Antenna radar scattering cross section test system

Abstract

The invention relates to the field of antenna radar cross section testing, in particular to an antenna radar cross section testing system which has an indoor use mode and an outdoor use mode and can meet requirements in different testing environments. The test system comprises a radar subsystem, an antenna feeder subsystem, an indoor target turntable, an outdoor scanning frame, an outdoor target turntable, a measurement and control and processing subsystem and test accessory equipment. The radar subsystem comprises a frequency synthesizer module, a transmitting module, a receiving module and an intermediate frequency signal processing module; the frequency synthesizer module adopts a hybrid technology combining direct digital frequency synthesis and a phase-locked loop, the direct digital frequency synthesis is used for realizing rapid frequency switching and high-resolution frequency stepping, and the phase-locked loop is responsible for expanding the frequency range and improving the long-term stability of the frequency; the antenna feeder subsystem adopts a dual-linear polarization design, switching of different polarization modes of the antenna is realized through a mechanical switch, and the antenna radar cross section testing system is suitable for antenna radar cross section testing.

Description

Technical Field

[0001] The present invention relates to the field of antenna radar cross-section testing, and particularly to an antenna radar cross-section testing system. Background Art

[0002] The radar cross-section is an important parameter for measuring the reflection characteristics of a target to radar waves, and is widely used in fields such as antenna design and stealth technology evaluation.

[0003] Existing radar cross-section testing systems, such as a radar cross-section testing system and detection method disclosed in CN111665399A, the testing system includes an anechoic chamber, and a detection robot, a vector network analyzer, a radio frequency transceiver device, a device-under-test robot, a tray, and an absorber baffle arranged in the anechoic chamber. The radio frequency transceiver device is electrically connected to the vector network analyzer and is driven by the detection robot to move for detecting the device under test. The device-under-test robot is arranged on the tray and can grab and place the device under test in the tray for detection. The absorber baffle is distributed between the detection robot and the device-under-test robot. By using this testing system, the device under test can be fully automatically tested, and the loading and unloading of the device under test are completely automatically controlled, without manual operation, and no additional interference will be brought to the anechoic chamber environment, and both the efficiency and accuracy are improved.

[0004] This system can only work in a single anechoic chamber, and has problems such as a limited test frequency range, insufficient measurement accuracy, and inability to adapt to complex polarization modes, and lacks the ability to adapt to harsh environments during outdoor testing. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an antenna radar cross-section testing system. This testing system has two usage modes, indoor and outdoor, can meet the requirements under different test environments, and greatly improves the adaptability.

[0006] The present invention adopts the following technical solutions to achieve the above purpose. The present invention provides an antenna radar cross-section testing system, including:

[0007] Including a radar subsystem and an antenna-feeding subsystem;

[0008] The radar subsystem includes a frequency synthesizer module, a transmitting module, a receiving module, and an intermediate frequency signal processing module;

[0009] The frequency synthesizer module adopts a hybrid technology combining direct digital frequency synthesis and a phase-locked loop. The direct digital frequency synthesis is used to achieve fast frequency switching and high-resolution frequency stepping, and the phase-locked loop is responsible for expanding the frequency range and improving the long-term stability of the frequency;

[0010] The transmitting module selects a broadband power amplifier module to ensure that the output power is not less than 30 dBmW in the frequency range of 4 GHz to 18 GHz, and a digitally controlled programmable attenuator is adopted to achieve that the output attenuation is programmably adjustable within the range of ≥ 25 dB, with an adjustment step of 1 dB;

[0011] The intermediate frequency signal processing module uses an analog-to-digital converter to achieve two-channel synchronous acquisition, uses a digital signal processing chip to achieve the intermediate frequency digital IQ demodulation function, and through optimizing the demodulation algorithm and combining with the receiving module, ensures that the dynamic range of the receiver is ≥ 80 dB @ 10 kHz intermediate frequency bandwidth;

[0012] The antenna-feeding subsystem adopts a dual-linear polarization design, and realizes the switching of different polarization modes of the antenna through a mechanical switch. The antenna consists of a feed horn and a transmitting surface.

[0013] Furthermore, the test system also includes an indoor target turntable;

[0014] The indoor target turntable is used for RCS measurement in both indoor and outdoor fields, and includes a turntable, a mobile base, turntable control, an anechoic protection vehicle, a local handheld controller, a wireless communication module, an optical fiber communication module, an optical fiber trigger module, and optical fiber communication cables.

