A radar signature passive simulator

Abstract

The present invention provides a radar feature passive simulator, including a Luneburg lens, a reflection layer and a modulation layer; the Luneburg lens has an incident end and a bottom end corresponding to the incident end, and the Luneburg lens is used to focus the electromagnetic waves incident on its surface; the modulation layer is conformal to the reflection layer, and both are spherical crowns; the modulation layer is attached between the bottom end of the Luneburg lens and the reflection layer; the emission layer is used to realize the reflection of electromagnetic waves to generate radar echoes; the modulation layer is used to modulate the radar echo power under different incident angles. The present invention comprehensively utilizes dielectric reflector design technology and absorbing material technology, and sets a modulation layer between the reflection layer and the Luneburg lens. The modulation layer can attenuate radar echoes in different regions with different amplitudes, and differentially modulate the radar echo power under different incident angles, thereby realizing refined passive simulation of target angular domain fluctuation characteristics.

Description

Technical Field

[0001] The invention relates to the technical field of radar target feature simulation, and in particular to a radar feature passive simulator. Background Art

[0002] With the promotion of actual combat requirements, high-fidelity characteristic simulation targets are becoming increasingly important test equipment. As for radar targets, most of them are economical and practical small motion platforms that are modified to adapt to electromagnetic scattering characteristics. According to the modification method, they can be divided into two types: active targets and passive targets. Active targets have the advantages of flexibility, high efficiency, and high repeatability. However, in terms of scattering mechanism, passive targets are closer to actual combat needs. Therefore, passive simulation of radar characteristics is one of the key technologies in target design and development.

[0003] Unlike sea targets and land targets, the modification of the electromagnetic scattering characteristics of the target is basically not restricted by the moving platform, while the design and development of the target for simulating the characteristics of air and space targets (referred to as air targets) will be severely limited by the platform load requirements to a large extent. Therefore, the radar characteristic simulation of air targets is usually achieved by simply loading metal corner reflectors or Luneberg spheres on the head, belly or wing of the platform; the advantages of this method are simple modification, good economy and short implementation cycle, but the disadvantage is that it cannot achieve the fine simulation of the angular fluctuation characteristics of air and space targets. With the development and application of high-resolution radars, the existing radar characteristic simulation methods of air targets have gradually failed to meet the needs of modern military; therefore, in order to solve the shortcomings of the existing technology, it is necessary to provide a new radar passive characteristic simulator to achieve the fine simulation of the angular fluctuation characteristics of air and space targets. Summary of the invention

[0004] The embodiment of the present invention provides a radar characteristic passive simulator, which can realize the fine simulation of the angular domain fluctuation characteristics of air and space targets.

[0005] An embodiment of the present invention provides a radar characteristic passive simulator, including a Luneburg lens, a reflection layer and a modulation layer; the Luneburg lens has an incident end and a bottom end corresponding to the incident end, and the Luneburg lens is used to focus the electromagnetic waves incident on its surface; the modulation layer is conformal to the reflection layer, both of which are spherical crowns; the modulation layer is attached between the bottom end of the Luneburg lens and the reflection layer; the reflection layer is used to realize the reflection of electromagnetic waves to generate radar echoes; the modulation layer is used to modulate the radar echo power under different incident angles.

[0006] In a possible design, the modulation layer includes a plurality of regions, and the plurality of regions correspond one-to-one to a plurality of angular domains divided by the target simulated relief feature;

[0007] The regions are covered with absorbing patches, and the absorbing rates of the absorbing patches covered on different regions are different.

[0008] In one possible design, the absorption rate of the absorbing patches covering different regions decreases as the target RCS value in the corresponding angular domain increases;

[0009] The area corresponding to the target maximum RCS value is not covered by the absorbing patch.

[0010] In a possible design, the height h of the reflective layer satisfies the following formula: h=(1-cos0.5θ)*R, where h is the height of the reflective layer, R is the radius of the Luneburg lens, and θ is the angular domain response; θ≥140°.

