An intelligent RCS tunable Luneburg lens system based on active metasurfaces

Abstract

The present invention discloses an intelligent RCS adjustable Luneburg lens system based on an active metasurface, which relates to the technical field of antennas. The system includes an active frequency selective surface, a Luneburg lens, an active absorbing metasurface, and an intelligent control system. The intelligent control system can respectively achieve the regulation of the RCS magnitude in a wide angular range and the regulation of the RCS enhancement angular range by controlling the states of all or specific angular regions of the active devices loaded on the active frequency selective surface and the active absorbing metasurface. The present invention has high integration, modular design, can be mass-produced, has good controllability and wide-frequency response, and can be used for the dynamic regulation of the RCS magnitude in the wide angular range of a target and the dynamic regulation of any RCS enhancement angular range.

Description

Technical Field

[0001] The present invention relates to the technical field of antennas, and particularly to an intelligent RCS tunable Luneburg lens system based on an active metasurface. Background Art

[0002] The radar cross section (RCS) is an attribute of weaponry. RCS enhancement can be used for target drones to simulate enemy air raid weapons or for setting up false targets on our side. However, existing RCS enhancement technologies often cannot achieve adjustable designs for RCS enhancement, or have a small controllable range of RCS enhancement and insufficient degrees of freedom for regulation.

[0003] Therefore, designing a system that can intelligently and dynamically regulate RCS is very important for dynamically simulating the real electromagnetic environment and saving simulation costs, and solving the problem that the existing Luneburg lens reflector cannot achieve active regulation of RCS. Summary of the Invention

[0004] The purpose of the present invention is to provide an intelligent RCS tunable Luneburg lens system based on an active metasurface, which can be used for dynamic regulation of the RCS size within a wide angular range of a target and dynamic regulation of any RCS enhancement angular range.

[0005] The present invention provides an intelligent RCS tunable Luneburg lens system based on an active metasurface, comprising:

[0006] An active frequency selective surface: including a plurality of active frequency selective surface units laid at equal intervals. Each active frequency selective surface unit includes a stacked first metal patch layer, a second metal patch layer, and a third metal patch layer. A dielectric substrate is provided between the first metal patch layer and the second metal patch layer, and a dielectric substrate is provided between the second metal patch layer and the third metal patch layer. Switching diodes are loaded between the square patches of the first metal patch layer along the y-axis direction, and switching diodes are loaded between the square patches of the third metal patch layer along the x-axis direction. The switching diodes are used to regulate the reflection or transmission of incident electromagnetic waves, and control the total reflection or total transmission of incident electromagnetic waves.

[0007] A Luneburg lens: receiving the incident electromagnetic waves passing through the active frequency selective surface and converging the incident electromagnetic waves to an active absorbing metasurface.

[0008] Active Absorbing Metasurface: It includes a number of active absorbing units laid at equal intervals. The active absorbing unit includes a top metal patch layer, an intermediate dielectric substrate, and a bottom metal reflector bonded together. The top metal patch layer includes a circular metal patch and a strip-shaped metal patch horizontally arranged inside the circular metal patch. The circular metal patch is loaded with a voltage-controlled varistor diode, and the strip-shaped metal patch is loaded with an inductor. The voltage-controlled varistor diode and the inductor are used to regulate the absorption of incident electromagnetic waves.

[0009] Intelligent control system, electrically connected to the switching diode, voltage-controlled varistor diode, and inductor. The intelligent control system generates a control signal according to a preset RCS and controls the voltage values of the switching diode, voltage-controlled varistor diode, and inductor.

[0010] Further, the first metal patch layer and the third metal patch layer have the same structure.

[0011] Further, a metal mesh grid is arranged on the surface of the second metal patch layer.

[0012] Further, the dielectric substrate is formed by compounding an F4B antenna board and PMI foam.

[0013] Further, the intermediate dielectric substrate is formed by compounding an FR4 antenna board and PMI foam.

