Radiation integrated low RCS antenna with high angle stability and design method thereof

Abstract

The invention relates to a radiation integrated low RCS antenna with high angle stability and a design method thereof, and belongs to the technical field of electromagnetic stealth. The problems that a traditional antenna RCS reduction technology is prone to deteriorate radiation performance, the bandwidth is narrow, and oblique incidence is unstable are solved. According to the technical scheme, a three-layer structure is adopted, an artificial surface plasmon polariton metasurface achieves RCS reduction through wave absorption, a metasurface array achieves RCS reduction through phase cancellation, and a feed network feeds through slot coupling; the design method comprises the steps of RCS reduction frequency band determination, metasurface unit design, feed network matching and the like. The technical effects are that the ultra-wideband RCS is reduced, the angle stability is high, the good radiation performance is maintained, the structure is simple, the work is stable, and the like.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic stealth technology and relates to a radiation-integrated low RCS antenna with high angular stability and its design method. Background Technology

[0002] In the field of electromagnetic stealth technology, antennas are key components of radar systems, and reducing their radar cross section (RCS) is crucial. Traditionally, antenna shape reduction has been achieved primarily through shape manipulation techniques, but this method has significant drawbacks. Firstly, shape manipulation techniques can easily interfere with the normal distribution of current on the radiating structure, leading to decreased antenna gain and distorted radiation patterns, severely impacting the antenna's radiation performance. Secondly, traditional techniques typically only achieve effective RCS reduction within narrow frequency bands, making it difficult to address the trend of modern detection radars moving towards ultra-wideband coverage.

[0003] With the development of metamaterials technology, metasurfaces offer a new solution to the aforementioned problems. Metasurfaces possess a powerful ability to manipulate electromagnetic waves, offering hope for simultaneously achieving good radiation performance and wideband RCS reduction. However, existing low-RCS antenna designs based on metasurfaces still face many challenges. First, it is often difficult to balance antenna radiation efficiency and stealth performance in the design. For example, choosing a metasurface or absorbing structure for the frequency loaded above the antenna often deteriorates the antenna's radiation characteristics. Second, the bandwidth limitation of RCS reduction remains significant, and most designs cannot maintain stable low RCS characteristics over an ultra-wide bandwidth. Finally, the sensitivity of the antenna to the incident angle of electromagnetic waves is a key issue. Existing metasurface structures often experience significant performance degradation under oblique incidence, leading to unstable RCS reduction effects and failing to meet the requirements of practical applications in complex electromagnetic environments. Therefore, there is an urgent need for a new antenna design scheme that can achieve ultra-wideband RCS reduction and high angular stability without sacrificing radiation performance. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a radiation-integrated low RCS antenna with high angular stability and a design method thereof.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A radiation-integrated low RCS antenna with high angular stability includes an artificial surface plasmon metasurface, a metasurface array, and a slot-coupled feed network. The three layers are of the same size and are stacked from top to bottom. The artificial surface plasmon metasurface reduces RCS by absorbing waves, the metasurface array reduces RCS by phase cancellation, and the slot-coupled feed network feeds the metasurface array through a microstrip line.

[0006] Furthermore, the artificial surface plasmon metasurface is composed of gradient comb-shaped metal strips, the length of which gradually increases from top to bottom, and is printed on an FR-4 substrate with a dielectric constant of 4.3.

[0007] Furthermore, the metasurface array consists of two metasurface units arranged in a checkerboard pattern to form an 8-row × 8-column array. The metasurface unit includes a bimetallic layer and a bilayer dielectric structure, and the phase difference of the reflected waves from the two units when incident perpendicularly is 180° ± 37°.

[0008] Furthermore, the metal layers of the metasurface unit are circular metal structures with different radii, and are arranged in a centrally symmetrical manner.

[0009] Furthermore, the slot-coupled power supply network includes a microstrip power divider, which is a two-way power divider with a 180° phase difference between its two output ports, and is printed on an F4B substrate with a dielectric constant of 2.2.

[0010] A method for designing a radiation-integrated low RCS antenna with high angular stability, comprising the following steps: The RCS reduction frequency range is determined to cover the C-band, X-band, Ku-band, K-band, and Ka-band; Two metasurface units are designed to ensure that the reflected wave has a phase difference of 180°±37° when the incident wave is perpendicular and that the reflection performance is stable when the incident wave is oblique. The power supply network is designed to have a 180° phase difference between its two output ports; Design the parameters of the bottom metal slots of the metasurface array to match the feeding network; The absorption band of the artificial surface plasmon metasurface is set far away from the antenna operating band and does not block the metasurface array. Verify the antenna's radiation performance and RCS reduction performance.

