Active regulation and control stealth ceramic antenna housing and design method thereof

Abstract

The invention belongs to the field of electromagnetic wave control, and particularly relates to an active regulation and control stealth ceramic antenna housing and a design method thereof. The antenna housing is integrated with the ceramic housing, directional metasurface passband range design is carried out on the basis of parameter performance requirements of a target antenna housing and the change condition of a used ceramic material along with temperature, and directional design of a controllable frequency selective surface is supplemented; and then active accurate calibration is carried out on the passband through a variable capacitance diode with a controllable frequency selective surface when the environment temperature changes, so that the influence caused by the change of the dielectric constant along with the temperature is compensated, and the working frequency point of the device is kept stable and is not influenced by the temperature fluctuation. According to the invention, the regulation and control range of a transmission passband can be 5.0 GHz-9 GHz, and the insertion loss is only-0.2 dB; the stealth frequency band covers 5 GHz-16 GHz, and the RCS (Radar Cross Section) of-9 dB is reduced on average; by adjusting the parameters of the frequency selective surface, the influence of the dielectric constant along with the temperature change can be compensated, and the working frequency point is kept stable and is not influenced by the temperature fluctuation.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic wave control, and specifically relates to an actively controlled stealth ceramic radome and a design method thereof. Background Art

[0002] With the development of electromagnetic stealth technology, the research on stealth materials and structures has received extensive attention, especially in the military and communications fields. As an important component of the antenna system, the stealth performance and electromagnetic transmittance of the radome directly affect the signal transmission and target protection effect of the entire system. Existing stealth radomes mostly use passive stealth technology, that is, by coating the surface with absorbing materials or designing a multi-layer structure to reduce the reflection of electromagnetic waves. However, passive stealth materials have poor adaptability in complex environments and cannot be adjusted in real time according to changes in the external electromagnetic environment, resulting in limitations in their stealth performance in different frequency bands and angles.

[0003] Ceramic materials not only have good high temperature resistance and mechanical strength, but also have excellent electromagnetic properties, making them ideal materials for the preparation of radomes. By combining adjustable materials or structures, dynamic regulation of electromagnetic waves can be achieved, so that they can maintain excellent stealth effects and electromagnetic transmittance under different frequency bands, angles and environmental conditions. In addition, active regulation technology can also reduce the amount of materials used and the complexity of the structure, and improve the lightweight and reliability of the system. Therefore, the study of a stealth ceramic radome that can be actively regulated and its preparation technology not only has important theoretical significance, but also has broad application prospects in the fields of military, aerospace and high-end communication equipment.

[0004] However, in actual use, the dielectric constant of the quartz ceramic cover will change with the increase of temperature, especially in high temperature environments up to 1000°C. This change may cause frequency shift problems in the operating frequency band, affecting the normal operation of the system. The relationship between dielectric constant and temperature can be described by a mathematical formula, such as: εr(T) = εr0 × f(T). Among them, εr(T) is the dielectric constant at temperature T, εr0 is the dielectric constant at a reference temperature (such as room temperature), and f(T) is a function that reflects the influence of temperature. The specific form depends on the temperature characteristics of the material. The increase in dielectric constant will change the propagation speed of electromagnetic waves in the material, which will cause the operating frequency to shift. Summary of the invention

[0005] In view of the above problems and shortcomings, in order to solve the problem that the operating frequency band of the existing stealth radome shifts due to temperature changes in the use environment, thereby affecting the normal operation of the system, the present invention provides an actively controlled stealth ceramic radome and a design method thereof. The radome is integrated with a ceramic outer cover and has broadband stealth and passband tunable functions, so that when the ambient temperature changes, the system mismatch caused by temperature changes can be reduced by actively adjusting parameters.

[0006] An actively controlled stealth ceramic radome comprises, from top to bottom in thickness direction, a ceramic layer A, a super surface layer B, air C and a controllable frequency selective surface D.

[0007] The metasurface layer B is constructed by two super units, super unit 0 and super unit 1, in a checkerboard manner. The two super units are alternately arranged in a single longitudinal and transverse direction (that is, two adjacent super units in a single direction are different). The checkerboard structure design allows electromagnetic waves to undergo phase interference and scattering attenuation in different directions, reducing the intensity and directionality of the reflected wave, thereby achieving the purpose of stealth or reducing radar detection.

[0008] The structure of the super unit in the thickness direction is a metal layer B1 and a dielectric layer B0 from top to bottom. The super unit in the horizontal direction is a large square composed of a 3×3 square basic unit matrix.

