A dual-band high-gain metasurface antenna for radar imaging

Abstract

This solution provides a dual-band high-gain metasurface antenna for radar imaging, comprising a metasurface layer, a first dielectric layer, a microstrip patch layer, a second dielectric layer, and a ground layer, arranged in sequence from top to bottom. The metasurface layer is a patch group consisting of multiple rectangular patches arranged in a rhombus, and the rectangular patches located on the diagonals of the patch group are etched with gaps corresponding to the diagonals of the patch group. The microstrip patch layer includes an SIW cavity, a feed line located at the bottom of the SIW cavity, and the metal surface at the top of the SIW cavity is a top microstrip patch containing a T-shaped power divider. The area of ​​the second dielectric layer corresponding to the microstrip patch layer is provided with a SIW array through-hole and a center short-circuit through-hole group. The metasurface antenna has wide bandwidth, high gain, low sidelobes, and good out-of-band suppression, and is suitable for high-speed communication and target detection in radar imaging.

Description

Technical Field

[0001] The present invention relates to the field of antenna design, and in particular to a dual-band high-gain metasurface antenna for radar imaging. Background Art

[0002] Antennas are key components in radio systems for transmitting and receiving electromagnetic waves, and their performance plays a decisive role in the overall quality of communication and detection systems. The advancement of radar technology toward higher resolution and precision, particularly in complex applications such as autonomous driving, security monitoring, and aerospace, places higher demands on radar imaging systems for image clarity, target recognition, and environmental adaptability. However, traditional radar antennas still have significant deficiencies in operating bandwidth, gain, beam steering capabilities, and compactness, severely hindering further improvements in system performance.

[0003] Metasurface (MTS), a two-dimensional electromagnetic functional material composed of periodic or non-periodic artificially designed microstructure units, has attracted widespread attention in recent years in the fields of radar imaging, stealth technology, and communication systems due to its high flexibility in controlling the phase, amplitude, polarization, and direction of electromagnetic waves. By precisely designing the metasurface unit structure, functions such as beam scanning, wavefront control, gain enhancement, and bandwidth expansion can be achieved, thus providing a new solution for high-performance radar imaging systems.

[0004] Substrate Integrated Waveguide (SIW) technology, as a feeding structure that combines the advantages of traditional metal waveguides and microstrip circuits, has significant advantages such as low loss, high quality factor, and easy integration and manufacturing. It has gradually become an ideal transmission method in the new generation of high-frequency communications and radar systems. Combining SIW technology with metasurface structures can not only effectively improve the radiation efficiency and frequency band performance of antennas, but also optimize the compactness and integration of antenna structures, meeting the requirements of radar imaging for miniaturization and high performance.

[0005] The patent with publication number "CN118137116A" discloses a substrate-integrated cavity metasurface antenna, which combines a substrate-integrated cavity with a metasurface structure to achieve multi-mode resonance and uses SIW as a feeding structure, thereby improving the bandwidth and gain of the antenna. However, the solution uses an upper substrate-integrated cavity and a lower SIW structure, which increases the complexity of the antenna. The patent with publication number "CN116365251A" discloses a millimeter-wave dual-band circularly polarized metasurface antenna based on substrate-integrated waveguide feeding. The antenna combines a metasurface and an SIW dual-band T-shaped slot antenna, and uses the SIW slot antenna as an excitation structure to excite the characteristic mode of the metasurface to achieve a dual-band effect. However, this solution does not introduce new SIW resonant modes by etching slots on the SIW. The resonance point of the SIW is limited by the size of the cavity, making it difficult to excite the characteristic mode of the metasurface within a wide bandwidth, resulting in a narrow bandwidth and low gain of the antenna. Summary of the Invention

[0006] The purpose of the present invention is to provide a dual-band high-gain metasurface antenna for radar imaging, which has wide bandwidth, high gain, low sidelobes and good out-of-band suppression effect, and is suitable for high-speed communication and target detection in radar imaging.

