Adjustable radar echo enhancement device

Abstract

The invention relates to an adjustable radar echo enhancement device, and relates to the field of radar echo enhancement, the adjustable radar echo enhancement device comprises a lens unit, a skin layer and a functional layer, the lens unit is of a multilayer spherical structure, the skin layer wraps the lens unit, the functional layer wraps the skin layer, a plurality of strip-shaped substrates are distributed on the outer edge of the spherical surface of the functional layer, a plurality of diodes are distributed on the substrate at intervals, conductive circuits are connected among the diodes to provide breakover voltage for two ends of the diodes, and the simulator has the advantages of being wide in angular domain, high in gain and easy to process, and meanwhile has excellent performance of small angular domain characteristic differentiation and large dynamic range. The application field of the passive simulator is further expanded, a practical and feasible technical means is provided for research and development of a target with a vivid simulation function of the large-fluctuation electromagnetic scattering characteristic, and the passive simulator has the advantage of having positive significance in promoting perfection and development of various sensors.

Description

Technical Field

[0001] The invention relates to the technical field of radar echo enhancement, and in particular to an adjustable radar echo enhancement device. Background Art

[0002] The rapid development of modern technology has objectively promoted the increasing maturity of target design and development technology. As the assessment scale and benchmark of system performance indicators, different systems have different requirements for target target characteristic simulation. Even for the same system, the requirements for the electromagnetic scattering characteristics of the target are different at different development stages and different assessment subjects. Or even for the same system and the same development stage, the RCS distribution requirements of various sensors for the target are very different. The target's characteristic simulation of the target is usually based on the principle of "small model large". In most cases, the target motion platform needs to be loaded with a radar echo enhancement device, and the performance of the latter largely determines the RCS characteristics of the former. Therefore, from multiple perspectives such as periodicity, economy, and simplicity, if the loaded radar echo enhancement device has the characteristics of adjustable RCS and response angle, it will bring great convenience to the design and application of the target.

[0003] Based on the generation mechanism of radar echo, radar echo enhancement devices are divided into two types: active and passive. The active type generates radar echo based on the radiation system, which has the advantages of flexibility, high efficiency, high repeatability, etc., and can achieve RCS and response angle adjustment by changing the antenna beam pointing and adjusting the power amplifier gain index. However, it also has many shortcomings such as long cycle, high cost, difficulty in achieving complete coherence of echo signals, signal processing delay, hidden dangers in general quality characteristics such as electromagnetic compatibility, and inability to reflect the scattering mechanism of echo.

[0004] Therefore, in view of the above shortcomings, it is necessary to provide an adjustable radar echo enhancement device. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is to solve the problem that it is difficult to achieve precise adjustment of RCS and response angle domain for physically reproducing high-value target characteristic simulation targets.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention provides an adjustable radar echo enhancement device, including a lens unit, a skin layer and a functional layer. The lens unit is a multi-layer spherical structure. The skin layer is coated on the outside of the lens unit, and the functional layer is coated on the outside of the skin layer. A plurality of strip-shaped substrates are distributed along the spherical surface outside the functional layer, and a plurality of diodes are distributed on the substrates at intervals. Conductive circuits are connected between the diodes to provide a conduction voltage to both ends of the diodes.

[0009] As a further illustration of the present invention, preferably, the lens unit is formed by foaming a polystyrene material, and the size of the lens unit satisfies:

[0010]

[0011] in,

[0012] D is the lens unit diameter, in m;

[0013] c is the constant speed of light, in m / s;

[0014] σ max is the maximum RCS value, in m 2 ;

[0015] f is the operating frequency in Hz.

[0016] As a further illustration of the present invention, preferably, the innermost layer of the lens unit is a core layer, the core layer is formed by splicing two hemispheres, and the core layer is coated with a plurality of spherical shell layers to form the lens unit.

[0017] As a further illustration of the present invention, preferably, the gap between the core layer and the spherical shell layer is less than 0.5 mm, and the core layer and the spherical shell layer and the spherical shell layer and the spherical shell layer are bonded by ethyl acetate.

