A dual-band metasurface antenna array for radar imaging

Abstract

The present invention provides a dual-band metasurface antenna array for radar imaging, comprising: at least one metasurface antenna unit arranged in an array, wherein the metasurface antenna unit is arranged from top to bottom: a metasurface layer, on the surface of which a patch group for exciting characteristic modes is laid, the patch group comprises a plurality of square patches laid in a square area and a plurality of right-angled triangle patches arranged at the corners of the square area, and at least one square patch is etched with at least one slit; a first dielectric layer; a seamed ground plate etched with a drum-shaped slit; a second dielectric layer; and a feed line layer, comprising a long feed line and a T-type power divider arranged on the top of the long feed line, which performs well in terms of return loss, gain, radiation pattern, etc., has a wide dual-frequency working bandwidth and significantly high gain, and can meet the application requirements of wireless communications, radar systems and other high-performance signal transmissions.

Description

Technical Field

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

[0002] Antennas are key components of communication systems, and their performance directly determines the performance ceiling of the entire communication system. With the rapid development of wireless communication and radio frequency technology, the demand for higher performance, smaller and more reliable antenna devices is increasing. High-performance antennas can improve signal transmission quality, coverage and data rate, thereby meeting the needs of modern communications for high efficiency and high reliability. Therefore, improving antenna design and improving its performance is an important direction of antenna design technology and communication technology research.

[0003] Metasurface antenna is a new type of antenna technology, which is based on the principle of metasurface and is constructed by a large number of tiny electromagnetic units. Metasurface antenna has excellent electromagnetic wave control ability and can achieve characteristics that traditional antennas cannot achieve, such as ultra-high gain, wide bandwidth and excellent directivity. Using characteristic mode analysis, we can deeply study the radiation characteristics and performance parameters of metasurface antennas, help design more efficient antenna structures, and thus achieve superior performance that traditional antennas cannot achieve. The flexible design of this antenna makes it show great potential in many application fields, especially in wireless communications and radar technology.

[0004] Although metasurface antennas have many advantages, they still face the problem of radiation blind spots in the radiation direction in practical applications. Metasurface antennas are composed of multiple tiny units, and the phase characteristics of these units may cause phase cancellation in specific directions. This problem leads to radiation blind spots in certain specific directions, and the signal strength is significantly reduced, affecting the radiation efficiency and overall performance of the antenna. This phenomenon limits the application of metasurface antennas in high-demand communication environments, and an effective solution is urgently needed.

[0005] In the field of radar communication, multiple operating frequency bands and high gain are key factors to ensure system performance. Multiple operating frequency bands support the use of multiple frequency resources and can adapt to different communication needs; high gain ensures the effective transmission of signals in complex environments. Therefore, the development of metasurface antenna arrays with multiple operating frequency bands and high gain characteristics has become an urgent need to improve the performance of radar communication systems, which has important theoretical significance and significant practical value. Summary of the invention

[0006] The purpose of the present invention is to provide a dual-band metasurface antenna array for radar imaging, which can realize the function of a dual-band antenna and solve the problem of radiation blind spots in the main radiation direction. It can achieve good radiation characteristics within the operating frequency range, has a high directivity, high-gain main lobe and a lower side lobe effect, and achieves a high-gain effect.

[0007] To achieve the above objectives, the present technical solution provides a dual-band metasurface antenna array for radar imaging, comprising: at least one metasurface antenna unit arranged in an array, wherein the metasurface antenna unit is arranged from top to bottom: a metasurface layer, a patch group for exciting characteristic modes is laid on the surface, the patch group includes a plurality of square patches laid in a square area and a plurality of right-angled triangle patches arranged at the corners of the square area, and at least one square patch is etched with at least one slit; a first dielectric layer; a seamed ground plate etched with a drum-shaped slit; a second dielectric layer; and a feed line layer, including a long feed line and a T-type power divider arranged on the top of the long feed line.