[0007] To achieve the above objectives, the present technical solution provides a dual-band high-gain metasurface antenna for radar imaging, comprising a metasurface layer, a first dielectric layer, a microstrip patch layer, a second dielectric layer and a ground layer arranged in sequence from top to bottom, wherein the metasurface layer is a patch group composed of multiple rectangular patches arranged in a diamond shape, and the rectangular patches located on the diagonals of the patch group are etched with gaps identical to the diagonals of the patch group; wherein the microstrip patch layer includes a SIW cavity, a feed line located at the bottom of the SIW cavity, and the metal surface at the top of the SIW cavity is a top microstrip patch containing a T-shaped power divider; the area corresponding to the microstrip patch layer on the second dielectric layer is provided with a SIW array through hole and a center short-circuit through hole group.

[0008] Compared with the existing technology, this technical solution has the following characteristics and beneficial effects:

[0009] This dual-band, high-gain metasurface antenna for radar imaging achieves breakthroughs in wideband, high gain, compact structure, and anti-interference capabilities through the innovative fusion of metasurface and SIW technologies. This significantly improves the communication efficiency and target detection accuracy of radar imaging systems, and possesses strong engineering application value. This dual-band, high-gain metasurface antenna for radar imaging boasts wideband and high gain characteristics, meeting the requirements of complex scenarios. Through the collaborative design of the metasurface layer (including rectangular patches of varying sizes) and the SIW structure, it achieves broadband operation in the 7.4-9.4 GHz and 13.3-14.6 GHz frequency bands, covering both high and low frequency bands commonly used by radars, making it suitable for target detection and communication in multiple scenarios. Its in-band gain reaches 5.4-8.2 dBi (low-band) and 5.6-8.2 dBi (high-band), significantly improving energy radiation efficiency compared to traditional antennas and enhancing the radar's ability to detect long-range targets. It also has the advantages of excellent radiation performance and strong anti-interference ability: the main polarization pattern presents sharp beams at 8.4GHz and 14.0GHz, with significant sidelobe suppression effect, reducing environmental clutter interference and improving radar imaging resolution; the cross-polarization pattern shows low polarization leakage to ensure the purity of signal transmission, making it suitable for radar communication scenarios that are sensitive to polarization. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a structural schematic diagram of a dual-band high-gain metasurface antenna designed by the present invention for radar imaging.

[0011] Figure 2 This is a structural schematic diagram of the metasurface layer of a dual-band high-gain metasurface antenna designed by the present invention for radar imaging.

[0012] Figure 3 This is a structural schematic diagram of the microstrip patch layer of a dual-band high-gain metasurface antenna designed by the present invention for radar imaging.

[0013] Figure 4 This is a side view of a metasurface antenna designed by the present invention, which is a dual-band high-gain metasurface antenna for radar imaging.

[0014] Figure 5 This is a back view of a dual-band high-gain metasurface antenna designed by the present invention for radar imaging.

[0015] Figure 6 This is a top view of a metasurface antenna designed by the present invention, which is a dual-band high-gain metasurface antenna for radar imaging.

[0016] Figure 7 This is a modal significance MS curve diagram of the characteristic modes at low frequencies and high frequencies of a dual-band high-gain metasurface antenna designed for radar imaging in the present invention.

[0017] Figure 8 This is a surface current distribution diagram of eight characteristic modes of a dual-band high-gain metasurface antenna designed by the present invention for radar imaging.

[0018] Figure 9 The present invention is a dual-band high-gain metasurface antenna input impedance Z11 for radar imaging.

[0019] Figure 10 The invention discloses a SIW resonant electric field without microstrip patch of a dual-band high-gain metasurface antenna for radar imaging.

[0020] Figure 11 The invention discloses a SIW resonant electric field containing a microstrip patch of a dual-band high-gain metasurface antenna for radar imaging.

[0021] Figure 12 It is the surface current on the metasurface of the resonance modes Z1 and Z2 of a dual-band high-gain metasurface antenna designed by the present invention for radar imaging.

