An antenna cover based on broadband wave-absorbing and wave-transmitting integrated metamaterials

Abstract

The application provides a radome based on broadband wave-absorbing and wave-transmitting integrated metamaterial, which comprises a wave-absorbing part and a frequency selection part, the wave-absorbing part comprises a fourth metal layer and a fifth metal layer, the fourth metal layer and the fifth metal layer comprise filter prongs and lumped resistors; the frequency selection part is located on the inner side of the wave-absorbing part, and the frequency selection part comprises a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer and a third metal layer arranged in sequence. The radome based on broadband wave-absorbing and wave-transmitting integrated metamaterial has three independent resonance points in the wave-transmitting frequency band by arranging the wave-absorbing part and the frequency selection part, and forms a radome with the band-pass filter characteristics of the third-order resonance characteristics; meanwhile, the radome can efficiently absorb electromagnetic waves in the low frequency band, effectively reduces the radar scattering cross section of the radome double war (multi-station), and improves the stealth performance; and the structural unit size of the radome metamaterial is small, the unit size is only three tenths of the working wavelength, and the radome has good angle stability.

Description

Technical Field

[0001] This invention relates to an antenna radome based on a broadband integrated absorber-transmitter metamaterial. Background Technology

[0002] Radomes are typically located at the front of an aircraft, protecting the internal radar system from harsh external environments such as rain, fog, frost, sandstorms, intense sunlight, or extreme temperatures, while also ensuring normal radar communication during flight. Therefore, the radome is a crucial component determining aircraft performance. With the continuous improvement of aircraft guidance accuracy and the expansion of communication bandwidth, the operating bandwidth of radar antennas is also constantly increasing, posing new challenges to radome design. On the one hand, radomes are required to achieve broadband wave transmission; on the other hand, due to the rapid development of electronic countermeasures technology, weapons face threats from multiple enemy base stations, networked interception, and multi-layered defenses during flight missions. To improve the penetration and deep strike capabilities of aircraft combat systems, the development and application of stealth technology has become an important direction for scientific research in various countries. Stealth technology refers to the effective control of target characteristics to reduce the target's detectability within a certain remote sensing environment. The key to this technology lies in scattering electromagnetic waves illuminating the target in various directions or converting electromagnetic energy into other forms of energy, reducing the target's radar cross section (RCS), making it impossible for radar to detect strong echo signals. Traditional absorbing materials, lacking a high-frequency transmission window with low transmission loss, degrade the radiation pattern of the radar antenna within the radome, reduce antenna gain, and consequently shorten the radar's detection range. While using frequency-selective surfaces can scatter electromagnetic waves to non-incident directions, effectively reducing single-station RCS, it cannot reduce bistatic (multistatic) RCS. Summary of the Invention

[0003] The purpose of this invention is to provide an antenna radome based on a broadband integrated absorption-transmission metamaterial, which has the advantages of high absorption rate and strong transmission rate.

[0004] To achieve the above objectives, the present invention provides an antenna radome based on a broadband integrated absorbing and transmitting metamaterial, comprising:

[0005] The absorbing section contains multiple lumped resistors. The absorbing section includes a fourth metal layer and a fifth metal layer with the same structure and parallel to each other, and a third dielectric layer disposed between the fourth metal layer and the fifth metal layer. The fourth metal layer and the fifth metal layer each include a number of filter units, and the filter units include a "trident" shaped filter fork.

[0006] A frequency selection part located on the side of the wave-absorbing part close to the antenna installation, the frequency selection part includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer and a third metal layer arranged in sequence.

[0007] Preferably, in the plane where the fourth metal layer or the fifth metal layer is located, there are a first direction and a second direction that are orthogonal to each other, and a plurality of the filtering units are arranged in sequence in the fourth metal layer and the fifth metal layer along the first direction and the second direction.

[0008] Preferably, the filtering unit includes two of the filtering forks, and the openings of the two filtering forks are arranged背离 each other.

[0009] Preferably, a lumped resistor is provided in each of the filtering units, and the lumped resistor is arranged between the two filtering forks in the filtering unit.

