An antistatic inductively loaded frequency selective surface for satellite antenna cover

Abstract

The invention discloses an anti-static inductor-loaded frequency selection surface applied to a satellite antenna cover, which is composed of a number of inductor-loaded frequency selection surface units with the same structure arranged periodically, each inductor-loaded frequency selection surface unit includes m layers of metal patches, (m-2) layers of dielectric layers, four inductors and interlayer support materials, the m layers of metal patches, (m-2) layers of dielectric layers and interlayer support materials are arranged at intervals, and two inductors are loaded on the top and bottom metal patches respectively; in the case of direct current, the isolated conduction in the inductor-loaded frequency selection surface unit is electrically connected by the inductor loading method, so that the whole frequency selection surface is an equipotential body to avoid electrostatic discharge; in the case of radio frequency, the high-frequency cutoff characteristics of the inductor element are used to ensure the isolation of the inductor-loaded frequency selection surface unit in the microwave frequency band, and realize frequency selection and out-of-band shielding functions. The present invention is suitable for high-orbit, medium-orbit, and ground-orbit satellite antenna frequency selection surface antenna covers, and can also be used for frequency selection surface applications that require electrostatic shielding.

Description

Technical Field

[0001] The invention relates to satellite frequency selective surface radome technology, and in particular to an anti-static inductance loaded frequency selective surface applied to a satellite antenna frequency selective surface radome. Background Art

[0002] Due to the harsh space environment, satellites flying in orbit for a long time will experience random discharges if there are non-isolated conductors that are not grounded, which may affect the performance of the device itself at the least, or even destroy the operation of the entire spacecraft at the worst.

[0003] Since the frequency selective surface structure has the characteristics of out-of-band suppression, there are independent conductors in the structure of the frequency selective surface unit. For the satellite frequency selective surface antenna cover, the existence of such independent conductors will bring about the problem of electrostatic discharge. In the harsh space environment, independent conductors will accumulate a large amount of charge, thus causing random electrostatic discharge. Electrostatic discharge may cause the antenna cover to be broken down, and may also cause the satellite's electronic devices to break down, causing damage to the satellite. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to address the problem that isolated conductors in traditional frequency selective surface units are prone to electrostatic discharge, and to propose a frequency selective surface that can prevent electrostatic breakdown, which can prevent the satellite from being broken down by electrostatic discharge while achieving the stealth of the antenna cover.

[0005] Technical solution: The present invention is an anti-static discharge inductively loaded frequency selective surface applied to a satellite antenna cover, wherein the frequency selective surface is composed of a periodic arrangement of a number of inductively loaded frequency selective surface units with the same structure, wherein the units include m layers of metal patches, (m-2) layers of dielectric layers, four inductors and interlayer support materials, wherein the m layers of metal patches, (m-2) layers of dielectric layers and interlayer support materials are arranged at intervals, and two inductors are loaded on the top metal patch and the bottom metal patch respectively; in the case of direct current, the isolated conduction in the inductively loaded frequency selective surface unit is electrically connected by the inductively loaded method, so that the whole frequency selective surface is an equipotential body to avoid electrostatic discharge; in the case of radio frequency, the high-frequency cutoff characteristics of the inductive element are utilized to ensure the isolation of the inductively loaded frequency selective surface unit in the microwave frequency band, thereby realizing frequency selection and out-of-band shielding functions.

[0006] Optionally, the inductor-loaded frequency selective surface unit includes, from top to bottom, a top cross-slot folded layer, a first dielectric layer, a curved pointed square ring layer, a first foam layer, a cross-folded layer, a second dielectric layer, a second foam layer, a metal fractal layer, a third dielectric layer and a bottom cross-slot folded layer. The top cross-slot folded layer has the same structure as the bottom cross-slot folded layer, and two inductors are loaded on the upper surfaces of the top cross-slot folded layer and the bottom cross-slot folded layer, respectively.

