A trihedral corner reflector and airborne active target

Abstract

The present invention provides a trihedral corner reflector and an airborne active target. The reflector includes a connecting frame of insulating material, and three right-angled triangular metal plates arranged on the connecting frame; the connecting frame includes three brackets, each bracket includes a connecting end, the three connecting ends are connected to one point, and the three brackets are perpendicular to each other; a metal plate is fixedly installed between each two mutually perpendicular brackets, and the two right-angled sides of each metal plate are respectively fixed on the two mutually perpendicular brackets; the three metal plates are not connected to each other. The present invention can isolate the three metal plates from each other through the insulating connecting frame to form a trihedral corner reflector, which can be used for passive targets to simulate radar interference targets, and can also load voltage signals on any two metal plates to equivalently form capacitors, which are used for active targets to achieve signal interference.

Description

Technical Field

[0001] The invention relates to the technical field of military equipment, and in particular to a trihedral corner reflector and an airborne active target. Background Art

[0002] A passive radar target is a device with a specific radar cross section (RCS) distribution characteristic. When a passive radar target is irradiated with a radar wave of a specified frequency, its RCS distribution characteristic in a specified spatial area is equivalent to that of the simulated target. It is usually used to simulate aircraft and warships to interfere with enemy radars.

[0003] Radar passive targets are combined with signal sources to form radar active targets, which can achieve electronic deception. Compared with radar passive targets, radar active targets use range-speed active radar for signal interference and are widely used in electronic warfare. Airborne active targets are carried and used by aircraft such as drones and fighter jets.

[0004] Passive targets mainly include spherical targets, Luneberg sphere targets and trihedral corner reflector targets. Spherical targets are large in size and are not suitable for airborne carrying. Luneberg sphere targets have complex processes and high costs. Trihedral corner reflector targets are light in weight, simple in manufacturing process and low in cost. The existing trihedral corner reflector is composed of three interconnected metal plates, which can be equivalent to a wire. If a voltage is applied to any two points on its surface, a short circuit will cause a large current and heating of the metal plate. Therefore, the trihedral corner reflector cannot be directly loaded with circuits and cannot be used to manufacture active targets. Summary of the invention

[0005] The embodiments of the present invention provide a trihedral corner reflector and an airborne active target to solve the problem that the existing trihedral corner reflector cannot be used to manufacture active targets.

[0006] In a first aspect, an embodiment of the present invention provides a trihedral corner reflector for an airborne active target, comprising:

[0007] A connecting frame of insulating material, and three right-angled triangular metal plates arranged on the connecting frame;

[0008] The connecting frame includes three brackets, each bracket includes a connecting end, the three connecting ends are connected at one point, and the three brackets are perpendicular to each other;

[0009] A metal plate is fixedly installed between two mutually perpendicular brackets, and two right-angled sides of each metal plate are respectively fixed on two mutually perpendicular brackets;

[0010] The three metal plates are not connected to each other.

[0011] In a possible implementation, a slot for connecting the metal plate is provided on the connecting frame.

[0012] In a possible implementation, the cross-sectional shape of the bracket is rectangular, circular or L-shaped.

[0013] In a possible implementation manner, the connecting frame is made of a wave-transparent material.

[0014] In a possible implementation manner, the connecting frame is made of PVC plastic material.

[0015] In a possible implementation manner, at least two of the metal plates are provided with fixed interfaces for electrical connection.

[0016] In a possible implementation manner, the metal plate is made of aluminum or stainless steel.

[0017] In a possible implementation, the length of the right-angle side of the metal plate satisfies the following relationship:

[0018]

[0019] Among them, σ is the target RCS maximum value, a is the length of the right-angle side of the metal plate, and λ is the test wavelength.

[0020] In a possible implementation, when the difference between an actual maximum RCS value of the trihedral corner reflector and a theoretical value is less than 1 dBsm, a distance between right-angle sides of two metal plates connected to the same bracket is less than or equal to 2.5 mm.

[0021] In a second aspect, an embodiment of the present invention provides an airborne active target, wherein the airborne active target comprises the trihedral corner reflector for an airborne active target as described in any one of the first aspects.