[0010] Preferably, the first metal layer and the third metal layer have the same structure, the first metal layer and the third metal layer include a plurality of first wave-transmitting units, the first wave-transmitting units are rectangular, and rectangular first metal sheets are provided at the four corners of the first wave-transmitting units.

[0011] Preferably, the second metal layer includes a plurality of second wave-transmitting units, the second wave-transmitting units are rectangular, and the second wave-transmitting units include an outer annular frame and a "field" - shaped second metal sheet arranged in the middle of the annular frame.

[0012] Preferably, rectangular slits are respectively arranged on the four sides of the annular frame, and the four rectangular slits are centrosymmetric about the center point of the second wave-transmitting unit.

[0013] Preferably, the second metal sheet includes a cross-shaped skeleton in the center and four bent sheets, and there are slits between the skeleton and the bent sheets.

[0014] Preferably, foam or air is filled between the wave-absorbing part and the frequency selection part.

[0015] In summary, compared with the prior art, the radome based on the broadband wave-absorbing and wave-transmitting integrated metamaterial provided by the present invention has the following beneficial effects:

[0016] The radome of this invention, based on a broadband integrated absorbing and transmitting metamaterial, has three independent resonant points in the transmitting frequency band by setting up an absorbing part and a frequency selection part, forming a radome with third-order resonant bandpass filter characteristics. At the same time, it can efficiently absorb electromagnetic waves in the low frequency band, effectively reducing the radar cross section of the radome for dual-station (multi-station) operations and improving stealth performance. Moreover, the structural unit size of the radome metamaterial is small, with the unit size being only three-tenths of the operating wavelength, and it has good angular stability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the radome based on the broadband absorbing-transmitting integrated metamaterial of this application.

[0018] Figure 2 This is a schematic diagram of the filter unit in the fourth or fifth metal layer of the radome based on the broadband absorbing-transmitting integrated metamaterial of this application.

[0019] Figure 3 This is a schematic diagram of the filtering unit in the fourth and fifth metal layers of the radome based on the broadband absorbing-transmitting integrated metamaterial of this application.

[0020] Figure 4 This is a schematic diagram of the structure of the first transparent unit of the first metal layer or the third metal layer of the antenna radome based on the broadband absorbing-transmitting integrated metamaterial of this application.

[0021] Figure 5 This is a schematic diagram of the structure of the second wave-transmitting unit of the second metal layer of the antenna radome based on the broadband wave-absorbing and wave-transmitting integrated metamaterial of this application.

[0022] Figure 6 The simulation results of the S-parameter TE polarization of the filtering unit of the fourth and fifth metal layers of the radome based on the broadband absorbing-transmitting integrated metamaterial in this application are shown.

[0023] Figure 7 The simulation results show the S-parameter TM polarization of the filtering unit of the radome based on the broadband absorbing-transmitting integrated metamaterial in this application.

[0024] Figure 8 The simulation results of the S-parameter TE polarization of the first transparent element of the first metal layer and the third metal layer of the radome based on the broadband absorbing-transmitting integrated metamaterial of this application are shown.

[0025] Figure 9 The simulation results show the S-parameter TM polarization of the first transparent element of the first metal layer and the third metal layer of the radome based on the broadband absorbing-transmitting integrated metamaterial of this application.

[0026] Figure 10 The results show the TE polarization S-parameter test results of the radome based on the broadband absorbing-transmitting integrated metamaterial of this application under different incident angles.

[0027] Figure 11 The results show the TM polarization S-parameter test results of the radome based on the broadband absorbing-transmitting integrated metamaterial of this application under different incident angles.

[0028] Explanation of reference numerals in the attached figures

[0029] radome 100

[0030] Absorbing section 110

[0031] Lumped resistance 111

[0032] Fourth metal layer 112

[0033] Fifth metal layer 113

[0034] Third dielectric layer 114

[0035] Filter fork 115

[0036] Frequency selection unit 120

[0037] First metal layer 121

[0038] First dielectric layer 122

[0039] Second metal layer 123

[0040] Second dielectric layer 124

[0041] Third metal layer 125

[0042] First metal sheet 126

[0043] Second metal sheet 127

[0044] Cross-shaped skeleton 1271

[0045] Bending piece 1272

[0046] 128 circular borders Detailed Implementation

[0047] The following will be combined with the appendix in the embodiments of the present invention. Figure 1 ~Attached Figure 11 The technical solutions, structural features, objectives and effects achieved in the embodiments of the present invention will be described in detail.