[0022] Figure 13 This is a graph showing the return loss S11 and gain curve of a dual-band high-gain metasurface antenna for radar imaging designed by the present invention.

[0023] Figure 14 The present invention discloses the main polarization and cross-polarization radiation patterns of a dual-band high-gain metasurface antenna for radar imaging at 8.4 GHz and 14.0 GHz.

[0024] In the accompanying drawings: 10-super surface layer, 11-patch group, 111-rectangular patch, 20-first dielectric layer, 30-microstrip patch layer, 31-feed line, 32-top microstrip patch, 33-SIW cavity, 40-second dielectric layer, 41-center short-circuit through-hole group, 42-SIW array through-hole, 50-ground layer. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] It should be understood by those skilled in the art that, in the disclosure of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, which 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, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0027] Example 1

[0028] This solution provides a dual-band high-gain metasurface antenna for radar imaging, including:

[0029] The super surface layer 10, the first dielectric layer 20, the microstrip patch layer 30, the second dielectric layer 40 and the ground layer 50 are arranged in sequence from top to bottom, wherein the super surface layer 10 is a patch group 111 composed of multiple rectangular patches 111 arranged in a diamond shape, and the rectangular patches 111 located on the diagonal of the patch group 111 are etched with gaps identical to the diagonal of the patch group 111; wherein the microstrip patch layer 30 includes an SIW cavity 33, a feed line 31 located at the bottom of the SIW cavity 33, and the metal surface at the top of the SIW cavity 33 is a top microstrip patch 32 containing a T-type power divider; the area of ​​the second dielectric layer 40 corresponding to the microstrip patch layer 30 is provided with a SIW array through hole 42 and a center short-circuit through hole group 41.

[0030] This solution's dual-band high-gain metasurface antenna for radar imaging combines SIW and MTS technologies to achieve wide-bandwidth, high-gain dual-band effects in the 7.4-9.4 GHz and 13.3-14.6 GHz frequency bands. Its in-band gains are 5.4-8.2 dBi and 5.6-8.2 dBi, respectively. It exhibits excellent performance and is suitable for efficient communication and target detection in radar imaging systems.

[0031] Specifically, such as Figure 2 As shown, regarding the metasurface layer 10 of the dual-band high-gain metasurface antenna for radar imaging of the present invention:

[0032] In this embodiment, the metasurface layer 10 is located at the center of the first dielectric layer 20, and the metasurface layer 10 is arranged in a staggered direction with the first dielectric layer 20. In other words, the first dielectric layer 20 is designed to be rectangular, and the diamond-shaped sides of the patch group 11 of the metasurface layer 10 are arranged at an angle to the rectangular sides of the first dielectric layer 20, and the center of the patch group 11 overlaps with the center of the first dielectric layer.

[0033] Adjacent rectangular patches 111 within the metasurface layer 10 of this embodiment are spaced apart, and the distances between rectangular patches 111 in the same row and those in adjacent rows are the same, and the distances between rectangular patches 111 in the same column and those in adjacent columns are the same, thereby forming vertically staggered horizontal and vertical gaps on the patch group 11. Specifically, the horizontal gaps on the patch group 11 are parallel to the horizontal edges of the patch group 11, and the vertical gaps on the patch group 11 are parallel to the vertical edges of the patch group 11.

[0034] In some specific embodiments, the widths of the horizontal gap and the vertical gap are the same, both 0.5 mm.

[0035] Furthermore, the rectangular patches 111 on the patch group 11 of this solution are axially symmetric with respect to the center position of the patch group 11 . Specifically, the rectangular patches 111 on the patch group 11 are vertically symmetric and left-right symmetric with respect to the center position of the patch group 11 .

[0036] It should be noted that the rectangular patch 111 located on the diagonal of the patch group 11 is etched with a gap that is the same as the diagonal of the patch group 111. The advantage of this is that it can reduce the interference of the magnetic current caused by the upper and lower symmetrical structure, help adjust the phase control and beamforming characteristics of the antenna, and enhance the radiation performance of the antenna.

