AMC structure, antenna and radar

Abstract

The utility model discloses an AMC structure, an antenna and a radar, which are applied to the technical field of millimeter wave radars, and the AMC unit structure is arranged on the surface of one side, back to a dielectric substrate, of a dielectric floor; the AMC unit structure comprises a first reflection unit and a second reflection unit, the first reflection unit is provided with a first patch, and the surface of the first patch is provided with a first gap extending along a first direction; the second reflection unit is provided with a second patch, and the surface of the second patch is provided with a second gap extending along a second direction; the first direction and the second direction are orthogonal, so that the reflection phase of the first reflection unit and the reflection phase of the second reflection unit have a 180-degree difference. By arranging the slits in the patch, the reflected wave can have a specific phase. Through the arrangement of the first gap and the second gap which are orthogonal, the reflection phases of the two reflection units have a 180-degree phase difference so as to offset each other, and RCS reduction is realized.

Description

Technical Field

[0001] This utility model relates to the field of millimeter-wave radar technology, and in particular to an AMC structure, an antenna, and a radar. Background Technology

[0002] For modern radar communication systems, reducing the radar cross section (RCS) plays a crucial role in achieving radar stealth. In automotive radar systems, when the antenna passes through the radome, incident and reflected waves are generated. These electromagnetic waves reflect and overlap between the floor and the radome, causing distortion of the antenna's radiation pattern at large angles. Therefore, it is necessary to reduce the radar antenna's RCS, absorb reflected waves from the antenna and radome, and reduce radiation pattern distortion.

[0003] In existing technologies, reducing RCS typically involves using absorbing materials, electromagnetic band gap (EBG) structures, or artificial magnetic conductor (AMC) structures. However, these solutions suffer from drawbacks such as high profile, frequency sensitivity, and bulkiness. Using conventional mushroom-shaped EBG structures requires metal grounding holes for each unit, and employing two types of AMC structures in a checkerboard pattern increases design and fabrication complexity. Therefore, providing a simple AMC structure to achieve RCS reduction is a pressing issue for those skilled in the art. Utility Model Content

[0004] The purpose of this invention is to provide an AMC structure that can reduce RCS through a simple structure; another purpose of this invention is to provide an antenna and a radar that can reduce RCS through a simple structure.

[0005] To solve the above-mentioned technical problems, this utility model provides an AMC structure, characterized in that it includes: a dielectric ground plane, a dielectric substrate, and an AMC unit structure;

[0006] The dielectric substrate is disposed on one side surface of the dielectric ground plane, and the AMC unit structure is disposed on the side surface of the dielectric ground plane facing away from the dielectric substrate;

[0007] The AMC unit structure includes a first reflective unit and a second reflective unit. The first reflective unit is provided with a first patch, and the surface of the first patch is provided with a first slit extending along a first direction. The second reflective unit is provided with a second patch, and the surface of the second patch is provided with a second slit extending along a second direction. The first direction and the second direction are orthogonal, such that the reflection phase of the first reflective unit and the reflection phase of the second reflective unit have a 180° phase difference.

[0008] Optionally, the first reflective unit includes a plurality of first patches, and the first patches are arranged in an array in the same first reflective unit;

[0009] And / or, the second reflective unit includes a plurality of the second patches, which are arranged in an array within the same second reflective unit.

[0010] Optionally, the first patch is distributed in an m×m array; the second patch is distributed in an n×n array.

[0011] Optionally, the number of first patches in the same AMC unit structure (3) is equal to the number of second patches, and the number of first gaps is equal to the number of second gaps.

[0012] Optionally, the first patch and the first gap are configured in a one-to-one correspondence, and the first gap is located at the center of the corresponding first patch;

[0013] And / or, the second patch and the second gap are provided in a one-to-one correspondence, with the second gap being located at the center of the corresponding second patch.

[0014] Optionally, the first patch is circular or square;

[0015] And / or, the second patch is circular or square;

[0016] And / or, the first gap is elliptical or rectangular;

[0017] And / or, the second gap is elliptical or rectangular.