[0011] Furthermore, the metal structure of the metasurface unit is centrosymmetric and has good radiation capability.

[0012] Furthermore, the verification of radiation performance includes comparing the radiation pattern performance of loaded and unloaded artificial surface plasmon metasurface structures.

[0013] Furthermore, the verification of RCS reduction performance includes performance verification under conditions of vertical incidence, 30° oblique incidence, 45° oblique incidence, and 60° oblique incidence.

[0014] Furthermore, the artificial surface plasmon metasurface is composed of gradient comb-shaped metal strips, the length of which gradually increases from top to bottom, and together with the metasurface array, it achieves ultra-wideband RCS reduction.

[0015] The beneficial effects of this invention are as follows: (1) This invention effectively solves the long-standing technical contradiction in traditional low RCS antenna design through an innovative three-layer integrated structure design. This design perfectly integrates radiation function and stealth performance, achieving a qualitative breakthrough without sacrificing antenna radiation characteristics. Specifically, the metasurface array effectively disperses electromagnetic wave scattering energy through a phase cancellation mechanism, while the artificial surface plasmon polariton (SSPP) metasurface further expands the operating bandwidth through wave absorption. The synergistic effect of the two mechanisms produces a significant performance improvement.

[0016] (2) The unique structural design of this invention ensures stable RCS reduction performance over a wide angle range, without performance degradation even under large-angle oblique incidence conditions. Simultaneously, the antenna exhibits excellent polarization-independent characteristics, enabling it to adapt to electromagnetic wave environments with different polarizations, greatly expanding its application scenarios. This high stability and adaptability make this invention exceptionally valuable in complex and ever-changing real-world electromagnetic environments.

[0017] (3) The present invention has a simple and reasonable structural design with clear coupling relationships between layers, which facilitates processing, manufacturing, and practical application. This simplicity not only reduces manufacturing costs but also improves product reliability and consistency. Compared with traditional complex antenna stealth solutions, the present invention provides a more practical and economical technical path, creating favorable conditions for the promotion and application of electromagnetic stealth technology in a wider range of fields.

[0018] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 The diagram shows the structure of the metasurface array unit cell; (a) is unit cell 1; (b) is unit cell 2. Figure 2 (a) is the phase difference of reflection between two metasurface units; (b) is the phase difference when incident perpendicularly; Figure 3 A metasurface array arranged in a chessboard pattern; Figure 4(a) RCS reduction performance of metasurface array; (b) RCS reduction structure under perpendicular incidence; (c) RCS reduction result under oblique incidence. Figure 5 (a) shows the feed network structure; (b) shows the antenna layer diagram; (c) shows the feed network. Figure 6 For antenna S11; Figure 7 The structure and properties of the SSPP metasurface are shown in Figure 1; (a) is a front view of the SSPP metasurface; (b) is a top view of the SSPP metasurface; (c) is the SSPP metasurface S11. Figure 8 This is a diagram of the overall antenna structure. Figure 9 (a) Radiation pattern of the antenna with SSPP metasurface loaded; (b) Radiation pattern of the antenna without SSPP metasurface loaded. Figure 10 For the antenna in x RCS reduction performance under polarized vertical and oblique incidence. Detailed Implementation

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0021] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0022] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0023] like Figure 1 The diagram shows the unit structure. Unit 1 consists of two dielectric layers and two metal layers, while unit 2 consists of two dielectric layers and one metal layer. h =0.5mm, r 1 = 1.8 mm, r 2=3.6mm, r 3 = 0.9 mm, p =8mm.

[0024] like Figure 2 As shown in (a), the reflected waves of the two units have a phase difference of 180°±37° in the range of 7.2-26GHz when the incident wave is perpendicular. (b) shows the phase difference between unit 1 and unit 2 when the incident wave is obliquely at 30°, 45° and 60°. It can be seen that even when the incident wave is obliquely at a large angle, the two units can still maintain a good phase difference in the range of 7.1~17.5GHz, which proves that the designed metasurface unit has good oblique incidence stability.

[0025] like Figure 3 As shown, two unit chessboards are arranged to form an 8×8 metasurface array.