[0048] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0049] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0050] like Figure 1 As shown, this invention provides an radome 100 based on a broadband absorbing-transmitting integrated metamaterial, with a transmission frequency band of X-band. The overall dimensions of the radome 100 are 400mm × 400mm × 13.024mm. The radome 100 includes an outer absorbing portion 110 and an inner frequency selective portion 120, the inner side being the side of the radome closest to where the antenna is mounted. Foam or air is filled between the absorbing portion 110 and the frequency selective portion 120 to form a foam layer or air layer. The thickness of the air layer or the foam layer is approximately half (λ0 / 2) of the wavelength corresponding to the center frequency (f0) of the transmission frequency band. In this embodiment, an air layer with a thickness of 8.9mm is filled between the absorbing portion 110 and the frequency selective portion 120.

[0051] The absorbing section 110 includes a fourth metal layer 112 and a fifth metal layer 113 with identical structures and arranged parallel to each other, and a third dielectric layer 114 disposed between the fourth metal layer 112 and the fifth metal layer 113. Both the fourth metal layer 112 and the fifth metal layer 113 include several filtering units. For example... Figure 2As shown, each filter unit includes two symmetrically arranged "trident"-shaped filter forks 115, with the openings of the two filter forks 115 facing away from each other. In this embodiment, the length of the microstrip lines on both sides of the filter fork 115 is L1 = 2.5 mm, and the length of the middle microstrip line is L2 = 2.8 mm. The width W1 of the three "tridents" of the "trident"-shaped filter fork 115 is the same (i.e., the width of the microstrip lines on both sides and the middle microstrip line is the same), which is 0.1 mm. The spacing between two adjacent "tridents" is the same, which is W2 = 0.85 mm (i.e., the spacing between the microstrip lines on both sides and the middle microstrip line is the same). The filter fork 115 also includes a rectangular connecting part, which is connected to the middle microstrip line of the filter fork 115 through a connecting microstrip line. Therefore, the filter fork 115 also has some other structural parameters, specifically the length of the connecting microstrip line L3 = 0.9 mm, the length of the connecting part L4 = 0.8 mm, and the width of the connecting part W3 = 0.4 mm. The absorbing section 110 contains multiple lumped resistors 111. Each filtering unit also contains a lumped resistor 111, which is connected between two filter forks 115 within the filtering unit. The two ends of the lumped resistor 111 are connected to the filter forks 115 via connecting parts. In this embodiment, the resistance value of the lumped resistor 111 is 500 ohms. By providing lumped resistors 111 and filter forks 115 within the fourth metal layer 112 and fifth metal layer 113 of the absorbing section 110, impedance matching with the air layer is achieved within the absorbing section, thereby reducing the radar reflection coefficient and lowering the target's radar cross section (RCS).

[0052] Within the plane of the fourth metal layer 112 or the fifth metal layer 113, there are mutually orthogonal first and second directions. A plurality of filter units are arranged in an array within the fourth metal layer 112 and the fifth metal layer 113, sequentially along the first and second directions. The first direction is... Figure 2 The x-direction shown is the second direction. Figure 2 The y direction shown in .

[0053] like Figure 3 As shown, in this embodiment, the filter units in the fourth metal layer 112 and the fifth metal layer 113 have the same structure. However, compared to the filter units in the fifth metal layer 113, the filter units in the fourth metal layer 112 need to be rotated 90° around a third direction. That is, the filter units in the fourth metal layer 112 and the filter units in the fifth metal layer 113 are arranged perpendicularly. The third direction is a direction that is perpendicular to both the first direction and the second direction. Figure 1 The z-direction in the equation.

[0054] In this embodiment, the material of the third dielectric layer 114 is F4B, with a dielectric constant of 2.65 and a loss tangent of 0.005. The substrate thickness d of the third dielectric layer 114 is 0.5 mm. In this embodiment, the unit structure of the absorbing part 110 of the radome 100 forms an "LC" parallel resonant circuit in the transmission frequency band. The "trident"-shaped filter fork 115 has a large inductance value, which can improve the bandwidth of the transmission frequency band of the radome 100.