[0014] Further, the active frequency selective surface and the active absorbing metasurface are laid to form a spherical surface, a cylindrical surface, a conical surface, or a curved surface.

[0015] Further, the shape of the Luneburg lens is spherical or cylindrical.

[0016] Compared with the prior art, the present invention has the following remarkable advantages:

[0017] An intelligent RCS tunable Luneburg lens system based on active metasurface proposed by the present invention is composed of four modules: an active frequency selective surface, a Luneburg lens, an active absorbing metasurface, and an intelligent control system. By changing the states of the active frequency selective surface and the active absorbing metasurface, the regulation of both the magnitude of RCS enhancement and the angular domain of RCS enhancement can be achieved simultaneously. Moreover, both the active frequency selective surface and the active absorbing metasurface can independently regulate the RCS or cooperate to regulate the RCS, resulting in a large degree of freedom in regulation work and flexible means. Each module of this system can be designed separately, facilitating integrated and batch production. The intelligent RCS tunable Luneburg lens system provided by the present invention can greatly save costs and reduce adjustment time by only changing the target RCS through voltage control, and at the same time can adapt to the RCS regulation in various complex electromagnetic environments. Description of the Drawings

[0018] Figure 1Schematic diagram of the overall structure provided by the embodiments of the present invention;

[0019] Figure 2 Three-dimensional coordinate schematic diagram of the overall structure provided by the embodiments of the present invention;

[0020] Figure 3 Schematic diagram of the overall structure of the active frequency selective surface provided by the embodiments of the present invention;

[0021] Figure 4 Detail diagram of the structure of the active frequency selective surface provided by the embodiments of the present invention;

[0022] Figure 5 Schematic diagram of the overall structure of the active absorbing metasurface provided by the embodiments of the present invention;

[0023] Figure 6 Simulation performance diagram of the active frequency selective surface when TE-polarized electromagnetic waves are incident;

[0024] Figure 7 Simulation performance diagram of the active frequency selective surface when TM-polarized electromagnetic waves are incident;

[0025] Figure 8 Absorbing performance diagram of the active absorbing metasurface under different voltages provided by the embodiments of the present invention;

[0026] Figure 9 RCS regulation performance diagram with wide angular range and wide frequency band achieved by changing the states of all active devices loaded in the structures of the active frequency selective surface and the active absorbing metasurface provided by the embodiments of the present invention;

[0027] Figure 10 RCS enhancement angular range regulation performance diagram achieved by changing the states of active devices within a specific angular range loaded in the structures of the active frequency selective surface and the active absorbing metasurface provided by the embodiments of the present invention.

[0028] Explanation of reference numerals: 1 - active frequency selective surface, 2 - Luneburg lens, 3 - active absorbing metasurface, 4 - intelligent control system, 7 - first metal patch layer, 8 - second metal patch layer, 9 - third metal patch layer, 10 - top metal patch layer. Detailed implementation manners

[0029] The following combines the accompanying drawings in the present invention to clearly and completely describe the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] Embodiment 1

[0031] Reference Figures 1 to 10 , the present invention provides an intelligent RCS tunable Luneburg lens system based on an active metasurface, including:

