Wave-absorbing metasurface low-profile wide-angle RCS reduction tight coupling dipole antenna

Abstract

The invention discloses a wave-absorbing metasurface low-profile wide-angle RCS (radar cross section) reduction tight coupling dipole antenna. The array is composed of a radiation layer, a middle layer, a wave-absorbing metasurface layer and a metal ground layer. The top layer of the radiation layer is a dipole antenna, and the tail ends of radiation arms of the dipole antenna are loaded with coupling patches through metal through holes; the middle layer is a dielectric substrate; the top layer of the wave-absorbing metasurface layer is a pair of symmetrical trident-shaped resistive films loaded with metal through holes, and the bottom layer of the wave-absorbing metasurface layer is a dielectric substrate; the metal ground layer is located at the lowermost layer. According to the invention, the wave-absorbing metasurface is embedded in the tight coupling dipole array antenna to replace a traditional metal ground, so that a low-profile structure is realized. According to the antenna, within the frequency band of 7-14 GHz, the wave absorbing efficiency is higher than 75% when electromagnetic waves are incident at the wide angle of 0-60 degrees, meanwhile, good radiation performance and wide-angle scanning capacity are kept, and the radar cross section is remarkably reduced. The method can be popularized to the low radar cross section design of a traditional antenna, and is suitable for radar and wireless communication systems.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a low-profile wide-angle RCS (Radar Cross Section) reduced tightly coupled dipole antenna with an absorbing metasurface. Background Technology

[0002] Stealth technology plays a crucial role in modern electronic warfare. Radar cross-section reduction (RCS) technology can lower the radar signature of military targets, forcing enemy electronic detection systems and weapon platforms to reduce their combat effectiveness, thereby enhancing the penetration and survivability of our military forces. Array antennas generally have a large radiating aperture, resulting in a large radar cross-section, making them easily detectable by radar. Therefore, reducing the radar cross-section of array antennas is essential for improving the stealth performance of the entire communication system.

[0003] Tightly coupled dipole array antennas, with their advantages of low profile and wide bandwidth scanning radiation performance, have become ideal candidates for next-generation phased array systems. However, their excellent radiation characteristics are accompanied by significant electromagnetic scattering, which greatly limits their application on stealth platforms. Existing techniques for reducing the RCS of array antennas mainly include: loading absorbing materials, frequency selective surfaces (FSS), and artificial magnetic conductors (AMC).

[0004] Therefore, while studying its radiation performance, exploring effective wide-angle radar cross section reduction techniques is crucial for broadening its application value and achieving an integrated trade-off between radiation and scattering performance. How to achieve RCS reduction over a wide angle range while maintaining the low profile and broadband radiation performance of tightly coupled dipole array antennas is a pressing technical problem to be solved in this field. Summary of the Invention

[0005] Technical issues:

[0006] The purpose of this invention is to design an array antenna with a low profile and wide bandwidth scanning angle, while also possessing the advantages of wide-angle radar cross-section reduction performance, low cost, and lightweight design.

[0007] Technical solution:

[0008] This invention provides a low-profile, wide-angle RCS-reduced, tightly coupled dipole antenna with a microwave-absorbing metasurface. The antenna is composed of a radiating layer, an intermediate layer, a microwave-absorbing metasurface layer, and a metal ground layer. The top layer of the radiating layer is a dipole antenna, with a coupling patch loaded at the end of the radiating arm through a metal via. A dielectric substrate is sequentially positioned below the dipole antenna. The intermediate layer is also a dielectric substrate. The top layer of the microwave-absorbing metasurface consists of a pair of symmetrical trident-shaped resistive film structures, each with a metal via in the center, and a dielectric substrate is positioned below them. The metal ground layer is located at the bottom layer.

[0009] The tightly coupled dipole array antenna consists of a dipole antenna, a coupling patch, a metal probe, and a metal via. The coupling patch is connected to the end of the radiating arm of the dipole antenna through the metal via, the metal probe is connected to the beginning of the radiating arm of the dipole antenna to feed the dipole antenna, and the metal via connects the other arm of the dipole antenna to the metal ground.

[0010] The aforementioned absorbing metasurface structure consists of a pair of symmetrical trident-shaped resistive films, with a metal via loaded in the middle of each resistive film structure.