[0037] In some embodiments, the rectangular patch 111 located on the diagonal of the patch group 11 is located at the center of the excitation structure, and the thickness of the etched gap is 0.5 mm, which is used to cut off the magnetic current to reduce the interference caused by the upper and lower symmetrical structure, thereby helping to optimize the phase control and beamforming characteristics of the antenna, thereby enhancing the radiation performance of the antenna.

[0038] In some embodiments, rectangular patch 111 is rectangular.

[0039] In a specific embodiment, the patch group 11 is composed of 4*4 rectangular patches 111 arranged in a diamond shape. At this time, each row of the patch group 11 is composed of 4 rectangular patches 111, and each column of the patch group 11 is also composed of 4 rectangular patches 111.

[0040] In order to ensure that the metasurface layer 10 can excite characteristic modes in both low-frequency and high-frequency bands, the side length a and spacing b of the rectangular patch 111 of this scheme need to satisfy the following formula: 3*a+2*b=1.5λ, where λ is the wavelength corresponding to the operating frequency.

[0041] In addition, the rectangular patches of the patch group 11 of this solution include a first rectangular patch, a second rectangular patch and a third rectangular patch of unequal sizes, wherein the first rectangular patch P1, the second rectangular patch P2 and the third rectangular patch P3 have different sizes.

[0042] In a specific embodiment of this solution, the first rectangular patch P1 and the third rectangular patch P3 are squares, and the second rectangular patch P2 is a rectangle with a length the same as that of the first rectangular patch P1 and a width the same as that of the third rectangular patch P2.

[0043] In some embodiments, the side length of the first rectangular patch P1 is 5~8 mm, which is used to excite the characteristic mode of the low frequency band; the side length of the third rectangular patch P3 is 3~4 mm, and the third rectangular patch P3 and the cut first rectangular patch P1 jointly excite the characteristic mode of the high frequency band; the second rectangular patch P2 can excite a strong surface current in the low frequency band or the high frequency band, and the second rectangular patch P2 plays a role in balancing the low frequency and high frequency during the frequency band transition.

[0044] Preferably, the side length of the first rectangular patch P1 is 6 mm, and the side length of the third rectangular patch P3 is 4 mm.

[0045] In some embodiments, a plurality of third rectangular patches are arranged in the center of the patch group 11 to form a small square, four first rectangular patches are arranged at the four corners of the patch group 11, and a plurality of second rectangular patches are arranged between the third rectangular patches and the first rectangular patches. Figure 2 In the structure shown, four third rectangular patches are arranged in the center of the patch group 11 to form a small square, four first rectangular patches are arranged at the four corners of the patch group 11, and eight second rectangular patches are arranged between the third rectangular patches and the first rectangular patches.

[0046] In some embodiments, the supersurface layer 10 is metallic copper.

[0047] This solution effectively reduces energy loss and simplifies antenna design and implementation by adjusting the placement angle and design structure of the metal patch 111 of the metasurface layer 10. Furthermore, the rotational placement and slotted design of the metasurface layer 10 effectively adjust the electric and magnetic field distribution, resulting in more uniform radiation performance and lower reflection losses.

[0048] Regarding the first dielectric layer 20 of this solution:

[0049] The first dielectric layer 20 of this solution is used to physically support the metasurface layer 10. In some embodiments, the first dielectric layer 20 is a dielectric substrate of Rogers RT3003 having low loss characteristics in high-frequency transmission, with a thickness of 2.28 mm, to support the structure of the metasurface layer and ensure the stability and efficient transmission of the antenna.

[0050] In this solution, the microstrip patch layer 30, the second dielectric layer 40, and the ground layer 50 form a SIW structure. The SIW structure is used to couple and excite the characteristic modes of the metasurface layer 10 to form the antenna operating frequency band. The SIW structure combines traditional metal waveguide technology with integrated circuit technology. It can effectively transmit electromagnetic waves while being compact and low-loss. The electric field resonance mode of the SIW is designed to excite specific characteristic modes (resonant modes) on the metasurface, thereby achieving control and modulation of electromagnetic waves.