[0032] Active frequency selective surface 1: As Figure 3 shown, it includes a plurality of active frequency selective surface units arranged at equal intervals. The active frequency selective surface unit includes a stacked first metal patch layer 7, a second metal patch layer 8, and a third metal patch layer 9. A dielectric substrate is provided between the first metal patch layer 7 and the second metal patch layer 8, and a dielectric substrate is provided between the second metal patch layer 8 and the third metal patch layer 9. The first metal patch layer 7 loads switching diodes between the square patches along the y-axis direction, and the third metal patch layer 9 loads switching diodes between the square patches along the x-axis direction. The switching diodes are used to control the reflection or transmission of incident electromagnetic waves, and control the total reflection or total transmission of incident electromagnetic waves; the structures of the first metal patch layer 7 and the third metal patch layer 9 are the same. The side length of the square patch of the first metal patch layer 7 and the third metal patch layer 9 is p1 = 7.2 mm, the side length of the metal patch of the active frequency selective surface unit is l1 = 3.4 mm, and the gap width s between the metal patches of the active frequency selective surface unit is 0.2 mm. The dielectric substrate is formed by compounding a 0.1 mm F4B antenna board and a 0.7 mm PMI foam. The relative dielectric constant of the F4B antenna board is 2.65, the loss tangent is 0.001, the relative dielectric constant of the PMI foam is 1.1, and the loss tangent is 0.0006. Reference Figure 4 , the structure of the second metal patch layer 8 is composed of a metal mesh grid, and the grid w1 of the second metal patch layer 8 is 1 mm.

[0033] Luneburg lens 2: Receives the incident electromagnetic waves passing through the active frequency selective surface 1 and converges the incident electromagnetic waves to the active absorbing metasurface 3, converges the incident electromagnetic waves to a certain point on the active absorbing metasurface 3. The Luneburg lens 2 is a lens with a gradient dielectric constant, used to realize the spherical convergence and directional reflection of electromagnetic waves, and is spherical or cylindrical. The Luneburg lens 2 is located between the active frequency selective surface 1 and the active absorbing metasurface 3;

[0034] Active absorbing metasurface 3: As Figure 5As shown in the figure, it includes several active absorbing units laid at equal intervals. The active absorbing unit includes a top metal patch layer 10, an intermediate dielectric substrate and a bottom metal reflector bonded together. The top metal patch layer 10 includes a ring-shaped metal patch and a strip-shaped metal patch arranged horizontally inside the ring-shaped metal patch. Voltage-controlled varistors are loaded on the four arms of the ring-shaped metal patch, and the voltage-controlled varistors are varistors of model BAP70-03 or model BAP70-02. An inductor is loaded on the strip-shaped metal patch. The voltage-controlled varistor and the inductor are used to regulate the absorption of incident electromagnetic waves. The structural parameters of the top metal patch layer 10 are: the arm length l2 of the ring-shaped metal patch of the active absorbing metasurface is 6.5 mm, the arm length l3 is 6.25 mm, the width w2 of the ring-shaped metal patch of the active absorbing metasurface is 2 mm, the diode welding gap g of the active absorbing metasurface is 1 mm, and the side length p2 of the active absorbing metasurface unit is 20 mm. The intermediate dielectric substrate is formed by compounding a 0.1-mm FR4 antenna board and a 7-mm PMI foam. The relative permittivity of the FR4 antenna board is 4.3, and the loss tangent is 0.025. The relative permittivity of the PMI foam is 1.1, and the loss tangent is 0.0006. Adjustable absorption of electromagnetic waves is achieved by loading one or more of active devices such as diodes, triodes, and graphene in the structural units of the active absorbing metasurface 3.

[0035] The intelligent control system 4 is electrically connected to the switching diode, the voltage-controlled varistor and the inductor. The intelligent control system 4 generates a control signal according to the preset RCS and transmits it to the active frequency selective surface and the active absorbing metasurface, and controls the voltage values of all or part of the active devices in the switching diode, the voltage-controlled varistor and the inductor.

[0036] Among them, the active frequency selective surface 1 and the active absorbing metasurface 3 are laid to form a spherical surface, a cylindrical surface, a conical surface or a curved surface. The shape of the Luneburg lens 2 is spherical or cylindrical. The active frequency selective surface 1 and the active absorbing metasurface 3 provide voltage for the active devices in a parallel feeding or series feeding manner; at the same time, the designed feeding network can provide the same or different voltages for the active devices in different regions of the active frequency selective surface 1 and the active absorbing metasurface 3.