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

[0009] The dual-band metasurface antenna array for radar imaging designed in this scheme solves the problem of radiation blind spots: the metasurface layer changes the surface current distribution path by etching gaps on the square patches, thereby reconstructing the radiation field, improving the radiation "blank area" (radiation blind spot) in the main radiation direction that was originally formed due to unreasonable current distribution. The arrangement of different types of square patches destroys the symmetry of the metasurface structure, reduces phase interference between patches, and reduces the phenomenon of radiation blind spots in specific directions.

[0010] The dual-band metasurface antenna array designed in this scheme for radar imaging can achieve high gain and good radiation characteristics: the square patches are used to excite characteristic modes, which can accurately excite characteristic modes that are conducive to achieving good radiation characteristics within the operating frequency range; the right-angled triangle patches are used to enhance surface currents, improve antenna directivity and gain, and the special structural design realizes multi-mode excitation, so that the antenna radiates more concentrated energy in a specific direction, with a high directivity, high-gain main lobe and lower sidelobe effect.

[0011] The dual-band metasurface antenna array for radar imaging designed in this scheme ensures good signal transmission and coupling. A drum-shaped gap is set on the seam grounding plate. Its length and other parameters are designed to meet the virtual open circuit conditions on both sides, ensuring the effective coupling of energy from the feeder layer to the drum-shaped gap, meeting the electromagnetic wave propagation. The gradual change of the width of the drum-shaped gap ensures continuity and smooth transition, effectively reducing reflection loss and improving the overall signal transmission reliability. In addition, a long feeder and a T-type power divider are designed in the feeder layer, which can achieve dual-frequency characteristics in two different working frequency bands. The feeder can excite the corresponding half-wavelength and full-wavelength electric field distribution at a specific frequency, so that the metasurface antenna unit can achieve a specific dual-band effect and achieve good performance within this frequency range. At the same time, the length and other parameters of the long feeder and the T-type power divider meet the resonance conditions, further ensuring the signal transmission effect.

[0012] The metasurface antenna unit and antenna array of the dual-band metasurface antenna array designed in this scheme for radar imaging perform well in terms of return loss, gain, radiation pattern, etc. It has a wide dual-band working bandwidth and significantly high gain, and can meet the application requirements of wireless communications, radar systems and other high-performance signal transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of a dual-band metasurface antenna array designed by the present invention for use in radar imaging.

[0014] Figure 2 It is a structural schematic diagram of a supersurface antenna unit of a dual-band supersurface antenna array designed by the present invention for use in radar imaging.

[0015] Figure 3 It is a structural schematic diagram of a feeder line layer of a supersurface antenna unit of a dual-band supersurface antenna array designed by the present invention for use in radar imaging.

[0016] Figure 4 It is a side view of a supersurface antenna unit of a dual-band supersurface antenna array designed by the present invention for use in radar imaging.

[0017] Figure 5 It is an MS curve diagram of a single supersurface antenna unit of a dual-band supersurface antenna array designed by the present invention for radar imaging under four characteristic modes.

[0018] Figure 6 The present invention discloses a radiation pattern of a single metasurface antenna unit of a dual-band metasurface antenna array for radar imaging before and after optimization in four characteristic modes.

[0019] Figure 7This is a schematic diagram of the electric field distribution of the drum-shaped slot of a single metasurface antenna unit of a dual-band metasurface antenna array designed by the present invention for radar imaging at 7.5 GHz, 9.0 GHz, 10.5 GHz, and 11.5 GHz.

[0020] Figure 8 It is a schematic diagram of return loss and gain of a single metasurface antenna unit of a dual-band metasurface antenna array designed by the present invention for radar imaging.

[0021] Fig. 9 It is a schematic diagram of the supersurface structure of a dual-band supersurface antenna array designed by the present invention for use in radar imaging.

[0022] Fig.10 It is a schematic diagram of the feeding structure of a dual-band metasurface antenna array designed by the present invention for use in radar imaging.

[0023] Fig.11 It is a schematic diagram of return loss and gain of a dual-band metasurface antenna array designed by the present invention for use in radar imaging.

[0024] Fig.12 The invention is a dual-band metasurface antenna array designed for radar imaging with E-plane main polarization and cross-polarization radiation patterns at 8 GHz and 11 GHz.