[0018] Optionally, the AMC unit structure (3) includes two first reflective units and two second reflective units forming a 2×2 array, with the two first reflective units located at opposite corners of the 2×2 array and the two second reflective units located at the other opposite corner of the 2×2 array.

[0019] Optionally, the AMC unit structure (3) includes the first reflective unit and the second reflective unit that are alternately distributed along a straight line.

[0020] This application also provides an antenna, including a comb antenna body and an AMC structure as described in any of the preceding claims, the AMC structure being located on at least one side of the comb antenna body.

[0021] This application also provides a radar, including the antenna as described above.

[0022] The present invention provides an AMC structure comprising: a dielectric ground plane, a dielectric substrate, and an AMC unit structure; the dielectric substrate is disposed on one surface of the dielectric ground plane, and the AMC unit structure is disposed on the surface of the dielectric ground plane facing away from the dielectric substrate; the AMC unit structure includes a first reflective unit and a second reflective unit, the first reflective unit having a first patch, the surface of the first patch having a first slit extending along a first direction; the second reflective unit having a second patch, the surface of the second patch having a second slit extending along a second direction; the first direction and the second direction are orthogonal, such that the reflection phase of the first reflective unit and the reflection phase of the second reflective unit have a 180° phase difference.

[0023] By setting slits in the patch, the reflected wave can be given a specific phase. By setting orthogonal first and second slits, the reflection phases of the two reflecting units can be 180° out of phase, thus canceling each other out and achieving RCS reduction.

[0024] This application also provides an antenna and a radar, which have the same beneficial effects as described above, and will not be described in detail here. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of an AMC structure provided in an embodiment of the present utility model;

[0027] Figure 2 This is a schematic diagram of the structure of an antenna provided in an embodiment of the present utility model;

[0028] Figure 3 for Figure 2 Simulation diagram of the structure;

[0029] Figure 4 This is a schematic diagram of the structure of a radar provided in an embodiment of the present utility model.

[0030] In the figure: 1. Dielectric ground plane, 2. Dielectric substrate, 3. AMC unit structure, 31. First reflective unit, 32. Second reflective unit, 311. First patch, 312. First gap, 321. Second patch, 322. Second gap;

[0031] 4. Transmitting antenna module; 40. Comb antenna body; 41. Single-string grounded parasitic antenna; 42. Single-string comb transmitting antenna; 43. Dual-string comb transmitting antenna;

[0032] 5. Electromagnetic bandgap (EBG) structure, 6. Receiving antenna, 7. Metal through-hole on board edge, 8. Radar chip, 9. Screw holes, 10. Adapter structure. Detailed Implementation

[0033] The core of this invention is to provide an AMC structure. In existing technologies, reducing RCS typically involves using absorbing materials, electromagnetic bandgap structures, or artificial magnetic conductor structures. However, these solutions suffer from drawbacks such as high profile, frequency sensitivity, and bulkiness. Furthermore, using a conventional mushroom-shaped EBG structure, requiring metal grounding holes for each unit, and employing two different AMC structures in a checkerboard pattern all increase design and manufacturing complexity.

[0034] The present invention provides an AMC structure comprising: a dielectric ground plane, a dielectric substrate, and an AMC unit structure; the dielectric substrate is disposed on one side surface of the dielectric ground plane, and the AMC unit structure is disposed on the side surface of the dielectric ground plane facing away from the dielectric substrate; the AMC unit structure includes a first reflective unit and a second reflective unit, the first reflective unit having a first patch, the surface of the first patch having a first slit extending along a first direction; the second reflective unit having a second patch, the surface of the second patch having a second slit extending along a second direction; the first direction and the second direction are orthogonal, such that the reflection phase of the first reflective unit and the reflection phase of the second reflective unit have a 180° phase difference.

[0035] By setting slits in the patch, the reflected wave can be given a specific phase. By setting orthogonal first and second slits, the reflection phases of the two reflecting units can be 180° out of phase, thus canceling each other out and achieving RCS reduction.

[0036] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Please refer to Figure 1 , Figure 1 This is a schematic diagram of an AMC structure provided in an embodiment of the present invention.