[0022] In a possible implementation manner, the airborne active target further includes a control circuit; the control circuit includes a positive terminal and a negative terminal respectively connected to the two metal plate circuits.

[0023] The embodiments of the present invention provide a trihedral corner reflector and an airborne active target, wherein the trihedral corner reflector comprises a connecting frame of insulating material, and three right-angled triangular metal plates arranged on the connecting frame. The connecting frame comprises three brackets, each bracket comprises a connecting end, the three connecting ends are connected at one point, and the three brackets are perpendicular to each other. A metal plate is fixedly installed between each two mutually perpendicular brackets, and the two right-angled sides of each metal plate are respectively fixed on the two mutually perpendicular brackets. The three metal plates are not connected to each other. The present application isolates the three metal plates from each other through an insulating connecting frame to form a trihedral corner reflector, which can be used for passive targets to simulate radar interference targets, and voltage signals can be loaded on any two metal plates to equivalently form capacitors, which are used for active targets to achieve signal interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, 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 only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 It is a schematic diagram of the three-dimensional structure of an existing trihedral corner reflector;

[0026] Figure 2 is a schematic diagram of the front three-dimensional structure of a trihedral corner reflector provided by an embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of the back three-dimensional structure of a trihedral corner reflector provided by an embodiment of the present invention;

[0028] Figure 4 is a top view of a trihedral corner reflector provided by an embodiment of the present invention;

[0029] Figure 5 is a physical picture of a trihedral corner reflector provided by an embodiment of the present invention;

[0030] Figure 6 is a diagram of RCS distribution simulation results for different gap widths provided by an embodiment of the present invention;

[0031] Figure 7 is an RCS distribution diagram of a trihedral corner reflector provided by an embodiment of the present invention;

[0032] Figure 8 This is an RCS distribution diagram of a trihedral corner reflector and UAV combination provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0034] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0035] The following is a detailed description of the implementation of the present invention in conjunction with the specific drawings:

[0036] A passive radar target is a device with a specific radar cross section (RCS) distribution characteristic. When a passive radar target is irradiated with a radar wave of a specified frequency, its RCS distribution characteristic in a specified spatial area is equivalent to that of the simulated target. It is usually used to simulate aircraft and warships to interfere with enemy radars.

[0037] Radar passive targets are combined with signal sources to form radar active targets, which can achieve electronic deception. Compared with radar passive targets, radar active targets use range-speed active radar for signal interference and are widely used in electronic warfare. Electronic warfare refers to military operations that use electromagnetic energy and directed energy to control the electromagnetic spectrum or attack the enemy. Airborne active targets are carried and used by aircraft such as drones and fighter jets. Radar active targets with a certain RCS value can not only be used to interfere with enemy radars, but also can be used as calibration bodies to measure the target RCS value.

[0038] Measured by the fixed RCS value distribution characteristics in a wider spatial area, passive targets mainly include spherical targets, Luneberg sphere targets and trihedral corner reflector targets.

[0039] The RCS of a sphere is constant over the entire sphere. Its RCS value is positively correlated with the sphere area. If a larger RCS value is required, such as 10dB 2 , the diameter of the ball must reach more than 3.5m, the volume is large, and the manufacturing process is relatively complicated. Therefore, the volume of the spherical passive target is large and it is not suitable for airborne carrying.

[0040] The Luneberg sphere is also called the Luneberg lens, which is usually composed of more than 5 layers of dielectrics with different dielectric constants. It has a large RCS and a wide secondary radiation direction coverage angle, and the RCS value has a stable spatial angle range of more than 110°. However, the process of the Luneberg sphere target is complex and the cost is high.

[0041] The trihedral corner reflector target is light in weight, simple in manufacturing process and low in cost. Figure 1 This is a schematic diagram of the three-dimensional structure of an existing trihedral corner reflector. Figure 1 The existing trihedral corner reflector is composed of three interconnected metal plates, which can be equivalent to a wire. If voltage is applied to any two points on its surface, a large current will be generated due to short circuit and the metal plate will heat up. Therefore, the trihedral corner reflector cannot be directly loaded with circuits and cannot be used to manufacture active targets.