[0025] In the figure: 10-super surface layer, 11-patch group, 100-square area, 111-square patch, 112-right triangle patch, 20-seam ground plate, 21-drum-shaped gap, 30-feeder layer, 31-long feeder, 32-T-type power divider, 40-first dielectric layer, 50-second dielectric layer. DETAILED DESCRIPTION

[0026] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0027] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "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 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.

[0028] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0029] like Figure 1 As shown, the present invention provides a dual-band metasurface antenna array for radar imaging, comprising:

[0030] At least one metasurface antenna unit arranged in an array, wherein the metasurface antenna unit is arranged from top to bottom:

[0031] A metasurface layer 10, on which a patch group 11 for exciting characteristic modes is laid, the patch group includes a plurality of square patches 111 laid in a square area 100 and a plurality of right-angled triangle patches 112 arranged at the corners of the square area 100, and at least one square patch 111 is etched with at least one slit;

[0032] A first dielectric layer 40;

[0033] A seamed ground plate 20 having a drum-shaped gap 21 etched therein;

[0034] The second dielectric layer 50 ; and the feed line layer 30 , including a long feed line 31 and a T-type power divider 32 disposed on the top of the long feed line 31 .

[0035] The metasurface layer of the dual-band metasurface antenna array for radar imaging provided by this solution is used to cut the surface current by etching one or two slits on the square patch, thereby directly changing the surface current distribution path of the metasurface layer. The change in current distribution will inevitably lead to the reconstruction of the radiation field. The design of the position and number of slits improves the radiation "blank area" (i.e., radiation blind area) in the main radiation direction that may have been formed due to unreasonable current distribution, thereby solving the problem of radiation blind areas in the main radiation direction. In addition, the setting of the patch group and the setting of the vertical analysis can make the radiation energy of the antenna in a specific direction more concentrated, thereby achieving good radiation characteristics within the operating frequency range, with a high directivity, high-gain main lobe and low side lobe effect, and achieving high gain.

[0036] like Figure 2 As shown, the square area 100 of the present scheme is a square area, and a plurality of square patches 111 are distributed in an array to obtain a directional area 100 presenting a square shape. The square patches 111 are used to excite characteristic modes, and thus can accurately excite characteristic modes that are conducive to achieving good radiation characteristics within the operating frequency range; the right-angled triangle patches 112 are used to enhance surface currents and improve the directivity and gain of the antenna. This special structural design realizes multi-mode excitation, reduces the radiation blind spot phenomenon in the main radiation direction, and achieves high gain and stability of the antenna.

[0037] The square patch 111 of this solution is divided into a first square patch without etched slits, a second square patch with a single slit etched, and a third square patch with two slits etched, wherein the second square patch has a surface current in the X-axis or Y-axis direction, and the third square patch has a surface current in the X-axis direction. The arrangement of these patches destroys the symmetry of the metasurface structure, reduces the phase interference between patches, and reduces the radiation blind spot phenomenon in a specific direction. Figure 2 As shown, P1 is the first square patch, P2 is the second square patch, and P3 is the third square patch.

[0038] Specifically, a cross-shaped slit is etched on the third square patch, and a slit set at a diagonal position or an obliquely set slit is etched on the second square patch. The cross-shaped slit is located in the middle of the third square patch and has a gap with the boundary of the third square patch, and the length of the horizontal slit and the vertical slit of the cross-shaped slit are the same. A single slit set at a diagonal position cuts the second square patch into two right triangles of equal area, and a single slit set obliquely cuts the second square patch into two parts of unequal area, a trapezoid and a triangle, and the slit is parallel to the diagonal of the second square patch.

[0039] In some specific embodiments, the patch group 11 includes 9 square patches 111 arranged in a 3*3 array, wherein a third square patch is arranged at the upper right corner and the lower right corner of the 3*3 array, and a second square patch is arranged at the upper left corner, the lower left corner, the position between the upper right corner and the lower right corner, the position between the upper left corner and the upper right corner, and the position between the lower left corner and the lower right corner of the 3*3 array.