[0039] See Figure 1In this embodiment of the present invention, the AMC structure includes: a dielectric ground plane 1, a dielectric substrate 2, and an AMC unit structure 3; the dielectric substrate 2 is disposed on one side surface of the dielectric ground plane 1, and the AMC unit structure 3 is disposed on the side surface of the dielectric ground plane 1 facing away from the dielectric substrate 2; the AMC unit structure 3 includes a first reflective unit 31 and a second reflective unit 32, the first reflective unit 31 being provided with a first patch 311, and the surface of the first patch 311 being provided with a first slit 312 extending along a first direction; the second reflective unit 32 being provided with a second patch 321, and the surface of the second patch 321 being provided with a second slit 322 extending along a second direction; the first direction and the second direction are orthogonal, such that the reflection phase of the first reflective unit 31 and the reflection phase of the second reflective unit have a 180° phase difference.

[0040] The aforementioned dielectric ground plane 1 is typically the ground layer in a radar antenna structure. It is usually a metal layer, such as copper. The specific material of the dielectric ground plane 1 is not specifically limited in this embodiment and depends on the specific circumstances. The aforementioned dielectric substrate 2 is disposed on one side surface of the dielectric ground plane 1. The dielectric substrate 2 is a substrate for mounting various components and is typically insulating. The specific material and thickness of the dielectric substrate 2 can be set according to actual conditions and are not specifically limited here.

[0041] In this embodiment, the main structure for achieving RCS reduction is the AMC unit structure 3, which includes a first reflection unit 31 and a second reflection unit 32. Both the first reflection unit 31 and the second reflection unit 32 can reflect electromagnetic waves from any incident angle with a specific phase, that is, adjust the electromagnetic waves that are reflected and superimposed back and forth between the floor and the radome to a specific phase. The reflection phase of the first reflection unit 31 and the reflection phase of the second reflection unit have a 180° phase difference, so that electromagnetic waves with opposite phases can cancel each other out, thereby achieving RCS reduction.

[0042] Specifically, the first reflective unit 31 has a first patch 311, which is typically a metal patch disposed on the surface of the dielectric substrate 2. The first patch 311 has a first gap 312, thus forming a hollow structure. The long axis direction of the first gap 312 is the extending direction of the first gap 312; in this embodiment, all first gaps 312 extend along a first direction. The second reflective unit 32 has a second patch 321, which is typically a metal patch disposed on the surface of the dielectric substrate 2. The second patch 321 has a second gap 322, thus forming a hollow structure. The long axis direction of the second gap 322 is the extending direction of the second gap 322; in this embodiment, all second gaps 322 extend along a second direction. In this embodiment, the first direction is orthogonal to the second direction, that is, the major axis direction of the first gap 312 is orthogonal to the major axis direction of the second gap 322. This structure can make the reflection phase of the first reflection unit 31 and the reflection phase of the second reflection have a 180° phase difference, so as to achieve RCS reduction.

[0043] Assuming the electromagnetic waves reflected by the first reflecting unit 31 and the second reflecting unit 32 have the same amplitude, A, and the reflection phases of the first reflecting unit 31 and the second reflecting unit 32 in the orthogonal direction are θ1 and θ2 respectively, the total reflected energy of the AMC unit structure 3 is: E r =2Ae jθ1 +2Ae jθ2 =2Ae jθ1 [1+ e j(θ2-θ1) When θ2-θ1=±180°, the total reflected energy of AMC unit structure 3 is 0, and the reflected energy of the mutually orthogonal first reflective unit 31 and second reflective unit 32 cancels each other out. The reflection phase of AMC unit structure 3 can be adjusted by adjusting the radius of the first patch 311 and the second patch 321, and the size of the first gap 312 and the second gap 322.

[0044] In this embodiment, the first patch 311 and the second patch 321 in the same AMC unit structure 3 are usually separated from each other, that is, the first gap 312 and the second gap 322 are usually not set in the same patch. In a single first patch 311, multiple first gaps 312 can be provided, or only one first gap 312 can be provided, depending on the actual patch material and the electromagnetic wave frequency targeted by the AMC unit structure 3, etc., and no specific limitation is made here. When each first patch 311 is provided with only one first gap 312, the first patch 311 and the first gap 312 will be provided in a one-to-one correspondence. In this case, the first gap 312 is usually located at the center of the corresponding first patch 311.

