Metamaterial antenna and metamaterial array antenna

Abstract

The invention relates to the field of radomes, in particular to a metamaterial antenna and a metamaterial array antenna. The metamaterial antenna comprises an antenna body and an antenna housing which are spaced from each other, the antenna body is wrapped in the antenna housing, the antenna housing is a frequency-selective antenna housing capable of shielding electromagnetic waves of a first wave band, and the antenna body comprises a wave absorbing plate, a supporting plate, a horizontal polarization unit and a vertical polarization unit. The wave-absorbing plate is a power-resistant wave-absorbing plate capable of absorbing electromagnetic waves of a second wave band, the wave-absorbing plate is connected with the supporting plate, the supporting plate is used for supporting the horizontal polarization unit and the vertical polarization unit, and the horizontal polarization unit and the vertical polarization unit are conformal with the wave-absorbing plate respectively; the isolation between the antennas can be improved through the innovative structural design of the metamaterial antenna, so that the active standing-wave ratio of the antenna is improved.

Description

Technical Field

[0001] This invention relates to the field of radomes, and more specifically, to a metamaterial antenna and a metamaterial array antenna. Background Technology

[0002] With the application and development of modern stealth technology, various stealth composite structures are increasingly being used in stealth aircraft. According to publicly available information, the US B-2 stealth bomber has excellent stealth characteristics against most centimeter-wave or decimeter-wave search and tracking radars. The stealth structure used at the wing edges, where forward reflection is strong, achieves an absorption effect of over 99.5% for frequencies below the S-band.

[0003] Currently, most stealth aircraft employ traditional metal antennas combined with absorbing cellular technology to achieve their stealth capabilities. However, traditional metal antennas have low antenna isolation when forming antenna arrays, resulting in an active standing wave ratio (VSWR) of typically greater than 10, leading to weak stealth performance. Furthermore, the existing combination of traditional metal antennas and absorbing cellular technology has consistently failed to improve the VSWR of the array antennas, making it impossible to achieve a balance between antenna electrical performance and low scattering performance.

[0004] Therefore, how to design a completely new antenna to improve the isolation between antennas and thus improve the active VSWR of the antenna has always been a problem that the industry urgently needs to solve. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a metamaterial antenna and a metamaterial array antenna. Through the innovative structural design of the metamaterial antenna, the isolation between antennas can be improved, thereby increasing the active VSWR of the antenna.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a metamaterial antenna, comprising an antenna body and an radome spaced apart from each other. The antenna body is enclosed inside the radome, which is a frequency-selective radome capable of shielding first-band electromagnetic waves. The antenna body includes an absorbing plate, a support plate, a horizontal polarization unit, and a vertical polarization unit. The absorbing plate is a power-tolerant absorbing plate capable of absorbing second-band electromagnetic waves. The absorbing plate is connected to the support plate, which supports the horizontal polarization unit and the vertical polarization unit. Each of the horizontal polarization unit and the vertical polarization unit is conformally fitted to the absorbing plate, forming a third-band horizontally polarized conformal antenna and a third-band vertically polarized conformal antenna, respectively.

[0008] Furthermore, the radome is bullet-shaped, and its cross-section is parabolic.

[0009] Furthermore, the antenna body is D-shaped, and the antenna body and the radome bulge in the same direction.

[0010] Furthermore, the absorbing plate includes a first absorbing plate and a second absorbing plate, and the antenna body further includes a reflector plate, and the reflector plate is attached to the first absorbing plate.

[0011] Furthermore, the second absorbing plate is attached to the reflector plate, the vertical polarization unit is attached to the second absorbing plate, the horizontal polarization unit is attached in the thickness direction of the second absorbing plate and is conformal with the edge of the second absorbing plate, and the vertical polarization unit is perpendicular to the horizontal polarization unit.

[0012] Furthermore, the antenna body further includes a feeding plate, and the feeding plate is arranged on the other side of the first absorbing plate and is perpendicularly connected to the first absorbing plate.

[0013] Furthermore, the feeding plate includes a first feeding portion and a second feeding portion which are connected to each other.