[0040] Specifically, a cross-shaped slit is provided on the square patch 111 located at the upper right corner and the lower right corner of the 3*3 array, a single slit is provided at a diagonal position on the square patch 111 located at the upper left corner and the lower left corner of the 3*3 array, a single slit is provided at a diagonal position on the square patch 111 located between the square patches 111 located at the upper right corner and the lower right corner, a single slit is provided at an oblique position on the square patch 111 located between the square patches 111 located at the upper left corner and the upper right corner, and a single slit is provided at an oblique position on the square patch 111 located between the square patches 111 located at the lower left corner and the lower right corner. This scheme sets different types of patterns on square patches 111 at different positions, destroys the symmetry of the metasurface antenna array, reduces phase interference between patches, and reduces the radiation blind spot phenomenon in a specific direction. It can make the surface current on the patch group more finely and diversifiedly adjusted, so that they can more accurately match the requirements of the target characteristic mode when exciting the characteristic mode.

[0041] The single slit on the square patch 111 located at the upper left corner is set along the direction from upper right to lower left, the single slit on the square patch 111 located at the lower right corner is set along the direction from upper left to lower right, and the slit on the square patch 111 between the square patches 111 at the upper right corner and the lower right corner is set along the direction from upper left to lower right; the single slit on the square patch 111 between the square patches 111 at the upper left corner and the upper right corner is set along the direction from upper right to lower left, and the single slit of the square patch 111 between the square patches 111 at the lower left corner and the lower right corner is set along the direction from upper left to lower right.

[0042] In order to enhance the surface current of the metasurface layer 10 to improve the directivity and gain of the antenna, a plurality of right-angled triangular patches 112 are arranged at the corners of the square area 100 on the patch group 11 of the present solution, and the right-angled triangular patches 112 located at the focus position of the square area 100 will generate additional induced current under the coupling of the square patches 111 in the square area 100. It is worth noting that the right-angled triangular patches 112 arranged at the corners of the square area 100 form a petal shape with the square area 100.

[0043] The right-angled sides of the right-angled triangle patches 112 of the patch group 11 of the present solution are arranged parallel to the sides of the diagonal positions of the square area 100, and two right-angled triangle patches 112 are arranged at each diagonal position of the square area 100. Specifically, the patch group 11 of the present solution includes 8 right-angled triangle patches 112, and each group of two right-angled triangle patches 112 is arranged at the diagonal positions of the square area 100.

[0044] The side length of the square patch 111 of this solution is equal to the right-angled side of the right-angled triangle patch 112. At this time, the right-angled side of the right-angled triangle patch 112 is arranged in the same axial direction relative to the side length of the square patch 111 at the diagonal position of the square area 100. In some embodiments, the side length of the square patch 111 and the side length of the right-angled side of the right-angled triangle patch 112 are 7-9 mm.

[0045] In addition, the spacing between the square patches 111 in the patch group 11 and between the square patches 111 and the right-angled triangle patches 112 are equal. In a specific embodiment, the spacing is 0.7-3.7 mm.

[0046] It should be noted that, assuming that the side length of the square patch 111 is a, and the spacing between the square patches 111 is b, in order for the patch group 11 to excite a characteristic mode at a specific wavelength, it is necessary to satisfy the empirical formula: 3*a+2*b=1.5λ. In a specific embodiment, the side length of the square patch 111 and the side length of the right angle side of the right triangle patch 112 are 9 mm, and the spacing between the square patches 111 is 0.7 mm.

[0047] The seamed ground plane 20 of this solution is used to excite the electric field mode, and further couple the metasurface layer 10 to excite the characteristic mode. In order to ensure that the antenna has good impedance matching, a drum-shaped gap 21 is set on the seamed ground plane 20 of this solution, and the length of the drum-shaped gap 21 is greater than half a wavelength but not too long, so that a complete half-wave cycle can be formed in the electric field distribution of the drum-shaped gap 21 to meet the virtual open circuit conditions on both sides, ensure the effective coupling of the energy from the feeder layer 30 to the drum-shaped gap 21, and meet the electromagnetic wave propagation. In the embodiment of this solution, the half-wavelength of the antenna at the operating frequency of 7GHz is required to be 21.4 mm, so the length of the drum-shaped gap 21 is greater than half a wavelength 21.4 mm, and the length of the drum-shaped gap 21 is 23mm.