[0037] In the embodiment of the present invention, the intelligent control system 4 can be an integrated circuit chip with signal processing capabilities. The intelligent control system 4 can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0038] The wide-angle RCS regulation method provided by this embodiment for applying an intelligent RCS adjustable Luneburg lens system based on an active metasurface includes the following steps:

[0039] Generate an RCS generation control signal within a preset wide-angle range;

[0040] Send the RCS generation control signal within the wide-angle range to the intelligent control system;

[0041] The intelligent control system calculates the magnitudes of the voltages to be loaded on the active devices in different regions of the active frequency selective surface and the active absorbing metasurface according to the preset RCS of the target, thereby generating control instructions;

[0042] The intelligent control system regulates the voltage values of all the loaded active devices. The active frequency selective surface controls the reflection or transmission of the incident electromagnetic wave according to the different loaded voltages;

[0043] The intelligent control system regulates the voltage values of all the loaded active devices. The active absorbing metasurface changes the absorption rate of the incident electromagnetic wave according to the different loaded voltages;

[0044] The incident electromagnetic wave passes through the active frequency selective surface, the Luneburg lens, and the active absorbing metasurface in sequence. Among them, the Luneburg lens is mainly used to converge the electromagnetic waves incident from all directions to the surface of the active absorbing metasurface, so that the electromagnetic waves can be absorbed or reflected.

[0045] The method for regulating the RCS in a specific angular range of an intelligent RCS-tunable Luneburg lens system based on an active metasurface provided in this embodiment includes the following steps:

[0046] Preset an RCS generation control signal within a specific angular range;

[0047] Send the RCS generation control signal within the specific angular range to the intelligent control system;

[0048] The intelligent control system calculates the magnitudes of the voltages to be loaded on the active devices in different regions of the active frequency selective surface and the active absorbing metasurface according to the preset RCS of the target, thereby generating control instructions;

[0049] The intelligent control system regulates the voltage values of some of the loaded active devices. The active frequency selective surface controls the reflection or transmission of the incident electromagnetic wave according to the different loaded voltages;

[0050] The intelligent control system regulates the voltage values of some of the loaded active devices. The active absorbing metasurface changes the absorption rate of the incident electromagnetic wave according to the different loaded voltages;

[0051] The incident electromagnetic wave passes through the active frequency selective surface, the Luneburg lens, and the active absorbing metasurface in sequence. Among them, the Luneburg lens is mainly used to converge the electromagnetic waves incident from all directions to the surface of the active absorbing metasurface, so that the electromagnetic waves can be absorbed or reflected.

[0052] In this embodiment, it is assumed that the entire system is irradiated by plane electromagnetic waves in free space. First, the performance of the active frequency selective surface and the active absorbing metasurface is simulated using commercial electromagnetic simulation software, and then the RCS in different states of the embodiment of the present invention is simulated.

[0053] Simulation 1: TE and TM polarizations are respectively used to vertically incident on the unit structure of the active frequency selective surface, and the boundary condition is set as the periodic boundary condition. The simulation performance is as Figure 6 and Figure 7 shown. The active frequency selective surface can fully reflect electromagnetic waves when the switching diode is turned on (ON), and can achieve high-efficiency transmission at large angles in the X-band when the switching diode is turned off (OFF).

[0054] Simulation 2: TE polarization is used to vertically incident on the unit structure of the active absorbing metasurface, and the boundary condition is set as the periodic boundary condition. The simulation performance is as Figure 8 shown. The regulation of the absorption rate of incident electromagnetic waves can be realized at different voltages; it can fully reflect incident electromagnetic waves at 0 mV, can achieve efficient absorption of incident electromagnetic waves at 35 mV, and the reflection coefficient is less than -15 dB in the X-band.

[0055] Simulation 3: At 10 GHz, the RCS is respectively simulated when the active frequency selective surface is in the "ON" state and the active frequency selective surface is in the "OFF" state, and the voltage of all varactor diodes loaded on the active absorbing metasurface is changed; it can be seen that by changing the loaded voltage, the present invention realizes the adjustable RCS size of the Luneburg lens in a wide frequency band and wide angle range.

