A radar-infrared multi-spectrum stealth antenna based on polarization-converting metasurface

Abstract

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. The present invention comprises, from top to bottom, an infrared shielding layer, an upper dielectric substrate, a double-axe-shaped metal patch, a lower dielectric substrate, and a metal floor. A patch antenna with a coaxial feeder is installed within the upper dielectric substrate. The present invention not only achieves effective broadband radar and infrared dual stealth, but also has advantages such as a wide antenna operating bandwidth, a miniaturized structure, low manufacturing cost, and a simple principle. Due to the above advantages, the antenna provides a new approach to the design of multi-spectrum stealth antennas and has potential application value in wireless communications, military, and other fields.

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 component of communication systems and play a vital role in the military. However, with the continuous advancement of detection and tracking technologies, antenna stealth technology, as the primary entity for energy radiation and signal reception, has become increasingly important. Radar stealth performance is measured by the radar cross section (RCS), with a smaller RCS indicating better stealth. Traditional approaches to achieving this often involve using radar-absorbing materials or reshaping the antenna structure, but this inevitably compromises radiation performance. With the continued development of metamaterials, researchers have proposed using metamaterial absorbers to dissipate electromagnetic wave energy through ohmic loss, thereby reducing RCS. However, to avoid this impact, the antenna's operating frequency band must sometimes be outside the stealth band. Stealth radomes based on frequency-selective surfaces offer a promising solution for RCS reduction, but their complex structure not only increases insertion loss but also makes them unsuitable in certain scenarios. The development of metasurfaces offers new avenues for improving radiation characteristics and controlling scattering. Electromagnetic bandgap structures and artificial magnetic conductors designed based on metasurfaces can achieve excellent radar stealth when arranged in a checkerboard pattern. 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, making 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 dual stealth against radar and infrared. 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 a polarization conversion metasurface, which has radar and infrared dual stealth capabilities and can ensure radiation performance.

[0004] It is achieved through such a technical solution, comprising a lower dielectric substrate, a metal floor provided on the lower layer of the lower dielectric substrate, a patch antenna with a coaxial feeder provided at the center of the upper layer of the lower dielectric substrate, and the lower end of the coaxial feeder passing 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 each include a first upper dielectric substrate, double-axe-shaped metal patches, and an infrared shielding layer. 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, with equal spacing between rows and columns. The lower layer of the first upper dielectric substrate is provided with double-axe-shaped metal patches distributed diagonally, and the double-axe-shaped metal patches are arranged on a ring surface in a U-shaped layout.

[0007] A second upper dielectric substrate is provided in the hollow position of the U-shaped layout, and the first upper dielectric substrate and the second upper dielectric substrate are provided as a whole to constitute 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 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.

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

[0013] 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.

[0014] 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 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.

[0015] 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.

[0016] Furthermore, the length a of the patch antenna is 8.6 mm, and the width b of the patch antenna is 6.2 mm.

[0017] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0018] This invention not only achieves effective broadband radar and infrared dual stealth, but also boasts a wide operating bandwidth, compact structure, low manufacturing cost, and simple principle. These advantages offer a new approach to the design of multi-spectral stealth antennas, with potential applications in wireless communications, military, and other fields.

[0019] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings of the present invention are described below.

[0021] Figure 1 Schematic diagram of the three-dimensional structure of the upper unit.

[0022] Figure 2 This is a top view of the infrared shielding layer and the double-axe-shaped metal patch.

[0023] Figure 3 Reflection coefficient curve and polarization conversion rate curve of the upper unit under x- and y-polarized incident waves.

[0024] Figure 4 The reflection coefficient S11 and transmission coefficient S21 of the infrared shielding layer in the microwave frequency band of 3-13 GHz.

[0025] Figure 5 Schematic diagram of the surface structure of the double-axe-shaped metal patch.

[0026] Figure 6 Schematic diagram of the double-axe-shaped metal patch arrangement structure.

[0027] Figure 7 Top view of the structure of the infrared shielding layer.

[0028] Figure 8 Schematic diagram of the patch antenna placement.

[0029] Figure 9 A 3D perspective diagram of the antenna's overall structure.

[0030] Figure 10 Schematic diagram of the operating frequency band of the line, namely S11, and the total efficiency of the actual test.

[0031] Figure 11 Comparison of antenna gain and radiation patterns at three frequency points within the bandwidth.

[0032] Figure 12Schematic diagram of the RCS reduction curve of the antenna under x- and y-polarized incident waves.

[0033] Figure 13 Schematic diagram of temperature test results of the antenna and reference antenna in a high temperature environment.

[0034] In the figure: 1. Upper dielectric substrate; 1-1. Infrared shielding layer; 2. Lower dielectric substrate; 3. Double-axe metal patch; 4. Metal floor; 5. Patch antenna; 5-1. Coaxial feed line. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings and examples.

[0036] A radar-infrared multi-spectrum stealth antenna based on a polarization conversion metasurface includes a lower dielectric substrate 2, a metal floor 4 is provided on the lower layer of the lower dielectric substrate 2, a patch antenna 5 with a coaxial feed line 5-1 is provided 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 provided above the lower dielectric substrate 2, and the upper layer units are arranged in a U-shaped pattern. The patch antenna 5 is smaller than the hollow size of the U-shaped pattern and is located on the lower dielectric substrate 2 at the center of the hollow; the upper layer units each include a first upper dielectric substrate, a double-axe Axe-shaped metal patches 3 and an infrared shielding layer 1-1 are provided. The square metal patches of the infrared shielding layer 1-1 are arranged in rows and columns on the upper layer of the first upper dielectric substrate. 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 3 along the diagonal line. The double-axe-shaped metal patches 3 are arranged on the ring surface of the U-shaped layout. A second upper dielectric substrate is provided 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 the upper dielectric substrate 1. A plurality of infrared shielding layers 1-1 with the same layout are distributed above the second upper dielectric substrate.