[0011] The edge of the reflective layer is 1 to 2 mm larger than the edge of the modulation layer.

[0012] In a possible design, the reflective layer is one of aluminum foil and copper foil; the thickness of the reflective layer is not greater than 0.2 mm.

[0013] In a possible design, the Luneburg lens body includes a core layer and a plurality of spherical shell layers; the plurality of spherical shell layers are nested and arranged on the surface of the core layer;

[0014] The interlayer gap between the core layer and the innermost spherical shell layer, and the interlayer gap between adjacent spherical shell layers are all no greater than 0.5 mm.

[0015] In a possible design, the Luneburg lens is formed by foaming polyethylene material; the radius of the Luneburg lens is 35 to 350 mm.

[0016] In a possible design, the radar characteristic passive simulator also includes a skin layer, which is coated on the outer surface of the reflection layer, and the skin layer is used to protect the reflection layer, the modulation layer and the Luneburg lens.

[0017] In a possible design, the thickness of the skin layer is 0.5-1.0 mm; the dielectric constant of the skin layer is 1.0-1.1C 2 / (N·M 2 ).

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: the present invention comprehensively utilizes dielectric reflector design technology and absorbing material technology, breaks through the traditional Luneburg lens reflector molding method, and sets a modulation layer between the Luneburg lens body and the reflecting layer. The modulation layer can attenuate radar echoes in different regions with different amplitudes, and differentially modulate the radar echo power under different incident angles, thereby realizing refined passive simulation of target angular domain fluctuation characteristics; the present invention overcomes the bottleneck that conventional radar characteristic passive simulators cannot realize the simulation of angular domain fluctuation characteristics of aerospace targets. On the basis of ensuring that such simulators have the characteristics of wide angular range, high gain, and easy processing, it also has the excellent performance of small angular domain characteristic differentiation and large dynamic range, further expanding the application field of such passive simulators, and providing a realistic and feasible technical means for the development of targets with realistic simulation functions of large fluctuation electromagnetic scattering characteristics, which has a very positive significance for promoting the improvement and development of various sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the composition of a radar characteristic passive simulator provided by an embodiment of the present invention;

[0021] Figure 2 It is a schematic diagram of the design of the reflection layer height of a radar characteristic passive simulator provided by an embodiment of the present invention;

[0022] Figure 3 It is a schematic diagram of the Luneburg lens structure of a radar characteristic passive simulator provided by an embodiment of the present invention;

[0023] Figure 4 It is a structural schematic diagram of a modulation layer of a radar characteristic passive simulator provided by an embodiment of the present invention;

[0024] In the figure: 1: skin layer; 2: reflection layer; 3: Luneburg lens; 4: modulation layer;

[0025] 301: core layer; 302: first spherical shell layer; 303: second spherical shell layer; 30N: outermost spherical shell layer; 401: first region; 402: second region; 403: third region; 40N: Nth region. DETAILED DESCRIPTION

[0026] In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] In view of the fact that the Luneburg lens reflector in the prior art cannot achieve fine simulation of the fluctuation characteristics of the angular domain characteristics of aerospace targets, the present invention improves the existing Luneburg lens reflector based on the electromagnetic wave transmission loss mechanism, and sets a modulation layer between the Luneburg lens body and the reflection layer. The modulation layer can adjust the radar echo power under different incident angles, thereby achieving fine passive simulation of the fluctuation characteristics of the target angular domain.

[0028] like Figure 1 As shown, an embodiment of the present invention provides a radar characteristic passive simulator, including a Luneburg lens 3, a reflective layer 2 and a modulation layer 4; the Luneburg lens 1 has an incident end and a bottom end corresponding to the incident end, and the Luneburg lens 1 is used to focus the electromagnetic waves incident on its surface; the modulation layer 4 is conformal to the reflective layer 2, both of which are spherical crowns; the modulation layer 4 is attached between the bottom end of the Luneburg lens 3 and the reflective layer 2, and the reflective layer 2 is located on the outer surface of the modulation layer 4; the emission layer 2 is used to realize the reflection of electromagnetic waves to generate radar echoes; the modulation layer 4 is used to modulate the radar echo power under different incident angles.