[0056] Simulation 4: At 10 GHz, when the active frequency selective surface is in the "OFF" state, the RCS is respectively simulated when the voltage of the varactor diodes loaded on the active absorbing metasurface in three angular ranges where α belongs to (-90°, 90°) and θ belongs to (0°, 20°), (30°, 50°), and (60°, 80°) is changed; it can be seen that by changing the voltage of the varactor diodes loaded in different angular ranges, the present invention realizes the adjustable angular range of the RCS enhancement of the Luneburg lens.

[0057] The above simulation results show that an intelligent RCS adjustable Luneburg lens system based on an active metasurface in this embodiment realizes the regulation of the RCS enhancement size and the RCS enhancement angular range in a wide angular range. At the same time, the present invention has a large degree of regulation freedom and a simple regulation method, and can be applied to the regulation of the RCS of a target in a complex electromagnetic environment.

[0058] The above-disclosed are only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be thought of by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An intelligent RCS tunable Luneburg lens system based on active metasurfaces, characterized in that, Comprising: Active frequency selective surface (1): Comprising a plurality of active frequency selective surface units laid at equal intervals. Each active frequency selective surface unit includes a stacked first metal patch layer (7), a second metal patch layer (8), and a third metal patch layer (9). A dielectric substrate is provided between the first metal patch layer (7) and the second metal patch layer (8), and a dielectric substrate is provided between the second metal patch layer (8) and the third metal patch layer (9). Switching diodes are loaded between the square patches of the first metal patch layer (7) along the y-axis direction, and switching diodes are loaded between the square patches of the third metal patch layer (9) along the x-axis direction. The switching diodes are used to control the reflection or transmission of incident electromagnetic waves, controlling the total reflection or total transmission of incident electromagnetic waves. The first metal patch layer (7) and the third metal patch layer (9) have the same structure, and the side length of the square patches of the first metal patch layer (7) and the third metal patch layer (9) is the side length of the active frequency selective surface unit. The structure of the second metal patch layer (8) is composed of a metal mesh grid. Luneberg lens (2): Receives the incident electromagnetic waves passing through the active frequency selective surface (1) and converges the incident electromagnetic waves to the active absorbing metasurface (3). Active absorbing metasurface (3): Comprising a plurality of active absorbing units laid at equal intervals. Each active absorbing unit includes a top metal patch layer (10), an intermediate dielectric substrate, and a bottom metal reflector bonded together. The top metal patch layer (10) includes a circular metal patch and strip-shaped metal patches horizontally arranged inside the circular metal patch. A voltage-controlled variable resistor diode is loaded on the circular metal patch, and an inductor is loaded on the strip-shaped metal patches. The voltage-controlled variable resistor diode and the inductor are used to control the absorption of incident electromagnetic waves. Intelligent control system (4), electrically connected to the switching diodes, the voltage-controlled variable resistor diodes, and the inductors. The intelligent control system (4) generates control signals according to a preset RCS and controls the voltage values of the switching diodes, the voltage-controlled variable resistor diodes, and the inductors.

2. The intelligent RCS adjustable Luneburg lens system based on an active metasurface according to claim 1, characterized in that, The dielectric substrate is formed by compounding an F4B antenna board and PMI foam.

3. The intelligent RCS tunable Luneburg lens system based on an active metasurface according to claim 1, wherein, The intermediate dielectric substrate is formed by compounding an FR4 antenna board and PMI foam.

4. The intelligent RCS tunable Luneburg lens system based on an active metasurface according to claim 1, wherein The active frequency selective surface (1) and the active absorbing metasurface (3) are laid to form a spherical surface, a cylindrical surface, a conical surface, or a curved surface.

5. The intelligent RCS adjustable Luneburg lens system based on active metasurface according to claim 1, characterized in that, The shape of the Luneberg lens (2) is spherical or cylindrical.

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