An array antenna for millimeter-wave automotive radar

Abstract

The present invention relates to the technical field of antennas, and specifically relates to an array antenna for millimeter-wave automotive radar, which includes an antenna substrate, a feeding layer, a reflection layer and a radiation layer. The feeding layer, the reflection layer and the radiation layer are sequentially distributed in the antenna substrate from bottom to top. An installation groove is formed in the antenna substrate. Dielectric materials are filled between the bottom of the antenna substrate, the feeding layer, the reflection layer and the radiation layer pairwise. Through holes are formed on the surface of the dielectric materials. The radiation layer is etched with an array composed of four or more combined antenna rings. The combined antenna rings are distributed in an array. The combined antenna is composed of a grid unit and a patch unit. The grid unit with a circular asymmetric radiation edge and the elliptical patch unit are staggered to form the combined antenna, thereby forming a dual-band multi-coupling mode, which meets different scenario requirements and improves the universality of antenna use.

Description

Technical Field

[0001] The invention relates to the technical field of antennas, in particular to an array antenna for millimeter wave automobile radar. Background Art

[0002] With the development of smart cars and driverless technology, automotive radar is becoming an increasingly important and indispensable part of cars. Millimeter-wave automotive radar array antenna is a multi-unit antenna system composed of regularly arranged radiating units (such as patches, slots, dipoles, etc.), which realizes beamforming and rapid scanning through phase or amplitude control, and is widely used in vehicle detection, ranging, speed measurement and imaging.

[0003] At present, in millimeter-wave automotive radars, multiple transmitting array antennas are required to achieve target detection and early warning at different ranges. Different detection distances will result in different antenna types required, and there are large differences in the scale of different antenna arrays, thereby meeting the needs of different gains and beams. In order to achieve the alternating start and stop function of multiple transmitting arrays, the front-end RF chip has to integrate multiple sets of parallel processing links. These links have significant time and space asynchronous characteristics in actual work, resulting in periodic idle waste of hardware resources. At the same time, the alternating work of antennas also increases the difficulty of front-end calculations.

[0004] In order to solve the above problems, the existing technology usually realizes the combination by connecting different antennas in series, so that the combined antenna forms multiple groups of resonances with different frequencies. However, due to the structural differences and functional requirements of the array antenna itself, the types of resonances are still fixed, which makes it difficult to meet the needs of different environments and situations when the car is used, which will limit the flexibility of the beam and thus cause limitations in automotive radar detection;

[0005] Based on this, in order to solve the problem that when facing complex beam reception, the automobile radar array antenna is difficult to activate different resonances according to the on-site conditions in real time, and thus it is difficult to achieve dynamic perception, thereby affecting the accuracy of the automobile radar antenna, the present invention designs an array antenna for millimeter-wave automobile radar. Summary of the invention

[0006] The present invention provides an array antenna for millimeter-wave automotive radar, which solves the problem that when facing complex beam reception, the automotive radar array antenna is difficult to activate different resonances in real time according to the on-site conditions, and thus it is difficult to achieve dynamic perception, thereby affecting the accuracy of the automotive radar antenna. The present application forms a combined antenna by interlacing grid units with annular asymmetric radiation edges with elliptical patch units, thereby forming a dual-band multi-coupling mode, thereby meeting different scene requirements and improving the wide range of antenna use.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] An array antenna for millimeter-wave automotive radar, comprising an antenna substrate, a feeding layer, a reflection layer and a radiation layer. The feeding layer, the reflection layer and the radiation layer are sequentially distributed in the antenna substrate from bottom to top. An installation groove is formed in the antenna substrate. Dielectric materials are filled between the bottom of the antenna substrate, the feeding layer, the reflection layer and the radiation layer in pairs. Through holes are formed on the surface of the dielectric materials. The radiation layer is etched with an array composed of four or more combined antenna rings. The combined antenna rings are distributed in an array. The combined antenna is composed of a grid unit and a patch unit. The grid units are symmetrically distributed. The radiation edge length of a single grid unit far from the center point of the combined antenna ring is greater than the radiation edge length of the grid unit close to the center point of the combined antenna ring. By means of a double-ring array, the whole antenna can form a ring array, thereby forming a spatial filtering effect and improving the multipath interference suppression rate. The patch unit maintains linear polarization. The grid unit is regulated by non-uniform current distribution to achieve surface wave suppression. The patch unit provides the main radiation mode. The combination of the two can achieve independent dual-band regulation. After combining the circular grid units, the suppression ratio of rain and fog clutter is improved.