[0051] Regarding the microstrip patch layer 30 of this solution:

[0052] like Figure 4 and Figure 6 As shown, in this embodiment, a top microstrip patch 32 is placed at the center of patch group 11. This allows the top microstrip patch 32 to effectively couple with the eigenmodes of patch group 11, improving the antenna's coupling efficiency and radiation performance. Specifically, the top microstrip patch 32 is positioned corresponding to the diagonal gaps of patch group 11, with the center of symmetry of the top microstrip patch 32 aligned with the center of symmetry of the patch group 11.

[0053] like Figure 3 As shown, the bottom of the microstrip patch layer 30 of this solution is loaded with a feed line 31 to efficiently transmit signals to the SIW structure. In some specific embodiments, the resistance of the feed line 31 is 50Ω.

[0054] It should be noted that one end of the feed line 31 is connected to the SIW cavity 33, and the other end is connected to the side of the second dielectric layer 40, so as to be used for feeding electrical signals through an external impedance-matched SMA port. In some embodiments, the feed line 31 is located on the central axis of the second dielectric layer 40, and the microstrip patch layer 10 has an axisymmetric design structure compared to the feed line 31.

[0055] A top microstrip patch 32 containing a T-type power divider is set on the top of the SIW cavity 33 to achieve more precise excitation so that the energy is effectively coupled to the metasurface layer 10. At this time, the top microstrip patch 32 containing the T-type power divider can be used to excite the characteristic mode of the metasurface layer 10.

[0056] In some embodiments, the SIW cavity 33 is concave with a recessed bottom, the top microstrip patch 32 is T-shaped, and a T-shaped power divider is provided inside the top microstrip patch 32 .

[0057] More specifically, the top microstrip patch 32 is designed to be a T-shaped arrangement of horizontal and vertical strips. The horizontal strips are designed to be dumbbell-shaped, with wider ends and narrower middle widths. The ends and middle of the horizontal strips are chamfered to achieve a good matching effect. In some specific embodiments, the horizontal strips of the top microstrip patch 32 are 28 mm long, 5 mm wide at both ends, and 1.5 mm wide in the middle.

[0058] Regarding the second dielectric layer 40 of this solution:

[0059] The second dielectric layer 40 is a 1.52 mm thick Rogers RT3003 dielectric substrate. An array of metal vias 42 and a center short-circuit via group 41 are inserted into the second dielectric layer 30. The metal vias 42 and the center short-circuit via group 41 connect the ground layer 50 and the microstrip patch layer 30. These vias help optimize the transmission path of electromagnetic waves and control the resonance characteristics of the antenna through electromagnetic coupling, further improving the bandwidth performance of the antenna.

[0060] like Figure 3 and Figure 5 As shown, the area of ​​the second dielectric layer 40 of this solution corresponding to the microstrip patch layer 30 is provided with a SIW array through hole 42 and a central short-circuit through hole group 41, wherein the SIW array through hole 42 is arranged corresponding to the side of the SIW cavity 33, and the central short-circuit through hole group 41 is arranged corresponding to the central axis of the SIW cavity 33 and is located in the middle area of ​​the SIW cavity 33.

[0061] In some embodiments, the central short-circuit through-hole group 41 includes two through-holes spaced apart from each other. In a specific embodiment, the radius of the two through-holes in the central short-circuit through-hole group 41 is 0.5 mm, and the distance between the through-holes is 1.5 mm.

[0062] Regarding the ground layer 50 of this solution:

[0063] The grounding layer 50 of this solution is a grounded plane metal copper layer to ensure a good electromagnetic shielding effect and reduce reflection and radiation losses. Figure 4 As shown, the ground layer 50 and the second dielectric layer 40 have the same size, and the first dielectric layer 20 is smaller than the second dielectric layer 40 .