[0026] Depend on Figure 4 As shown in (a), the metasurface array can achieve an RCS reduction of over 6 dB in the 7.25-31.4 GHz range under vertical incidence, with a relative bandwidth of approximately 125%. This achieves ultra-wideband RCS reduction. As shown in (b), the RCS reduction performance of the metasurface array is well maintained under oblique incidence; even at a 60° oblique incidence, it can still achieve an RCS reduction of over 6 dB in the 10.4-30.6 GHz range, with a relative bandwidth of approximately 98.5%. Depend on Figure 5 As shown in (a), the feed network, dielectric substrate, and metasurface array are respectively. In (b)... t 1 = 0.5mm w 1 = 1.5mm w 2=2.4mm w 3=2.8mmw 4 = 26mm.

[0027] Depend on Figure 6 As shown, it can be seen that the frequency range of antenna S11 below -10dB is 6.3-10.35GHz, and the impedance bandwidth is 49.6%.

[0028] Depend on Figure 7 As shown in (a) in the figure, where l 1=8mm l 2=5.15mm l 3=2mm l 4 = 0.2mm H =4.3mm; from Figure 7 As shown in (b), it can be seen that the absorption band of the SSPP metasurface is 21.5~32.8GHz, which is far from the operating band of the metasurface antenna and will not affect the radiation performance of the antenna.

[0029] Depend on Figure 9 (a) and Figure 9 As can be seen from comparison (b) in the figure, loading the SSPP metasurface did not affect the radiation performance of the antenna. Figure 9 In (a), the peak gain of the antenna without the SSPP metasurface is 11.62 dBi, and the peak gain of the antenna with the SSPP metasurface is 11.24 dBi.

[0030] Depend on Figure 10 As shown, the overall structure can achieve an RCS reduction of over 6dB in the 7.1GHz-32.4GHz range under vertical incidence, with a relative bandwidth of approximately 128%; under 60° oblique incidence, it can achieve an RCS reduction of over 6dB in the 9.2-34.1GHz range, with a relative bandwidth of approximately 115%. It can be seen that the designed structure has good oblique incidence stability and maintains its ultra-wideband RCS reduction performance under vertical incidence.

[0031] The electromagnetic properties of the metasurface were simulated using the numerical simulation software CSTMicrowaveStudio.

[0032] The unit structures designed in this invention are centrosymmetric, and therefore all possess polarization-independent characteristics. In the simulation, the incident waves all use... x Polarized incident.

[0033] Example 1: Implementation of a Low RCS Antenna The core of this antenna lies in its three-layer integrated design, with strict dimensional matching between each layer.

[0034] First, prepare three identical dielectric substrates, each with a side length of 64mm. The first substrate uses FR-4 material with a dielectric constant of 4.3 and a thickness of 0.5mm. A gradient comb-shaped metal strip structure is printed on the surface of this substrate, with the strip length gradually changing from 0.2mm at the top to 8mm at the bottom, and the spacing between adjacent strips is 0.5mm. This gradient design enables broadband electromagnetic wave absorption.

[0035] Both the second and third layers use F4B dielectric material with a dielectric constant of 2.2. The second layer substrate is 1 mm thick, with metal patterns printed on its top and bottom surfaces. The top surface consists of an 8×8 array of circular metal patches, where cell 1 has a radius of 3.6 mm and cell 2 has a radius of 1.8 mm, arranged alternately in a checkerboard pattern. The bottom surface is a metal ground plane with two coupling slots.

[0036] The third substrate layer is 0.5 mm thick, with a microstrip feed network printed on its upper surface. This network employs a T-shaped power divider structure, with a main microstrip line width of 1.5 mm and a branch microstrip line width of 2.4 mm. Impedance matching is achieved through a quarter-wavelength conversion segment. The two output ports are aligned with the coupling gaps of the second layer via metallized vias.

[0037] During assembly, the three substrates are precisely aligned and secured with locating pins, then bonded together with an adhesive whose dielectric constant matches that of the substrates. Finally, an SMA connector is soldered to the lower surface of the third substrate to complete the antenna fabrication.

[0038] Example 2: Implementation process of antenna design method This method ensures the achievement of various antenna performance indicators through a systematic design process.

[0039] The first step is to determine the frequency range for RCS reduction. Based on commonly used radar bands, the target frequency band is set to 4~40GHz, covering multiple important bands such as C, X, Ku, K, and Ka. Establishing this range provides a clear target for subsequent design.

[0040] The second step involves designing the metasurface unit. Electromagnetic simulation software is used to build the unit model, and the radius of the circular metal patch is optimized to maintain a phase difference of approximately 180°±37° between the two units in the 7–28 GHz range. Simultaneously, symmetry design ensures that the unit exhibits polarization-independent characteristics.