[0009] Preferably, the radiation edge is divided into a concave edge and a convex edge. The concave edge is the a radiation edge of the grid unit far from the center point of the combined antenna ring, and the convex edge is the radiation edge of the grid unit close to the center point of the combined antenna ring. An impedance gradient transition is formed through a coupling gap, thereby improving the reflection coefficient.

[0010] Preferably, both the concave edge and the convex edge are of asymptotic width. The width value of the concave edge decreases from both ends to the center, and the width value of the convex edge increases from both ends to the center. The concave edge forms a gradient equivalent inductor through width change to suppress high-frequency surface wave resonance, while the convex edge introduces a distributed capacitor to compensate for the phase delay in the high-frequency section.

[0011] Preferably, a unit connection section is provided between the grid units. The patch unit is installed between single grid units and is elliptical. The non-radiating edges of the patch unit and the grid unit are connected by a microstrip line. The patch unit and the unit connection section form a series patch antenna. By using the series patch structure, the unit connection section and the elliptical patch form a cascaded resonant cavity, and multi-beam radiation is generated through phase superposition, thereby realizing dynamic scene perception.

[0012] Preferably, via holes are provided between the feeding layer and the radiation layer. The via holes are located at the intersection of the non-radiating edges of the grid units and the unit connection section. The via holes are symmetric about the center points of multiple combined antenna rings. The via holes are located at the intersection of the non-radiating edges of the grid units and the unit connection section. Through symmetric differential feeding, on the one hand, it ensures that the currents on the radiation edges of the grids are in phase, thereby enhancing the radiation efficiency in the low-frequency band.

[0013] Preferably, the area of the middle region of the grid cell is smaller than that of the patch cell. The patch cell forms high-frequency resonant radiation, and the grid cell forms low-frequency resonant radiation. The grid cell with a smaller middle region area covers the low-frequency band through a low-order resonance mode, thereby being used for long-distance target detection; the patch cell occupies a larger area and covers the high-frequency band through a high-order resonance mode, being used for short-distance wide-angle coverage. The two cooperate to expand the total bandwidth of the dual band and support the simultaneous processing of scene requirements at different distances.

[0014] Preferably, endpoint patches are provided at both ends of the patch cell. The endpoint patches are trapezoidal, and the trapezoidal endpoint patches form an impedance gradient transition region through the gradient structure from the wide bottom edge to the narrow top edge.

[0015] Preferably, the feeding layer includes a power splitting and phase shifting structure. One end of the power splitting and phase shifting structure is connected to the input strip line, and the other end of the power splitting and phase shifting structure is connected to the radiation layer through a via hole.

[0016] Preferably, the unit connection segment is divided into a radiation part and an inclined part. The inclination angle of the inclined part is 12°, and a cut-off waveguide effect is formed at the edge of the radiation part, reducing the surface wave attenuation.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. An array antenna for a millimeter-wave automotive radar proposed by the present invention changes the radiation edge length of the grid cell, thereby making the wavelength width of the grid cell different. The long radiation edge far from the center of the ring generates a wide beam through a low resonance frequency mode for wide-area short-distance coverage; while the short radiation edge close to the center generates a narrow beam through a high-frequency resonance mode for long-distance high-precision detection; thus realizing a dual-band mode to meet different scene requirements. At the same time, the multi-mode coupling effect is introduced through the asymmetric structure, and the asymmetric layout of the long radiation edge and the short radiation edge of the adjacent cell destroys the periodic coupling path, thereby reducing the interference to the main radiation mode.

[0019] 2. An array antenna for a millimeter-wave automotive radar proposed by the present invention forms wide-beam radiation through the regulation of the curvature radius of the concave edge, which is suitable for wide-area short-distance coverage; the convex edge realizes narrow-beam high gain through a gradient structure for long-distance target tracking. At the same time, the bandwidths of the two match, and an impedance gradient transition is formed through the coupling gap, thereby improving the reflection coefficient; at the same time, the asymmetric distribution of the concave edge and the convex edge destroys the periodic grating lobes, thereby optimizing the sidelobe level, and the asymmetric structure prolongs the fatigue life during vibration through stress dispersion design.