[0064] In some embodiments, the overall dimensions of the dual-band high-gain metasurface antenna for radar imaging are 42.8 mm * 33.7 mm * 3.83 mm, corresponding to the dimensions of the ground layer 50 and the second dielectric layer 40. Experimental verification has shown that the dual-band high-gain metasurface antenna for radar imaging proposed in this solution achieves wide bandwidth and high gain in the 7.4-9.4 GHz and 13.3-14.6 GHz frequency bands, with in-band gains of 5.4-8.2 dBi and 5.6-8.2 dBi, respectively. This demonstrates excellent performance and is suitable for efficient communication and target detection in radar imaging systems.

[0065] Example 2 Performance Test of Dual-Band High-Gain Metasurface Antenna for Radar Imaging

[0066] According to the design of Example 1, a dual-band high-gain metasurface antenna for radar imaging is obtained, and its structure is as follows:

[0067] Metasurface layer: The surface consists of a patch group consisting of 4×4 rectangular patches arranged in a diamond shape. The rectangular patches in the patch group are numbered P1, P2, and P3 according to their size. P1 and P3 are square patches with side lengths of 6 mm and 4 mm, respectively. The spacing between P1, P2, and P3 is 0.5 mm. The four rectangular patches located in the center of the patch group are at the center of the excitation and are etched with a 0.5 mm wide gap.

[0068] The first dielectric layer is a 2.28 mm thick Rogers RT3003 dielectric substrate with low loss characteristics at high frequency transmission.

[0069] Microstrip patch layer: The bottom is loaded with a 50Ω feed line, the top microstrip patch is 28mm long, 5mm wide at both ends, and 1.5mm wide in the middle. The widths of the two ends and the middle are transitioned by chamfers.

[0070] The second dielectric layer is a 1.52 mm thick Rogers RT3003 dielectric substrate. The area corresponding to the microstrip patch layer is provided with a SIW array through hole and a center short-circuit through hole group. A center short-circuit through hole group is provided in the middle. The radius of the two through holes in the center short-circuit through hole group is 0.5 mm, and the through hole spacing is 1.5 mm.

[0071] Ground layer: metallic copper.

[0072] The modal significance MS curve of the characteristic mode of the dual-band high-gain metasurface antenna for radar imaging at low frequency or high frequency is shown as follows: Figure 7 As shown, Figure 7(a) is the modal significance at low frequency, and (b) is the modal significance at high frequency. It can be seen that the dual-band high-gain metasurface antenna for radar imaging can excite four characteristic modes in both frequency bands and has high modal significance. Therefore, it is proved that the metasurface layer of the diamond-shaped patch group enables the dual-band high-gain metasurface antenna for radar imaging to excite characteristic modes with efficient energy coupling and radiation in different frequency bands, thereby ensuring the good performance of the dual-band high-gain metasurface antenna for radar imaging in the entire working frequency band.

[0073] Further testing of the surface current distribution of the eight characteristic modes of the dual-band high-gain metasurface antenna for radar imaging is shown in the figure below. Figure 8 As shown, the current J 1, J 2, J 3 and J 4 correspond to the surface currents of the four characteristic modes of mode 1, mode 2, mode 3 and mode 4 at 8.4GHz, and the current J 5. J 6. J 7 and J 8 correspond to the surface currents of the four characteristic modes, Mode 5, Mode 6, Mode 7, and Mode 8, at 14.0 GHz. Specifically, the surface current distribution of Modes 1 to 4 exhibits a relatively uniform radiation pattern in the low-frequency band, while Modes 5 to 8 form a more concentrated current distribution in the high-frequency band. This indicates that the dual-band high-gain metasurface antenna for radar imaging can effectively control the propagation characteristics of electromagnetic waves in different frequency bands. The surface current distribution in the low-frequency band is relatively broad, reflecting the radiation characteristics of the dual-band high-gain metasurface antenna for radar imaging at a larger scale. In the high-frequency band, due to the shorter wavelength, the current distribution becomes more concentrated, indicating that the metasurface layer can more precisely control the radiation characteristics at high frequencies. Through this optimized design, the dual-band high-gain metasurface antenna for radar imaging can achieve excellent gain and beamforming capabilities in both high and low frequency bands, meeting the radar imaging system's requirements for wide bandwidth, high gain, and low sidelobes.