[0015] The turntable is used to carry the object to be measured and drive the object to be measured to rotate during RCS measurement;

[0016] The mobile base is used to carry the turntable and drive the turntable to transfer the site. The mobile base is equipped with movable universal wheels and deployable support legs;

[0017] The turntable control is integrated inside the turntable and serves as the control core and interface of the turntable, having the capabilities of positioning, speed regulation, and emergency stop of the turntable.

[0018] The anechoic protection vehicle uses anechoic materials for anechoic protection. The anechoic protection is designed in two forms: a circular anechoic protection trolley and a ramp-type splicing. The circular anechoic protection trolley is installed with universal wheels at the bottom, which is convenient for protection installation and transportation. The ramp-type splicing form is divided into 4 pieces for splicing to achieve the shielding of all metal parts of the turntable;

[0019] The local handheld controller adopts a handheld form and is taken out from the storage box and connected to the turntable through a cable during use to achieve local function control;

[0020] The wireless communication module is used for wireless communication between the turntable and the console. During use, the communication antenna is connected to the turntable wireless communication interface through a cable;

[0021] The optical fiber trigger module triggers the position of the turntable through an optical fiber.

[0022] Furthermore, the test system further includes an outdoor scanning rack, which is used for vertically scanning and testing the antenna in an outdoor field, and the scanning rack adopts a multi-stage telescopic structure.

[0023] Furthermore, the test system further includes a measurement and control and processing subsystem, which is used for measuring the radar cross section of the target at different frequencies and angles, supporting one-dimensional, two-dimensional, and three-dimensional imaging, quickly obtaining the local scattering characteristics of the target, and achieving high-precision measurement through near-field testing and far-field extrapolation technology.

[0024] Furthermore, the test system further includes test auxiliary equipment;

[0025] The test auxiliary equipment includes an antenna lifting structure, an absorbing baffle, an antenna chamber, and a lifting vehicle;

[0026] The antenna lifting structure is used to ensure that the height of the antenna is flush with the center of the test target;

[0027] The absorbing baffle is used to shield the indoor turntable;

[0028] The antenna chamber is used to place the antenna. The antenna is divided into three sections, with the transmitter installed in one shielding cavity of the antenna chamber and the receiver installed in another shielding cavity of the antenna chamber;

[0029] The lifting vehicle is used to place the calibration body and the target.

[0030] The beneficial effects of the present invention are as follows:

[0031] The present invention has strong compatibility and can adapt to existing microwave anechoic chambers and outdoor test fields. It has high test accuracy and meets the requirements of wide-band and multi-polarization testing. It has strong environmental adaptability and can work stably in indoor and outdoor environments. It has strong data processing ability and supports various imaging and data analysis functions. The system design is modular, which is convenient for expansion and maintenance. Description of the Drawings

[0032] Figure 1 is a structural block diagram of an antenna radar cross section test system provided by an embodiment of the present invention;

[0033] Figure 2 is a schematic layout diagram of an indoor test system provided by an embodiment of the present invention;

[0034] Figure 3 is a schematic layout diagram of an outdoor test system provided by an embodiment of the present invention;

[0035] Figure 4 is a schematic diagram of an antenna structure provided by an embodiment of the present invention;

[0036] Figure 5 is a structural block diagram of a turntable subsystem provided by an embodiment of the present invention;

[0037] Figure 6 It is a schematic diagram of the antenna lifting structure provided by an embodiment of the present invention;

[0038] Figure 7 It is a schematic diagram of the wave-absorbing baffle structure provided by an embodiment of the present invention;

[0039] Figure 8 It is a schematic diagram of the antenna cabin structure provided by an embodiment of the present invention. Detailed implementation manners

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0041] The present invention provides an antenna radar cross-section test system, as Figure 1 shown, which includes a radar subsystem, an antenna-feeder subsystem, an indoor target turntable, an outdoor scanning frame, an outdoor target turntable, a measurement, control, and processing subsystem, and test auxiliary equipment.

[0042] The radar subsystem specifically includes a frequency synthesis module, a transmitting module, a receiving module, and an intermediate-frequency signal processing module. The frequency synthesis module adopts a hybrid technology combining direct digital frequency synthesis and a phase-locked loop. The direct digital frequency synthesis is used to achieve fast frequency switching and high-resolution frequency stepping to meet the frequency stepping requirement of at least 100 kHz; the phase-locked loop is responsible for expanding the frequency range and improving the long-term stability of the frequency to ensure a frequency stability of 0.05 ppm.