[0020] 3. The present invention proposes an array antenna for millimeter-wave automotive radar, which forms a dual-band excitation mechanism through the combination of grid units and patch units. The low-frequency resonance mode is excited by the grid units with asymmetric radiation edge design, and the high-frequency resonance mode is generated by the difference in the current path of the elliptical patch units in the short axis direction, thereby realizing the combination of long-distance target coverage and close-range wide-angle coverage. At the same time, the high-frequency band reflection coefficient is optimized through the microstrip line connection with gradual impedance transformation; the series patch structure is used to make the unit connection segment and the elliptical patch form a cascade resonant cavity, and multi-beam radiation is generated by phase superposition, thereby realizing dynamic scene perception, activating different resonance modes in time-sharing, and shortening the switching time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation mode of the present invention or the technical solution in the prior art, the drawings required for use in the specific implementation mode or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are one implementation mode of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 is a schematic diagram of each layer in the antenna substrate of the present invention;

[0024] Figure 3 is a schematic diagram of a via hole of the present invention;

[0025] Figure 4 yes Figure 3 The enlarged view of point A in the middle;

[0026] Figure 5 is a top view of the present invention;

[0027] Figure 6 is a schematic structural diagram of a single radiator of the present invention;

[0028] Figure 7 It is a schematic diagram of the power distribution structure of the present invention;

[0029] Figure 8 It is a schematic diagram of the unit connection section of the present invention;

[0030] Figure 9 yes Figure 8 Enlarged view of point B in the middle.

[0031] In the figure: 1. Antenna substrate; 11. Placement groove; 2. Feeding layer; 21. Power division and phase shift structure; 22. Input strip line; 3. Reflection layer; 4. Radiation layer; 5. Dielectric material; 51. Through hole; 6. Combined antenna; 7. Grid unit; 71. Radiation edge; 711. Concave edge; 712. Convex edge; 72. Non-radiation edge; 73. Unit connection segment; 731. Radiation part; 732. Inclined part; 8. Patch unit; 81. End point patch; 9. Via hole. Detailed implementation mode

[0032] To better understand the above solution, the above technical solution will be described in detail below in combination with the accompanying drawings of the specification and the specific implementation mode.

[0033] As Figure 1-2 shown, an array antenna for millimeter-wave automotive radar includes an antenna substrate 1, a feeding layer 2, a reflection layer 3 and a radiation layer 4. The feeding layer 2, the reflection layer 3 and the radiation layer 4 are sequentially distributed in the antenna substrate 1 from bottom to top. An placement groove 11 is provided in the antenna substrate 1.

[0034] The antenna substrate 1 serves as the dielectric support substrate of the multi-layer structure. It can provide mechanical stability and an electromagnetic wave propagation environment, and at the same time is also the carrier of the feeding layer 2, the reflection layer 3 and the radiation layer 4, thereby improving the integrity of the array antenna; the feeding layer 2 realizes signal distribution and phase control through a strip line power division network, and is the core functional layer for beamforming; the reflection layer 3 serves as a full-metal floor, enhancing the forward radiation efficiency by reflecting electromagnetic wave energy, while suppressing the backward leakage of electromagnetic waves; the radiation layer 4 is located on the surface layer and is composed of a grid unit 7 and a patch unit 8 to form a radiator, directly realizing electromagnetic wave radiation and multi-field coverage.

[0035] In the above-mentioned layers, the signal flow transmission is enhanced in the reverse direction of the feeding layer 2 → radiation layer 4 → reflection layer 3; the heat conduction path is the radiation layer 4 → reflection layer 3 → external radiator, thereby forming a complete array antenna.

[0036] Dielectric materials 5 are filled between the bottom of the antenna substrate 1, the feeding layer 2, the reflection layer 3 and the radiation layer 4 pairwise. Through holes 51 are provided on the surface of the dielectric materials 5. The dielectric materials 5 are used for electromagnetic performance regulation and thermal management. On the basis of bypassing the via holes 9, holes with a diameter of 0.1 - 0.2 mm are provided in the dielectric materials 5 for heat dissipation. The aperture here cannot be too large, otherwise electromagnetic leakage will be caused, and if it is too small, the heat dissipation effect will be poor; at this aperture, the holes for heat dissipation can also be used as annular barrier holes for isolating the via holes 9. However, on the one hand, compared with traditional heat dissipation holes, its aspect ratio is less than 3:1, thereby ensuring the uniformity of copper plating on the hole wall. At the same time, a highly thermally conductive and conductive coating is sprayed around the holes to compensate for the heat dissipation capacity after the aspect ratio changes.