[0048] like Figure 3As shown, the width of the drum-shaped gap 21 of the present solution decreases from the two sides to the middle side. In other words, the width of the two end sides of the drum-shaped gap 21 is greater than the width of the middle side, and the width of the two end sides gradually decreases toward the width of the middle side. In some embodiments, the width of the two end sides of the drum-shaped gap 21 gradually decreases toward the width of the middle side in an arc manner, thereby ensuring the continuity and smooth transition of the drum-shaped gap 21, effectively reducing reflection loss, and improving the reliability of overall signal transmission.

[0049] In some embodiments, the drum-shaped gap 21 of the present solution is a symmetrical structure.

[0050] In some embodiments, the width of the drum-shaped gap 21 is between 0.01 and 0.1 times the wavelength, and is controlled between 2 and 4 mm. In a specific embodiment of this solution, the maximum width of the two end sides of the drum-shaped gap 21 is 3.4 mm, and the minimum width of the middle side is 2.5 mm.

[0051] The feed line layer 30 is used to connect the SMA connector to realize the input of the feed signal. The feed line layer 30 of this scheme is designed with a long feed line 31 for obtaining the working bandwidth at a low frequency and a T-type power divider 32 for obtaining the working bandwidth at a high frequency, thereby realizing that the dual-band metasurface antenna array of this scheme can realize dual-frequency characteristics in two different working frequency bands.

[0052] Correspondingly, the feed line of the feed line layer 30 of the present solution is used to excite the half-wavelength and full-wavelength electric field distributions at the drum-shaped slots 21 at 7GHz and 9GHz, respectively. Due to the asymmetry of the metasurface layer 10, the electrical signals of the two left and right metal strips of the T-type power divider 32 of the feed line layer 30 have hysteresis within a certain frequency range when feeding. At the same time, the drum-shaped slot 21 can be regarded as two left and right cavities. The drum-shaped slot at 10.5GHz excites the half-wavelength electric field distribution alternating left and right, and the drum-shaped slot at 11.5GHz excites the full-wavelength electric field distribution synchronously left and right. This enables the metasurface antenna unit of the present invention to achieve dual-band effects of 7.0-9.1GHz and 10.3-11.9GHz, and achieve good performance within this frequency range.

[0053] Specifically, the long feed line 31 of the feed line layer 30 of the present scheme is arranged perpendicular to the drum-shaped gap 21 and is located on the central axis of the drum-shaped gap 21. The T-shaped power divider 32 on the top of the long feed line 31 has two parallel metal strips, and the left and right metal strips of the T-shaped power divider 32 are symmetrically arranged relative to the central axis of the drum-shaped gap 21 and relative to the gap space of the drum-shaped gap 21.

[0054] In some embodiments, the length of the long feed line 31 of the present solution also needs to be greater than half the wavelength 21.4 mm to meet the resonance condition, and the length of the long feed line 31 is greater than the length of the drum-shaped slot 21 to ensure effective coupling of energy from the antenna unit feed line to the drum-shaped slot. In some specific embodiments, the length of the long feed line 31 is 30 mm.

[0055] In some embodiments, the length of the T-type power divider 32 is 10-15 mm, and the range of the T-type power divider 32 is 10-15 mm, which is used to generate resonance at 10-12 GHz. In a specific embodiment, the length of the T-type power divider 32 is 11 mm.

[0056] The thickness of the first dielectric layer 40 of this solution is 3 to 4 times the thickness of the second dielectric layer 50. In a specific embodiment of this solution, the thickness of the first dielectric layer 40 is 3.04 mm, and the thickness of the second dielectric layer 50 is 0.76 mm.