[0074] In order to verify the advantages of the structural design of the microstrip patch layer of the dual-band high-gain metasurface antenna for radar imaging, a SIW without a microstrip antenna is designed: the microstrip patch layer of the SIW without a microstrip antenna is not designed with a microstrip patch; a SIW with a microstrip antenna is designed: the SIW with a microstrip antenna is provided with a microstrip patch, but the first dielectric layer and the metasurface layer are not set. The dual-band high-gain metasurface antenna for radar imaging of this scheme is defined as the final antenna; the input impedances of the SIW without a microstrip antenna, the SIW with a microstrip antenna, and the final antenna are obtained as follows: Figure 9 As shown, Figure 10The electric field distribution inside the cavity of SIW without microstrip patch in four electric field resonance modes. Figure 11 The electric field distribution inside the cavity of a SIW with a microstrip patch under six electric field resonance modes is given. It can be seen that the SIW without a microstrip patch excites four electric field resonance modes at 8.6, 12.0, 13.2, and 14.9 GHz: TE120, hybrid mode, half-TE310, and TE320. The TE120 is introduced by inserting a group of short-circuit vias into the cavity, while the hybrid mode is introduced by the synthesis of the TE120 and half-TE310 electric field resonance modes. The SIW with a microstrip patch excites new electric field modes at 9.4 GHz and 14.2 GHz, which are introduced by the full-wavelength mode and 1.5-times-wavelength mode of the microstrip patch. The TE120, hybrid mode, half-TE310, and TE320 excited by the SIW cavity all induce the full-wavelength or 1.5-times-wavelength electric field modes of the top microstrip patch.

[0075] The SIW structure is used to excite the characteristic mode of the metasurface layer to form the antenna operating frequency band. Specifically, the microstrip patch with the electric field mode acts as a radiating element to excite the characteristic mode of the metasurface structure. Therefore, the antenna has a potential operating bandwidth between the 7.9GHz TE120 and the 9.4GHz full-wavelength mode, and between the 12.4GHz half TE310 and TE320. Figure 9 As shown in FIG, the complete antenna after loading the metasurface excites two resonant modes, Z1 and Z2, at 8.2 GHz and 13.6 GHz. These two modes are introduced by the characteristic modes excited by the metasurface.

[0076] Figure 12 It is the surface current on the metasurface of resonant modes Z1 and Z2. By observing the surface current, it can be seen that Z1 is the superposition of modes 3 and 4 in the characteristic mode, while Z2 is the superposition of modes 6 and 7. Although the metasurface layer is located in the center of the microstrip patch, the lower end is affected by the SIW edge electric field to a certain extent, so the current intensity in the lower part of the metasurface layer is stronger.

[0077] Figure 13 is the return loss S of the dual-band high-gain metasurface antenna for radar imaging 11 From the graph of gain, it can be seen that the operating bandwidth of the dual-band high-gain metasurface antenna for radar imaging is 7.4-9.4 GHZ and 13.3-14.6 GHz, and the in-band gain is 5.4-8.2 dBi and 5.6-8.2 dBi, respectively. It has the characteristics of wide bandwidth, high gain, low loss and low profile.

[0078] Figure 14The main polarization and cross-polarization patterns of the dual-band high-gain metasurface antenna for radar imaging at 8.4 GHz and 14.0 GHz demonstrate the radiation performance of the dual-band high-gain metasurface antenna for radar imaging at these two frequencies. At 8.4 GHz, the main polarization pattern exhibits significant directivity, with high gain and small sidelobes; while the cross-polarization pattern indicates that the antenna has good polarization performance at this frequency and significant cross-polarization suppression. At 14.0 GHz, the main polarization pattern maintains a relatively consistent radiation pattern with stable gain performance, while the cross-polarization pattern further verifies that the antenna has a low level of cross-polarization.