[0043] The transmitting module selects a broadband power amplifier module to ensure that a power of not less than 30 dBmW can be output in the frequency range of 4 GHz to 18 GHz. Through multi-stage amplification and power combining technologies, the transmitting power is increased while ensuring the linearity of the signal.

[0044] A digitally controlled programmable attenuator is adopted to achieve programmable adjustment of the output attenuation in the range of ≥ 25 dB, with an adjustment step of 1 dB. Through the interface circuit between the microcontroller and the attenuator, the attenuation amount is accurately controlled to meet the precise adjustment requirements of the transmitting power in different test scenarios. Based on high-speed switching circuits and digital signal processing technologies, a hardware gate pulse function is designed. By optimizing the circuit parameters and signal processing algorithms, it is ensured that the pulse rising edge ≤ 15 ns, the pulse width can be set in the range of 20 ns to 200 ns, and the step resolution ≤ 5 ns.

[0045] The intermediate frequency signal processing module uses a high-speed and high-precision analog-to-digital converter to achieve two-channel synchronous acquisition, ensuring the accuracy and real-time performance of the acquired data. A digital signal processing chip is used to implement the intermediate frequency digital IQ demodulation function. By optimizing the demodulation algorithm and combining with the receiving subsystem, the dynamic range of the receiver is guaranteed to be ≥80 dB @ 10 kHz intermediate frequency bandwidth.

[0046] The antenna-feeding subsystem has a working frequency band covering 4 GHz to 18 GHz, which is divided into three sub-bands: 4 GHz to 8 GHz, 8 GHz to 12 GHz, and 12 GHz to 18 GHz. The system adopts a dual-polarization design and realizes the switching of different polarization modes of the antenna through a mechanical switch, so that it can work efficiently in different frequency bands and polarization states. As Figure 4 shown, the antenna consists of a feed horn and a transmitting surface. Compared with traditional linear arrays or horn antennas, its back size is significantly reduced, the structure is more compact, and it is convenient to integrate with the usage platform. This design not only improves the flexibility and applicability of the antenna, but also simplifies the installation and maintenance process, especially suitable for application scenarios with strict requirements on space and structure.

[0047] Antenna Design Index Table

[0048]

[0049] The specific antenna design, as shown in the antenna design index table, can be optimized and adjusted according to the overall specific indicators.

[0050] It can be seen from the above simulation of 8 GHz to 12 GHz that the antenna indicators meet the following requirements:

[0051] ① Frequency band coverage: 4 GHz to 18 GHz; broadband antenna, with segments ≤ 3 segments, programmable switching;

[0052] ② Antenna feeding method: dual-polarization feeding, vertical and horizontal dual-polarization; automatic polarization switching function can be realized;

[0053] ③ Antenna input VSWR: ≤ 1.8:1;

[0054] ④ Antenna gain: ≥ 10 dBi;

[0055] ⑤ The antenna has shaped flat beam illumination. Under two polarizations, the 3 dB beam width of the wide-side beam is greater than 35°, and the 3 dB beam width of the narrow-side beam is greater than 10°.

[0056] Indoor and Outdoor Target Turntable Design:

[0057] The turntable is mainly used for radar cross-section measurement in indoor and outdoor fields. It mainly consists of a movable base of the turntable, a turntable, an absorbing protection, a local hand-held controller, a wireless communication module, an optical fiber communication module, an optical fiber communication cable, etc.

[0058] The turntable can carry the model to be tested to complete the rotation action, realizing the rotational motion for radar cross-section measurement. The protection level of the turntable can reach IP64, with functions such as anti-overturning, low scattering, arbitrary movement, and position adjustment. After the overall erection of the turntable, anechoic panels are laid around for protection.

[0059] The turntable subsystem is mainly used for radar cross-section measurement. Its structure is as Figure 5 shown, including a turntable, a movable base, turntable control, anechoic protection vehicle, a local controller, a wireless communication module, an optical fiber communication module, an optical fiber trigger module, and optical fiber communication cables.

[0060] The turntable, as the main moving part of the entire turntable system, drives the object to be tested to rotate for RCS measurement and also serves as the main bearing device for the object to be tested.