[0018] As a further illustration of the present invention, preferably, the skin layer is formed by curing a mixture of epoxy resin, alkali-free fiberglass cloth, polyamide resin and tetraethylenepentamine, and the thickness of the skin layer is between 0.5 mm and 1.0 mm.

[0019] As a further illustration of the present invention, preferably, the dielectric constant of the skin layer is between 1.0 and 1.1.

[0020] As a further illustration of the present invention, preferably, a plurality of diodes are laid out using a frequency selective surface design technique.

[0021] As a further illustration of the present invention, preferably, when the diode is turned off, the FSS is in a bandpass state, and the electromagnetic wave penetrates the functional layer into the lens unit or penetrates the lens unit into free space.

[0022] As a further illustration of the present invention, preferably, when the diode is turned on, the FSS is in a band-stop state, and the functional layer forms a reflection surface to reflect the incident electromagnetic wave.

[0023] As a further illustration of the present invention, preferably, when the reflective region of the functional layer is in the shape of a spherical crown, then:

[0024]

[0025] in,

[0026] θ is the angular domain response range;

[0027] h is the height of the reflection area;

[0028] R is the radius of the lens element.

[0029] (III) Beneficial effects

[0030] The above technical solution of the present invention has the following advantages:

[0031] The present invention uses metamaterial technology and dielectric reflector technology in combination, breaks through the traditional Luneburg lens reflector forming method, loads a functional layer on the outer surface, and based on the diode frequency-selective surface transmission-reflection transformation mechanism, combined with the radar feature simulation requirements of variable target RCS and response angle domain, the functional layer is placed in a specific transmission or reflection state at a specific time point in different regions under the action of the control unit, so as to achieve the purpose of adjusting the RCS performance index and effective response angle domain of the radar echo enhancement device, and provide technical support for improving the versatility of the target system and realizing a multi-mode working system. It also overcomes the bottleneck that conventional passive radar echo enhancement devices are difficult to achieve accurate adjustment of RCS and response angle domain, and realizes that such devices can have excellent performances such as large RCS dynamic range, fine simulation of angle domain characteristics, and multi-beam forming on the basis of having wide angle domain and high gain characteristics, further expanding the application field of such products, providing a realistic and feasible technical approach for the development of universal targets, and having extremely positive significance for promoting the improvement and development of various sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the device composition of the present invention;

[0033] Figure 2 is a schematic diagram of the lens unit structure of the present invention;

[0034] Figure 3 It is a schematic diagram of the functional layer structure of the present invention;

[0035] Figure 4 It is a schematic diagram of the working principle of the present invention in a transmission state;

[0036] Figure 5 It is a schematic diagram of the working principle of the reflection state of the present invention;

[0037] Figure 6 It is a schematic diagram of the response angle design of the present invention.

[0038] In the figure: 1, lens unit; 11, core layer; 12, spherical shell layer; 2, skin layer; 3, functional layer; 31, diode; 32, substrate; 33, conductive circuit. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] An adjustable radar echo enhancement device, such as Figure 1 As shown, it includes a lens unit 1, a skin layer 2 and a functional layer 3. The lens unit 1 is a multi-layer spherical structure. The skin layer 2 is coated on the outside of the lens unit 1, and the functional layer 3 is coated on the outside of the skin layer 2.

[0041] Combination Figure 1 , Figure 2 , the lens unit 1 is composed of a core layer 101 and a plurality of spherical shell layers 23 from the inside to the outside. The core layer 101 can be composed of two hemispheres, and each spherical shell layer 12 can be composed of two hemisphere shells, which are all made of foamed polystyrene material. In the passive radar echo enhancement device, the lens unit 1 is mainly used to focus electromagnetic waves. In engineering applications, the diameter of the lens unit 1 is determined by the maximum RCS value and the operating frequency within the angular range to be simulated. The size of the lens unit 1 satisfies:

[0042]

[0043] in,

[0044] D is the lens unit diameter, in m;

[0045] c is the constant speed of light, in m / s;

[0046] σ max is the maximum RCS value, in m 2 ;

[0047] f is the operating frequency, in Hz. When the operating frequency f = 9375MHz (operating wavelength λ = 3.2cm), if the electrical center is offset The beam pattern will tilt by 0.4 half-power width. Therefore, the concentricity must be less than 0.4mm, which will not affect the performance of the dielectric lens.