[0037] The radiation layer 4 is etched with an array formed by four or more combined antennas 6 in a ring shape. The combined antenna 6 is distributed in a ring array. The combined antenna 6 is composed of a grid unit 7 and a patch unit 8. By means of a double-ring array, the antenna as a whole can form a ring array, thereby forming a spatial filtering effect and improving the multipath interference suppression rate. The patch unit 8 maintains linear polarization, and the grid unit 7 is regulated by non-uniform current distribution to achieve surface wave suppression. The patch unit 8 provides the main radiation mode. The combination of the two can achieve dual-band independent regulation. After combining the ring-shaped grid unit 7, the suppression ratio of rain and fog clutter is improved.

[0038] The grid units 7 are symmetrically distributed. The length of the radiation edge 71 of a single grid unit 7 far from the center point of the combined antenna 6 in the ring shape is greater than the length of the radiation edge 71 of the grid unit 7 close to the center point of the combined antenna 6 in the ring shape.

[0039] By changing the length of the radiation edge of the grid unit 7, the wavelength width of the grid unit 7 is made different. The long radiation edge 71 far from the center point of the ring generates a wide beam through the low resonance frequency mode for wide-area short-distance coverage (such as blind area monitoring).

[0040] The short radiation edge 71 close to the center point generates a narrow beam through the high-frequency resonance mode for long-distance high-precision detection (such as adaptive cruise control). Thus, a dual-band mode is realized, meeting different scenario requirements. At the same time, through the non-symmetric structure, a multi-mode coupling effect is introduced. The non-symmetric layout of the long radiation edge 71 and the short radiation edge 71 of the adjacent unit destroys the periodic coupling path. The isolation between units is increased from about -18 dB to about -25 dB. The surface wave attenuation non-symmetric edge current distribution increases the surface wave scattering loss, and the surface wave propagation efficiency is reduced by about 40%. Thus, the interference to the main radiation mode is reduced, and at the same time, the etching difficulty is also reduced. Through the setting of the long and short radiation edges 71, the etching deviation can be tolerated.

[0041] Such as Figure 1-2 As shown, the radiation edge 71 is divided into a concave edge 711 and a convex edge 712. The concave edge 711 is the radiation edge 71 of the grid unit 7 far from the center point of the combined antenna 6 in the ring shape, and the convex edge 712 is the radiation edge 71 of the grid unit 7 close to the center point of the combined antenna 6 in the ring shape.

[0042] The concave edge 711 forms a wide-beam radiation through curvature radius regulation, suitable for wide-area short-distance coverage; the convex edge 712 realizes a narrow-beam high gain through a gradient gradient structure for long-distance target tracking. At the same time, their bandwidths match, and an impedance gradient transition is formed through the coupling gap, thereby improving the reflection coefficient. At the same time, the non-symmetric distribution of the concave edge 711 and the convex edge 712 destroys the periodic grating lobes, thereby optimizing the sidelobe level. And the non-symmetric structure prolongs the fatigue life during vibration through stress dispersion design.

[0043] like Figure 3-4 As shown, the inner concave edge 711 and the outer convex edge 712 are both of asymptotic width, the width of the inner concave edge 711 decreases from both ends to the center, and the width of the outer convex edge 712 increases from both ends to the center.

[0044] As the width of the inner concave edge 711 gradually decreases, a high impedance zone is formed in the central area, and a low impedance zone is formed in the edge area. A broadband matching is achieved through a gradual impedance transformation, thereby expanding the bandwidth. When the width of the outer convex edge 712 gradually increases, a capacitive load is formed at the radiation end to compensate for the high-frequency reactance component, thereby optimizing the reflection coefficient; the inner concave edge 711 induces high-density current aggregation at the smallest center width, and the outer convex edge 712 expands the current diffusion range at the largest end width. At the same time, the inner concave edge 711 forms a gradual equivalent inductance through width changes to suppress high-frequency surface wave resonance, while the outer convex edge 712 introduces distributed capacitance to compensate for the high-frequency phase delay.

[0045] like Figure 7-8 As shown, a unit connection section 73 is provided between the grid units 7, the patch unit 8 is installed between the individual grid units 7 and is elliptical, the patch unit 8 is connected to the non-radiating edge 72 of the grid unit 7 through a microstrip line, and the patch unit 8 and the unit connection section 73 constitute a series patch antenna.