[0014] Furthermore, the first feeding portion is in a hollowed-out loop shape, and the second feeding portion is in a Π shape.

[0015] The present invention also provides a metamaterial array antenna, and the metamaterial array antenna is formed by arranging the metamaterial antennas according to any one of the above in an array manner.

[0016] Furthermore, the distance between the vertical polarization units in any two adjacent metamaterial array antennas is 0.25λmax, where λmax is the maximum value of the wavelength of the incident electromagnetic wave.

[0017] In the metamaterial antenna and the metamaterial array antenna of the present invention, through an innovative structural design, the metamaterial antenna is designed to include an antenna body and a radome spaced apart from each other, the antenna body is wrapped inside the radome, the radome is a frequency-selective radome capable of shielding electromagnetic waves in the first band, the antenna body includes an absorbing plate, a support plate, a horizontal polarization unit and a vertical polarization unit, the absorbing plate is a high-power absorbing plate capable of absorbing electromagnetic waves in the second band, and at the same time, the horizontal polarization unit and the vertical polarization unit are each conformal with the absorbing plate, respectively forming a third-band horizontally polarized conformal antenna and a third-band vertically polarized conformal antenna. Through this innovative structural design, the isolation between antennas can be improved, thereby improving the active voltage standing wave ratio of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0019] Figure 1 This is a schematic cross-sectional view of the metamaterial antenna of the present invention;

[0020] Figure 2 This is a schematic diagram of the active standing wave ratio (VSWR) test results of the metamaterial antenna of this invention;

[0021] Figure 3 This is a schematic diagram showing the antenna isolation test results comparing the metamaterial antenna of this invention with that of a metal antenna in the prior art;

[0022] Figure 4 This is a schematic diagram of the layout result of the metamaterial array antenna of the present invention;

[0023] Figure 5 This is a schematic diagram comparing the scattering test curves of the metamaterial array antenna of this invention and the equivalent metal-shaped antenna in the prior art.

[0024] The attached figures are labeled as follows: 1. Radome; 2. First absorbing plate; 3. Second absorbing plate; 4. Support plate; 5. Horizontal polarization unit; 6. Vertical polarization unit; 7. Reflector; 8. First feed section; 9. Second feed section. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] like Figure 1 As shown, an embodiment of the metamaterial antenna of the present invention includes an antenna body and an radome 1 spaced apart from each other. The antenna body is enclosed inside the radome 1. The radome 1 is a frequency-selective radome capable of shielding electromagnetic waves in a first band, specifically the X-Ku band. The radome 1 can be used to shield electromagnetic waves in the X-Ku band and serves as the frequency-selective radome of the metamaterial antenna of the present invention, and can be referred to as a metamaterial frequency-selective radome. In a preferred embodiment, the radome 1 has an outwardly convex shape, and the convex ends gradually decrease in size or even converge to a point. For example, the radome 1 may be bullet-shaped or conical, or its shape may conform to other shapes where the convex ends gradually decrease in size or even converge to a point. This is not limited here. Furthermore, the cross-sectional view of the radome 1 may be parabolic or triangular, or its shape may conform to other shapes where the convex ends gradually decrease in size or even converge to a point. This is not limited here.

[0027] The antenna body is D-shaped, and the antenna body and the antenna cover 1 protrude in the same direction. Specifically, the antenna body includes an absorbing plate, a support plate 4, a horizontal polarization unit 5, and a vertical polarization unit 6. The absorbing plate is a power-resistant absorbing plate that can absorb electromagnetic waves in the second band, which is the S-C band. The absorbing plate consists of two parts, namely, a first absorbing plate 2 and a second absorbing plate 3. The absorbing plate is connected to the support plate 4. The absorbing plate can absorb electromagnetic waves in the S-C band and has power-resistant characteristics.