[0011] Furthermore, in the symmetrical trident-shaped resistive film structure, the end of each trident branch is an open structure, with a metal through-hole located at the central intersection of the tridents and perpendicularly penetrating the dielectric substrate to connect to the metal ground. This array antenna consists of multiple elements arranged periodically along the E-plane and H-plane, with the first and last rows in the E-direction designated as sub-elements that do not participate in radiation, thus reducing edge truncation effects. The dielectric substrates are all made of F4B material with thicknesses of 0.5mm, 1.4mm, and 3.3mm, respectively. This invention achieves an absorption efficiency of no less than 75% with wide-angle incidence of 0°~60° within the 7-14GHz frequency band, a main polarization gain loss of less than 1.5dB, a maximum vertical incidence RCS reduction of 36.5dB, and beam scanning of ±50° E-plane and ±55° H-plane.

[0012] Beneficial effects:

[0013] Compared to the traditional method of loading an absorbing metasurface onto the outside of a tightly coupled dipole array antenna structure, this invention is the first to attempt loading the absorbing metasurface inside the tightly coupled dipole array antenna structure, replacing the original metallic ground structure. This significantly reduces the structural cross-section of the tightly coupled dipole array antenna and simplifies the array architecture. Furthermore, the tightly coupled dipole array antenna based on the absorbing metasurface proposed in this invention exhibits wide-bandwidth angle-scanning radiation performance, while simultaneously achieving radar cross-section reduction over a wide angle range. These advantages make it a promising candidate for applications in radar and wireless communication systems. Specifically:

[0014] This invention achieves a low profile design by embedding the absorbing metasurface between the radiating layer and the metal ground layer, with an overall profile height of only 5.2 mm (0.5 mm for the radiating layer dielectric substrate, 1.4 mm for the intermediate layer, and 3.3 mm for the absorbing metasurface layer dielectric substrate), which facilitates conformal installation.

[0015] Within the 7-14GHz operating frequency band, when electromagnetic waves are incident at a wide angle of 0° to 60°, the absorption efficiency is no less than 75%, achieving wide-angle broadband absorption and effectively reducing the radar cross-section.

[0016] The main polarization gain loss is less than 1.5dB, and the E-plane scanning range reaches ±50° and the H-plane scanning range reaches ±55° at 10GHz, maintaining the wide bandwidth angle scanning capability of the tightly coupled dipole array antenna.

[0017] When electromagnetic waves are incident perpendicularly, the radar cross section is reduced by a maximum of 36.5 dB. Under oblique incidence conditions of 20°, 40°, and 60°, it can still achieve broadband RCS reduction within the operating frequency band, thus possessing wide-angle stealth capability.

[0018] By setting sub-elements (which do not participate in radiation) at both ends of the E direction, the array edge truncation effect is effectively reduced, and the consistency of radiation and scattering performance of large-aperture arrays is improved. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the tightly coupled dipole array antenna based on the absorbing metasurface of the present invention; wherein, (a) is a front view of the radiating layer dipole antenna; and (b) is a front view of the absorbing metasurface layer.

[0020] Figure 2 A layered structural diagram of a tightly coupled dipole array antenna element based on an absorbing metasurface is presented.

[0021] Figure 3 The absorption efficiency curve of a tightly coupled dipole array antenna element under wide-angle electromagnetic wave incidence is given.

[0022] Figure 4 A comparison diagram of the main polarization gain of the tightly coupled dipole array antenna of the present invention within the operating frequency band is provided.

[0023] Figure 5 The scanning patterns of the tightly coupled dipole array antenna at 10 GHz are given. (a) is the E-plane scanning pattern and (b) is the H-plane scanning pattern.

[0024] Figure 6 The radar cross section (RCS) performance diagrams of the tightly coupled dipole array antenna of the present invention are given. Among them, (a) is a comparison of the RCS performance of the antenna with and without the absorbing metasurface in the operating frequency band when the electromagnetic wave is incident perpendicularly; (b) is a comparison of the RCS performance of the two antennas at 8 GHz when the electromagnetic wave is incident over a wide angle range (0°~60°); (c) is a comparison of the RCS performance of the two antennas in the operating frequency band when the electromagnetic wave is incident at a 20° oblique angle; (d) is a comparison of the RCS performance of the two antennas in the operating frequency band when the electromagnetic wave is incident at a 40° oblique angle; and (e) is a comparison of the RCS performance of the two antennas in the operating frequency band when the electromagnetic wave is incident at a 60° oblique angle.

