Radar-infrared multi-spectrum stealth antenna based on polarization conversion metasurface

Abstract

The invention relates to the technical field of radars, in particular to a radar-infrared multi-spectrum stealth antenna based on a polarization conversion metasurface. An infrared shielding layer, an upper dielectric substrate, a double-axe-shaped metal patch, a lower dielectric substrate and a metal floor are sequentially arranged from top to bottom, and a patch antenna with a coaxial feeder line is mounted in the upper dielectric substrate. The broadband radar and infrared dual-stealth antenna not only realizes broadband radar and infrared dual-stealth with good effects, but also has the advantages of relatively wide antenna working bandwidth, miniaturized structure, low manufacturing cost, simple principle and the like. Due to the advantages, the antenna provides a new thought for the design of a multispectral stealth antenna, and has potential application value in the fields of wireless communication, military affairs and the like.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a radar-infrared multi-spectrum stealth antenna based on a polarization conversion metasurface. Background Art

[0002] Antennas are an indispensable part of communication systems and play a vital role in the military field. However, with the continuous development of detection and tracking technology, as the main entity for energy radiation and signal reception, the stealth technology of antennas has become increasingly important. The indicator for measuring radar stealth performance is the radar cross-section (RCS). The smaller the RCS, the better the stealth performance. Traditional implementation methods are mostly to use radar absorbing materials or to reshape the antenna structure, but this is bound to affect the radiation performance. With the continuous development of metamaterials, people have proposed a method of using metamaterial absorbers to consume electromagnetic wave energy through ohmic loss to reduce RCS, but sometimes to avoid the impact, the working frequency band of the antenna still needs to avoid the stealth band. Stealth radomes based on frequency selective surfaces provide a promising solution for RCS reduction, but the complex structure not only increases the insertion loss, but is also not applicable in some scenarios. The development of metasurfaces provides a new way to improve radiation characteristics and scattering control. Electromagnetic bandgap structures, artificial magnetic conductors and other structures designed based on metasurfaces can achieve good radar stealth through chessboard arrays. Among them, polarization conversion metasurfaces are particularly suitable for broadband RCS reduction due to their polarization control capabilities and ease of design. In recent years, the development of multi-band composite detection technology has expanded modern target detection to the infrared spectrum, which has made the infrared stealth capability of antennas increasingly important. Preparing infrared stealth coating materials with low emissivity characteristics is a common method. However, in order to avoid affecting radiation, some studies have designed frequency selective absorbers with different structures to achieve radar and infrared dual stealth. However, these structures are separated from the antenna and do not have radiation capabilities themselves, which greatly limits their application flexibility. Summary of the invention

[0003] The present invention discloses a radar-infrared multi-spectrum stealth antenna based on polarization conversion metasurface, which has radar and infrared dual stealth capabilities and can ensure radiation performance.

[0004] It is realized by such a technical solution, comprising a lower dielectric substrate, a metal floor is arranged on the lower layer of the lower dielectric substrate, a patch antenna with a coaxial feeder is arranged at the center of the upper layer of the lower dielectric substrate, and the lower end of the coaxial feeder passes through the metal floor without contact;

[0005] A plurality of upper units are arranged above the lower dielectric substrate. The upper units are arranged in a U-shaped pattern. The patch antenna is smaller than the hollow size of the U-shaped pattern and is located on the lower dielectric substrate at the center of the hollow.

[0006] The upper layer units all include a first upper dielectric substrate, a double-axe-shaped metal patch and an infrared shielding layer, wherein the square metal patches of the infrared shielding layer are arranged in rows and columns on the upper layer of the first upper dielectric substrate, and the spacing between rows and columns is equal; the lower layer of the first upper dielectric substrate is provided with double-axe-shaped metal patches along the diagonal, and the double-axe-shaped metal patches are arranged on a ring surface arranged in a U-shaped pattern;

[0007] A second upper dielectric substrate is disposed in the hollow position of the U-shaped layout, and the first upper dielectric substrate and the second upper dielectric substrate are integrally disposed to form an upper dielectric substrate;

[0008] A plurality of infrared shielding layers with the same layout are distributed above the second upper dielectric substrate.

[0009] Furthermore, the lower dielectric substrate is divided into four quadrants by the cross center line, each quadrant is evenly distributed with upper layer units of the same data, the upper layer units of two opposite quadrants are oriented in the same direction, and the directions of two adjacent quadrants differ by 90 degrees.