[0048] The radius R of the lens unit 1 can be flexibly set according to the magnitude of the RCS to be simulated. Considering the defocusing effect and electromagnetic loss of the functional layer 3, the radius of the lens unit 1 can be selected by referring to a value 1 to 3 dB greater than the maximum RCS value to be simulated. The preferred range of the radius R of the lens unit 1 is: 30 mm ≤ R ≤ 800 mm.

[0049] The symmetry of the electrical performance of the lens unit 1 is greatly affected by the accuracy of the concentricity of each spherical shell, and the continuous change and uniformity of the dielectric constant of each layer have a great impact on the electrical performance. If the dielectric constant of each layer is not uniform, defocusing will occur, and the focusing radius cannot be constant, causing the beam to tilt and the directional pattern to be distorted. For a uniform medium lens unit 1 with a diameter of 30λ, when the refractive index (i.e., refractive index) of a certain ray to the central ray changes by 0.01, that is, the dielectric constant changes by 0.1, then the phase of the ray on the aperture surface changes by 0.3λ relative to the central ray, and the electromagnetic path difference increases, which is a serious problem. The dielectric constant tolerance of each layer is determined based on the relevant conditions, pre-production and molding processes, and the accuracy of the test equipment that are already available in China. Under normal circumstances, the dielectric constant tolerance of each layer is ±0.02, and the dielectric constant tolerance of the core layer 11 is ±0.01.

[0050] In addition, after the spherical shell layers 12 outside the core layer 11 are made, if the assembly is not ideal or the electromagnetic loss of the adhesive is too large, the designed performance index will not be achieved. Therefore, low-loss ethyl acetate is selected as the adhesive; at the same time, in order to ensure that there is no defocusing and scattering between the layers, the gap between each wide layer is usually less than 0.5mm, and shaking is not allowed.

[0051] like Figure 1 As shown, the skin layer 2 can be made of epoxy resin, alkali-free fiberglass cloth, polyamide resin, and tetraethylenepentamine mixed and cured. The skin layer 2 is coated on the outer surface of the lens unit 1 to protect the internal structure, so that the passive radar echo enhancement device has a certain mechanical strength during use, transportation, and storage. In order to make the skin layer 2 have a certain mechanical strength, minimize the transmission loss of electromagnetic waves, and have good wave transmission performance, the thickness of the skin layer 2 should be between 0.5mm and 1.0mm. In addition, the dielectric constant of the skin layer 2 should be between 1.0 and 1.1.

[0052] Combination Figure 1 , Figure 3The functional layer 3 is a spherical structure, conformal with the lens unit 1 and the skin layer 2, and covers the entire outer surface of the skin layer 2. Different from the conventional fiberglass skin or metal surface, the functional layer 3 is a switch-type frequency selective surface (FSS) based on metamaterial technology. FSS is usually composed of a switch-type diode 31, a substrate 32 and a conductive line 33. The diode 31 is fixed on the substrate 32 in a specific layout. The layout of the diode 31 depends on the frequency and polarization mode of the incident radar wave and the angular domain response requirements of the radar reflector. The layout design can adopt the frequency selective surface design technology, which is a mature technology. The substrate 32 is a flexible dielectric material, and the conductive line 33 is used to provide a conduction voltage for both ends of the diode 31.

[0053] like Figure 4 As shown, when the diode 31 in the frequency selective surface FSS is turned off, the FSS is in a bandpass state, that is, an "ON" state. At this time, the radar reflector is in a transmission state, and the electromagnetic wave penetrates the functional layer 3 into the lens unit 1 or penetrates the lens unit 1 into the free space.

[0054] like Figure 5 As shown, when the diode 31 is turned on, the FSS is in a band-stop state, that is, an "OFF" state, similar to a metal reflective surface. At this time, the radar echo enhancement device is in a reflection state, reflecting the incident electromagnetic wave back to form a radar echo.