[0025] The diagram includes: a dipole antenna 1; a metal probe 1-2; a metal via 1-3; an interlayer metal via 1-4; and a coupling patch 1-5.

[0026] Microwave-absorbing metasurface 4: a pair of symmetrical trident-shaped resistive film structures 4-1, and two central metal through holes 4-2;

[0027] Upper dielectric substrate 2, middle dielectric substrate 3, lower dielectric substrate 5, and metal ground layer 6. Detailed Implementation

[0028] The present invention relates to a low-profile, wide-angle radar cross-section reduction, tightly coupled dipole array antenna based on an absorbing metasurface, which consists of a dipole antenna and an absorbing metasurface. The absorbing metasurface is loaded inside the dipole antenna, achieving low-profile performance. The absorbing metasurface consists of a pair of symmetrical trident-shaped resistive films, with a metal through-hole loaded in the middle of each resistive film structure. It has good absorption performance in the 7-14 GHz range when electromagnetic waves are incident over a wide angle. At the same time, the trident shape of the resistive films reduces their impact on the radiation performance of the dipole antenna, resulting in wide-bandwidth, wide-angle scanning radiation performance in the 7-14 GHz range.

[0029] The dipole antenna can be divided into two layers: a radiating layer and a metal ground layer. The radiating layer consists of a pair of dipole antennas 1-1, a grounding metal via 1-3, a metal probe 1-2, and a coupling patch 1-5. The metal probe 1-2 is connected to the beginning of the radiating arm of the dipole antenna 1-1. The grounding metal via 1-3 is used to connect the other arm of the dipole antenna 1-1 to the metal ground layer 6. The coupling patch 1-5 is connected to the end of the radiating arm of the dipole antenna 1-1 through a metal via 1-4. The metal probe 1-2 passes sequentially through the upper dielectric substrate 2, the middle dielectric substrate 3, and the lower dielectric substrate 5 and connects to the coaxial connector (an SMP connector is used in this embodiment). A clearance hole is provided at the corresponding position on the metal ground layer 6 to keep the metal probe insulated from the metal ground layer.

[0030] The aforementioned absorbing metasurface consists of a pair of symmetrical trident-shaped resistive film structures 4-1, with a metal via 4-2 loaded in the center of each resistive film structure 4-1. In each of the symmetrical trident-shaped resistive film structures 4-1, the ends of each trident branch are open structures. The metal via 4-2 is located at the central intersection of the tridents and vertically penetrates the lower dielectric substrate 5 to connect to the metal ground layer 6. The symmetrical trident-shaped resistive film structure 4-1 reduces the impact of the absorbing metasurface on the antenna radiation performance and exhibits good absorption performance in the 7-14 GHz range.

[0031] In this invention, the tightly coupled dipole array antenna with low profile and wide-angle radar cross-section reduction based on an absorbing metasurface is composed of antenna elements arranged along the E-plane and H-plane, respectively. The antenna elements in the first and last rows of the E-plane are designated as sub-elements, which do not participate in the radiation of the tightly coupled dipole array antenna, thus reducing the influence of array edge truncation effects. The structure of the sub-elements is the same as that of the radiating elements, but their metal probes are suspended and not fed, and the grounded metal vias are still connected to the metal ground layer. The absorbing metasurface layer remains intact to simulate the boundary conditions of an infinitely large array.

[0032] Figure 1 The structural diagram of a low-profile wide-angle radar cross-section reduced tightly coupled dipole array antenna based on an absorbing metasurface is given. Figure 1 (a) shows the structure of the upper dipole antenna, and (b) shows the structure of the absorbing metasurface. Figure 2 A layered structure diagram of a tightly coupled dipole array antenna element with an absorbing metasurface is presented. The array structure consists of four layers: a radiating layer 1, an intermediate layer 3, an absorbing metasurface layer 4, and a metallic ground layer 6. The upper dielectric substrate 2 of the radiating layer is a 0.5 mm thick F4B dielectric substrate. The intermediate layer 3 is a 1.4 mm thick F4B dielectric substrate, used to adjust the electromagnetic coupling strength between the radiating layer and the absorbing metasurface layer and to support the overall structure. The lower dielectric substrate 5 of the absorbing metasurface layer is a 3.3 mm thick F4B dielectric substrate.