[0045] In a second patch 321, multiple second slits 322 can be provided, or only one second slit 322 can be provided. The specific configuration depends on the actual patch material and the electromagnetic wave frequency targeted by the AMC unit structure 3, and is not specifically limited here. When each second patch 321 has only one second slit 322, the second patches 321 and the second slits 322 will be provided in a one-to-one correspondence. In this case, the second slit 322 is usually located at the center of the corresponding second patch 321. Of course, in this embodiment, each first patch 311 can have multiple slits, while each second patch 321 can have only one slit; each first patch 311 can have one slit, while each second patch 321 can have multiple slits; or each first patch 311 and each second patch 321 can have only one slit or multiple slits, and is not specifically limited here.

[0046] In this embodiment, the first patch 311 is circular or square; and / or, the second patch 321 is circular or square; and / or, the first gap 312 is elliptical or rectangular; and / or, the second gap 322 is elliptical or rectangular. That is, the shapes of the first patch 311 and the second patch 321 are generally circular or square. The shapes of the first gap 312 and the second gap 322 are generally rectangular or elliptical. The shapes of the two types of patches and the two types of gaps can be arbitrarily combined in pairs to form the first reflective unit 31 and the second reflective unit 32. Of course, in this embodiment, the specific shapes of the first reflective unit 31 and the second reflective unit 32 are not specifically limited, but depend on the specific circumstances.

[0047] Specifically, in this embodiment, a reflective unit can be formed by combining multiple patches arranged in an array within the same reflective unit, with gaps provided in each patch. That is, the first reflective unit 31 includes multiple first patches 311, which are arranged in an array within the same first reflective unit 31; and / or, the second reflective unit 32 includes multiple second patches 321, which are arranged in an array within the same second reflective unit 32.

[0048] Taking a 3×3 array as an example, in this embodiment, the first reflective unit 31 may include nine first patches 311, which can form a 3×3 array. Each first patch 311 may have a first gap 312 at its center, resulting in nine first gaps 312 parallel to the first direction for the entire first reflective unit 31. Similarly, the second reflective unit 32 may include nine second patches 321, which can form a 3×3 array. Each second patch 321 may have a second gap 322 at its center, resulting in nine second gaps 322 parallel to the second direction for the entire second reflective unit 32. It should be noted that other array shapes can also be formed in this embodiment, such as 2×2 or 2×3 arrays. The sizes of the arrays formed by the first reflective unit 31 and the second reflective unit 32 in the same AMC unit structure 3 can be equal or unequal, depending on the specific circumstances, and are not specifically limited here.

[0049] Specifically, in this embodiment, the first patch 311 can be arranged in an m×m array; the second patch 321 can be arranged in an n×n array. That is, the patch matrix in the first reflection unit 31 and the second reflection unit 32 is a square matrix. This structure facilitates the mutual cancellation of reflected electromagnetic waves between the first reflection unit 31 and the second reflection unit 32 in different directions.

[0050] Typically, in this embodiment, the number of first patches 311 and the number of second patches 321 in the same AMC unit structure 3 are equal, and the number of first gaps 312 and the number of second gaps 322 are equal. At this time, the morphology of the first reflective unit 31 and the second reflective unit 32 are roughly the same, and the second reflective unit 32 is generally equivalent to the structure of the first reflective unit 31 after rotating 90° along the circumferential direction of the patch.

[0051] This embodiment will specifically provide two AMC structures, both of which can effectively achieve RCS reduction.

[0052] In the first embodiment, the AMC unit structure 3 includes two first reflective units 31 and two second reflective units 32 forming a 2×2 array, with the two first reflective units 31 located at opposite corners of the 2×2 array and the two second reflective units 32 located at the other opposite corner of the 2×2 array.