[0057] In some embodiments, the dielectric material of the first dielectric layer 40 and the second dielectric layer 50 is Rogers 3003 material with a dielectric constant of 3, and the material of the super surface layer 10, the seam ground plate 20 and the feed line layer 30 is metallic copper, thereby improving the radiation performance and stability of the antenna.

[0058] The side view of the metasurface antenna unit is shown in Figure 4 As shown, the thickness of the first dielectric layer 40 is much greater than that of the second dielectric layer 50, and the seam grounding plate 20 is placed between the first dielectric layer 40 and the second dielectric layer 50. The first dielectric layer 40 of this solution is used to carry the metasurface layer 10 and provide necessary mechanical support and electrical isolation; the second dielectric layer 50 is used to carry the feeder layer 20 to ensure the stability and effective connection of the feeder. The feeder of the antenna unit feeder layer 30 is coupled to the seam grounding plate 20, and a special half-wavelength or full-wavelength electric field distribution is excited on the drum-shaped gap 21 on the seam grounding plate 20.

[0059] The dual-band metasurface antenna array for radar imaging of the present invention includes metasurface antenna units arranged in an array, wherein the spacing between the metasurface antenna units is greater than 50 mm, so as to effectively avoid mutual coupling between adjacent antenna units, thereby ensuring the radiation characteristics of the array.

[0060] like Fig. 9As shown, in a specific embodiment, a dual-band metasurface antenna array for radar imaging includes a 2*2 array of metasurface antenna units, and the spacing between each metasurface antenna unit is greater than half a wavelength, which can effectively avoid coupling between units and reduce mutual interference, thereby improving the overall performance and radiation efficiency of the antenna array. The arrangement of the array can realize spatial multiplexing and multipath propagation of signals, thereby effectively improving the gain and anti-interference ability of the system. In addition, the design of the antenna array also allows for optimization of beamforming through phase control to achieve directional radiation and better coverage. This makes the dual-band metasurface antenna array of the present invention perform well in practical applications and can meet the strict requirements of efficient communication and radar systems for antenna performance.

[0061] In a specific embodiment, the overall length of the dual-band metasurface antenna array is 140 mm, the overall width is 120 mm, and the spacing between the metasurface antenna units is 58 mm. This layout can not only obtain high gain, but also effectively realize the MIMO (multiple input multiple output) antenna system. This combined design enables the antenna array to have stronger adaptability and flexibility in modern wireless communications and radar applications, meeting the growing demand for high-performance antennas.

[0062] In addition, if Fig.10 As shown, when the dual-band metasurface antenna array used for radar imaging includes a 2*2 array of metasurface antenna units, the feed line layer 30 of different metasurface antenna units constitutes the feed line layer of the dual-band metasurface antenna array. At this time, the feed line layer of the dual-band metasurface antenna array includes a first impedance-matching T-type power divider, a second impedance-matching T-type power divider, and a third impedance-matching T-type power divider, wherein the second impedance-matching T-type power divider and the third impedance-matching T-type power divider are respectively connected to the two ends of the first impedance-matching T-type power divider, the second impedance-matching T-type power divider is connected to the long feed line 31 of the feed line layer 30 of the two metasurface antenna units on the left, and the third impedance-matching T-type power divider is connected to the long feed line 31 of the feed line layer 30 of the two metasurface antenna units on the right. Such a design of this scheme can effectively divide the feed signal into four, and can realize the synchronous excitation of the four antenna units. This design not only ensures the uniform distribution of the feeding signal, but also improves the overall performance and signal transmission efficiency of the antenna array, ensuring that all metasurface antenna units can obtain stable and uniform feeding signals, thereby achieving efficient synchronous feeding effects.

[0063] This solution designs a 2*2 dual-band metasurface antenna array of an embodiment:

[0064] The overall length of the dual-band metasurface antenna array is 140mm, the overall width is 120mm, the spacing between the metasurface antenna units is 58mm, the thickness of the first dielectric layer 40 is 3.04mm, the thickness of the second dielectric layer 50 is 0.76mm, the side length of the square patch 111 and the right-angled side of the right-angled triangle patch 112 are 9mm, the spacing is 0.7mm, the length of the drum-shaped gap 21 is 23mm, the maximum width on both sides is 3.4mm, and the narrowest width in the center is 2.5mm, the length of the long feed line 31 is 30mm, and the length of the T-type power divider 32 is 11mm.