[0033] A coupling patch 1-5 is loaded at the end of the radiating arm of the dipole antenna 1-1 through a metal via 1-4. The first radiating arm of the dipole antenna 1-1 is connected to a metal probe 1-2, and the second radiating arm of the dipole antenna 1-1 is connected to a metal ground layer 6 through a grounding metal via 1-3. The metal probe 1-2 passes through the upper dielectric substrate 2, the middle dielectric substrate 3, and the lower dielectric substrate 5, and then connects to the bottom SMP connector.

[0034] In this embodiment, the periodic spacing of the antenna elements in the E and H directions is 12.8 mm and 12.4 mm, respectively. At both ends of the E direction, the first and last rows are set as sub-elements. These sub-elements are not connected to the feed signal and do not participate in radiation. They are only used to simulate the boundary conditions of an infinite array and reduce the impact of edge truncation effect on the performance of the internal radiating elements.

[0035] Figure 3 The absorption efficiency of a tightly coupled dipole array antenna element under wide-angle electromagnetic wave incidence is presented. When electromagnetic waves are incident from 0° to 60°, the antenna element achieves an absorption efficiency of over 75% in the 7-14 GHz range.

[0036] Figure 4The radiation performance of the tightly coupled dipole array antenna is presented. Compared with the main polarization gain curve of the tightly coupled dipole array antenna without an absorbing metasurface, the gain curve trend of the tightly coupled dipole array antenna with an absorbing metasurface is more consistent within the operating frequency band, and the gain loss is within 1.5 dB. This indicates that the absorbing metasurface has a certain impact on the radiation performance of the designed tightly coupled dipole antenna, but the decrease in radiation performance is not significant throughout the operating frequency band, and it still maintains a high radiation efficiency within the operating frequency band.

[0037] Figure 5 The scanning pattern of a tightly coupled dipole array antenna at 10 GHz is presented. The designed tightly coupled dipole antenna achieves ±50° beam scanning in the E-plane and ±55° scanning performance in the H-plane. This demonstrates that the designed array antenna has good radiation performance within the operating frequency band.

[0038] Figure 6 The scattering performance of a tightly coupled dipole array antenna is presented. The measured and simulated frequency response curves of the radar cross-section of the array antenna with and without an absorbing metasurface are compared when electromagnetic waves are incident perpendicularly. Figure 6 As shown in (a), the results demonstrate that the array antenna with the absorbing metasurface achieves a significant reduction in radar cross section (RCS) compared to the reference array antenna in the 7-14 GHz range, with a maximum reduction of 36.5 dB. The ability of this design method to reduce RCS within a certain angular domain was investigated. Taking 8 GHz as an example, the measured RCS reduction performance of the array antenna with the absorbing metasurface and the reference array antenna (without the absorbing metasurface) under oblique electromagnetic wave incidence is shown in (a). Figure 6 As shown in (b), the array antenna with the absorbing metasurface has a significant radar cross section reduction effect in the incident angle range of 0° to 60° compared to the reference array antenna. Figure 6 Figures (c), (d), and (e) show the radar cross-section curves of the reference array antenna and the designed array antenna as a function of frequency when electromagnetic waves are incident at angles of 20°, 40°, and 60°, respectively. It can be seen that under large-angle oblique incidence, the loaded absorbing metasurface can achieve good radar cross-section reduction performance over a wide bandwidth. The measured and simulated radar cross-section curves are in good agreement. However, errors in sample fabrication and assembly, as well as the tilt of the sample's elevation plane during testing causing angular shifts in the incident electromagnetic waves, can lead to discrepancies between the measured and simulated results. Figure 6 The results demonstrated that loading an absorbing metasurface into the array antenna structure can effectively suppress the radar cross section of the array antenna.