[0028] The support plate 4 supports the horizontal polarization unit 5 and the vertical polarization unit 6. The antenna body also includes a reflector 7, which is a shaped reflector attached to the first absorbing plate 2. The second absorbing plate 3 is attached to the reflector 7, specifically with its reverse side attached to the reflector 7. The vertical polarization unit 6 is attached to the second absorbing plate 3. Both the horizontal polarization unit 5 and the vertical polarization unit 6 are conformally fitted to the absorbing plates, forming a third-band horizontal polarization conformal antenna and a third-band vertical polarization conformal antenna, respectively. The third band is the L-band. Specifically, the support plate 4 also operates in the L-band and is an L-band antenna support plate. The horizontal polarization unit 5 is attached to the thickness direction of the second absorbing plate 3 and conforms to the edge of the second absorbing plate 3. This conformal design allows it to have a low RCS (Radar Cross Section). Due to the characteristics of Section), the horizontal polarization unit 5 and the second absorbing plate 3 can form an L-band horizontally polarized low RCS metamaterial conformal antenna; the vertical polarization unit 6 is perpendicular to the horizontal polarization unit 5, and the vertical polarization unit 6 is attached to the front of the second absorbing plate 3 and conforms to the front length direction of the second absorbing plate 3. This conformal design can give it electromagnetic transparency characteristics of a preset band. Therefore, the vertical polarization unit 6 and the second absorbing plate 3 can form an L-band vertically polarized metamaterial electromagnetic transparent conformal antenna.

[0029] In addition, the antenna body also includes a feed plate, which is disposed on the other side of the first absorbing plate 2 and perpendicularly connected to the first absorbing plate 2. The reflector 7 is attached to one side of the first absorbing plate 2, and the other side of the first absorbing plate 2 is connected to the feed plate. The feed plate includes a first feed section 8 and a second feed section 9 connected to each other. The first feed section 8 is hollowed out in a U-shape, meaning it is hollow inside and has a U-shaped outline. The second feed section 9 is Π-shaped and includes a horizontal side and two vertical sides. The two vertical sides are perpendicularly connected to the horizontal side. The horizontal side is attached to the other side of the first absorbing plate 2 and extends along the edge of the first absorbing plate 2, with its extension direction parallel to one side of the U-shaped first feed section 8. The extension length is not greater than the length of one side of the parallel U-shaped first feed section 8. The process includes at least one protrusion approaching the first feed section 8 in a U-shape. This protrusion is close to but not connected to the first feed section 8. Moreover, the other side of the U-shaped first feed section 8 is connected to and collinear with one vertical side of the Π-shaped second feed section 9. The end of the other vertical side of the Π-shaped second feed section 9 has an extension segment that extends away from the U-shaped first feed section 8 and the extension direction is parallel to the horizontal side of the second feed section 9. Through this special structure of the feed plate design, the signal can be effectively fed in and the stability of the fed signal can be maintained. Through the interaction between the feed plate and other structures of the antenna body (such as the absorbing plate, support plate 4, horizontal polarization unit 5, vertical polarization unit 6 and reflector 7), electromagnetic wave signals within a preset frequency band can be effectively radiated.

[0030] like Figure 2 As shown, Figure 1 The diagram shows the active VSWR test results of the metamaterial antenna. The test results of the active VSWR indicate that the present invention… Figure 1 The metamaterial antenna shown can improve the active VSWR of the antenna, with test results between 1 and 2, lower than the target value of 2. Furthermore, compared to traditional metal antennas, whose active VSWR is typically greater than 10 when forming an antenna array, this invention... Figure 1 The metamaterial antenna shown significantly improves the active VSWR of the antenna.

[0031] like Figure 3 As shown, Figure 1 The diagram shows a comparison of antenna isolation test results between the metamaterial antenna and the existing metal antenna. Figure 3 The solid line in the figure represents the antenna isolation curve obtained by testing metal antennas during array formation in existing technology. Figure 3 The dashed lines in the text represent the present invention. Figure 1 The antenna isolation curve shown is obtained by testing the metamaterial antenna during array formation. Figure 3 A comparison of the solid and dashed lines reveals that the present invention... Figure 1The metamaterial antenna shown can improve the isolation between antennas. The S21 isolation test index is significantly lower than that of metal antennas in the prior art. Therefore, this invention... Figure 1 The metamaterial antenna shown greatly improves the isolation between antennas.