[0041] The third step is to design the power supply network. Based on the antenna's operating frequency band requirement of 6-10 GHz, a microstrip line structure is used to achieve a two-way power divider. By optimizing the branch line lengths, a precise 180° phase difference is achieved between the two output ports at the center frequency of 8 GHz.

[0042] The fourth step is to design the slot coupling. Two rectangular slots are made on the metal floor of the second substrate. The length of the slots is approximately one-quarter wavelength, and the width is determined through simulation optimization to ensure good matching with the feed network.

[0043] The fifth step is to design the SSPP metasurface. The key is to keep the absorption band (21-33 GHz) far from the antenna's operating band to avoid affecting radiation performance. Simultaneously, electromagnetic simulations are used to verify that the structure does not obstruct radiation from the underlying layers.

[0044] Finally, performance verification was conducted. After fabricating the physical sample, the antenna's S-parameters and radiation pattern were first measured in a microwave anechoic chamber to verify its impedance characteristics and gain performance. Then, the scattering characteristics at different incident angles were measured using a single-station RCS testing system.

[0045] Test results show that the antenna achieves significant RCS reduction in the 7–32 GHz range and maintains good performance stability even at a large incident angle of 60°. Radiation performance tests show that the antenna gain only slightly decreases after loading the SSPP metasurface, and the radiation pattern shows no significant distortion, proving that the invention achieves excellent stealth performance while maintaining radiation performance.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A radiation-integrated low RCS antenna with high angular stability, characterized in that: The structure includes an artificial surface plasmon metasurface, a metasurface array, and a slot-coupled feeding network. The three layers are of the same size and are stacked from top to bottom. The artificial surface plasmon metasurface reduces the RCS by absorbing waves. The metasurface array reduces the RCS by phase cancellation. The slot-coupled feeding network feeds the metasurface array through a microstrip line.

2. The high-angle-stability integrated low-RCS antenna according to claim 1, characterized in that: The surface plasmon metasurface is composed of gradient comb-shaped metal strips, the length of which gradually increases from top to bottom, and is printed on an FR-4 substrate with a dielectric constant of 4.

3.

3. The high-angle-stability integrated low-RCS antenna according to claim 1, characterized in that: The metasurface array consists of two metasurface units arranged in a checkerboard pattern to form an 8-row × 8-column array. Each metasurface unit includes a bimetallic layer and a bilayer dielectric structure, and the phase difference between the reflected waves from the two units when incident perpendicularly is 180° ± 37°.

4. The high-angle-stability integrated low-RCS antenna according to claim 1, characterized in that: The metal layers of the metasurface unit are circular metal structures with different radii, and are arranged in a centrally symmetrical manner.

5. The high-angle-stability integrated low-RCS antenna according to claim 3, characterized in that: The slot-coupled power supply network includes a microstrip power divider, which is a two-way power divider with a 180° phase difference between its two output ports, and is printed on an F4B substrate with a dielectric constant of 2.

2.

6. A method for designing a radiation-integrated low RCS antenna with high angular stability, characterized in that: The method includes the following steps: The RCS reduction frequency range is determined to cover the C-band, X-band, Ku-band, K-band, and Ka-band; Two metasurface units are designed so that the reflected wave has a phase difference of 180°±37° when it is incident perpendicularly and the reflection performance is stable when it is incident obliquely. The power supply network is designed to have a 180° phase difference between its two output ports; Design the parameters of the bottom metal slots of the metasurface array to match the feeding network; The absorption band of the surface plasmon metasurface is set far away from the antenna operating band and does not block the metasurface array. Verify the antenna's radiation performance and RCS reduction performance.

7. The design method according to claim 6, characterized in that: The metal structure of the metasurface unit is centrosymmetric and has good radiation capability.

8. The design method according to claim 6, characterized in that: The verification of radiation performance includes comparing the radiation pattern performance of loaded and unloaded surface plasmon metasurface structures.

9. The design method according to claim 6, characterized in that: The verification of RCS reduction performance includes performance verification under conditions of vertical incidence, 30° oblique incidence, 45° oblique incidence, and 60° oblique incidence.

10. The design method according to claim 6, characterized in that: The surface artificial plasmon metasurface is composed of gradient comb-shaped metal strips, the length of which gradually increases from top to bottom, and together with the metasurface array, it achieves ultra-wideband RCS reduction.

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