[0009] The basic unit is a square dielectric layer B0 with a side length of p0, on which a patterned metal layer B1 is arranged; the patterned metal layer B1 is composed of two axially symmetrical bent metal lines B01 and B02. The bent metal lines in the B01 part extend the induced current path within the basic unit range through multiple bending, thereby increasing the equivalent inductance of the basic unit, thereby significantly improving the low-frequency transmission performance of the basic unit, thereby expanding the passband range.

[0010] The connecting direction of the two end points of the bent metal line of the basic unit metal layer B1 is defined as horizontal, which is parallel to the edge of the square dielectric layer B0 and is used as the basic unit 00; the basic unit 00 is rotated 90° counterclockwise around its center to obtain the basic unit 11; and then the basic unit 00 is arranged in a 3×3 matrix to form a super unit 0, and the basic unit 11 is arranged in a 3×3 matrix to form a super unit 1.

[0011] The impedance matching is achieved by adjusting the thickness of the air layer C, thereby optimizing the scattering performance of the metasurface layer B to the incident electromagnetic waves.

[0012] The basic unit of the controllable frequency selective surface D is a square laminated structure with a period of p1, which is composed of a metal layer D0, a dielectric layer D1, a metal layer D2, a dielectric layer D3 and a metal layer D4 laminated in sequence in the thickness direction, for a total of 5 layers.

[0013] The metal layer D0 is identical to the metal layer D4 and is composed of a special-shaped metal outer ring D00 and a central metal patch D05.

[0014] The special-shaped metal outer ring D00 is based on a square ring whose outer ring is the same as the square period p1 (that is, the four outer edges of the square ring coincide with the sides of the square), and a regular octagon is divided into four equal parts by its two mutually perpendicular diagonals to obtain a quadrilateral, and then the right-angled vertices and two right-angled sides of the quadrilateral are adaptively replaced with the outer corners of the square ring and the corresponding two sides, and the four quadrilaterals replace the four outer corner areas of the square ring one by one, thus forming the special-shaped metal outer ring D00.

[0015] The central metal patch D05 is a regular octagonal metal patch, the center of which coincides with the center of the basic unit, and the central metal patch D05 does not intersect with the special-shaped metal outer ring D00, and the diagonal of the basic unit square overlaps with the two diagonals of the regular octagon.

[0016] At the four gaps where the two diagonal lines of the basic unit connect the special-shaped metal outer ring D00 and the central metal patch D05, four varactor diodes are arranged one by one and symmetrically along the diagonal lines. The controllable frequency selective surface D dynamically controls the working passband by adjusting the capacitance value of the varactor diode to achieve selective regulation of the electromagnetic wave frequency.

[0017] The metal layer D2 is a horizontal and vertical cross metal wire grid D20 based on the basic unit square, and the four endpoints of the cross metal wire grid intersect with the four sides of the basic unit square; a metallized through hole S is also provided at the center point of the cross metal wire, and the metallized through hole S passes through the dielectric layers D1 and D3, and is further connected to the center of the metal layers D0, D2 and D4.

[0018] The size area of ​​a basic unit (11 and 00) of a metasurface is equal to that of four basic units of the controllable frequency selective surface D, that is, p0=2p1, and they are adaptively aligned in the thickness direction.

[0019] Furthermore, the bent metal line of B01 is bent 6 times, and the bent metal lines include: transverse metal line E1, longitudinal bent metal line E2, transverse bent metal line E3, longitudinal bent metal line E4, transverse bent metal line E5, longitudinal bent metal line E6 and transverse bent metal line E7; and it is connected to the axisymmetric part B02 through the transverse bent metal line E7.

[0020] Furthermore, the tuning of the D channel of the controllable frequency selective surface is achieved according to the capacitance range of the varactor diode, thereby achieving system adaptation when the ambient temperature changes.

[0021] Furthermore, the varactor diode adopts a GaAs varactor diode of model MA46H120.

[0022] Furthermore, the air C is replaced by electromagnetic foam.

[0023] Furthermore, the design method of the active control stealth ceramic radome comprises the following steps:

[0024] Step 1: According to the parameter performance requirements of the target antenna, the dielectric constant of the ceramic material used, and the frequency shift range of the working frequency band that changes with temperature, simulation modeling and design are used to determine the basic unit parameter size of the metasurface layer B, the basic unit parameter size of the controllable frequency selective surface D, and the thickness of the air C.

[0025] The basic unit parameter size of the metasurface layer B is expanded through the graphically bent metal lines to expand its passband range so that it is compatible with the frequency shift range of the working frequency band of the ceramic layer A that changes with temperature.