[0032] pass Figure 1 The innovative structural design of the metamaterial antenna shown comprises an antenna body and a radome spaced apart from each other. The antenna body is enclosed inside the radome, which is a frequency-selective radome capable of shielding first-band electromagnetic waves. The antenna body includes an absorbing plate, a support plate, horizontal polarization elements, and vertical polarization elements. The absorbing plate is a power-resistant absorbing plate capable of absorbing second-band electromagnetic waves. Simultaneously, the horizontal polarization elements and vertical polarization elements are each conformally fitted to the absorbing plate, forming a third-band horizontally polarized conformal antenna and a third-band vertically polarized conformal antenna, respectively. This innovative structural design can improve the isolation between antennas, thereby increasing the active VSWR of the antenna.

[0033] The traditional metal antenna + absorbing cell combination method commonly used in existing technologies has been unable to improve the active standing wave ratio of its array antenna, and cannot achieve a balance between antenna electrical performance and low scattering performance. Moreover, in order to achieve phased array and differential beam scanning, the traditional metal antennas in existing technologies are usually formed into an array and the spacing between antenna elements in the array is fixed. However, after the spacing between antenna elements in the array is fixed, the traditional metal antenna + absorbing cell combination method cannot simultaneously solve the scattering grating lobe problem of S and C bands and the high-power radiation problem.

[0034] In existing technologies, to solve the scattering grating lobe problem, the common approach is to arrange existing metal antennas in an array and reduce the spacing between antenna elements in the array to 0.5Dmm (D=0.25λmax). However, this approach of reducing the spacing between antenna elements in the array has disadvantages such as complex antenna feeding structure, difficult manufacturing process, and high cost. Therefore, solving the scattering grating lobe problem by reducing the spacing between antenna elements in the array will increase the difficulty of antenna matching design and increase the coupling between antennas, which is not conducive to wide-angle scanning of the 9th harmonic broadband phased array antenna. Increasing the number of antenna elements in the array and increasing the number of transceiver components will also increase the difficulty of antenna manufacturing process and increase cost.

[0035] To address these issues, the present invention also provides a metamaterial array antenna, which is composed of the aforementioned metamaterial antennas arranged in an array, wherein the spacing between any two adjacent vertical polarization units in the metamaterial array antenna is 0.25λmax, where λmax is the maximum value of the incident electromagnetic wave wavelength.

[0036] like Figure 4 The diagram shown is a schematic representation of the layout of the metamaterial array antenna provided by this invention. Figure 4This invention Figure 1 The metamaterial antenna shown is arranged in an array. According to the scattering mechanism of array antennas, for an array using the same array elements (i.e., array elements) and uniformly arranged, its scattering pattern can be calculated using the array pattern product theorem. Its scattering pattern is the product of the scattering pattern of the antenna elements and the scattering array factor.

[0037]

[0038] in, It is the direction function of the array. It is the direction function of the antenna array element. It is the scattering array factor, n x and n y dx and dy are the number of array elements in the x-axis and y-axis directions, respectively, and the spacing between the array elements in the x-axis and y-axis directions are, respectively. il / I 11 It is the current ratio between the (i,l)th array element and the first reference array element.

[0039] The scattering factor is related to the spatial distribution of the array antenna, the number of array elements, and the current distribution of the array elements. When the scattering factor of an L-band phased array antenna cannot be changed, existing technologies can only reduce the RCS of the array antenna by reducing the number of antenna elements. However, the metamaterial array antenna provided by this invention does not reduce the spacing between antenna elements in the array to 0.5Dmm (D=0.25λmax). The spacing between antenna elements in the metamaterial array antenna provided by this invention is 0.25λmax. In this way, the metamaterial array antenna provided by this invention will not increase the complexity of the antenna feeding structure, increase the manufacturing process difficulty, or increase the cost. RCS reduction can be achieved without reducing the spacing between antenna elements in the array. Specifically, this invention uses the vertical polarization unit 6 and the second absorbing plate 3 to form an L-band vertically polarized metamaterial electromagnetic transparent conformal antenna. This metamaterial electromagnetic transparent conformal antenna reduces scattering from the antenna elements in the array antenna. Based on the scattering mechanism of array antennas, compared to antennas with the same metallic shape, this invention reduces scattering grating lobes by nearly 10 dB using the metamaterial electromagnetic transparent conformal antenna to suppress the metamaterial array antenna. This can be seen from… Figure 5 This can be intuitively derived from the text.