[0010] Furthermore, the center of the double-axe-shaped metal patch is located at the center of the first upper dielectric substrate and is symmetrically arranged along the diagonal line of the first dielectric substrate;

[0011] The two axe blades at the far ends of the double-axe-shaped metal patch are symmetrically provided with arc-shaped openings.

[0012] Further, the unit cross section of the first upper dielectric substrate is a square, and the side length p is 10 mm;

[0013] The unit cross section of the second dielectric substrate is a square, and the side length l is 120 mm;

[0014] The row and column spacing of the infrared shielding layer g l The cross section of the infrared shielding layer is a square with a side length of 0.1 mm. l It is 0.9mm.

[0015] Furthermore, the length r2 of the ends of the two axe blade openings along the diagonal is 6.93 mm, the length r1 of the center distance of the double axe-shaped metal patch from the farthest end along the diagonal is 4.8 mm, the width g1 of the arc-shaped opening is 0.2 mm, and the shortest distance g2 between the two arc-shaped openings on the same side is 1 mm.

[0016] Furthermore, the thickness h2 of the lower dielectric substrate is 4.9 mm, and the thickness h1 of the upper dielectric substrate is 0.256 mm.

[0017] Furthermore, the length a of the patch antenna is 8.6 mm, and the width b of the patch antenna is 6.2 mm.

[0018] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0019] The present invention not only achieves good broadband radar and infrared dual stealth, but also has the advantages of wide antenna working bandwidth, small structure, low manufacturing cost, simple principle, etc. Due to the above advantages, the antenna provides a new idea for the design of multi-spectral stealth antenna, and has potential application value in wireless communication, military and other fields.

[0020] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings of the present invention are as follows.

[0022] Figure 1 Schematic diagram of the three-dimensional structure of the upper unit.

[0023] Figure 2 It is a top view of the infrared shielding layer and the double-axe-shaped metal patch.

[0024] Figure 3 Reflection coefficient curve and polarization conversion rate curve of the upper unit under x- and y-polarized incident waves.

[0025] Figure 4 The reflection coefficient S11 and transmission coefficient S21 of the infrared shielding layer in the microwave frequency band of 3-13GHz

[0026] Figure 5 Schematic diagram of the surface structure of a double-axe-shaped metal patch.

[0027] Figure 6 This is a schematic diagram of the double-axe-shaped metal patch arrangement structure.

[0028] Figure 7 Top view of the structure of the infrared shielding layer.

[0029] Figure 8 Schematic diagram of the patch antenna position setting.

[0030] Fig. 9 A 3D perspective diagram of the overall structure of the antenna.

[0031] Fig.10 Schematic diagram of the operating frequency band of the line, namely S11, and the total efficiency of the actual test.

[0032] Fig.11 Comparison of antenna gain and radiation patterns at three frequency points within the bandwidth.

[0033] Fig.12 Schematic diagram of the RCS reduction curve of the antenna under x- and y-polarized incident waves.

[0034] Fig.13 Schematic diagram of temperature test results of the antenna and the reference antenna in a high temperature environment.

[0035] In the figure: 1. upper dielectric substrate; 1-1. infrared shielding layer; 2. lower dielectric substrate; 3. double-axe-shaped metal patch; 4. metal floor; 5. patch antenna; 5-1. coaxial feed line. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0037] A radar-infrared multi-spectrum stealth antenna based on a polarization conversion metasurface, comprising a lower dielectric substrate 2, a metal floor 4 is arranged on the lower layer of the lower dielectric substrate 2, a patch antenna 5 with a coaxial feed line 5-1 is arranged at the center of the upper layer of the lower dielectric substrate 2, and the lower end of the coaxial feed line 5-1 passes through the metal floor 4 without contact; a plurality of upper layer units are arranged above the lower dielectric substrate 2, the upper layer units are arranged in a U-shaped layout, the patch antenna 5 is smaller than the hollow size of the U-shaped layout, and is located on the lower dielectric substrate 2 at the hollow center; the upper layer units each include a first upper dielectric substrate, a double-axe A square metal patch 3 and an infrared shielding layer 1-1, the square metal patches of the infrared shielding layer 1-1 are distributed in rows and columns on the upper layer of the first upper dielectric substrate, the spacing between rows is equal, and the spacing between columns is equal; the lower layer of the first upper dielectric substrate is distributed with double-axe-shaped metal patches 3 along the diagonal, and the double-axe-shaped metal patches 3 are arranged on the ring surface of the U-shaped layout; a second upper dielectric substrate is arranged in the hollow position of the U-shaped layout, the first upper dielectric substrate and the second upper dielectric substrate are arranged as a whole to constitute an upper dielectric substrate 1; a plurality of infrared shielding layers 1-1 with the same layout are distributed above the second upper dielectric substrate.