[0026] Step 2: Based on the model determined in step 1, and on the premise that the antenna cover parameters have met the current performance requirements, determine the capacitance range of the varactor diode of the controllable frequency selective surface D of the constructed model, so that the capacitance range of the varactor diode is adapted to the frequency shift range of the working frequency band of the ceramic layer A that changes with temperature.

[0027] In summary, the antenna cover of the present invention integrates a ceramic outer cover, and is based on a directional metasurface passband range design based on the parameter performance requirements of the target antenna cover and the temperature changes of the ceramic material used, supplemented by the directional design of the controllable frequency selective surface. Then, the passband is actively and accurately calibrated through the varactor diode of the controllable frequency selective surface when the ambient temperature changes, so as to compensate for the influence of the dielectric constant changing with temperature, and ensure that the operating frequency of the device remains stable and is not affected by temperature fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A perspective view of an actively controlled stealth ceramic radome according to an embodiment of the present invention;

[0029] Figure 2 It is a schematic diagram of the structure of a super unit and a basic unit of the super surface layer B of an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the basic unit transmission performance of the super surface layer B of the embodiment;

[0031] Figure 4 A schematic diagram of the structure of a controllable frequency selective surface D according to an embodiment of the present invention;

[0032] Figure 5 It is a schematic diagram of electromagnetic performance of an embodiment of the present invention; DETAILED DESCRIPTION

[0033] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0034] A design method for actively regulating a stealth ceramic radome comprises the following steps:

[0035] Step 1: According to the parameter performance requirements of the target antenna, the dielectric constant of the ceramic material used, and the frequency shift range of the working frequency band that changes with temperature, design and determine the basic unit parameter size of the metasurface layer B, the basic unit parameter size of the controllable frequency selective surface D, and the thickness of the air C.

[0036] The basic unit parameter size of the metasurface layer B is expanded through the graphically bent metal lines to expand its passband range so that it is compatible with the frequency shift range of the working frequency band of the ceramic layer A that changes with temperature.

[0037] Step 2: Perform simulation modeling based on the parameters determined in step 1. Under the premise that the antenna cover parameters meet the current performance requirements, determine the capacitance range of the varactor diode of the controllable frequency selective surface D of the constructed model, so that the capacitance range of the varactor diode is adapted to the frequency shift range of the working frequency band of the ceramic layer A that changes with temperature.

[0038] The active control stealth ceramic radome structure finally designed in this embodiment is as follows Figure 1 As shown. The thickness direction of the antenna cover from top to bottom is ceramic layer A, super surface layer B, air C and controllable frequency selective surface D. Each layer is bonded by adhesive film and cured by heating to form a composite. Super surface layer B is an array constructed by super unit 0 and super unit 1 in a checkerboard manner, and the two super units are alternately arranged in a single direction of longitudinal and transverse directions. The ceramic cover uses high-purity quartz fiber needle-punched preform as a reinforcement and high-purity silica sol as a matrix. After multiple impregnation composites, drying, and high-temperature calcination, the green body is obtained, and it is prepared by precision CNC machining and post-processing technology. The thickness of the air layer C is 6 mm.

[0039] The schematic diagram of the metasurface unit structure is shown in Figure 2 As shown: It is composed of a dielectric layer B0 with a thickness of 0.25 mm and a metal layer B1. Super unit 0 is composed of 3×3 basic units 00, and super unit 1 is composed of 3×3 basic units 11. The basic unit p0 = 8 mm. Super unit 1 is obtained by rotating super unit 0 90° counterclockwise around its center.

[0040] The patterned metal layer B1 is composed of two parts of axially symmetrical bent metal lines, B01 and B02. For the basic unit 00, the bent metal lines of the B01 part include, from bottom to top: a 2mm long transverse metal strip E1, a 2.9mm long longitudinal bent metal strip E2, a 1mm long transverse bent metal strip E3, a 3.4mm long longitudinal bent metal strip E4, a 2.2mm long transverse bent metal strip E5, a 2.2mm long longitudinal bent metal strip E6, and a 0.5mm long transverse bent metal strip E7.

[0041] Figure 3 This is a schematic diagram of the basic unit transmittance performance of the metasurface layer B of this embodiment. The bent metal line structure in the metasurface extends the path of the induced current, increases the equivalent inductance of the unit, and significantly improves the low-frequency transmittance performance of the unit, thereby expanding the passband range and further enhancing the energy transmission effect of the bottom FSS.