[0039] In summary, this invention provides a low-profile, broadband, wide-angle radar scattering reduction tightly coupled dipole array antenna that achieves scanning performance of ±50° / ±55° in the E / H plane. It also achieves excellent radar scattering reduction performance when electromagnetic waves are incident within a ±60° range. This array exhibits excellent scanning and radiation performance, along with good radar scattering reduction, and boasts advantages such as low cost and low profile, making it a promising candidate for applications in radar and wireless communication.

[0040] The above description is merely a preferred embodiment of the present invention. It should be noted that any modifications made by those skilled in the art without departing from the principles of the present invention should be within the scope of protection of the present invention.

Claims

1. A microwave-absorbing metasurface low-profile wide-angle RCS-reduced tightly coupled dipole antenna, characterized in that, From bottom to top, the layers are: metallic stratum (6), microwave absorbing metasurface layer (4), intermediate layer (3) and radiation layer (1). in, The radiating layer (1) includes a top dipole antenna (1-1) and an upper dielectric substrate (2) below it. A coupling patch (1-5) is loaded at the end of one radiating arm of the dipole antenna (1-1) through a metal through-hole (1-4). The intermediate layer (3) is an intermediate dielectric substrate; The microwave absorbing metasurface layer (4) includes a top resistive film structure and a lower dielectric substrate (5) below it. The resistive film structure is a pair of symmetrical trident-shaped resistive film structures (4-1), and a metal through hole (4-2) is loaded at the center of each resistive film structure (4-1). The metal ground layer (6) is located on the lower surface of the lower dielectric substrate (5); The absorbing metasurface layer (4) is loaded between the dipole antenna (1-1) and the metal ground layer (6) to absorb incident electromagnetic waves to reduce the radar cross section and maintain the low profile of the antenna.

2. The absorbing metasurface low-profile wide-angle RCS-reduced tightly coupled dipole antenna according to claim 1, characterized in that, The dipole antenna (1-1) has two radiating arms, wherein the beginning of the first radiating arm is connected to a metal probe (1-2) for feeding, and the second radiating arm is connected to the metal ground layer (6) through a grounded metal through-hole (1-3).

3. The absorbing metasurface low-profile wide-angle RCS-reduced tightly coupled dipole antenna according to claim 1, characterized in that, The coupling patch (1-5) is connected to the end of one of the radiating arms of the dipole antenna (1-1) through the metal through hole (1-4) to enhance the tight coupling effect between antenna elements.

4. The absorbing metasurface low-profile wide-angle RCS-reduced tightly coupled dipole antenna according to claim 1, characterized in that, In the symmetrical trident-shaped resistive film structure (4-1), the end of each trident branch is an open structure, and the metal through hole (4-2) is located at the center intersection of the tridents and vertically penetrates the lower dielectric substrate (5) to connect to the metal ground layer (6).

5. The absorbing metasurface low-profile wide-angle RCS-reduced tightly coupled dipole antenna according to claim 1, characterized in that, The antenna consists of an array of multiple antenna elements arranged periodically along the E and H planes; wherein, in the E direction, the antenna elements in the first and last rows are set as sub-elements, which do not participate in radiation and are used to reduce the array edge truncation effect.

6. The absorbing metasurface low-profile wide-angle RCS-reduced tightly coupled dipole antenna according to claim 1, characterized in that, The upper dielectric substrate (2), the middle dielectric substrate (3) and the lower dielectric substrate (5) are all F4B dielectric substrates; the thickness of the upper dielectric substrate (2) is 0.5 mm, the thickness of the middle dielectric substrate (3) is 1.4 mm, and the thickness of the lower dielectric substrate (5) is 3.3 mm.

7. The absorbing metasurface low-profile wide-angle RCS-reduced tightly coupled dipole antenna according to claim 1, characterized in that, The antenna operates in the 7-14 GHz frequency band; when electromagnetic waves are incident at a wide angle of 0° to 60°, the absorption efficiency is not less than 75%; the main polarization gain loss is less than 1.5 dB; at 10 GHz, the E-plane scanning range reaches ±50° and the H-plane scanning range reaches ±55°; when electromagnetic waves are incident perpendicularly, the maximum reduction in radar cross section is 36.5 dB.

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