[0029] In some embodiments, the modulation layer 4 includes a plurality of regions, and the plurality of regions correspond one to one with the plurality of angular domains divided by the target simulated undulation characteristics; the regions are covered with absorbing patches, and the absorbing patches covered on different regions have different absorbances. In this embodiment, the regional division of the modulation layer can be determined according to the characteristics of the target angular domain undulation by the user. For example, when the user has a high requirement for the precision of the target angular domain undulation characteristics, it can be divided into a plurality of angular domains according to the target simulated undulation characteristics, and the number of divided regions of the modulation layer is increased accordingly; when the precision of the target angular domain undulation characteristics is low, the angular domains can be divided less according to the target simulated undulation characteristics, and the number of divided regions of the modulation layer is reduced accordingly; for example Figure 1As shown in the figure, the modulation layer is divided into a plurality of regions according to the target simulation fluctuation characteristics, and absorbing patches with different absorbency are covered on each region, so that the modulation layer can attenuate the radar echoes in different regions with different amplitudes, thereby realizing the refined passive simulation of the target angular fluctuation characteristics; the thickness of the modulation layer 4 is not more than 3mm; in the present invention, the greater the thickness of the modulation layer, the greater the target fluctuation range that can be simulated, but at the same time, the more serious the defocusing effect of the electromagnetic wave. Therefore, the thickness of the modulation layer in engineering applications should be considered by weighing the two indicators of fluctuation range and maximum RCS value. In the present invention, the defocusing effect can be minimized and the reflection effect of the reflection layer on the electromagnetic wave can be improved by setting the thickness of the modulation layer.

[0030] In some embodiments, the absorption rate of the absorbing patches covering different regions decreases as the target RCS value in the corresponding angular domain increases; the region corresponding to the target maximum RCS value is not covered with the absorbing patch.

[0031] In this embodiment, the number of angular domain divisions is first determined according to the precision of the target simulated undulation by the user, and then the area of ​​the modulation layer is divided according to the angular domain division of the undulation characteristics to be simulated by the target, wherein each area of ​​the modulation layer corresponds to each angular domain of the simulated undulation characteristics one by one, and the modulation layer is formed into a spherical crown shape by absorbing patches with specific electromagnetic wave absorption rates, and the absorption rates of the absorbing patches in different areas of the modulation layer are different, such as Figure 4As shown, the modulation layer may include a first area 401, a second area 402, a third area 403, ..., and an Nth area 40N, wherein the first area 401 corresponds to a first absorbing patch 401, the second area 402 corresponds to an absorbing patch 402, the third area corresponds to an absorbing patch 403, ..., and the Nth area 40N corresponds to an absorbing patch 40N. Areas with different colors in the figure represent different absorbencies of the absorbing patches; the absorbency of the absorbing patch decreases as the target RCS value under the corresponding angular domain increases. For example, the absorbency of the absorbing patch in the area corresponding to the maximum RCS value of the target is the smallest. At this time, the absorbing patch with a smaller absorbency may be covered in the corresponding area. When the radar echo generated by the reflecting layer passes through the area of ​​the modulation layer, substantially no energy attenuation occurs. In the present invention, the preferred It is selected that the area corresponding to the maximum RCS value of the target is not covered with an absorbing patch; the absorbing patch in the area corresponding to the minimum RCS value of the target has the largest absorbency, and an absorbing patch with a larger absorbency can be covered in the area corresponding to the minimum RCS value of the target. At this time, the radar echo generated by the reflection layer is completely absorbed when passing through the area of ​​the modulation layer, and the radar echo is greatly attenuated, so that the radar echo power in the angular domains corresponding to different areas can be differentially modulated, and a refined simulation of the fluctuation of the target angular domain characteristics can be achieved; when covering the absorbing patch in the modulation layer, the absorbing patch in each area can be one layer or multiple layers, and the absorptivity of each layer of the absorbing patch can be the same or different, as long as the total absorptivity of the absorbing patch in the area corresponds to the corresponding RCS value of the target.