[0038] The lower dielectric substrate 2 is divided into four quadrants by a cross center line, each quadrant is evenly distributed with upper layer units of the same data, the upper layer units of two opposite quadrants are oriented in the same direction, and the directions of two adjacent quadrants differ by 90 degrees.

[0039] The center of the double-axe-shaped metal patch 3 is located at the center of the first upper dielectric substrate and is symmetrically arranged along the diagonal line of the first dielectric substrate;

[0040] The two axe blades at the far ends of the double-axe-shaped metal patch 3 are symmetrically provided with arc-shaped openings.

[0041] The upper unit is designed as Figure 1 and Figure 2As shown, the unit period of the upper unit is p. The thickness of the infrared shielding layer with the first upper dielectric substrate is h1. The size of the infrared shielding layer is p l , the spacing is g l The thickness of the lower dielectric substrate 2 is h2.

[0042] Figure 3 The reflection coefficient curves and polarization conversion rate curves of the proposed upper unit under x- and y-polarized incident waves are given. In the 4.5-12.5GHz band, the co-polarization reflection coefficient r xx Less than -10dB, cross-polarization reflection coefficient r yx Almost 0dB. The polarization conversion rate is defined as According to the results, the PCR of the upper unit exceeds 90% within the operating frequency band. In addition, the double-axe metal patch is placed at ±45°, thereby achieving high-efficiency conversion between x and y polarized waves. On the other hand, the infrared shielding layer has high microwave transmittance and low reflectivity characteristics, so it does not affect the polarization deflection characteristics of the lower layer and can be considered as a low-pass filter. Figure 4 The reflection coefficient S11 and transmission coefficient S21 of the infrared shielding layer in the microwave frequency band of 3-13 GHz are given. In addition, the designed infrared shielding layer also has low emissivity characteristics. The emissivity of the material can be calculated using the formula ε I =ε m f+ε s (1-f) is calculated, ε m represents the metal emissivity, ε s "f" represents the emissivity of the medium, and the area ratio of the metal is represented by "\frac{\mathcal {E}". Therefore, it can be finally calculated that the emissivity of the unit is 0.21, which has significant infrared stealth characteristics.

[0043] When polarization conversion metasurfaces are used in RCS reduction design, a chessboard structure consisting of two alternating arrays is generally used. Figure 5 As shown, the arrangement is Figure 6 The structure shown in . The numbers "0" and "1" represent two types of units with a 180° reflection phase difference, and arrays I and II consist of 6×6 units that are mirror images of each other. Due to the properties of the polarization conversion metasurface, a mirror unit can be obtained by rotating the original unit 90°. When the reflection amplitude is the same, the phase difference between the two polarization conversion units is 180°±37°, which can theoretically meet a 10dB RCS reduction.

[0044] In this design, the upper dielectric substrate and the infrared shielding layer play the role of infrared shielding together. Its structure is as follows: Figure 7 shown.

[0045] The patch antenna, the lower dielectric substrate, and the metal floor play the role of radar scattering layer and are placed at the center of the polarization conversion metasurface, e.g. Figure 8 The overall structure of the antenna is shown in 3D perspective. Fig. 9 shown.

[0046] like Fig.10 As shown, the center frequency of the antenna is 5 GHz, the operating bandwidth is 4.75-5.36 GHz (12.2%), and the total efficiency is greater than 80% within the bandwidth. Fig.11 The achievable gain (RG) and far-field patterns measured at different frequencies are shown. The maximum gain of the antenna measured at 5.1 GHz is 8.6 dBi, which is close to the simulation result and is improved compared to the reference antenna. Good radiation performance is demonstrated based on the normalized far-field radiation patterns of the E plane (φ=0°) and H plane (φ=90°) at 4.9 GHz, 5 GHz, and 5.1 GHz. Fig.12 As shown, in the case of vertically incident x and y polarized waves, in the 4.44-12.76GHz band, the proposed antenna can obtain an RCS reduction greater than 10dB with a bandwidth of 85.5%, and a maximum RCS reduction of 39dB at 8.1GHz. In addition, the bandwidth reduction rate of 8dB RCS can also reach 94.5%. In addition, the infrared stealth capability of the antenna was tested. Both the proposed antenna sample and the reference antenna sample were placed in a constant temperature experimental furnace at 70°C for heating, and their temperatures were measured using a thermal imager (HM-TPH21Pro-3AQF) working at 7.5-14μm. Fig.13 In the experiment, when the metal surface temperature of the heating furnace was fixed at 30°C, under the same temperature conditions, the test temperature of the antenna sample was only 32.2°C, which was very close to the temperature of the metal, while the temperature of the reference antenna was 57.6°C, which was 25.4°C lower than the former. The test data showed that the antenna sample had good low emissivity characteristics and could achieve effective infrared stealth.