[0042] The structural schematic diagram of the controllable frequency selective surface D in this embodiment is as follows Figure 4 As shown: the metal layer D0 includes a special-shaped metal outer ring D00 and a central metal patch D05 from the outside to the inside, and the metal layer D4 is exactly the same as the metal layer D0.

[0043] The special-shaped metal outer ring D00 is based on a square ring with an outer ring and the same period p1=4mm as the square. A regular octagon (the radius of the corresponding circumscribed circle is 1.25mm) is divided into 4 equal parts by its two mutually perpendicular diagonals to obtain a quadrilateral. Then, the right-angled vertices and two right-angled sides of the quadrilateral are adaptively used to replace the outer corners and the corresponding two sides of the square ring. The four quadrilaterals replace the four outer corner areas of the square ring (quadrilateral metal patches D01, D02, D03 and D04) one by one.

[0044] The regular octagonal metal patch D05 is located at the center of the basic unit (the radius of the corresponding circumscribed circle is 1.3 mm). The variable capacitance diodes V1, V2, V3 and V4 are located in the gaps between the metal patches D01, D02, D03, D04 and the center patch D05, arranged in a diagonal manner, with two diodes set on each diagonal line.

[0045] The metal through hole S runs through the center of the basic unit, with a radius of 0.2mm; the dielectric layer D1 and the dielectric layer D3 are F4B220m, with a thickness of 1.85mm and a dielectric constant of 2.2. The metal layer D2 is a horizontal and vertical cross metal wire grid D20, with a length of 4mm and a width of 0.2mm.

[0046] The entire active control stealth ceramic radome structure of this embodiment is fully simulated. Under plane wave excitation, the boundary condition is set to open add space, and the diode is set to RLC model. According to the capacitance range of Macom's MA46H120 variable capacitance diode, the capacitance range adopted in the simulation is 0.3-0.7pF. Figure 5 As shown, when the varactor changes from 0.3-0.7pF, the tuning range of the passband covers 5-9GHz.

[0047] At the same time, the RCS reduction performance of the radome was analyzed for each capacitance value state. The average RCS reduction from 5GHz to 16GHz in each state was 9dB. In the process of passband tuning, the broadband stealth characteristics were also ensured.

[0048] It can be seen from the above embodiments that the actively controlled stealth ceramic antenna cover of the present invention has the ability to actively control the communication passband, broadband stealth characteristics and high temperature resistance characteristics. The passband is controlled by the capacitance of the varactor diode, and the control range covers 5-9GHz, with a maximum insertion loss of 0.2dB. In the 5GHz to 16GHz frequency band, the RCS reduction average reaches 9dB. The introduction of the ceramic cover enables the structure to have high-temperature ablation resistance, which can meet the needs of more high-temperature application scenarios; its excellent active control, stealth and high-temperature ablation resistance make it suitable for communication and stealth applications in high-temperature environments; and it has broadband stealth and passband tunable functions, which can reduce the system incompatibility caused by temperature changes by actively adjusting parameters when the ambient temperature changes.