[0007] Optionally, the top cross-slot folding layer and the bottom cross-slot folding layer are both rotationally symmetrical structures, consisting of a complete rectangular patch, starting from the center point of the metal sheet, with bending slots opened in directions perpendicular to the four rectangular sides, and then inductance is loaded at the third section of the slot perpendicular to the rectangular side between two adjacent slots.

[0008] Optionally, two inductors loaded on the top cross-slot folded layer correspond vertically to two inductors loaded on the bottom cross-slot folded layer.

[0009] Optionally, the curved pointed-top square ring layer is composed of four curved pointed-top square metal patches of the same structure, and the four metal patches are distributed at four corners of the first dielectric layer in a rotationally symmetrical distribution.

[0010] Optionally, the cross-folded layer is a cross-folded metal patch, including an outer square ring metal patch and four inner rotationally symmetrical metal patches, wherein the four inner rotationally symmetrical metal patches start from the center of the outer square ring metal patch and extend perpendicularly to the four sides of the square ring to communicate with the square ring metal patch.

[0011] Optionally, the size of the square ring metal patch on the outer ring is the same as that of the second dielectric layer.

[0012] Optionally, the metal fractal layer is a polygonal metal patch, which is smaller than the third dielectric layer.

[0013] Optionally, the dielectric constants of the dielectric substrates of the first dielectric layer, the second dielectric layer and the third dielectric layer all satisfy: 2.2≤ε≤20, and the thicknesses thereof satisfy: 0.01mm≤h4≤10mm.

[0014] Optionally, the material of the first foam layer and the second foam layer is polyacrylimide foam board.

[0015] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are: ensuring that the antenna cover avoids electrostatic breakdown through electrical connectivity while having good performance; in the case of DC, the isolated conduction in the frequency selective surface unit is electrically connected through the method of inductor loading, so that the entire frequency selective surface is an equipotential body to avoid electrostatic discharge; in the case of RF, the high-frequency cutoff characteristics of the inductor element are utilized to ensure that the unit has good isolation in the microwave frequency band, thereby realizing frequency selection and out-of-band shielding functions; it is suitable for frequency selective surface antenna covers of high-orbit, medium-orbit, and ground-orbit satellite antennas, and can also be used in the design of frequency selective surfaces that require electrostatic shielding. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of a three-dimensional structure of an optional inductively loaded frequency selection surface in a specific embodiment of the present invention;

[0017] Figure 2 A schematic diagram of an optional layered structure of an inductively loaded frequency selective surface unit in a specific embodiment of the present invention;

[0018] Figure 3 A top view of a top cross-groove folded layer of an optional inductively loaded frequency selective surface unit in a specific embodiment of the present invention;

[0019] Figure 4 A top view of a curved pointed square ring layer of an optional inductively loaded frequency selective surface unit in a specific embodiment of the present invention;

[0020] Figure 5 A top view of a cross-folded layer of an optional inductively loaded frequency selective surface unit in a specific embodiment of the present invention;

[0021] Figure 6 A top view of a metal fractal layer of an optional inductively loaded frequency selective surface unit in a specific embodiment of the present invention;

[0022] Figure 7 is a schematic diagram of a frequency selective surface response of an inductively loaded frequency selective surface unit in a specific embodiment of the present invention;

[0023] Figure 8 is a schematic diagram of the passband of an inductively loaded frequency selective surface unit in a specific embodiment of the present invention;

[0024] In the figure: top cross-slot folded layer 1, first dielectric layer 2, curved pointed square ring layer 3, first foam layer 4, cross-folded layer 5, second dielectric layer 6, second foam layer 7, metal fractal layer 8, third dielectric layer 9 and bottom cross-slot folded layer 10, first inductor 11, second inductor 12, third inductor 13, fourth inductor 14. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only 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 making creative work are within the scope of protection of this application.

