Radar antenna and vibration suppression method thereof based on end cabin moment of mass control

Abstract

The application discloses a radar antenna based on end cabin moment of mass control and a vibration suppression method thereof. The radar antenna based on end cabin moment of mass control comprises an antenna support rod and an end cabin. The end cabin is arranged at the top end of the antenna support rod. The end cabin is in a cuboid or cylindrical structure. The end cabin comprises a moment of mass, a pendulum structure, an electromagnetic field generating structure and a shell. The vibration suppression method adopted by the application realizes the improvement of the structural modal damping ratio, effectively reduces the antenna low-frequency vibration caused by external excitation, and the structure layout method of setting the end cabin at the end point of the extension dimension of the radar antenna. Without increasing the structural stiffness, the vibration caused by external excitation can be greatly reduced. The mass moment control effect is maximized by utilizing the antenna scale. The proportion of the moment of mass to the overall mass of the antenna is less than 5%, which has a small influence on the mass characteristics of the radar satellite and has wide spectrum applicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the overall technical field of microwave radar satellites, and particularly to a radar antenna based on end cabin moment of mass control and a vibration suppression method thereof. BACKGROUND

[0002] Radar detection has the advantages of all-weather and all-day, and when applied to a satellite platform, the wide coverage advantage of the satellite not being limited by geographical and climate conditions can be utilized to effectively detect targets in the space of land, air and sea, and can provide strong support for the application of emergency disaster reduction, national defense construction and other military and civilian fields. Effectively detecting weak, small and slow targets is one of the important technical directions of current satellite-borne radar systems. The detection efficiency of a radar depends on both the power of the radar itself and the microwave scattering characteristics of the target. Due to the constraints of target characteristics, the scale of the radar load must be increased to achieve the detection purpose.

[0003] For a radar satellite, under the same detection sensitivity requirement, the power demand of the satellite system is proportional to the square of the action distance, but the antenna size demand is proportional to the first power of the action distance, so increasing the antenna size is the most effective method to improve the detection sensitivity of the system and improve the working efficiency of the system. Through experimental verification and theoretical analysis, a one-dimensional on-orbit deployable / assembleable antenna has been listed as one of the main technical directions of current radar satellites, and a super large aspect ratio is its main feature. However, the vibration characteristic frequency of the antenna will be significantly reduced as its size increases, and the influence of environmental disturbances such as space thin atmosphere and solar pressure will increase exponentially, inevitably introducing the problem of on-orbit low-frequency vibration of large-scale structures. This will cause a large deformation of the antenna profile, resulting in phase distortion of the radar beam wavefront, affecting the beam pointing accuracy and radar radiation efficiency. Therefore, vibration suppression measures must be taken to specifically improve the low-frequency vibration problem of the radar antenna and effectively improve the on-orbit use efficiency of the radar. SUMMARY

[0004] The purpose of the present application is to provide a radar antenna based on end cabin moment of mass control and a vibration suppression method thereof, which fully utilizes the characteristics of passive control of the end cabin moment of mass to improve the structural modal damping ratio, unlike the conventional vibration reduction measures of improving the structural stiffness, without the need to excessively increase the scheme cost and engineering difficulty, only the mass moment control structure is arranged at the end position, the proportion of the mass of the end cabin moment of mass to the total mass of the antenna is less than 5%, and the influence on the mass characteristics of the satellite is small, so that the vibration caused by external excitation can be greatly reduced.

[0005] To achieve the above-mentioned purpose, the present application provides a radar antenna based on end cabin moment of mass control, which comprises an antenna support rod and an end cabin, the end cabin is arranged at the top end of the antenna support rod, and the end cabin is a cuboid or a cylindrical structure.

[0006] A radar antenna vibration suppression method based on terminal cabin mass moment control includes the following steps:

[0007] Step 1: Set up the end cabin at the top of the antenna support pole.

[0008] Step 2: The electromagnetic field generating structure generates an electromagnetic field in the region where the mass moment is located;

[0009] Step 3: When the antenna vibrates, the mass moment will move along the x and y directions perpendicular to the antenna extension direction. The mass moment cuts the magnetic flux lines to generate induced current and induced magnetic field, which damps the movement of the mass moment.

[0010] Preferably, the end cabin includes a mass moment, a pendulum structure, an electromagnetic field generating structure and an outer shell.

[0011] Preferably, the mass moment is a good conductor material.

[0012] Preferably, the pendulum structure is realized by electrostatic force, magnetic force, or mechanical spring.

[0013] Preferably, the electromagnetic field of the electromagnetic field generating structure includes a current-controlled coil generating a magnetic field and a permanent magnet generating a fixed magnetic field.

[0014] Preferably, the mass moment accounts for less than 5% of the overall mass of the antenna.