[0055] like Figure 6 As shown, the beam direction of the radar echo enhancement device is determined by the reflection area, and the inner normal vector of the reflection area is the beam direction. By setting the on-off state of the FSS in different areas of the functional layer 3, the reflection surface can be placed in different positions, thereby realizing the transformation of the beam direction, and even multiple beams in different directions can be generated at the same time, and the device can be applied to electronic countermeasures or other needs. Among them, when the reflection area of ​​the functional layer 2 is in the shape of a spherical cap, then:

[0056]

[0057] in,

[0058] θ is the angular domain response range;

[0059] h is the height of the reflection area;

[0060] R is the radius of the lens element.

[0061] It can be seen that by adjusting the height of the reflection area, different angular response ranges can be achieved. To achieve wide angular response, θ is greater than or equal to 140°. In addition, when the radar wave enters the echo enhancement device, the area covered by the radar wave is a hemispherical surface. The more areas on the hemispherical surface are in the "reflection" state, the less radar wave energy enters the lens unit 1, the less echo energy is reflected by the device, and the smaller the RCS is. Therefore, by adjusting the reflection and transmission state in the radar wave incident area, the flexible and adjustable RCS of the device can be achieved.

[0062] In addition, the present invention also provides a control unit for applying a suitable control voltage across the diode 31 to control the orderly on and off of the diode 31, so that the frequency selective surface FSS is periodically switched between the "ON" and "OFF" states, so that different areas of the functional layer 3 are in different states at different times according to the control requirements, and finally the radar echo enhancement device can achieve precise adjustment of the RCS and the response angle.

[0063] 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. An adjustable radar echo enhancement device, characterized in that: The invention comprises a lens unit (1), a skin layer (2) and a functional layer (3); the lens unit (1) is a multi-layer spherical structure; the skin layer (2) is coated on the outside of the lens unit (1); the functional layer (3) is coated on the outside of the skin layer (2); a plurality of strip-shaped substrates (32) are distributed along the spherical surface of the functional layer (3); a plurality of diodes (31) are distributed at intervals on the substrate (32); and conductive lines (33) are connected between the diodes (31) to provide a conduction voltage to both ends of the diodes (31).

2. The adjustable radar echo enhancement device according to claim 1, characterized in that: The lens unit (1) is formed by foaming a polystyrene material, and the size of the lens unit (1) satisfies: in, D is the diameter of the lens unit (1), in m; c is the constant speed of light, in m / s; σ max is the maximum RCS value, in m 2 ; f is the operating frequency in Hz.

3. The adjustable radar echo enhancement device according to claim 2, characterized in that: The innermost layer of the lens unit (1) is a core layer (11), which is formed by splicing two hemispheres together. The core layer (11) is coated with a plurality of spherical shell layers (12) to form the lens unit (1).

4. The adjustable radar echo enhancement device according to claim 3, characterized in that: The gap between the core layer (11) and the spherical shell layer (12) is less than 0.5 mm, and the core layer (11) and the spherical shell layer (12) as well as the spherical shell layer (12) and the spherical shell layer (12) are bonded by ethyl acetate.

5. The adjustable radar echo enhancement device according to claim 4, characterized in that: The skin layer (2) is formed by curing a mixture of epoxy resin, alkali-free fiberglass cloth, polyamide resin and tetraethylenepentamine, and the thickness of the skin layer (2) is between 0.5 mm and 1.0 mm.

6. The adjustable radar echo enhancement device according to claim 5, characterized in that: The dielectric constant of the skin layer (2) is between 1.0 and 1.

1.

7. The adjustable radar echo enhancement device according to claim 6, characterized in that: A plurality of diodes (31) are designed for layout using a frequency selective surface design technique.

8. The adjustable radar echo enhancement device according to claim 7, characterized in that: When the diode (31) is turned off, the FSS is in a bandpass state, and the electromagnetic wave penetrates the functional layer (3) and enters the lens unit (1) or penetrates the lens unit (1) and enters the free space.

9. The adjustable radar echo enhancement device according to claim 8, characterized in that: When the diode (31) is turned on, the FSS is in a band-stop state, and the functional layer (3) forms a reflection surface to reflect the incident electromagnetic wave.

10. The adjustable radar echo enhancement device according to claim 9, characterized in that: When the reflection area of ​​the functional layer (3) is spherical, then: in, θ is the angular domain response range; h is the height of the reflection area; R is the radius of the lens element.

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