[0026] The technical solutions provided by various embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0027] The present invention discloses an anti-static inductor-loaded frequency selective surface applied to a satellite antenna cover, which is composed of a periodic array of N×N inductor-loaded frequency selective surface units, where N is a natural number greater than or equal to 1. The inductor-loaded frequency selective surface unit structure includes m layers of metal patches, (m-2) layers of dielectric substrates, four inductors and interlayer support materials. Taking m=5 as an example, the inductor-loaded frequency selective surface unit includes five layers of metal patches, three layers of dielectric substrates, four inductors and two layers of foam support layers. The inductors arranged at the top and bottom layers of the inductor-loaded frequency selective surface unit avoid electrostatic breakdown through electrical connection without affecting the performance of the frequency selective surface. The frequency selective surface works together through the metal patch layer, the dielectric layer and the inductor, so that the frequency selective surface can avoid electrostatic breakdown through electrical connection while maintaining a good passband and good out-of-band suppression; in the case of DC, the isolated conduction in the inductor-loaded frequency selective surface unit is electrically connected through the inductor loading method, so that the entire frequency selective surface is an equipotential body to avoid electrostatic discharge; in the case of RF, the high-frequency cutoff characteristics of the inductor element are used to ensure that the inductor-loaded frequency selective surface unit has good isolation in the microwave frequency band, thereby realizing frequency selection and out-of-band shielding functions.

[0028] like Figure 1 , which is a schematic diagram of a three-dimensional structure of an inductor-loaded frequency selective surface unit of an optional inductor-loaded frequency selective surface in a specific implementation manner of the present invention, wherein the first inductor 11 and the second inductor 12 are arranged on the top layer.

[0029] like Figure 2 As shown, it is a schematic diagram of the layered structure of an inductively loaded frequency selective surface unit of an optional inductively loaded frequency selective surface in a specific embodiment of the present invention. The inductively loaded frequency selective surface unit is, from top to bottom, a top cross-groove folded layer 1, a first dielectric layer 2, a curved pointed square ring layer 3, a first foam layer 4, a cross-folded layer 5, a second dielectric layer 6, a second foam layer 7, a metal fractal layer 8, a third dielectric layer 9 and a bottom cross-groove folded layer 10. The top cross-groove folded layer 1 and the curved pointed square ring layer 3 are respectively attached to the top and bottom surfaces of the first dielectric layer 2, the cross-folded layer 5 is attached to the upper layer of the second dielectric layer 6, the first foam layer 4 is between the curved pointed square ring layer 3 and the cross-folded layer 5, the bottom cross-groove folded layer 10 and the metal fractal layer 8 are respectively attached to the bottom and top surfaces of the third dielectric layer 9, and the second foam layer 7 is between the second dielectric layer 6 and the metal fractal layer 8. The top cross-groove folding layer 1 has the same structure as the bottom cross-groove folding layer 10 , wherein the first inductor 11 and the second inductor 12 are loaded on the upper surface of the top cross-groove folding layer 1 , and the third inductor 13 and the fourth inductor 14 are loaded on the upper surface of the bottom cross-groove folding layer 10 .

[0030] The top cross-groove folding layer 1 and the bottom cross-groove folding layer 10 have the same structure, which is a complete rectangular patch. Starting from the center point of the metal sheet, bending grooves are opened perpendicular to the four rectangular sides, and then the inductance is loaded at the third section of the groove perpendicular to the rectangular side of the two adjacent grooves. The first inductor 11 and the second inductor 12 are loaded on the top cross-groove folding layer 1, and the third inductor 13 and the fourth inductor 14 are loaded on the bottom cross-groove folding layer 10, and the first inductor 11, the second inductor 12 and the third inductor 13, the fourth inductor 14 correspond to each other up and down. According to one embodiment of the present invention, the first dielectric layer 2, the second dielectric layer 6 and the third dielectric layer 9 are the main supporting materials of the entire inductor loading frequency selection surface, which mainly play a supporting role in mechanical properties. Furthermore, the sandwich dielectric substrate is implemented by a high-frequency circuit board, such as Rogers 5880, Taixing Microwave F4B, Arlon, Taconic, etc. In this embodiment, the dielectric constants of the three-layer dielectric substrate all satisfy: 2.2≤ε≤20, and their thicknesses satisfy: 0.01mm≤h4≤10mm. According to one embodiment of the present invention, the first foam layer 4 and the second foam layer 7 are also the main supporting materials of the entire inductive loading frequency selection surface, and mainly play a supporting role in mechanical properties. The material is poly (methyl) acrylimide foam board, which has good mechanical properties, thermal deformation temperature and chemical stability, and is an ideal core layer material for high-performance sandwich structure composite materials. The foam layer is used instead of the traditional air layer to make the antenna cover have better mechanical properties and supporting effects.