[0061] The movable base, as the bearing device for the turntable and the object to be tested, is used to drive the turntable for site transfer and is equipped with movable universal wheels and deployable support legs.

[0062] The turntable control is integrated inside the turntable. As the control core of the turntable, it has functions such as positioning and speed regulation of the turntable, and has functions such as emergency stop. It also serves as the main interface for the programmable turntable.

[0063] The anechoic protection vehicle uses anechoic materials for anechoic protection. The anechoic protection is designed in two forms: a circular anechoic protection trolley and a ramped splicing. The circular anechoic protection trolley is equipped with universal wheels at the bottom for easy installation and transportation of the protection. There are 2 anechoic protection vehicles in total, which can shield all metal parts of the turntable. The ramped splicing form is divided into 4 pieces for splicing and can also shield all metal parts of the turntable, minimizing the impact of all metal parts of the turntable on the measurement.

[0064] The local controller is in a handheld form. When in use, it is taken out from the storage box and connected to the turntable through a cable to achieve local function control.

[0065] The wireless communication module can achieve wireless communication between the turntable and the console. When in use, the communication antenna is taken out from the storage box and connected to the wireless communication interface of the turntable through a cable.

[0066] The optical fiber communication module enables communication between the turntable and the console through optical fiber connection.

[0067] The optical fiber trigger module can trigger the position of the turntable through optical fiber.

[0068] The optical fiber communication cable serves as the connection cable between the turntable and the optical fiber communication module of the console to meet the communication requirements.

[0069] Turntable control design:

[0070] The functions of the turntable control subsystem mainly include motion control, triggering function, fiber optic communication control, wireless communication, and local control. The hardware selection of the turntable control subsystem mainly uses servo drivers, motion control units, control units, trigger conversion modules, fiber optic to Ethernet modules, wireless communication modules, etc. Among them, the wireless communication module is located outside the turntable.

[0071] The outdoor scanning frame is used for vertical scanning tests of the antenna in the outdoor field. The total height of the scanning frame is 12.6m, the vertical stroke is 12m, and the lowest height is 1.5m. The scanning frame adopts a multi-stage design and is telescopic. After retraction, the maximum height does not exceed 4.5m.

[0072] The measurement and control and processing subsystem has multiple functions, can accurately measure the radar cross-section of the target at different frequencies and angles, supports one-dimensional, two-dimensional, and three-dimensional imaging, quickly obtains the local scattering characteristics of the target, and realizes high-precision measurement through near-field testing and far-field extrapolation technology. The system also provides a variety of calibration algorithms to eliminate system errors and improve measurement accuracy.

[0073] The system has the ability of automatic data acquisition, processing, and analysis, can display one-dimensional images and two-dimensional images in real time, and supports the fusion display of target digital models and imaging. The system also has a scattering test database, supporting multi-field query and data export functions.

[0074] The test auxiliary equipment mainly guarantees the entire test task, ensuring the accuracy and portability of the test. It includes the lifting structure of the antenna, microwave absorbing baffle, antenna cabin, and lifting vehicle, etc.

[0075] The antenna lifting structure is to ensure that the antenna height is flush with the center of the test target, and the maximum lifting height is 4m. The design structure is as Figure 6 shown.

[0076] The microwave absorbing baffle is as Figure 7 shown, and is used for shielding the indoor turntable to prevent electromagnetic waves from irradiating the turntable and affecting the test results. According to the minimum test frequency of 4GHz, the height of the microwave absorbing material is selected as 200mm.

[0077] The design of the antenna cabin is mainly to ensure that environmental noise or interference does not affect the test results, mainly to ensure high-performance test results. As Figure 8 shown, a shaped flat beam antenna is used, which is divided into three sections. The transmitter is installed in one shielding cavity, and the receiver is installed in another shielding cavity.

[0078] For the lifting vehicle, the upper surface of the foam support is currently 3m from the ground. Therefore, the designed height of the mobile lifting platform is 2m, which can ensure that the measured target can move up and down the test platform. An microwave absorbing baffle is laid between the lifting platform and the measuring equipment to shield the lifting platform, ensuring that the test area has a good test background.

[0079] In the indoor mode, the system utilizes the existing anechoic chamber and adapts to the indoor RCS test requirements by means of modifying the shielding door, adding absorbing material baffles, and extending the traveling crane stroke. The system can achieve near-field RCS testing of the target and calculate the far-field scattering data by back-calculation using the near-to-far field transformation algorithm.

