum radial dimension. The pulse repetition period T≥2R / c=0.29μs. To fully ensure that the received echo does not alias, 10μs is selected.

[0095] A 0.6m diameter standard sphere and a model of the ship under test were placed successively on a foam support structure. The projections of the geometric centers of both onto the ground coincided with the projection of the turntable center onto the ground. With the transmitting and receiving antennas fixed, high-resolution imaging of the electromagnetic scattering characteristics of the standard sphere and the ship under test was performed. A two-dimensional colorimetric map was generated with an echo energy dynamic range of no less than 50dB, showing the location of the electromagnetic scattering sources of the standard sphere and the ship under test and their corresponding relative echo energy amplitudes. Figures 9 to 10 As shown.

[0096] By analyzing the scattering resolution units in the two-dimensional color scale diagram, the regions containing the electromagnetic scattering sources corresponding to the standard sphere and the tested ship model are extracted. Then, through the vector superposition of the scattered fields from each resolution unit, the total scattered fields of the standard sphere and the tested ship model are reconstructed, i.e.:

[0097]

[0098] Among them, R n Let k be the one-way distance from the nth structural unit to the sensor, and k be the free space wavenumber, k = 2πf / c. This represents the scattering field of the nth resolution unit. In this embodiment, the results of scattering source extraction and echo energy reconstruction in the two-dimensional color scale diagram are as follows: Figure 11 As shown.

[0099] Using the relative calibration method, the total scattering field data of the standard sphere and the ship model are processed according to the following formula:

[0100]

[0101] Where, σ T For the RCS of the ship model, σ S For the RCS of a standard ball, The total scattered field of the ship model The total scattering field of a standard sphere.

[0102] The RCS of the ship model generated in this embodiment is compared with the RCS pattern curve test results of the same ship model under horizontal incident conditions. Figure 12 As shown, the average RCS contrast deviation of the ship model generated using the method provided in this embodiment is 0.37dB, which is significantly more accurate than the 3dB RCS contrast deviation under the standard compressed field RCS test under horizontal incident conditions.

[0103] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A ship model RCS testing system for complex outdoor environments, characterized in that: The system includes: an RCS system, a rotary table, a ship model, and test auxiliary components; The RCS system includes a vector network analyzer, a broadband radio frequency processing unit, a power amplifier, a radio frequency transceiver antenna, radio frequency cables, and a test control and processing analysis system. The rotating platform is a platform with controllable rotational accuracy and a load-bearing capacity greater than or equal to the weight of the ship model. A foam support structure is provided on the rotating platform. The ship model is set on the foam support structure, and the center point of the rotating platform coincides with the geometric center of the ship model. The test auxiliary components include a low-scattering metallic planar shielding screen; The RCS system, rotary table, ship model and test auxiliary components are set up in the test site according to the test requirements; In the RCS system, the receiving antenna of the RF transceiver antenna is sequentially connected to the low-noise amplifier, the broadband RF processing unit, and the vector network analyzer via an RF cable; the transmitting antenna of the RF transceiver antenna is sequentially connected to the power amplifier, the broadband RF processing unit, and the vector network analyzer via an RF cable; the vector network analyzer transmits data with the test control and processing analysis system via a GPIB / LAN interface; the test control and processing analysis system is connected to the rotary table via a cable and controls the rotation of the rotary table. The RCS test system was constructed based on the linear frequency sweeping system. The normal of the aperture surface of the radio frequency transceiver antenna was parallel to the ground, and the height of the aperture center was the same as the height of the geometric center of the ship model. Set the test parameters of the test system, including center frequency, transmit pulse width, bandwidth, and pulse repetition period; A standard sphere and a ship model were placed on a foam support structure. With the radio frequency transceiver antenna fixed, the electromagnetic scattering characteristics of the standard sphere and the ship model in different orientations were tested by rotating the rotating table. The location of the electromagnetic scattering source of the standard sphere and the ship model and the corresponding relative amplitude of the echo energy were displayed by a two-dimensional color scale diagram with adjustable echo energy dynamic range. By analyzing the longitudinal and transverse positional distribution of the scattering resolution units in the two-dimensional color scale diagram, the regions where the electromagnetic scattering sources corresponding to the standard sphere and the ship model are located are extracted. The total scattering field is obtained by vector superposition of the scattering fields of each resolution unit. Based on the RCS value of the standard sphere theory, the RCS of the ship model is generated by comparing the total scattering field data of the standard sphere and the ship model.

2. The RCS test system for a ship model body under complex outdoor environment as described in claim 1, characterized in that: The radio frequency transceiver antenna and its front-end components of the RCS system are located near the edge of the test site. Along the direction from the radio frequency transceiver antenna to the ship model, the distance from the geometric center of the ship model to its near edge of the test site is greater than or equal to twice its total length.