[0031] like Figure 3 As shown, a top view of a top cross-groove folded layer 1 of an optional inductor-loaded frequency selective surface unit in a specific embodiment of the present invention, the top cross-groove folded layer 1 is rotationally symmetrical, and is formed by a complete rectangular patch, starting from the center point of the metal sheet, opening bending grooves perpendicular to the rectangular sides, and then loading the first inductor 11 and the second inductor 12 at the third section of the grooves perpendicular to the rectangular sides of two adjacent grooves. The bottom cross-groove folded layer 10 has the same structure as the top cross-groove folded layer 1, and is loaded with a third inductor 13 and a fourth inductor 14.

[0032] like Figure 4 As shown, a top view of a curved pointed square ring layer 3 of an optional inductively loaded frequency selective surface unit in a specific embodiment of the present invention. The curved pointed square ring layer 3 is composed of four square metal patches with the same structure and bent with pointed tops, and the four metal patches are distributed at the four corners of the first dielectric layer 2 in a rotationally symmetrical distribution.

[0033] like Figure 5As shown, a top view of a cross-folded layer 5 of an optional inductively loaded frequency selective surface unit in a specific embodiment of the present invention. The cross-folded layer 5 is a cross-folded metal patch, including an outer square ring metal patch and four internal rotationally symmetrical metal patches. The four internal rotationally symmetrical metal patches start from the center of the outer square ring metal patch and extend perpendicular to the four sides of the square ring to connect with the square ring metal patch. The size of the outer square ring metal patch is the same as that of the second dielectric layer 6.

[0034] like Figure 6 FIG. 8 is a top view of a metal fractal layer 8 of an optional inductively loaded frequency selective surface unit in a specific embodiment of the present invention. The metal fractal layer 8 is a polygonal metal patch, slightly smaller than the third dielectric layer 9. The centers of the five layers of metal patches are on the same central axis.

[0035] To further illustrate the technical effect of the present invention, based on the above-mentioned scheme setting, an embodiment of a 5-layer structure with m=5 is selected, and a simulation analysis is performed on it to verify the performance of the energy selective surface; see Figure 7 and Figure 8 As shown in the figure, the insertion loss within 1dB is defined as the passband, the passband is 1.255-1.58GHz, the relative bandwidth is 20.5%, and the center frequency is 1.4175GHz. The insertion loss above 10dB is defined as suppression, and the suppression band is 1.76-20GHz. It can be seen that after the inductor is loaded, the passband of the frequency selective surface becomes narrower, and the suppression effect does not change significantly.

[0036] Due to the harsh space environment, satellites flying in orbit for a long time will experience random discharges if there are non-isolated conductors that are not grounded, which may affect the performance of the device itself or even destroy the operation of the entire aircraft. The inductively loaded frequency selective surface provided by the embodiment of the present invention realizes the electrical connection of all metal structures of the frequency selective surface by adding inductors between frequency selective surface units, forming FSS equipotential surfaces, eliminating the electrostatic discharge of the FSS without affecting the function of the frequency selective surface, and solving the problem that isolated conductors in traditional frequency selective surface units are prone to electrostatic discharge. It is suitable for high-orbit satellite antenna frequency selective surface antenna covers (solving the problem of electrostatic breakdown of satellite frequency selective surface antenna covers), and can also be used for medium-orbit and ground-orbit satellite antenna frequency selective surface antenna covers, and can also be used for frequency selective surface applications that require electrostatic shielding.