[0015] Preferably, the pendulum structure moves along the x-direction and the y-direction perpendicular to the extension direction of the antenna.

[0016] Preferably, the end cabin is configured as a two-dimensional vibration suppression end cabin.

[0017] Therefore, the present invention adopts the above-mentioned structure of a radar antenna based on end cabin mass moment control and its vibration suppression method, and utilizes the characteristics of passive control of the end cabin mass moment to achieve an improvement in the structural modal damping ratio, effectively reducing the low-frequency vibration of the antenna caused by external excitation; adopts a structural layout method of setting the end cabin at the end point of the antenna extension dimension, which can greatly reduce the vibration caused by external excitation without increasing the structural stiffness, and utilizes the antenna scale to improve the mass moment control effect, with wide spectrum applicability.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of an embodiment of a radar antenna based on terminal cabin mass moment control and a vibration suppression method thereof according to the present invention;

[0020] Figure 2 This is a topological diagram of a radar antenna based on terminal cabin mass moment control and a vibration suppression method thereof according to the present invention;

[0021] Figure 3 This is a schematic diagram of the structure of a fixed damping end cabin for achieving vibration damping based on a permanent magnet stator according to the present invention;

[0022] Figure 4 This is a schematic diagram of the structure of the adjustable damping end cabin for achieving vibration suppression based on the electromagnetic coil stator of the present invention;

[0023] Figure 5 This is a cross-sectional view of the two-dimensional vibration suppression end cabin perpendicular to the extension direction of the antenna arm of the present invention;

[0024] Reference numerals

[0025] 1. Antenna support rod; 2. End cabin; 3. Mass block; 4. Pendulum structure; 5. Electromagnetic field generating structure; 6. Outer shell. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the accompanying drawings and examples.

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0029] Example

[0030] The present invention provides a radar antenna based on terminal mass moment control, comprising an antenna support rod 1 and an terminal pod 2. The terminal pod is disposed at the top of the antenna support rod and is a rectangular or cylindrical structure. The terminal pod comprises a mass moment, a pendulum structure 4, an electromagnetic field generating structure 5, and a housing 6. The mass moment is made of a good conductor material, such as iron, copper, or aluminum.

[0031] A radar antenna vibration suppression method based on terminal cabin mass moment control includes the following steps:

[0032] Step 1: Set up the end cabin at the top of the antenna support pole.

[0033] Step 2: The electromagnetic field generating structure generates an electromagnetic field in the region where the mass moment is located;

[0034] Step 3: When the antenna vibrates, the mass moment will move in the x and y directions perpendicular to the antenna extension. The mass moment cuts the magnetic flux lines to generate induced current and induced magnetic field, which damps the movement of the mass moment, thus preventing the antenna from vibrating.

[0035] The pendulum structure is implemented through, but not limited to, electrostatic force, magnetic force, and mechanical springs. It is fixed in the direction of antenna extension (z-axis) and moves in the x- and y-directions perpendicular to the antenna extension. Electromagnetic induction creates a damping effect, which, combined with the pendulum structure, forms a satellite-borne vibration damper.

[0036] The electromagnetic field structure has two implementation forms. One uses a current-controlled coil to generate a magnetic field, and adjusts the damping coefficient by adjusting the current size, which can adapt to the vibration suppression capability requirements of various satellite working modes in orbit; the other uses a permanent magnet to generate a fixed magnetic field, and generates a damping force through the electromagnetic induction effect of the conductor cutting the magnetic field. The structure is simple and there is no additional power consumption.

[0037] The topology diagram of the large radar antenna vibration suppression method based on terminal cabin mass moment control is as follows: Figure 2 As shown. The above system can be abstracted into Figure 2 The damped dual-flexure topology shown in Figure 1 is shown. Here, M is the total mass of the antenna and antenna support arm structure, k1 is the antenna's equivalent stiffness coefficient, m is the end pod mass, k2 is the equivalent stiffness coefficient of the pendulum structure connecting the end pod shell and the mass moment, and β is the damping coefficient generated by the electromagnetic induction effect. According to the principle of signal time-frequency transformation, any external interference process can be viewed as the superposition of a series of interference forces with fixed frequency and amplitude. Therefore, the following analysis can be performed without loss of generality.

[0038] When there is an external interference force with an amplitude of F0 and a frequency of ω, in the absence of damping, the antenna vibration amplitude X0 can be expressed as:

[0039]

[0040] Under the vibration suppression topology of the present invention, the vibration amplitude X0 of the antenna can be expressed as:

[0041]

[0042] The damping capacity of the system is defined as K = -101g (X s / X0), the larger K is, the stronger the damping capacity of the system is.