[0042] Figure 2 It is a schematic diagram of the front three-dimensional structure of a trihedral corner reflector provided in an embodiment of the present invention. Figure 3 It is a schematic diagram of the back three-dimensional structure of a trihedral corner reflector provided in an embodiment of the present invention. Figure 4 This is a top view of a trihedral corner reflector provided by an embodiment of the present invention. Figure 5 : is a physical picture of a trihedral corner reflector provided by an embodiment of the present invention. Figure 2 , 3 , 4 and 5, the trihedral corner reflector comprises: a connecting frame 100 of insulating material, and three right-angled triangular metal plates 200 arranged on the connecting frame 100.

[0043] The connecting frame 100 includes three brackets, each bracket includes a connecting end, the three connecting ends are connected to one point, and the three brackets are perpendicular to each other.

[0044] A metal plate 200 is fixedly installed between two mutually perpendicular brackets, and two right-angled sides of each metal plate 200 are respectively fixed on two mutually perpendicular brackets.

[0045] The three metal plates 200 are not connected to each other.

[0046] That is, the connecting frame 100 includes a first bracket, a second bracket and a third bracket that are perpendicular to each other. The connecting end of the first bracket, the connecting end of the second bracket and the connecting end of the third bracket are connected to each other. The metal plate 200 includes a first metal plate, a second metal plate and a third metal plate. The first right-angled side of the first metal plate is connected in parallel with the first bracket. The right-angled side of the metal plate 200 is connected in parallel with the bracket, that is, the right-angled side is parallel to the bracket and fixedly connected. The second right-angled side of the first metal plate is connected in parallel with the second bracket. The first right-angled side of the second metal plate is connected in parallel with the first bracket. The second right-angled side of the second metal plate is connected in parallel with the third bracket. The first right-angled side of the third metal plate is connected in parallel with the second bracket. The second right-angled side of the third metal plate is connected in parallel with the third bracket. The first, second and third brackets of the straight type are perpendicular to each other, and the connecting end of the first bracket, the connecting end of the second bracket and the connecting end of the third bracket are connected to each other. That is, the three brackets constitute a quadrant of a three-dimensional rectangular coordinate system. Exemplarily, the lengths of the three brackets are equal.

[0047] The three metal plates 200 are not connected to each other, that is, the three metal plates 200 are connected by a connecting frame 100 of insulating material, and the three metal plates 200 are not directly connected. The metal plates 200 are electrically insulated from each other. Exemplarily, the thickness of the metal plates 200 is the same. Exemplarily, the lengths of the right angles of the metal plates 200 are the same. The distance between the right angles of the two metal plates 200 connected to the same bracket is the gap distance between the metal plates 200. Exemplarily, the gap distances between the metal plates 200 are the same.

[0048] A trihedral corner reflector provided by an embodiment of the present invention isolates three metal plates 200 from each other through an insulating connecting frame 100 to form a trihedral corner reflector, which can be used for passive targets to simulate radar interference targets, and can also load voltage signals on any two metal plates 200 to equivalently form a capacitor, which is used for active targets to achieve signal interference. The trihedral corner reflector is light in weight, simple in manufacturing process and low in cost, and is cost-effective for active targets. At the same time, the three metal plates 200 are connected by an insulating connecting frame 100 to provide structural support for the trihedral corner reflector, which can be suitable for airborne flight and reduce the impact of wind.

[0049] In the existing corner reflector, three metal plates 200 are interconnected and are equivalent to a conductor. When the existing corner reflector is used simply as an antenna, for example, when the wavelength is 0.0125 and the distance is above 9m, the antenna gain is almost 0, which is equivalent to the antenna signal being unable to be transmitted. At the same time, it is also impossible to receive signals, and the received signals are all background noise, with a signal-to-noise ratio of almost 1. A trihedral corner reflector provided in an embodiment of the present invention can also be connected to a coaxial cable for loading an antenna. Exemplarily, the radar antenna function is achieved by electrically connecting the outer conductive shielding layer of the coaxial cable to a metal plate 200 and the internal signal line to another metal plate 200.