Claims

1. An actively controlled stealth ceramic radome, characterized in that: From top to bottom in thickness direction, they are ceramic layer A, super surface layer B, air C and controllable frequency selective surface D; The metasurface layer B is constructed by two super units, super unit 0 and super unit 1, in a checkerboard manner. The two super units are alternately arranged in a single longitudinal and transverse direction. The checkerboard structure design allows the electromagnetic waves to undergo phase interference and scattering attenuation in different directions, thereby reducing the intensity and directionality of the reflected waves, thereby achieving the purpose of stealth or reducing radar detection; The structure of the super unit in the thickness direction is a metal layer B1 and a dielectric layer B0 from top to bottom. The super unit in the horizontal direction is a large square composed of a 3×3 square basic unit matrix arrangement. The basic unit is a square dielectric layer B0 with a side length of p0, on which a patterned metal layer B1 is arranged; the patterned metal layer B0 is composed of two parts, B01 and B02, which are axially symmetrical bent metal lines. The bent metal lines of the B01 part extend the induction current path within the basic unit range through multiple bends, thereby increasing the equivalent inductance of the basic unit; The connecting direction of the two end points of the bent metal line of the basic unit metal layer B1 is defined as the horizontal direction, which is parallel to the side of the square dielectric layer B0 and is used as the basic unit 00; the basic unit 00 is rotated 90° counterclockwise around its center to obtain the basic unit 11; and then the basic unit 00 is arranged in a 3×3 matrix to form a super unit 0, and the basic unit 11 is arranged in a 3×3 matrix to form a super unit 1; The air layer C achieves impedance matching, thereby optimizing the scattering performance of the metasurface layer B to the incident electromagnetic wave; The basic unit of the controllable frequency selective surface D is a square laminated structure with a period of p1, which is composed of a metal layer D0, a dielectric layer D1, a metal layer D2, a dielectric layer D3 and a metal layer D4 stacked in sequence in the thickness direction, for a total of 5 layers; The metal layer D0 is identical to the metal layer D4, and is composed of a special-shaped metal outer ring D00 and a central metal patch D05; The special-shaped metal outer ring D00 is based on a square ring with an outer ring having the same period p1 as the square. A regular octagon is divided into four equal parts by its two mutually perpendicular diagonals to obtain a quadrilateral. Then, the right-angled vertices and two right-angled sides of the quadrilateral are adaptively used to replace the outer corners of the square ring and the corresponding two sides. The four quadrilaterals replace the four outer corner areas of the square ring one by one, thus forming the special-shaped metal outer ring D00. The central metal patch D05 is a regular octagonal metal patch, the center of which coincides with the center of the basic unit, and the central metal patch D05 does not intersect with the special-shaped metal outer ring D00, and the diagonal of the basic unit square overlaps with the two diagonals of the regular octagon; At the four gaps where the two diagonal lines of the basic unit connect the special-shaped metal outer ring D00 and the central metal patch D05, four varactor diodes symmetrically arranged along the diagonal lines are arranged one by one; the controllable frequency selective surface D dynamically controls the working passband by adjusting the capacitance value of the varactor diode to achieve selective regulation of the electromagnetic wave frequency; The metal layer D2 is a cross metal wire grid D20 that is horizontally and vertically aligned based on the basic unit square, and the four endpoints of the cross metal wire grid intersect with the four sides of the basic unit square; a metallized through hole S is also provided at the center point of the cross metal wire, and the metallized through hole S penetrates the dielectric layers D1 and D3, and is further connected to the center of the metal layers D0, D2 and D4; The size area of ​​a basic unit of a metasurface is equal to that of four basic units of the controllable frequency selective surface D, that is, p0=2p1, and they are adaptively aligned in the thickness direction.

2. The actively controlled stealth ceramic radome according to claim 1, characterized in that: The bent metal line of B01 is bent 6 times, and the bent metal lines include: transverse metal line E1, longitudinal bent metal line E2, transverse bent metal line E3, longitudinal bent metal line E4, transverse bent metal line E5, longitudinal bent metal line E6 and transverse bent metal line E7; and it is connected to the axisymmetric part B02 through the transverse bent metal line E7.

3. The actively controlled stealth ceramic radome according to claim 1, characterized in that: The tuning of the D channel of the controllable frequency selective surface is achieved according to the capacitance range regulation of the variable capacitance diode, thereby achieving system adaptation when the ambient temperature changes.

4. The actively controlled stealth ceramic radome as claimed in claim 1, characterized in that: The varactor diode is a GaAs varactor diode, model MA46H120.

5. The actively controlled stealth ceramic radome as claimed in claim 1, characterized in that: The air C is replaced by electromagnetic foam.

6. The actively controlled stealth ceramic radome as claimed in claim 1, characterized in that: The dielectric constant of the ceramic layer A is 2.4 and the thickness is 8 mm; the thickness of all metal layers is 0.035 mm; the thickness of the dielectric layer B1 is 0.25 mm, the thickness of the dielectric layers D1 and D2 is 1.85 mm, the dielectric constant is 2.2, and the dielectric loss is 0.001; p0=8 mm, p1=4 mm.

7. The design method of the actively controlled stealth ceramic radome according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: According to the parameter performance requirements of the target antenna, the dielectric constant of the ceramic material used, and the frequency shift range of the working frequency band that changes with temperature, simulation modeling and design are used to determine the basic unit parameter size of the metasurface layer B, the basic unit parameter size of the controllable frequency selective surface D, and the thickness of the air C; The basic unit parameter size of the metasurface layer B is extended through the graphically bent metal lines to adapt the frequency shift range of the working frequency band of the ceramic layer A with temperature changes; Step 2: Based on the model determined in step 1, and on the premise that the antenna cover parameters have met the current performance requirements, determine the capacitance range of the varactor diode of the controllable frequency selective surface D of the constructed model, so that the capacitance range of the varactor diode is adapted to the frequency shift range of the working frequency band of the ceramic layer A that changes with temperature.

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