[0079] Overall, the dual-band high-gain metasurface antenna for radar imaging exhibits good directivity, polarization performance, and low cross-polarization characteristics within the frequency band, making it suitable for efficient wireless communication systems.

[0080] Those skilled in the art should understand that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] The above embodiments merely illustrate several embodiments of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A dual-band high-gain metasurface antenna for radar imaging, characterized in that: include: The super surface layer (10), the first dielectric layer (20), the microstrip patch layer (30), the second dielectric layer (40) and the ground layer (50) are arranged in sequence from top to bottom. The first dielectric layer (20) is designed to be rectangular. The rhombus side of the patch group (11) of the super surface layer (10) is set at an angle of inclination with the rectangular side of the first dielectric layer (20). The center of the patch group (11) overlaps with the center of the first dielectric layer. The super surface layer (10) is a patch group (11) composed of a plurality of rectangular patches (111) arranged in a rhombus. The rectangular patches of the patch group (11) include first rectangular patches, second rectangular patches of unequal sizes, and the like. Patches and a third rectangular patch, wherein the first rectangular patch, the second rectangular patch and the third rectangular patch have different sizes, the first rectangular patch and the third rectangular patch are squares, the second rectangular patch is a rectangle with a length side the same as the side length of the first rectangular patch and a width side the same as the side length of the third rectangular patch, and a gap the same as the diagonal of the patch group (11) is etched on the rectangular patch (111) located on the diagonal of the patch group (11); wherein the microstrip patch layer (30) includes an SIW cavity (33), a feed line (31) located at the bottom of the SIW cavity (33), and the metal surface at the top of the SIW cavity (33) is a top microstrip patch (32) containing a T-type power divider; and an SIW array through hole (42) and a center short-circuit through hole group (41) are provided in an area corresponding to the microstrip patch layer (30) on the second dielectric layer (40).

2. The dual-band high-gain metasurface antenna for radar imaging according to claim 1, characterized in that: Adjacent rectangular patches (111) in the super surface layer (10) are spaced apart, and the distances between rectangular patches (111) in the same row and rectangular patches (111) in adjacent rows are the same, and the distances between rectangular patches (111) in the same column and rectangular patches (111) in adjacent columns are the same.

3. The dual-band high-gain metasurface antenna for radar imaging according to claim 1, characterized in that: The rectangular patches (111) on the patch group (11) are axially symmetrical with respect to the center position of the patch group (11).

4. The dual-band high-gain metasurface antenna for radar imaging according to claim 1, characterized in that: The first rectangular patch has a side length of 5 to 8 mm and is used to excite the characteristic mode in the low-frequency band; The side length of the third rectangular patch is 3 to 4 mm. The third rectangular patch (P3) and the cut first rectangular patch jointly excite the characteristic mode of the high frequency band.

5. The dual-band high-gain metasurface antenna for radar imaging according to claim 1, characterized in that: The top microstrip patch (32) is placed at the center of the patch group (11).

6. The dual-band high-gain metasurface antenna for radar imaging according to claim 1, characterized in that: The SIW array through holes (42) are arranged corresponding to the sides of the SIW cavity (33), and the central short-circuit through hole group (41) is arranged corresponding to the central axis of the SIW cavity (33) and is located in the middle area of ​​the SIW cavity (33).

7. The dual-band high-gain metasurface antenna for radar imaging according to claim 1, characterized in that: The first dielectric layer (20) and the second dielectric layer (40) are Rogers RT3003 dielectric substrates, and the super surface layer (10) and the ground layer (50) are metal copper.

8. The dual-band high-gain metasurface antenna for radar imaging according to claim 1, characterized in that: The dual-band effect in the 7.4-9.4 GHz and 13.3-14.6 GHz frequency bands has an in-band gain of 5.4-8.2 dBi and 5.6-8.2 dBi, which are used for efficient communication and target detection in radar imaging systems.

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