[0055] The frequency selection unit 120 is located inside the absorbing unit 110, where "inner" refers to the side of the radome 100 used to mount the antenna. The frequency selection unit 120 includes a first metal layer 121, a first dielectric layer 122, a second metal layer 123, a second dielectric layer 124, and a third metal layer 125 arranged sequentially. In this embodiment, copper foil is used as the material for each metal layer.

[0056] like Figure 1 As shown, in this embodiment, the first dielectric layer 122 and the second dielectric layer 124 of the frequency selection section 120 of the radome 100 both serve a supporting function, and the first dielectric layer 122 and the second dielectric layer 124 have the same thickness, both being 1.524 mm. The first dielectric layer 122 and the second dielectric layer 124 are made of the same material, Arlon AD350, with a dielectric constant of 3.5 and a loss tangent of 0.003.

[0057] like Figure 4 As shown, the first metal layer 121 and the third metal layer 125 have the same structure, and each includes a plurality of first wave-transmitting units. Each first wave-transmitting unit is square, and a square first metal sheet 126 is provided at each of its four corners. In this embodiment, the side length L5 of the first metal sheet 126 is 2.8 mm, and the distance between two first metal sheets 126 within the same first wave-transmitting unit is L6 = 3.4 mm. Within the plane of the first metal layer 121 or the third metal layer 125, there are mutually orthogonal first and second directions. The plurality of first wave-transmitting units are arranged in an array along both the first and third metal layers 121 and 125.

[0058] like Figure 5As shown, the second metal layer 123 includes a plurality of second wave-transmitting units. The second wave-transmitting units are square. Each second wave-transmitting unit includes an outer annular frame 128 and a “field”-shaped second metal sheet 127 disposed in the middle of the annular frame 128. The second metal sheet 127 includes a cross-shaped skeleton 1271 at the center and four bent sheets 1272. There are gaps between the skeleton 1271 and each of the bent sheets 1272. In this embodiment, the length L7 of the long side of the cross-shaped skeleton 1271 is 4.6 mm, the length L8 of the short side is 0.8 mm, and the width W4 is 0.2 mm. The cross-shaped skeleton 1271 includes two long sides. The two mutually perpendicular long sides form a cross. One cross-shaped skeleton 1271 includes four short sides. The four short sides are respectively disposed at the ends of the long sides, and the midpoints of the short sides are located at the endpoints of the long sides, and the widths of the long sides and the short sides are the same, both being 0.2 mm. The midpoints of the two long sides of the cross-shaped skeleton 1271 are both located at the center of the second wave-transmitting unit.

[0059] The four bent sheets 1272 have the same structure. The side length L9 is 1.6 mm, and the width W5 is 0.2 mm. That is, the width of the bent sheet is the same as the width of the cross-shaped skeleton 1271. The width W6 of the annular frame 128 is 1.8 mm. In the plane where the second metal layer 123 is located, there are a first direction and a second direction that are orthogonal to each other. A plurality of second wave-transmitting units are arranged in an array in the second metal layer 123 along the first direction and the second direction in sequence. The short sides of the cross-shaped skeleton 1271 and the bent sheets 1272 are aligned along the width direction of the short sides.

[0060] In addition, rectangular gaps are respectively provided on the four sides of the annular frame 128. The four rectangular gaps are centrosymmetric about the center point of the second wave-transmitting unit. The length L 10 of the rectangular gap is 4.0 mm, the width W7 of the rectangular gap is 0.2 mm, and the distance W8 between the rectangular gap and the boundary of the second wave-transmitting unit is 0.8 mm.

[0061] The four first metal sheets 126 in the same first wave-transmitting unit are symmetric about the x-axis and the y-axis; and the “field”-shaped second metal sheet 127 and the four rectangular gaps on the annular frame 128 are also symmetric about the x-axis and the y-axis, so that the formed radome 100 has polarization-insensitive characteristics. And along the x-axis and the y-axis directions, the numbers of the filtering units, the first wave-transmitting units, and the second wave-transmitting units are the same.