[0043] To maximize K, the optimal damping design value of the system is:

[0044]

[0045] Where μ = m1 / m2 is the system mass ratio, η = 2m2ω2 is the system critical damping coefficient, is the natural frequency of the end-bay swing structure. Under the optimal damping design value, a system damping capacity of more than 6dB can be achieved, effectively suppressing changes in the surface shape of large radar antennas.

[0046] The vibration suppression end cabin structure of the vibration suppression method of the radar antenna based on the end cabin mass moment control of the present invention has two forms, one is a fixed damping end cabin structure that realizes vibration suppression based on a permanent magnet stator, and the other is an adjustable damping end cabin structure that realizes vibration suppression based on an electromagnetic coil stator.

[0047] The end cabin structure based on permanent magnet stator to achieve vibration suppression is as follows Figure 3 As shown in the figure, two permanent magnets are placed on either side of the fixed dimension of the end cabin mass block 3. The magnetic field between the north and south poles forms a damping magnetic field. When the antenna vibrates, causing the mass block 3 to move along the movable dimension, it cuts the magnetic flux lines, generating a damping effect, thereby effectively suppressing the antenna vibration. The structure is simple and does not consume additional power.

[0048] The adjustable damping end cabin structure based on electromagnetic coil stator to achieve vibration suppression is as follows Figure 4 As shown in the figure, an electromagnetic coil surrounds the terminal mass 3, using a current-controlled coil to generate a magnetic field. When the coil is energized, a magnetic field is generated in the area of ​​mass 3. When antenna vibration causes mass 3 to move along its movable dimension, the magnetic flux within the mass changes, generating an induced magnetic field that damps the movement of mass 3, effectively suppressing antenna vibration. Adjusting the damping coefficient by adjusting the current can meet the vibration suppression requirements of various satellite operating modes in orbit.

[0049] Considering that the antenna can vibrate in two dimensions in the plane perpendicular to the arm, a two-dimensional vibration suppression terminal cabin is designed as follows: Figure 5 As shown in the figure, mass block 3 is connected to the end nacelle shell via two sets of orthogonal pendulum structures, ensuring that it has two degrees of freedom perpendicular to the extension of the antenna arm. When antenna vibration causes mass block 3 to move along its movable dimension, the motion is decomposed along its two degrees of freedom, generating a damping effect in two orthogonal directions, effectively suppressing the two-dimensional vibration of the antenna in a plane perpendicular to the arm.

[0050] Therefore, the present invention adopts a radar antenna based on terminal cabin mass moment control and a vibration suppression method thereof, which has the following beneficial effects: the terminal cabin mass moment is used to improve the structural modal damping ratio, and the suppression effect of the low-frequency vibration of the antenna caused by external excitation can reach more than 6dB; the vibration caused by external excitation can be greatly reduced without increasing the structural stiffness, thereby reducing the cost and engineering difficulty of the radar antenna solution; the proportion of the terminal cabin mass moment mass to the overall mass of the antenna is less than 5%, which has little impact on the satellite mass characteristics and can be applied to the application requirements of multi-spectrum radar satellites.

[0051] 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 the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for suppressing vibration of a radar antenna based on terminal cabin mass moment control, characterized in that: The radar antenna includes an antenna support rod and an end cabin, wherein the end cabin is arranged at the top end of the antenna support rod and is a rectangular parallelepiped or cylindrical structure; The end cabin includes a mass moment, a pendulum structure, an electromagnetic field generating structure and a shell; The mass moment is connected to the outer shell of the end cabin through two sets of the pendulum structures. The two sets of the pendulum structures are orthogonal in design. The mass moment extends perpendicular to the antenna arm and has two-dimensional degrees of freedom. The pendulum structure is realized by electrostatic force, magnetic force and mechanical spring; The pendulum structure moves along the x-direction and the y-direction perpendicular to the extension direction of the antenna; The electromagnetic field of the electromagnetic field generating structure includes a current controllable coil generating a magnetic field and a permanent magnet generating a fixed magnetic field; The vibration suppression method includes the following steps: Step 1: Set up the end cabin at the top of the antenna support pole. Step 2: The electromagnetic field generating structure generates an electromagnetic field in the region where the mass moment is located; Step 3: When the antenna vibrates, the mass moment will move along the x and y directions perpendicular to the antenna extension direction. The mass moment cuts the magnetic flux lines to generate induced current and induced magnetic field, which damps the movement of the mass moment.

2. The vibration suppression method of a radar antenna based on terminal cabin mass moment control according to claim 1, characterized in that: The mass moment is that of a good conductor material.

3. The vibration suppression method of a radar antenna based on terminal cabin mass moment control according to claim 1, characterized in that: The mass moment accounts for less than 5% of the overall mass of the antenna.

4. The vibration suppression method of a radar antenna based on terminal cabin mass moment control according to claim 1, characterized in that: The end cabin is configured as a two-dimensional vibration suppression end cabin.

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