3. The ship model RCS test system for complex outdoor environments as described in claim 1, characterized in that: The shortest test distance required from the RF transceiver antenna to the geometric center of the ship model satisfies the following relationship: （1） in, R The minimum test distance required for the transmitting and receiving antennas to the ship model. L For the overall length of the ship model, This is the half-power beamwidth of the transmit and receive antenna.

4. The RCS testing system for a ship model in a complex outdoor environment as described in claim 1, characterized in that: The rotation angle accuracy of the rotary table must meet the following requirement: （2） in, To achieve the required rotation angle accuracy of the turntable for lateral resolution, L For the overall length of the ship model, c For the speed of light, f This is the test frequency.

5. The RCS test system for a ship model body under complex outdoor environment as described in claim 1, characterized in that: The vertical distance from the bottom surface of the ship model to the ground is greater than or equal to 1.5 times the total height of the ship model, and the exposed surface of the rotating platform is covered with wave-absorbing wedge material.

6. The RCS test system for a ship model body under complex outdoor environment as described in claim 1, characterized in that: The width of the shielding screen is greater than or equal to 1.5 times the diameter of the rotating platform, and the height of the shielding screen is lower than the bottom surface of the ship model.

7. A method for RCS testing of a ship model under complex external environment, characterized in that: Using the test system described in any one of claims 1-6, the following steps are performed: Step 1: Construct far-field simulation conditions based on beam uniformity coverage: Step 1.1: Measure the maximum length, width and height of the ship model as the total length, total width and total height. Survey the test site environment. Under the condition of no obvious obstacles and a relatively flat open ground, determine the longitudinal and transverse range of the site. Step 1.2: Arrange the test system's RF transceiver antenna and the ship model on the longitudinal axis of the site to maximize the distance between the RF transceiver antenna and the ship model; Step 1.3: Adjust the half-power beamwidth of the RF transceiver antenna and the transmit power of the test system to ensure that the incident electromagnetic beam can uniformly cover the ship model while effectively receiving the electromagnetic scattered echo from the ship model. Step 2: Strong coupling scattering shielding between the ship model and the erection area Step 2.1: Adjust the center point of the turntable to coincide with the geometric center of the ship model, and set up a foam support structure on the turntable to support the ship model; Step 2.2: On the longitudinal axis between the radio frequency transceiver antenna and the ship model, arrange a low-scattering metal planar shield at the same height as the bottom surface of the ship model. Use the optical bouncing ray analysis method to track and evaluate the area where the ship model and the ground scatter multiple times, so that the distance between the low-scattering metal planar shield and the ship model is greater than the area of ​​multiple scattering mentioned above. Step 3: Identification of longitudinal and transverse discrete sources of environmental scattering and RCS reconstruction Step 3.1: Construct an RCS test system based on a linear frequency sweeping system. The normal of the aperture surface of the radio frequency transceiver antenna is parallel to the ground, and the height of the aperture center is the same as the height of the geometric center of the ship model. Step 3.2: Set the test parameters of the test system, including center frequency, transmit pulse width, bandwidth, and pulse repetition period; Step 3.3: Place a standard sphere and a ship model on the foam support structure one after the other. With the radio frequency transceiver antenna fixed, rotate the turntable to test the electromagnetic scattering characteristics of the standard sphere and the ship model in different directions using high-resolution imaging. The location of the electromagnetic scattering source of the standard sphere and the ship model and its corresponding relative amplitude of echo energy are displayed by a two-dimensional color scale diagram with adjustable echo energy dynamic range. Step 3.4: By analyzing the vertical and horizontal positional distribution of the scattering resolution units in the two-dimensional color scale diagram, the regions where the electromagnetic scattering sources corresponding to the standard sphere and the ship model are located are extracted. The total scattering field is obtained by vector superposition of the scattering fields of each resolution unit. Step 3.5: Based on the standard sphere theoretical RCS value, the RCS of the ship model is generated by comparing the total scattering field data of the standard sphere and the ship model.

8. The method for RCS testing of a ship model in a complex outdoor environment as described in claim 7, characterized in that: In step 3.2, the center frequency is selected as the RCS test frequency required for the test. The distance corresponding to half of the transmitted pulse width is not less than 1.5 times the maximum radial dimension of the target. The radial resolution corresponding to the test bandwidth is not greater than 1 / 5 of the minimum radial dimension of the ship model. The distance corresponding to the pulse repetition period is twice the test distance and is not less than the distance from the RF transceiver antenna to the geometric center of the ship model.

9. The method for RCS testing of a ship model in a complex outdoor environment as described in claim 8, characterized in that: In step 3.4, the total scattered field can be expressed as: （3） in, R n For the first n The one-way distance from each structural unit to the sensor. k For free space wavenumber, k =2πf / c, For the first n The scattering field of each resolution unit.

10. The method for RCS testing of a ship model body under complex outdoor environment as described in claim 9, characterized in that: In step 3.5, the relative calibration method is used to process the total scattering field data of the standard sphere and the ship model using the following formula: （4） in, RCS for ship models For the RCS of a standard ball, The total scattered field of the ship model The total scattering field of a standard sphere.

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