[0037] The above contents are merely examples of specific solutions of the present invention. For devices and structures not described in detail therein, it should be understood that they can be implemented by adopting general devices and general methods available in the art.

[0038] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An antistatic inductively loaded frequency selective surface for use in a satellite antenna cover, characterized in that: The invention is composed of a plurality of inductor-loaded frequency selective surface units with the same structure arranged periodically, wherein each inductor-loaded frequency selective surface unit comprises, from top to bottom, a top cross-groove folded layer (1), a first dielectric layer (2), a curved pointed square ring layer (3), a first foam layer (4), a cross-folded layer (5), a second dielectric layer (6), a second foam layer (7), a metal fractal layer (8), a third dielectric layer (9) and a bottom cross-groove folded layer (10), wherein the top cross-groove folded layer (1) has the same structure as the bottom cross-groove folded layer (10), and two inductors are loaded on the upper surfaces of the top cross-groove folded layer (1) and the bottom cross-groove folded layer (10) respectively; The fork slot folding layer (1) and the bottom cross slot folding layer (10) are both rotationally symmetrical structures, and are formed by opening bending slots from the center point of the metal sheet in directions perpendicular to the four rectangular sides, and then loading inductors at the third section of the slots perpendicular to the rectangular sides between two adjacent slots; in the case of direct current, the isolated conduction in the inductor-loaded frequency selection surface unit is electrically connected by the inductor loading method, so that the entire frequency selection surface is an equipotential body, thereby avoiding electrostatic discharge; in the case of radio frequency, the high-frequency cutoff characteristics of the inductor element are utilized to ensure the isolation of the inductor-loaded frequency selection surface unit in the microwave frequency band, thereby realizing frequency selection and out-of-band shielding functions.

2. The anti-static inductively loaded frequency selective surface for satellite antenna cover according to claim 1, characterized in that: The two inductors loaded on the top cross-slot folded layer (1) correspond vertically to the two inductors loaded on the bottom cross-slot folded layer (10).

3. The anti-static inductively loaded frequency selective surface for satellite antenna cover according to claim 1, characterized in that: The curved pointed-top square ring layer (3) is composed of four curved pointed-top square metal patches of the same structure. The four metal patches are distributed at the four corners of the first dielectric layer (2) in a rotationally symmetrical distribution.

4. The anti-static inductively loaded frequency selective surface for satellite antenna cover according to claim 1, characterized in that: The cross-folded layer (5) is a cross-folded metal patch, comprising an outer square ring metal patch and four inner rotationally symmetrical metal patches. The four inner rotationally symmetrical metal patches start from the center of the outer square ring metal patch and extend perpendicularly to the four sides of the square ring to communicate with the square ring metal patch.

5. The anti-static inductively loaded frequency selective surface for satellite antenna cover according to claim 4, characterized in that: The size of the square ring metal patch on the outer ring is the same as that of the second dielectric layer (6).

6. The anti-static inductively loaded frequency selective surface for satellite antenna cover according to claim 1, characterized in that: The metal fractal layer (8) is a polygonal metal patch, which is smaller than the third dielectric layer (9).

7. The anti-static inductively loaded frequency selective surface for satellite antenna cover according to claim 1, characterized in that: The dielectric constants of the dielectric substrates of the first dielectric layer (2), the second dielectric layer (6) and the third dielectric layer (9) all satisfy: 2.2≤ε≤20, and their thicknesses satisfy: 0.01mm≤h4≤10mm.

8. The anti-static inductively loaded frequency selective surface for satellite antenna cover according to claim 1, characterized in that: The material of the first foam layer (4) and the second foam layer (7) is poly(meth)acrylimide foam board.

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