[0032] The present invention breaks through the traditional Luneburg lens reflector forming method by comprehensively applying the dielectric reflector design technology and the absorbing material technology, loads a modulation layer between the reflective layer and the lens unit, and based on the loss mechanism of electromagnetic waves during transmission in the absorbing material, combined with the simulation requirements of the target angular domain fluctuation characteristics, divides the effective angular domain of the Luneburg lens reflector into regions, and performs different degrees of amplitude attenuation on the radar echo in each region, completing the differentiated modulation of the radar echo power under different incident angles, thereby realizing the refined passive simulation of the target angular domain fluctuation characteristics.

[0033] In some embodiments, Figure 2 As shown, the height h of the reflective layer 2 is designed according to the radius of the Luneburg lens 3 and the angular response requirement θ. The height of the reflective layer 2 satisfies the following formula: h = (1-cos0.5θ)*R, wherein h is the height of the reflective layer, R is the radius of the Luneburg lens, and θ is the angular response; θ≥140°. The height of the reflective layer is determined according to the above formula, which can ensure that the reflective layer has a good electromagnetic wave reflection effect, thereby better meeting the angular response requirements required by users.

[0034] In some embodiments, the edge of the reflection layer is 1 to 2 mm larger than the edge of the modulation layer; if the edge of the reflection layer is the same as or larger than the edge of the modulation layer, the electromagnetic waves after passing through the modulation layer will not fall into the range of the reflection layer, which is not conducive to the reflection layer reflecting the electromagnetic waves and forming radar echoes.

[0035] In some embodiments, the reflective layer 2 is one of aluminum foil and copper foil; in this embodiment, the reflective layer 2 may also be other metal foils; in specific implementation, the reflective layer 2 may be cut from a whole metal foil, or may be spliced ​​from multiple metal foils. It should be noted that when multiple metal foils are spliced, it is best not to have gaps at the joints of adjacent metal foils; the reflective layer 2 also satisfies: the thickness of the reflective layer 2 is not greater than 0.2 mm, so as to avoid strong electromagnetic scattering at the edge of the reflective layer due to excessive thickness, thereby adversely affecting the reflection performance distribution of the entire radar characteristic passive simulator.

[0036] like Figure 3 As shown, in some embodiments, the Luneburg lens body 3 includes a core layer 301 and a plurality of spherical shell layers (such as 302, 303 ... 30N); the plurality of spherical shell layers are nested on the surface of the core layer 301; the interlayer gap between the core layer 301 and the innermost spherical shell layer and the interlayer gap between adjacent spherical shell layers are not greater than 0.5 mm;

[0037] In this embodiment, the Luneburg lens body 3 is a multi-layer spherical structure, for example, including a core layer 301, a first spherical shell layer 302, a second spherical shell layer 303, ..., arranged in sequence from the inside to the outside, until the outermost spherical shell layer 30N; the core layer 301 is composed of two hemispheres, and the spherical shell layer is composed of two hemisphere shells. The spherical shell layers are nested in the core layer to form a Luneburg lens body. In order to avoid defocusing, beam tilt and radiation pattern distortion as much as possible, in the present invention, the interlayer gap between the core layer 301 and the outermost spherical shell layer (i.e., the first spherical shell layer 302), and the interlayer gap between adjacent spherical shell layers (such as the first spherical shell layer 302 and the second spherical shell layer 303) is not greater than 0.5 mm.

[0038] In some embodiments, the Luneburg lens 3 is made of foamed polyethylene material; the radius of the outermost spherical shell 30N of the Luneburg lens 3 is 35 to 350 mm; in a specific implementation, the radius R of the Luneburg lens can be flexibly set according to the magnitude of the RCS to be simulated. In the present invention, taking into account the defocusing effect of the modulation layer, the radius R of the Luneburg lens can be determined by referring to 1 to 3 dB greater than the maximum RCS value to be simulated.