[0065] Performance Test:

[0066] The MS curves of the four characteristic modes of a single metasurface antenna unit are shown below: Figure 5 As shown by Figure 5 It can be seen that the metasurface antenna unit has good mode significance in 7-9GHz.

[0067] The radiation patterns of the metasurface antenna unit before and after optimization in four characteristic modes are shown in the figure below. Figure 6 As shown, J 01 , J 02 , J 03 , J 04 The radiation patterns of the four characteristic modes of the seven square patches of the metasurface structure without vertical gaps, J 11 , J 12 , J 13 , J 14 The radiation patterns of the four characteristic modes after the 7 square patches of the metasurface structure are cut with vertical slits. Figure 6 As shown in the figure, when the square patch of the antenna unit metasurface 6 is not slit, the radiation patterns under the four characteristic modes show obvious radiation blind spots in the radiation direction. After the symmetry of the metasurface structure is destroyed by loading the metasurface patch slits, the radiation blind spot problem is significantly improved, indicating that this optimized design effectively improves the performance of the antenna in the main radiation direction, making it more efficient in practical applications.

[0068] The schematic diagram of the electric field distribution of the drum-shaped gap of the test metasurface antenna unit at 7.5GHz, 9.0GHz, 10.5GHz, and 11.5GHz is shown in the figure. Figure 7 As shown, it can be seen that the drum-shaped slot 21 of the feed line at 7 GHz and 9 GHz respectively excites half-wavelength and full-wavelength electric field distributions, and the drum-shaped slot 21 of the T-type power divider 32 at 10.5 GHz and 11.5 GHz respectively excites alternating half-wavelength and superimposed full-wavelength electric field distributions.

[0069] The return loss and gain diagram of the test metasurface antenna unit is shown in the figure. Figure 8 As shown, from Figure 8 It can be seen that the impedance bandwidth of the metasurface antenna unit of the example of the present invention with a return loss less than -10dB is 7.0-9.1GHz and 10.3-11.9GHz, the relative bandwidth reaches 26.1% and 14.4%, and the gain within the working bandwidth is 5.6-9.3dBi and 5.8-7.8dBi respectively.

[0070] The return loss and gain diagram of the dual-band metasurface antenna array is shown in the figure. Fig.11 As shown, it can be seen that the impedance bandwidth of the metasurface antenna array of the example of the present invention with a return loss less than -10dB is 7.6-8.6GHz and 10.1-11.6GHz, the relative bandwidth reaches 12.4% and 13.9%, and the gain within the working bandwidth is 10.0-13.4dBi and 9.0-11.5dBi respectively. Since the wavelength of the low-frequency band is longer, there is still a certain degree of coupling between the metasurface antenna units, so the low-frequency working bandwidth is narrowed, but the metasurface antenna array of the example of the present invention still has a wide dual-frequency working bandwidth and significantly high gain, which can meet the application requirements of wireless communications, radar systems and other high-performance signal transmission.

[0071] The E-plane main polarization and cross-polarization radiation patterns of the dual-band metasurface antenna array at 8GHz and 11GHz are shown in the figure below. Fig.12 As shown in the figure, it can be seen that the example metasurface antenna array of the present invention exhibits good radiation characteristics, and the radiation patterns of the main polarization and cross-polarization both show a relatively ideal beam shape, with a main lobe with high gain and strong directivity and a lower side lobe effect, indicating that the antenna can effectively concentrate energy in a specific direction.