[0046] The combination of the grid unit 7 and the patch unit 8 forms a dual-band excitation mechanism. The low-frequency resonance mode is excited by the grid unit 7 with an asymmetric radiation edge design, and the high-frequency resonance mode is generated by utilizing the difference in the current path in the short axis direction of the elliptical patch unit 8, thereby achieving a combination of long-distance target coverage and close-range wide-angle coverage. At the same time, the high-frequency band reflection coefficient is optimized through the microstrip line connection with gradual impedance transformation; the series patch structure is utilized to make the unit connection section 73 and the elliptical patch form a cascade resonant cavity, and multi-beam radiation is generated through phase superposition, thereby realizing dynamic scene perception, activating different resonance modes in time-sharing, and shortening the switching time.

[0047] like Figure 3-4 As shown, a via hole 9 is provided between the feed layer 2 and the radiation layer 4 , and the via hole 9 is located at the intersection of the non-radiating edge 72 of the grid unit 7 and the unit connecting section 73 , and the via hole 9 is symmetrical about the circular midpoint of the plurality of combined antennas 6 .

[0048] The via 9 is located at the intersection of the non-radiating edge 72 of the grid unit 7 and the unit connection section 73. The symmetrical differential feeding ensures that the currents of the grid radiation edge are in phase, thereby enhancing the radiation efficiency in the low frequency band. On the other hand, the currents of the non-radiating edge 72 are reversely offset, suppressing the propagation of surface waves and reducing the intensity of the near field. At the same time, the symmetrical layout forms a two-port balanced resonant cavity, which improves the isolation between the low-frequency mode of the grid unit 7 and the high-frequency mode of the patch unit 8, avoiding bandwidth compression caused by mode mixing.

[0049] The via 9 layout symmetric about the center of the ring reduces the phase error between array elements through equal-path transmission delay design. The symmetric feeding network generates a complementary current distribution, breaking the condition for generating periodic grating lobes, and thus optimizing the sidelobes.

[0050] As Figure 5-6 shown, the area of the middle region of the grid cell 7 is smaller than the area of the patch cell 8. The patch cell 8 forms high-frequency resonant radiation, and the grid cell 7 forms low-frequency resonant radiation. The grid cell 7 with a smaller middle region area covers the low-frequency band through a low-order resonant mode, thus being used for long-distance target detection, and the small-area design can suppress the interference of high-order modes. The patch cell 8 occupies a larger area and covers the high-frequency band through a high-order resonant mode, being used for short-distance wide-angle coverage. The two cooperate to expand the total bandwidth of the dual band and support simultaneously processing the scene requirements at different distances;

[0051] The reduction of the area of the middle region of the grid cell 7 reduces the edge coupling strength with the patch cell 8 and avoids the efficiency reduction caused by mode aliasing;

[0052] The low-frequency current is concentrated at the edge of the grid cell 7, and the high-frequency current is distributed at the center of the patch. The radiation efficiency is improved through impedance gradient matching;

[0053] The grid cell 7 generates a high-gain narrow beam through a compact structure for long-distance vehicle tracking with a high-frequency wide beam; while the patch cell 8 forms a wide-angle coverage beam using a wide area, which is suitable for blind area monitoring and short-distance pedestrian detection, etc.

[0054] As Figure 5 shown, the two ends of the patch cell 8 are provided with end patches 81, and the end patches 81 are trapezoidal; the trapezoidal end patches 81 form an impedance gradient transition region through the gradient structure from the wide bottom edge to the narrow top edge. At the same time, the trapezoidal hypotenuse destroys the parallel current distribution at the edge of the patch, reducing the attenuation of surface waves, and the trapezoidal gradient structure realizes the impedance overlap of the dual band.

[0055] As Figure 6 shown, the feeding layer 2 includes a power splitting and phase shifting structure 21. One end of the power splitting and phase shifting structure 21 is connected to the input strip line 22, and the other end of the power splitting and phase shifting structure 21 is connected to the radiation layer 4 through a via 9. The impedance transformation is formed through the gradual change of the branch line width. At the same time, the phase compensation is formed by using a microstrip line to compensate for the phase delay in the high-frequency band, and further reduce the error between each radiation element. The ring is used to replace the traditional tree-shaped power divider, shortening the total path length, reducing the high-frequency insertion loss, and at the same time realizing multi-beam synchronous scanning. Multiple groups of vias 9 are arranged with the center of the ring as the axis of symmetry to suppress the coupling of resonant cavity modes.