[0062] In this embodiment, the unit sizes of the filtering units, the first wave-transmitting units, and the second wave-transmitting units are the same. As Figure 2 、 Figure 4 and Figure 5 shown, the side length p of each unit is 9 mm. Along the third direction, the centers of the filtering units, the first wave-transmitting units, and the second wave-transmitting units coincide.

[0063] like Figure 1 , Figure 8 and Figure 9 As shown, in this embodiment, multiple equivalent "LC" parallel resonant circuits are generated by coupling between the metal structures of each layer in the frequency selection section 120 of the radome 100, forming a transmission passband with a third-order bandpass filter, thus widening the transmission frequency bandwidth of the radome 100.

[0064] like Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown, in this embodiment, the absorbing part 110 and the frequency selection part 120 of the radome 100 coincide in the transmission frequency band. Within the transmission frequency band, when electromagnetic waves radiated by an external detection radar irradiate the surface of the radome 100 or when electromagnetic waves radiated by an internal radar irradiate the surface of the radome 100, the electromagnetic waves can be transmitted without loss (or with low loss). Outside the transmission frequency band, when electromagnetic waves radiated by an external detection radar irradiate the absorbing part 110 of the radome 100, the input impedance of the radome 100... When matched with air impedance Z0, the reflection coefficient Γ = (Z ω -Z0) / (Z ω When +Z0) approaches 0, electromagnetic waves radiated toward the radome are absorbed, thereby reducing the radar reflection coefficient and the target's radar cross section (RCS).

[0065] like Figure 10 and Figure 11 As shown, the radome 100 of this application has an absorption rate of more than 80% in the frequency range of 3.3-8 GHz and a transmission loss of less than 1 dB in the frequency range of 8.9-11.9 GHz.

[0066] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A radome based on a broadband integrated absorbing and transmitting metamaterial, characterized in that, The radome includes: an absorbing part, in which a plurality of lumped resistors are provided. The absorbing part includes a fourth metal layer and a fifth metal layer which have the same structure and are parallel to each other, and a third dielectric layer disposed between the fourth metal layer and the fifth metal layer. Both the fourth metal layer and the fifth metal layer include a plurality of filtering units, and each filtering unit includes a "trident"-shaped filtering fork; a frequency selection part located on the side of the absorbing part close to the antenna installation, and the frequency selection part includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer and a third metal layer arranged in sequence; in the plane where the fourth metal layer or the fifth metal layer is located, there are a first direction and a second direction perpendicular to each other, and a plurality of the filtering units are arranged in sequence along the first direction and the second direction in the fourth metal layer and the fifth metal layer; each filtering unit includes two of the filtering forks, and the openings of the two filtering forks are arranged with their openings facing away from each other.

2. The radome based on a broadband absorbing-transmitting integrated metamaterial as described in claim 1, characterized in that, Each of the filtering units is provided with the lumped resistor, and the lumped resistor is disposed between the two filtering forks in the filtering unit.

3. The radome based on a broadband absorbing-transmitting integrated metamaterial as described in claim 1, characterized in that, The first metal layer and the third metal layer have the same structure. The first metal layer and the third metal layer include a plurality of first wave-transmitting units, and the first wave-transmitting units are rectangular, and rectangular first metal sheets are provided at the four corners of the first wave-transmitting unit.

4. The radome based on a broadband absorbing-transmitting integrated metamaterial as described in claim 3, characterized in that, The second metal layer includes a plurality of second wave-transmitting units, and the second wave-transmitting units are rectangular. The second wave-transmitting unit includes an outer ring-shaped border and a "field"-shaped second metal sheet disposed in the middle of the ring-shaped border.

5. The radome based on a broadband absorbing-transmitting integrated metamaterial as described in claim 4, characterized in that, Rectangular slits are respectively provided on the four sides of the ring-shaped border, and the four rectangular slits are centrosymmetric about the center point of the second wave-transmitting unit.

6. The radome based on a broadband absorbing-transmitting integrated metamaterial as described in claim 4 or 5, characterized in that, The second metal sheet includes a cross-shaped skeleton at the center and four bent pieces, and there are slits between the skeleton and the bent pieces.

7. The radome based on a broadband absorbing-transmitting integrated metamaterial as described in claim 1, characterized in that, Foam or air is filled between the absorbing part and the frequency selection part.

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