[0080] In the outdoor mode, the system uses a mobile test platform and a scanning frame to conduct near-field scattering tests on large targets. The system features a large beam coverage range, high measurement accuracy, and strong environmental adaptability, and can meet the test requirements in complex outdoor environments.

[0081] The indoor and outdoor designs of the antenna radar cross-section test system are described in detail below.

[0082] The indoor design of the antenna radar cross-section test system is as Figure 2 shown:

[0083] To ensure that the beam of the feed can cover the entire target, the distances from the center of the antenna instrument cabin to the target are calculated separately to meet the requirements of vertical and horizontal beam coverage. The following is the detailed calculation process and analysis:

[0084] 1. Vertical beam coverage calculation

[0085] Known conditions:

[0086] The vertical beam angle θ of the feed = 35°;

[0087] The target length: 8 meters;

[0088] Analysis: To ensure that the vertical beam of the feed can cover the entire target, it is necessary to calculate the distance from the center of the antenna instrument cabin to the target.

[0089] Design:

[0090] Beam coverage range formula:

[0091] Coverage length = 2 × tan(θ / 2) × d;

[0092] where θ = 35°, and d is the distance from the center of the antenna instrument cabin to the target.

[0093] Calculate the coverage length:

[0094] tan(35° / 2) = tan(17.5°) ≈ 0.315 Coverage length = 2 × 0.315 × d = 0.63 × d;

[0095] Target length:

[0096] The target length = 8 meters;

[0097] Calculate the minimum distance d:

[0098] 0.63×d ≥ 8 m, d ≥ 8 / 0.63 ≈ 12.698 m;

[0099] Conclusion: According to the vertical beam coverage requirement, the minimum distance from the center of the antenna instrument cabin to the target should be 12.698 m.

[0100] 2. Horizontal beam coverage calculation

[0101] Known conditions:

[0102] The horizontal beam angle φ of the feed ≥ 10°;

[0103] Target height: 3 m;

[0104] Analysis:

[0105] To ensure that the horizontal beam of the feed can cover the entire height of the target, the distance from the center of the antenna instrument cabin to the target needs to be calculated.

[0106] Calculation:

[0107] Beam coverage range formula:

[0108] Coverage height = 2 × tan(φ / 2) × d;

[0109] Where: φ = 10°, d is the distance from the center of the antenna instrument cabin to the target.

[0110] Calculate the coverage height:

[0111] tan(10° / 2) = tan(5°) ≈ 0.0875, Coverage height = 2 × 0.0875 × d = 0.175 × d;

[0112] Target height:

[0113] Target height = 3 m;

[0114] Calculate the minimum distance d:

[0115] 0.175 × d ≥ 3 m, d ≥ 3 / 0.175 ≈ 17.143 m;

[0116] Conclusion: According to the horizontal beam coverage requirement, the minimum distance from the center of the antenna instrument cabin to the target should be 17.143 m.

[0117] 3. Comprehensive design

[0118] Known conditions:

[0119] Vertical beam coverage requirement: The distance between the antenna and the target shall not be less than 12.698 m.

[0120] Horizontal beam coverage requirement: The distance between the antenna and the target shall not be less than 17.143 meters.

[0121] Analysis:

[0122] In order to meet the requirements of both vertical and horizontal beam coverage simultaneously, the present invention needs to select a larger distance as the design basis.

[0123] Conclusion: Horizontal beam coverage requirement: The distance between the antenna and the target shall not be less than 17.143 meters;

[0124] Vertical beam coverage requirement: The distance between the antenna and the target shall not be less than 12.698 meters.

[0125] Comprehensive design: Select a larger distance, that is, the distance between the antenna and the target shall not be less than 17.143 meters.

[0126] 4. Design of the foam column and the target height

[0127] Known conditions:

[0128] The height of the top of the foam column from the ground, the height of the target center from the ground;

[0129] Key points:

[0130] The target height is 3 meters, and the height of the target center from the ground should be the height of the top of the foam column plus half of the target height.

[0131] Analysis:

[0132] In order to ensure the stability of the target during the test and the distance between the target and the antenna instrument compartment meets the test conditions, it is necessary to determine the heights of the foam column and the target.