[0053] In this structure, for any given reflecting unit, there is another reflecting unit with a 180° phase difference above or below it, and another reflecting unit with a 180° phase difference to its left or right, thereby enabling the reflected electromagnetic waves to cancel each other out at as many angles as possible. Structurally, it roughly forms a grid-like structure to maximize the RCS reduction effect of the AMC unit structure 3.

[0054] The second type, the AMC unit structure 3 includes the first reflective unit 31 and the second reflective unit 32 alternately distributed along a straight line. In this structure, the first reflective unit 31 and the second reflective unit 32 are distributed in a straight line. Compared with the previous structure, this structure saves more space and can be adapted to different spaces, but the effect of reducing RCS is lower.

[0055] It should be noted that in the AMC structure provided in this embodiment, the first patch and the second patch are both disposed on the surface of the dielectric substrate 2 in the form of patches, without needing to be connected to the dielectric ground plane 1. That is, in this embodiment, there is no need to set ground holes at the positions of the first patch and the second patch to connect them to the dielectric ground plane 1, making the overall structure simpler and easier to process.

[0056] The AMC structure provided in this embodiment of the invention allows the reflected wave to have a specific phase by setting slits in the patch. By setting orthogonal first slit 312 and second slit 322, the reflection phases of the two reflecting units can be made to have a phase difference of 180°, thus canceling each other out and achieving RCS reduction. This AMC structure has broadband characteristics and can cover the radar frequency bands commonly used by current millimeter-wave radars.

[0057] Example 2

[0058] Please refer to Figure 2 as well as Figure 3 , Figure 2 This is a schematic diagram of the structure of an antenna provided in an embodiment of the present utility model; Figure 3 for Figure 2 Simulation diagram of the structure.

[0059] See Figure 2 In this embodiment, the antenna includes a comb antenna body 40 and an AMC structure as described in any of the above embodiments, wherein the AMC structure is located on at least one side of the comb antenna body 40. The specific structure of the comb antenna body 40 can be set according to actual conditions and is not specifically limited here. Typically, space is left on at least one side of the comb antenna body 40 to accommodate the AMC structure, and the length direction of the AMC structure is usually consistent with the length direction of the comb antenna body 40.

[0060] To verify that the AMC structure in this embodiment has the characteristic of reducing RCS, the monostatic RCS of the antenna with and without the AMC structure was compared. A plane wave incident perpendicularly above the antenna was placed using simulation software. The simulation results with and without the AMC structure are as follows: Figure 3 As shown, the antenna RCS is reduced by more than 10dB in the operating frequency range of 75GHz-79GHz, making it particularly suitable for autonomous driving scenarios with high precision and high concealment requirements.

[0061] Example 3

[0062] Please refer to Figure 4 , Figure 4 This is a schematic diagram of the structure of a radar provided in an embodiment of the present utility model.

[0063] The radar provided in this embodiment is applicable to millimeter-wave radar. See [link / reference] Figure 4 In this embodiment, the radar includes the antenna described in the above embodiments. This radar typically includes a radio frequency substrate, an EBG structure 5 for improved isolation, an AMC structure for reduced RCS, a transmitting antenna, a receiving antenna 6, an radome, and other structures. Figure 4As shown, the radar includes 12 transmit antenna channels and 16 receive antenna channels. The entire board includes a dielectric ground plane 1, a dielectric substrate 2, an AMC unit structure 3, a transmit antenna module 4 including a single-string grounded parasitic antenna 41, a single-string comb-shaped transmit antenna 42 and a double-string comb-shaped transmit antenna 43, an electromagnetic bandgap EBG structure 5, a receive antenna 6, metal through holes on the board edge 7, a radar chip 8, screw holes 9, and a transition structure 10 from the ground coplanar waveguide (GCPW) to the substrate integrated waveguide (SIW). The design utilizes an orthogonally arranged AMC unit structure 3 to cancel the reflected electromagnetic wave energy between the ground and the radome using an orthogonal layout with a 180° phase difference, thereby reducing the antenna RCS and minimizing the impact of reflected electromagnetic waves on the antenna pattern. The high-resistivity surface electromagnetic bandgap (EBG) structure 5 suppresses surface waves, improves the isolation between antennas, and increases antenna gain. The transmitting antenna in this example consists of a single-string grounded parasitic antenna 41, a single-string comb-shaped transmitting antenna 42, and a double-string comb-shaped transmitting antenna 43. The single-string comb-shaped transmitting antenna 42 can serve as an auxiliary antenna to improve the radar's large-angle detection capability, while the grounded parasitic antenna 41 reduces the impact of ground inhomogeneity on the radiation pattern. The chip output port adopts a transition form from a grounded coplanar waveguide (GCPW) to a substrate integrated waveguide (SIW) to reduce the impact of microstrip radiation on the antenna during the transition. The SIW is then connected to each antenna via microstrip lines. Therefore, in this embodiment, the signal transmission structure from the radar chip 8 to each antenna along the signal transmission direction can be as follows: radar chip 8 → grounded coplanar waveguide GCPW → transition structure 10 → substrate integrated waveguide SIW → microstrip line → antenna. The antenna is fed using a combination of SIW and microstrip lines. By adjusting the bending form and length of the SIW and microstrip lines, an unequal length, equal phase layout of the transmission lines can be achieved, thus optimizing transmission performance.