[0039] In some embodiments, the radar characteristic passive simulator further includes a skin layer 1 , wherein the skin layer 1 is coated on the outer surface of the reflective layer 2 , and the skin layer 1 is used to protect the reflective layer 2 , the modulation layer 4 and the Luneburg lens 3 .

[0040] In this embodiment, a skin layer 1 is provided on the outer surface of the reflective layer 2, so that the radar characteristic passive simulator of the present invention has a certain mechanical strength and is not easily damaged during use, transportation and storage. Therefore, the material of the skin layer 1 should be selected from materials with a certain mechanical strength. In addition, the skin layer of the present invention is mainly formed by curing epoxy resin, alkali-free fiberglass cloth, polyamide resin and tetraethylenepentamine. At the same time, in order to minimize the transmission loss of the skin layer 1 to electromagnetic waves and make it have good wave transmission performance, in some embodiments, the thickness of the skin layer 1 is 0.5-1.0 mm, and the dielectric constant of the skin layer 1 is 1.0-1.1C. 2 / (N·M 2 ). In this way, the loss of electromagnetic waves can be reduced while ensuring the good mechanical strength of the skin layer.

[0041] It should be understood that the above general description and the detailed description below are only exemplary and explanatory and cannot limit the present application. In the present application, the term "multiple" refers to two or more, unless otherwise expressly defined. In the present application, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Terms such as "installed", "connected", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0042] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A radar characteristic passive simulator, characterized in that: It includes a Luneburg lens, a reflection layer and a modulation layer; the Luneburg lens has an incident end and a bottom end corresponding to the incident end, and the Luneburg lens is used to focus the electromagnetic waves incident on its surface; the modulation layer is conformal to the reflection layer, and both are spherical crown-shaped; the modulation layer is attached between the bottom end of the Luneburg lens and the reflection layer; the reflection layer is used to realize the reflection of electromagnetic waves to generate radar echoes; the modulation layer is used to modulate the radar echo power under different incident angles; the modulation layer includes multiple areas, and the multiple areas correspond one by one to multiple angular domains divided by the target simulated undulation characteristics; the areas are covered with absorbing patches, and the absorbing patches covered on different areas have different absorption rates.

2. The radar characteristic passive simulator according to claim 1, characterized in that: The absorption rate of the absorbing patches covered on different areas decreases as the target RCS value under the corresponding angular domain increases; The area corresponding to the target maximum RCS value is not covered by the absorbing patch.

3. The radar characteristic passive simulator according to claim 1, characterized in that: The height h of the reflective layer satisfies the following formula: , Where h is the height of the reflection layer, R is the radius of the Luneburg lens, θ is the angular domain response; θ ≥140°.

4. The radar characteristic passive simulator according to claim 1, characterized in that: The edge of the reflective layer is 1-2 mm larger than the edge of the modulation layer.

5. The radar characteristic passive simulator according to claim 1, characterized in that: The reflective layer is one of aluminum foil and copper foil; the thickness of the reflective layer is not greater than 0.2 mm.

6. The radar characteristic passive simulator according to claim 1, characterized in that: The Luneburg lens body comprises a core layer and a plurality of spherical shell layers; the plurality of spherical shell layers are nested and arranged on the surface of the core layer; The interlayer gap between the core layer and the innermost spherical shell layer, and the interlayer gap between adjacent spherical shell layers are all no greater than 0.5 mm.

7. The radar signature passive simulator according to claim 1, characterized in that: The Luneburg lens is formed by foaming polyethylene material; the radius of the Luneburg lens is 35-350 mm.

8. The radar signature passive simulator according to any one of claims 1 to 7, characterized in that: It also includes a skin layer, which is coated on the outer surface of the reflective layer. The skin layer is used to protect the reflective layer, the modulation layer and the Luneburg lens.

9. The radar signature passive simulator according to claim 8, characterized in that: The thickness of the skin layer is 0.5~1.0mm; the dielectric constant of the skin layer is 1.0~1.1C² / (N·M²).

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