[0133] Calculation:

[0134] Target center height:

[0135] Target center height = height of the top of the foam column + 3 meters / 2;

[0136] Height of the top of the foam column:

[0137] Height of the top of the foam column = target center height - 3 meters / 2;

[0138] Conclusion:

[0139] Height of the top of the foam column: Assuming the height of the target center from the ground is 4 meters, then the height of the top of the foam column is:

[0140] 4 meters - 3 meters / 2 = 2.5 meters;

[0141] Target center height: 4 meters;

[0142] Final design:

[0143] According to the above calculations and analyses, the distance from the center of the antenna instrument cabin to the target is designed to be 18 meters to ensure that the beam of the feed can fully cover the vertical and horizontal directions of the target. At the same time, the height of the top of the foam column from the ground is 2.5 meters, and the height of the target center from the ground is 4 meters to meet the layout requirements of the test system.

[0144] Through detailed calculations and analyses, the following conclusions are obtained:

[0145] For vertical beam coverage, the distance between the antenna and the target should be not less than 12.698 meters.

[0146] For horizontal beam coverage, the distance between the antenna and the target should be not less than 17.143 meters.

[0147] The comprehensive design suggests that the distance between the antenna and the target is 18 meters to meet all coverage requirements.

[0148] The height of the top of the foam column from the ground is 2.5 meters, and the height of the target center from the ground is 4 meters.

[0149] Outdoor design of the antenna radar cross-section test system, as Figure 3 shown:

[0150] Calculate the distance from the center of the antenna instrument cabin to the target to ensure that the vertical and horizontal beams of the feed can cover the entire target. The following is the detailed calculation process and results:

[0151] 1. Calculation of vertical beam coverage

[0152] Known conditions:

[0153] The vertical beam angle θ of the feed = 35°;

[0154] Target height: 12 meters;

[0155] Height of the center of the antenna instrument cabin from the ground: 12 meters;

[0156] Height of the lowest irradiation point from the ground: 1.5 meters;

[0157] Calculate the vertical coverage range of the target:

[0158] To ensure that the feed can cover the target from the lowest point (1.5 meters) to the highest point (12 meters), it is necessary to calculate the distance from the center of the antenna instrument cabin to the target.

[0159] 1. Vertical coverage range of the target:

[0160] Coverage height = 12 meters - 1.5 meters = 10.5 meters;

[0161] 2. Beam coverage formula:

[0162] Coverage height = 2×tan(θ / 2)×d;

[0163] Where: θ = 35°, and d is the distance from the center of the antenna instrument compartment to the target.

[0164] 3. Calculate the minimum distance d:

[0165] Tan(35° / 2) = tan(17.5°) ≈ 0.3152×0.315×d ≥ 10.5 m, d ≥ 2×0.31510.5 ≈ 16.67 m;

[0166] Therefore, to meet the requirements of vertical beam coverage, the distance from the center of the antenna instrument compartment to the target should be not less than 16.67 m.

[0167] 2. Horizontal beam coverage calculation

[0168] Known conditions:

[0169] The horizontal beam angle φ of the feed ≥ 10°;

[0170] Target width: 8 m;

[0171] Calculate the horizontal coverage range of the target:

[0172] To ensure that the feed can cover the entire width of the target, it is necessary to calculate the distance from the center of the antenna instrument compartment to the target.

[0173] 1. Beam coverage formula:

[0174] Coverage width = 2×tan(φ / 2)×d;

[0175] Where:

[0176] φ = 10°, and d is the distance from the center of the antenna instrument compartment to the target.

[0177] 2. Calculate the minimum distance d:

[0178] tan(10° / 2) = tan(5°) ≈ 0.08752×0.0875×d ≥ 8 m, d ≥ 2×0.08758 ≈ 45.71 m;

[0179] Therefore, to meet the requirements of horizontal beam coverage, the distance from the center of the antenna instrument compartment to the target should be not less than 45.71 m.

[0180] 3. Comprehensive design

[0181] Considering the requirements of both vertical and horizontal beam coverage, the distance from the center of the antenna instrument compartment to the target should be selected as the larger value, i.e., 45.71 m.

[0182] Final design:

[0183] The distance from the center of the antenna instrument compartment to the target: not less than 46 meters;

[0184] The horizontal distance between the antenna and the instrument compartment: 40 meters;

[0185] Through calculation, the present invention draws the following conclusions:

[0186] 1. The vertical beam coverage requires that the distance between the antenna and the target is not less than 16.67 meters.