[0050] In a possible implementation, the connecting frame 100 is provided with a slot for connecting the metal plate 200. That is, a slot is provided at the connection between the connecting frame 100 and the metal plate 200. The right-angled side of the metal plate 200 is arranged in the slot.

[0051] Each bracket is provided with two slots parallel to the length direction of the bracket, wherein the length direction of the bracket is the direction from the connecting end of the bracket to the other end thereof. The opening directions of the two slots on each bracket are perpendicular to each other. The opening direction of each slot is toward the length direction of one of the adjacent brackets. The right-angled sides of each metal plate 200 are arranged in the slot. Exemplarily, the slot is a U-shaped slot. Exemplarily, the width of the slot is the same as the thickness of the metal plate 200.

[0052] In a possible implementation, the cross-sectional shape of the bracket is rectangular, circular or L-shaped. The normal direction of the cross-sectional shape is the length direction of the bracket.

[0053] In a possible implementation, the material of the connecting frame 100 is a wave-transmitting material. A wave-transmitting material refers to a material that can transmit electromagnetic waves and hardly change the properties and energy of the electromagnetic waves. The connecting frame 100 uses a wave-transmitting material, and the radar waves irradiated on the connecting frame 100 are transmitted through the gaps between the metal plates 200 to avoid reflection, thereby avoiding the echo of the connecting frame 100 from interfering with the radar echo signal of the trihedral corner reflector. Exemplarily, the transmittance of the wave-transmitting material to the incident wave is greater than 90%.

[0054] In a possible implementation, the material of the connecting frame 100 is PVC plastic material. PVC plastic is polyvinyl chloride (PVC for short). Exemplarily, the connecting frame 100 is prepared by 3D printing using PVC plastic.

[0055] In a possible implementation, a fixing interface for electrical connection is provided on at least two metal plates 200. Exemplarily, a fixing interface for electrical connection is provided on the back side of the metal plate 200. The back side of the metal plate 200 is the side opposite to the length direction of the bracket perpendicular to the metal plate 200.

[0056] In a possible implementation, the metal plate 200 is made of aluminum or stainless steel.

[0057] In a possible implementation, the length of the right-angle side of the metal plate 200 satisfies the following relationship:

[0058]

[0059] Wherein, σ is the target RCS maximum value, a is the length of the right-angle side of the metal plate 200, and λ is the test wavelength. Exemplarily, the lengths of the right-angle sides of the metal plate 200 are the same, and when the maximum RCS value that the trihedral corner reflector needs to meet and the wavelength of the test radar wave are known, the length of the right-angle side of the metal plate 200 can be calculated by the above formula.

[0060] Exemplarily, when the radar wave frequency is 24 GHz and the maximum RCS value of the trihedral corner reflector is 10 dBsm, the length of the right-angle side of the metal plate 200 is greater than or equal to 150 mm.

[0061] In a possible implementation, when the difference between the actual maximum RCS value of the trihedral corner reflector and the theoretical value is less than 1 dBsm, the distance between the right-angle sides of the two metal plates 200 connected to the same bracket is less than or equal to 2.5 mm.

[0062] The distance between adjacent right-angled sides of the metal plates 200 is the gap width between the metal plates 200. The greater the gap width, the greater the impact on RCS. Exemplarily, the actual maximum RCS value of the corner reflector with different gap widths is obtained by simulation. Exemplarily, the theoretical RCS value is obtained according to the length of the right-angled side of the metal plate 200. In order to examine the influence of the gap width between the two metal plates 200 on the RCS distribution characteristics of the corner reflector, exemplarily, the corner reflectors with different gap widths are simulated and calculated by FEKO simulation software. Figure 6 1 is a diagram showing the simulation results of RCS distribution of different gap widths provided by an embodiment of the present invention. Figure 6 When the gap width is less than 2.5 mm, the RCS maximum value drops by less than 1dBsm, and the RCS stable spatial angle range does not change. Therefore, the gap width should be designed to be less than 2.5 mm.

[0063] An embodiment of the present invention provides an airborne active target, and the airborne active target includes any one of the trihedral corner reflectors for airborne active targets provided by the above-mentioned embodiments of the present invention.