[0056] As Figure 8As shown, the unit connection section 73 is divided into a radiation section 731 and an inclined section 732. The inclination angle of the inclined section 732 is 12°. By setting the inclined section 732, the beam skew is reduced through inclination angle compensation, thereby improving the main lobe gain. The 12° inclination angle changes the surface current direction, forming a cut-off waveguide effect at the edge of the radiation section 731, reducing the surface wave attenuation. At the same time, the inclined section 732 and the radiation section 731 form a gradient heat conduction structure, thereby improving the heat dissipation effect.

[0057] A dual-frequency radiation structure is formed by the grid unit 7 and the patch unit 8. Differential feeding is formed by using symmetric vias 9. At the same time, the annular power divider and phase shifter structure 21 is used to transmit signals. When different situations occur suddenly in the outside world, the emitted electromagnetic waves are dispersed to the grid unit 7 and the patch unit 8 when reflected to the radar antenna. The grid unit 7 and the patch unit 8 detect different waves, and then differential feed through the vias 9 to the feeding layer 2. The feeding layer 2 forms the transmission of signals through the annular power divider and phase shifter structure 21.

[0058] The above shows and describes the basic principles and beneficial effects of the present invention. At the same time, the present invention is not limited by the above embodiments. Without departing from the effects and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. An array antenna for millimeter-wave automotive radar, characterized in that: It includes an antenna substrate (1), a feeding layer (2), a reflection layer (3) and a radiation layer (4). The feeding layer (2), the reflection layer (3) and the radiation layer (4) are distributed in the antenna substrate (1) from bottom to top in sequence. An accommodation groove (11) is formed in the antenna substrate (1). Dielectric materials (5) are filled between the bottom of the antenna substrate (1), the feeding layer (2), the reflection layer (3) and the radiation layer (4) pairwise. Through holes (51) are formed on the surface of the dielectric materials (5). A combined antenna (6) is etched on the radiation layer (4). Four or more of the combined antennas (6) are annularly formed into an array and etched on the upper surface of the radiation layer (4). The combined antennas (6) are distributed in an annular array. The combined antenna (6) is composed of a grid unit (7) and a patch unit (8). The grid units (7) are symmetrically distributed. The grid unit (7) is divided into a radiation edge (71) and a non-radiation edge (72). The radiation edge (71) is divided into a concave edge (711) and a convex edge (712). The concave edge (711) is the radiation edge of the grid unit (7) close to the annular midpoint of the combined antenna (6). The convex edge (712) is the radiation edge of the grid unit (7) far from the annular midpoint of the combined antenna (6). The length of the concave edge (711) of a single grid unit (7) close to the annular midpoint of the combined antenna (6) is greater than the length of the convex edge (712) of the grid unit (7) far from the annular midpoint of the combined antenna (6). A unit connection segment (73) is provided between the grid units (7). The patch unit (8) is installed between single grid units (7) and is elliptical. The patch unit (8) is connected to the non-radiation edge (72) through a microstrip line. The patch unit (8) and the unit connection segment (73) form a series patch antenna.

2. The array antenna for millimeter-wave automotive radar according to claim 1, characterized in that: Both the concave edge (711) and the convex edge (712) are of asymptotic width. The width value of the concave edge (711) increases from both ends to the center. The width value of the convex edge (712) decreases from both ends to the center.

3. The array antenna for millimeter-wave automotive radar according to claim 1, characterized in that: A via hole (9) is provided between the feeding layer (2) and the radiation layer (4). The via hole (9) is located at the intersection of the non-radiation edge (72) and the unit connection segment (73). The via hole (9) is symmetric about the annular midpoint of multiple combined antennas (6).

4. The array antenna for millimeter-wave automotive radar according to claim 1, wherein: The area of the middle region of the grid unit (7) is smaller than the area of the patch unit (8). The patch unit (8) forms high-frequency resonant radiation. The grid unit (7) forms low-frequency resonant radiation.

5. The array antenna for millimeter-wave automotive radar according to claim 3, wherein: The feeding layer (2) includes a power splitting and phase shifting structure (21). One end of the power splitting and phase shifting structure (21) is connected to an input strip line (22) installed on the feeding layer (2). The other end of the power splitting and phase shifting structure (21) is connected to the radiation layer (4) through a via hole (9).

6. The array antenna for millimeter-wave automotive radar according to claim 3, wherein: The unit connection segment (73) is divided into a radiation part (731) and an inclined part (732). The inclination angle of the inclined part (732) is 12°.

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