[0187] 2. The horizontal beam coverage requires that the distance between the antenna and the target is not less than 45.71 meters.

[0188] 3. The comprehensive design suggests that the distance between the antenna and the target is 46 meters to meet all coverage requirements.

[0189] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in the relevant field. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. An antenna radar cross section test system, characterized in that: It includes a radar subsystem and an antenna feed subsystem, wherein the radar subsystem includes a frequency synthesis module, a transmitting module, a receiving module and an intermediate frequency signal processing module; The frequency synthesis module adopts a hybrid technology combining direct digital frequency synthesis and phase-locked loop. Direct digital frequency synthesis is used to achieve fast frequency switching and high-resolution frequency stepping, and the phase-locked loop is responsible for expanding the frequency range and improving the long-term stability of the frequency. The transmitting module uses a broadband power amplifier module to ensure that the output power is not less than 30dBmW in the frequency range of 4GHz to 18GHz, and adopts a digitally controlled programmable attenuator to achieve programmable adjustment of output attenuation within the range of ≥25dB, with an adjustment step of 1dB; The intermediate frequency signal processing module uses an analog-to-digital converter to achieve 2-channel synchronous acquisition, and uses a digital signal processing chip to achieve the intermediate frequency digital IQ demodulation function. By optimizing the demodulation algorithm and combining the receiving module, the receiver dynamic range is guaranteed to be ≥80dB@10kHz intermediate frequency bandwidth; The antenna feed subsystem adopts a dual-line polarization design, and realizes the switching of different polarization modes of the antenna through a mechanical switch. The antenna consists of a feed horn and a transmitting surface.

2. The antenna radar cross section test system according to claim 1, characterized in that: The test system also includes an indoor target turntable; The indoor target turntable is used for indoor and outdoor RCS measurement, and includes a turntable, a mobile base, a turntable control, a wave absorbing protection vehicle, a local handheld controller, a wireless communication module, an optical fiber communication module, an optical fiber trigger module and an optical fiber communication cable. The turntable is used to carry the object to be measured and drive the object to be measured to rotate during RCS measurement; The mobile base is used to carry the turntable and drive the turntable to move to the site. The mobile base has movable universal wheels and movable supporting legs. The turntable control is integrated inside the turntable, serving as the control core and interface of the turntable, and has the capabilities of positioning, speed regulation, and emergency stop of the turntable; The wave-absorbing protection vehicle adopts wave-absorbing materials for wave-absorbing protection. The wave-absorbing protection is designed into two forms: a circular wave-absorbing protection vehicle and a slope-type splicing. Universal wheels are installed at the bottom of the circular wave-absorbing protection vehicle to facilitate protection installation and transportation. The slope-type splicing form is divided into 4 pieces to achieve shielding of all metal parts of the turntable. The local handheld controller is in handheld form and is taken out from the storage box and connected to the turntable via a cable to achieve local function control when in use; The wireless communication module is used for wireless communication between the turntable and the control console. When in use, the communication antenna is connected to the wireless communication interface of the turntable via a cable; The optical fiber trigger module triggers the position of the turntable through the optical fiber.

3. The antenna radar cross section test system according to claim 1, characterized in that: The test system also includes an outdoor scanning frame, which is used to perform vertical scanning tests on antennas in outdoor fields. The scanning frame adopts a multi-stage telescopic structure.

4. The antenna radar cross section test system according to claim 1, characterized in that: The test system also includes a measurement, control and processing subsystem, which is used to measure the radar scattering cross section of the target in different frequency bands and angles, supports one-dimensional, two-dimensional and three-dimensional imaging, quickly obtains the local scattering characteristics of the target, and achieves high-precision measurement through near-field testing and far-field extrapolation technology.

5. The antenna radar cross section test system according to claim 1, characterized in that: The test system also includes test accessory equipment; The test auxiliary equipment includes an antenna lifting structure, a wave-absorbing baffle, an antenna compartment and a lifting vehicle; The antenna lifting structure is used to ensure that the antenna height is flush with the center of the test target; The wave-absorbing baffle is used to shield the indoor turntable; The antenna compartment is used to place the antenna, which is divided into three sections. The transmitter is installed in a shielded cavity of the antenna compartment, and the receiver is installed in another shielded cavity of the antenna compartment. The lifting vehicle is used to place the calibration object and the target.

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