[0037] The lower dielectric substrate 2 is divided into four quadrants by a cross center line. Upper units with the same data are evenly distributed in each quadrant. The upper units of two opposite quadrants have the same orientation, and the orientations of two adjacent quadrants differ by 90 degrees.

[0038] 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;

[0039] The two axe edges at the distal ends of the double-axe-shaped metal patch 3 are symmetrically provided with arc-shaped openings.

[0040] The upper unit is designed as Figure 1 and Figure 2 As 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.

[0041] Figure 3 The reflection coefficient curves and polarization conversion rate curves of the proposed upper layer unit under x and y polarization 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 0 dB. The polarization conversion rate is defined as PCR = The results show that the PCR of the upper unit exceeds 90% within the operating frequency band. Furthermore, the double-axe metal patches are placed at ±45°, enabling highly efficient conversion between x- and y-polarized waves. On the other hand, the infrared shielding layer has high microwave transmittance and low reflectivity, so it does not affect the polarization deflection characteristics of the lower layer and can be considered 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 3-13GHz 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 Perform calculations, represents the metal emissivity, "f" represents the emissivity of the medium, and the area ratio of the metal is represented by "f". Therefore, it can be calculated that the emissivity of the unit is 0.21, which has significant infrared stealth characteristics.

[0042] When polarization conversion metasurfaces are used in RCS reduction designs, a checkerboard structure consisting of two alternating arrays is generally used. Figure 5 As shown, the arrangement is Figure 6 The structure is 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 mirrored 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 theoretically meets a 10dB RCS reduction.

[0043] In this design, the upper dielectric substrate and the infrared shielding layer work together to provide infrared shielding. Figure 7 shown.

[0044] The patch antenna, lower dielectric substrate, and metal floor act as radar scattering layers 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. Figure 9 shown.

[0045] like Figure 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. Figure 11 The achievable gain (RG) and far-field patterns measured at different frequencies are shown. The antenna achieves a maximum gain of 8.6 dBi at 5.1 GHz, which is close to the simulation result and improves 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. Figure 12 As shown, in the case of vertically incident x and y polarized waves, the proposed antenna can obtain an RCS reduction greater than 10 dB in the 4.44-12.76 GHz band with a bandwidth of 85.5%, and a maximum RCS reduction of 39 dB at 8.1 GHz. In addition, the bandwidth reduction rate of 8 dB 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) operating at 7.5-14 μm. Figure 13 In the experiment, when the metal surface temperature of the heating furnace was fixed at 30°C, the antenna sample's test temperature was only 32.2°C, very close to the metal temperature, under the same temperature conditions. The reference antenna's temperature was 57.6°C, a decrease of 25.4°C. The test data demonstrates that the antenna sample exhibits excellent low-emissivity characteristics, enabling effective infrared stealth.

[0046] In this embodiment, the dimensions of each parameter are shown in the following table:

[0047]

[0048] In summary, the proposed radar-infrared multi-spectrum stealth antenna based on a functional polarization-converting metasurface exhibits excellent broadband radar and infrared stealth capabilities, achieving a design that is compatible with cross-band stealth. Test results generally agree with simulations, demonstrating excellent overall performance and promising potential for practical applications.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the 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 by 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 antenna includes a lower dielectric substrate, a metal floor is provided on the lower layer of the lower dielectric substrate, and a patch antenna with a coaxial feeder is provided at the center of the upper layer of the lower dielectric substrate, wherein the lower end of the coaxial feeder passes through the metal floor without contact; Several upper-layer units are disposed above the lower dielectric substrate. Each of the upper-layer units includes a first upper dielectric substrate, a double-axe-shaped metal patch, and an infrared shielding layer. 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, with equal spacing between rows and columns. The lower layer of the first upper dielectric substrate has double-axe-shaped metal patches symmetrically distributed along the diagonal line. The double-axe-shaped metal patches are arranged on a ring surface in a U-shaped layout. The patch antenna is smaller than the hollow space of the U-shaped layout and is located on the lower dielectric substrate at the center of the hollow space. A second upper dielectric substrate is provided in the hollow position of the U-shaped layout, and the first upper dielectric substrate and the second upper dielectric substrate are provided as a whole to constitute an upper dielectric substrate; A plurality of infrared shielding layers with the same layout are distributed above the second upper dielectric substrate; The two axe blades at the far ends of the double-axe-shaped metal patch are symmetrically provided with arc-shaped openings.

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. Upper units with the same data are evenly distributed in each quadrant. The upper units of two opposite quadrants have the same orientation, and the orientations 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 in each unit structure is located at the center of the first upper dielectric substrate and is symmetrically arranged along the diagonal line of the first dielectric substrate.

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 with a side length p of 10 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 two axe blade opening ends along the diagonal is 6.93mm, the length r1 of the double axe-shaped metal patch from the center to the farthest end along the diagonal is 4.8mm, the width g1 of the arc opening is 0.2mm, and the shortest distance g2 between the two arc 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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