[0072] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A dual-band metasurface antenna array for radar imaging, characterized in that: include: At least one metasurface antenna unit arranged in an array, wherein the metasurface antenna unit is arranged from top to bottom: A super surface layer (10), on which a patch group (11) for exciting characteristic modes is laid, the patch group comprising a plurality of square patches (111) laid in a square area (100) and a plurality of right-angled triangle patches (112) arranged at corners of the square area (100), at least one square patch (111) being etched with at least one slit, wherein the square patches (111) are divided into a first square patch without etched slits, a second square patch with a single slit etched, and a third square patch with two slits etched, wherein the second square patch has a surface current in the X-axis or Y-axis direction, and the third square patch has a surface current in the X-axis direction; A first dielectric layer (40); A seamed grounding plate (20) etched with a drum-shaped gap (21), wherein the length of the drum-shaped gap (21) is greater than half the wavelength, the width of the two end sides of the drum-shaped gap (21) is greater than the width of the middle side, and the width of the two end sides gradually decreases toward the width of the middle side; A second dielectric layer (50); and a feeder layer (30), comprising a long feeder (31) and a T-shaped power divider (32) arranged on the top of the long feeder (31), wherein the long feeder (31) of the feeder layer (30) is arranged perpendicular to the drum-shaped gap (21) and is located on the central axis of the drum-shaped gap (21), and the T-shaped power divider (32) on the top of the long feeder (31) has two parallel metal strips, and the left and right metal strips of the T-shaped power divider (32) are symmetrically arranged relative to the central axis of the drum-shaped gap (21) and relative to the gap space of the drum-shaped gap (21).

2. The dual-band metasurface antenna array for radar imaging according to claim 1, characterized in that: A cross-shaped slit is etched on the third square patch, and a diagonally arranged slit or an obliquely arranged slit is etched on the second square patch. The cross-shaped slit is located in the center of the third square patch and leaves a gap with the boundary of the third square patch. The horizontal slit and the vertical slit of the cross-shaped slit are of the same length. The single diagonally arranged slit cuts the second square patch into two right-angled triangles of equal area. The single obliquely arranged slit cuts the second square patch into two parts of a trapezoid and a triangle of unequal area, and the slit is parallel to the diagonal of the second square patch.

3. The dual-band metasurface antenna array for radar imaging according to claim 1, characterized in that: The patch group (11) comprises 9 square patches (111) arranged in a 3*3 array, wherein a third square patch is arranged at the upper right corner and the lower right corner of the 3*3 array, and a second square patch is arranged at the upper left corner, the lower left corner, the position between the upper right corner and the lower right corner, the position between the upper left corner and the upper right corner, and the position between the lower left corner and the lower right corner of the 3*3 array.

4. The dual-band metasurface antenna array for radar imaging according to claim 1, characterized in that: The right-angled sides of the right-angled triangle patches (112) of the patch group (11) are arranged parallel to the sides at the diagonal positions of the square area (100), and two right-angled triangle patches (112) are arranged at each diagonal position of the square area (100).

5. The dual-band metasurface antenna array for radar imaging according to claim 1, characterized in that: It includes a 2*2 array-arranged metasurface antenna unit, and the spacing between each metasurface antenna unit is greater than half a wavelength.

6. The dual-band metasurface antenna array for radar imaging according to claim 5, characterized in that: The feed line layer (30) of the same metasurface antenna unit forms a feed line layer of a dual-band metasurface antenna array, and the feed line layer of the dual-band metasurface antenna array comprises a first impedance matching T-type power divider, a second impedance matching T-type power divider and a third impedance matching T-type power divider, wherein the second impedance matching T-type power divider and the third impedance matching T-type power divider are respectively connected to the two end sides of the first impedance matching T-type power divider, the second impedance matching T-type power divider is connected to the long feed lines (31) of the feed line layer (30) of the two metasurface antenna units on the left, and the third impedance matching T-type power divider is connected to the long feed lines (31) of the feed line layer (30) of the two metasurface antenna units on the right.

7. The dual-band metasurface antenna array for radar imaging according to claim 1, characterized in that: The drum-shaped slots (21) of the feed line layer (30) at 7 GHz and 9 GHz respectively excite half-wavelength and full-wavelength electric field distributions, and the metasurface antenna unit realizes dual frequency bands of 7.0-9.1 GHz and 10.3-11.9 GHz.

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