[0064] In a possible implementation, the above-mentioned airborne active target further includes a control circuit. The control circuit includes a positive terminal and a negative terminal respectively connected to the two metal plates 200. That is, illustratively, one metal plate 200 is connected to the positive terminal circuit, and the other metal plate 200 is connected to the negative terminal circuit. The control circuit is used to control the metal plate 200 to transmit an interference signal.

[0065] The embodiment of the present invention provides an RCS testing method for testing the RCS distribution of the above trihedral corner reflector. The testing method includes: under the same test conditions, by comparing the trihedral corner reflector with a calibration body with known RCS, determining the RCS distribution characteristics of the trihedral corner reflector.

[0066] Exemplarily, the length of the right-angle side of the trihedral corner reflector is 150 mm, the width of the gap between the metal plates 200 is less than 2.5 mm, and the test frequency is 24 GHz. Figure 7 is an RCS distribution diagram of a trihedral corner reflector provided by an embodiment of the present invention. Figure 7 : The measured RCS distribution characteristics of the corner reflector in the horizontal angle range of -90° to 90°. After theoretical calculation, it is known that the maximum RCS value of the corner reflector with a diameter of 150 mm is 10dBsm at 24GHz. The average maximum RCS value of 30 measurement results is 10.6148dBsm, with an error of 0.6148dBsm. The stable spatial angle range of the RCS value is -18° to 16°, a total of 34°, which meets the requirement of not less than 30°.

[0067] Figure 8 : is an RCS distribution diagram of a trihedral corner reflector and a drone assembly provided by an embodiment of the present invention. Figure 8 : The measured trihedral corner reflector and UAV combination are placed horizontally, at the frequency of 24GHz, when placed at 0°, RCS peaks appear near -135°, -90°, -45°, 45°, 90° and 135°, among which the RCS value of -135° is -0.3944dBsm, the RCS value of -45° is 1.692dBsm, the RCS value of 45° is 1.859dBsm, the RCS value of 135° is -0.2744dBsm, the RCS value of -90° is 0.8034dBsm, and the RCS value of 90° is 1.188dBsm. A higher peak appears at 0°, with an RCS value of 10.51dBsm. The angle range of 3dB drop is -15.3° to 15.3°. Peaks appear at -39° and 39°, with RCS values ​​of 6.727dBsm and 6.594dBsm respectively.

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. 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 trihedral corner reflector for airborne active targets, characterized in that: include: A connecting frame of insulating material, and three right-angled triangular metal plates arranged on the connecting frame; The connecting frame includes three brackets, each bracket includes a connecting end, the three connecting ends are connected at one point, and the three brackets are perpendicular to each other; A metal plate is fixedly installed between two mutually perpendicular brackets, and two right-angled sides of each metal plate are respectively fixed on two mutually perpendicular brackets; The three metal plates are not connected to each other; The length of the right-angle side of the metal plate satisfies the following relationship Among them, σ is the maximum value of the target RCS, a is the length of the right-angle side of the metal plate, and λ is the test wavelength; When the difference between the actual maximum value of RCS of the trihedral corner reflector and the theoretical value is less than 1 dBsm, the distance between the right-angle sides of two metal plates connected to the same bracket is less than or equal to 2.5 mm.

2. The trihedral corner reflector for airborne active targets according to claim 1, characterized in that: The connecting frame is provided with a slot for connecting the metal plate.

3. The trihedral corner reflector for airborne active targets according to claim 1, characterized in that: The cross-sectional shape of the bracket is rectangular, circular or L-shaped.

4. The trihedral corner reflector for airborne active targets according to claim 1, characterized in that: The material of the connecting frame is wave-transparent material.

5. The trihedral corner reflector for airborne active targets according to claim 4, characterized in that: The material of the connecting frame is PVC plastic material.

6. The trihedral corner reflector for airborne active targets according to claim 1, characterized in that: The material of the metal plate is aluminum or stainless steel.

7. An airborne active target, characterized in that: The airborne active target comprises the trihedral corner reflector for an airborne active target according to any one of claims 1 to 6.

8. An airborne active target according to claim 7, characterized in that: The airborne active target further comprises a control circuit; the control circuit comprises a positive terminal and a negative terminal respectively connected to the two metal plate circuits.

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