[0040] like Figure 5 The diagram shown is a comparison of scattering test curves between the metamaterial array antenna provided by this invention and an existing metallic antenna of the same shape. Figure 5 The dark curve in the image represents the metamaterial array antenna provided by this invention. Figure 5 The scattering test curve of the antenna (indicated by the electromagnetic metamaterial array antenna) Figure 5The light-colored curves in the image represent antennas with the same metallic shape in existing technologies. Figure 5 The scattering test curve of the metal array antenna (marked in the middle) shows that, compared with the same metal shape antenna, the present invention can reduce the grating lobes of the array antenna by nearly 10dB by using a low scattering grating lobe suppression metamaterial array antenna. At the same time, the metamaterial antenna of the present invention can improve the antenna gain and power tolerance, and can also improve the antenna isolation, thereby improving the active VSWR of the phased array antenna. The combination of metamaterial electromagnetic transparent conformal antenna and shape structure design achieves a balance between antenna electrical performance and low scattering performance.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A metamaterial antenna, characterized by, The metamaterial antenna comprises mutually spaced antenna body and antenna cover, the antenna body is wrapped inside the antenna cover, the antenna cover is frequency selective antenna cover capable of shielding first wave band electromagnetic wave, the antenna body comprises wave absorbing plate, support plate, horizontal polarization unit and vertical polarization unit, the wave absorbing plate is power resistant wave absorbing plate capable of absorbing second wave band electromagnetic wave, the wave absorbing plate is connected with the support plate, the support plate is used for supporting the horizontal polarization unit and the vertical polarization unit, the horizontal polarization unit and the vertical polarization unit each are conformal with the wave absorbing plate, respectively forming third wave band horizontal polarization conformal antenna and third wave band vertical polarization conformal antenna.

2. The metamaterial antenna of claim 1, wherein, The antenna cover is bullet-shaped in appearance, and the antenna cover is parabolic in cross-sectional view.

3. The metamaterial antenna of claim 2, wherein, The antenna body is D-shaped, and the antenna body and the antenna cover protrude in the same direction.

4. The metamaterial antenna of claim 1, wherein, The wave absorbing plate comprises first wave absorbing plate and second wave absorbing plate, the antenna body further comprises reflecting plate, and the reflecting plate is attached to the first wave absorbing plate.

5. The metamaterial antenna of claim 4, wherein, The second wave absorbing plate is attached to the reflecting plate, the vertical polarization unit is attached to the second wave absorbing plate, the horizontal polarization unit is attached to the thickness direction of the second wave absorbing plate and is conformal with the edge of the second wave absorbing plate, and the vertical polarization unit is perpendicular to the horizontal polarization unit.

6. The metamaterial antenna of claim 4, wherein, The antenna body further comprises feeding plate, the feeding plate is arranged on the other side of the first wave absorbing plate and is connected perpendicularly with the first wave absorbing plate.

7. The metamaterial antenna of claim 6, wherein, The feeding plate comprises mutually connected first feeding part and second feeding part.

8. The metamaterial antenna of claim 7, wherein, The first feeding part is hollow back-shaped, and the second feeding part is Π-shaped.

9. A metamaterial array antenna, characterized by, The metamaterial array antenna is arranged in array mode by the metamaterial antenna of any one of claims 1-8.

10. The metamaterial array antenna of claim 9, wherein, The interval between the vertical polarization units in any two adjacent metamaterial array antennas is 0.25λmax, wherein λmax is the maximum value of the wavelength of incident electromagnetic wave.

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