[0064] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0065] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0066] The AMC structure, antenna, and radar provided by this utility model have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that those skilled in the art can make several improvements and modifications to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. An AMC structure, characterized in that, include: The dielectric floor (1), the dielectric substrate (2), and the AMC unit structure (3); The dielectric substrate (2) is disposed on one side surface of the dielectric floor (1), and the AMC unit structure (3) is disposed on the side surface of the dielectric floor (1) facing away from the dielectric substrate (2); The AMC unit structure (3) includes a first reflective unit (31) and a second reflective unit (32). The first reflective unit (31) is provided with a first patch (311), and the surface of the first patch (311) is provided with a first slit (312) extending along a first direction. The second reflective unit (32) is provided with a second patch (321), and the surface of the second patch (321) is provided with a second slit (322) extending along a second direction. The first direction and the second direction are orthogonal, so that the reflection phase of the first reflective unit (31) and the reflection phase of the second reflective unit have a phase difference of 180°.

2. The AMC structure according to claim 1, characterized in that, The first reflective unit (31) includes a plurality of first patches (311), and the first patches (311) are arranged in an array in the same first reflective unit (31); And / or, the second reflective unit (32) includes a plurality of second patches (321), which are arranged in an array in the same second reflective unit (32).

3. The AMC structure according to claim 2, characterized in that, The first patch (311) is distributed in an m×m array; the second patch (321) is distributed in an n×n array.

4. The AMC structure according to claim 3, characterized in that, In the same AMC unit structure (3), the number of first patches (311) is equal to the number of second patches (321), and the number of first gaps (312) is equal to the number of second gaps (322).

5. The AMC structure according to claim 1, characterized in that, The first patch (311) and the first gap (312) are provided in a one-to-one correspondence, and the first gap (312) is located at the center of the corresponding first patch (311); And / or, the second patch (321) and the second gap (322) are provided in a one-to-one correspondence, and the second gap (322) is located at the center of the corresponding second patch (321).

6. The AMC structure according to claim 1, characterized in that, The first patch (311) is circular or square; And / or, the second patch (321) is circular or square; And / or, the first slit (312) is elliptical or rectangular; And / or, the second slit (322) is elliptical or rectangular.

7. The AMC structure according to claim 1, characterized in that, The AMC unit structure (3) includes two first reflective units (31) and two second reflective units (32) forming a 2×2 array. The two first reflective units (31) are located at opposite corners of the 2×2 array, and the two second reflective units (32) are located at the other opposite corner of the 2×2 array.

8. The AMC structure according to claim 1, characterized in that, The AMC unit structure (3) includes the first reflective unit (31) and the second reflective unit (32) which are alternately distributed along a straight line.

9. An antenna, characterized in that, It includes a comb antenna body (40) and an AMC structure as described in any one of claims 1 to 8, wherein the AMC structure is located on at least one side of the comb antenna body (40).

10. A radar, characterized in that, Including the antenna as described in claim 9.

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