[0047] In this embodiment, the dimensions of each parameter are shown in the following table:

[0048]

[0049] In summary, the proposed functional polarization conversion metasurface radar-infrared multi-spectrum stealth antenna has good broadband radar and infrared stealth capabilities, and realizes the design of antenna compatible with cross-band stealth. After testing, the results obtained are basically consistent with the simulation, the overall performance of the antenna is good, and it has good practical application potential.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A radar-infrared multi-spectrum stealth antenna based on polarization conversion metasurface, characterized in that: The radar comprises a lower dielectric substrate, a metal floor is arranged on the lower layer of the lower dielectric substrate, a patch antenna with a coaxial feeder is arranged at the center of the upper layer of the lower dielectric substrate, and the lower end of the coaxial feeder passes through the metal floor without contact; A plurality of upper units are arranged above the lower dielectric substrate. The upper units are arranged in a U-shaped pattern. The patch antenna is smaller than the hollow size of the U-shaped pattern and is located on the lower dielectric substrate at the center of the hollow. The upper layer units all include a first upper dielectric substrate, a double-axe-shaped metal patch and an infrared shielding layer, wherein the square metal patches of the infrared shielding layer are arranged in rows and columns on the upper layer of the first upper dielectric substrate, and the spacing between rows and columns is equal; the lower layer of the first upper dielectric substrate is provided with double-axe-shaped metal patches along the diagonal, and the double-axe-shaped metal patches are arranged on a ring surface arranged in a U-shaped pattern; A second upper dielectric substrate is disposed in the hollow position of the U-shaped layout, and the first upper dielectric substrate and the second upper dielectric substrate are integrally disposed to form an upper dielectric substrate; A plurality of infrared shielding layers with the same layout are distributed above the second upper dielectric substrate.

2. The radar-infrared multi-spectrum stealth antenna based on polarization conversion metasurface according to claim 1, characterized in that: The lower dielectric substrate is divided into four quadrants by a cross center line, each quadrant is evenly distributed with upper layer units of the same data, the upper layer units of two opposite quadrants are oriented in the same direction, and the directions of two adjacent quadrants differ by 90 degrees.

3. The radar-infrared multi-spectrum stealth antenna based on polarization conversion metasurface according to claim 1, characterized in that: The center of the double-axe-shaped metal patch is located at the center of the first upper dielectric substrate and is symmetrically arranged along the diagonal line of the first dielectric substrate; The two axe blades at the far ends of the double-axe-shaped metal patch are symmetrically provided with arc-shaped openings.

4. The radar-infrared multi-spectrum stealth antenna based on polarization conversion metasurface according to claim 1, characterized in that: The unit cross section of the first upper dielectric substrate is a square, and the side length p is 10 mm; The unit cross section of the second dielectric substrate is a square, and the side length l is 120 mm; The row and column spacing of the infrared shielding layer g l The cross section of the infrared shielding layer is a square with a side length of 0.1 mm. l It is 0.9mm.

5. The radar-infrared multi-spectrum stealth antenna based on polarization conversion metasurface according to claim 3, characterized in that: The length r2 of the ends of the two axe blade openings along the diagonal is 6.93mm, the length r1 of the center distance of the double axe-shaped metal patch from the farthest end along the diagonal is 4.8mm, the width g1 of the arc-shaped opening is 0.2mm, and the shortest distance g2 between the two arc-shaped openings on the same side is 1mm.

6. The radar-infrared multi-spectrum stealth antenna based on polarization conversion metasurface according to claim 1, characterized in that: The thickness h2 of the lower dielectric substrate is 4.9 mm, and the thickness h1 of the upper dielectric substrate is 0.256 mm.

7. The radar-infrared multi-spectrum stealth antenna based on polarization conversion metasurface according to claim 1, characterized in that: The length a of the patch antenna is 8.6 mm, and the width b of the patch antenna is 6.2 mm.

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