A bidirectional millimeter-wave radar antenna

Abstract

This application relates to the field of antenna technology, providing a bidirectional millimeter-wave radar antenna, including a dielectric substrate and antenna elements respectively disposed on both sides of the dielectric substrate. Each antenna element includes a waveguide cavity and a waveguide cover disposed on the waveguide cavity. The waveguide cavity has multiple square openings, the waveguide cover has multiple slots, and multiple coplanar waveguide microstrip lines are disposed on both sides of the dielectric substrate. The coplanar waveguide microstrip lines connect to the square openings, and the other side of each square opening connects to the slots. In practical applications, the antenna elements of the bidirectional millimeter-wave radar antenna employ a waveguide slot array configuration, achieving broadband coverage of 77GHz-81GHz, including both 77GHz and 79GHz detection radar frequency bands. This enables high-precision radiation detection, strong radar antenna compatibility, and a wide channel coverage angle. Furthermore, the bidirectional millimeter-wave radar antenna's antenna elements achieve bidirectional radiation through a double-sided configuration, realizing a 360° radiation coverage range.

Description

Technical Field

[0001] This application relates to the field of antenna technology, and in particular to a bidirectional millimeter-wave radar antenna. Background Technology

[0002] Radar antennas are an indispensable and important component of radar systems. They are devices that propagate and receive electromagnetic waves and determine the radar detection direction. Therefore, radar antennas can be widely used in security monitoring or detection fields where directionality is the primary function.

[0003] Common radar antennas are microstrip antennas. Microstrip antennas use printed circuit boards as substrates, with a thin metal layer attached to one side of the substrate as a ground plane, and a metal patch of a certain shape made using photolithography and other methods on the other side. Microwave transmission and reception are achieved by feeding the patch using microstrip lines, coaxial probes, and electrically coupled resonators. Due to the limitations of the microstrip antenna structure, signal propagation loss is high at high frequencies and the bandwidth is relatively narrow. Therefore, it can only operate in the 24GHz and 34.5GHz frequency bands, and the targets detected are mostly humanoid targets and vehicles. It cannot achieve high-precision detection of small objects. At the same time, microstrip antennas can only radiate in one direction. Due to structural reasons, the radiation coverage in the rear direction is not involved, resulting in a certain scanning blind zone.

[0004] In summary, it is necessary to provide a bidirectional millimeter-wave radar antenna to address the problems of low coverage frequency, narrow bandwidth, high loss, low detection accuracy, and small coverage angle that exist in traditional radar antennas. Summary of the Invention

[0005] To address the problems of low coverage frequency, narrow bandwidth, high loss, low detection accuracy, and small coverage angle of traditional radar antennas, this application provides a bidirectional millimeter-wave radar antenna.

[0006] The bidirectional millimeter-wave radar antenna includes a dielectric substrate and antenna units respectively disposed on both sides of the dielectric substrate.

[0007] The antenna unit includes a waveguide cavity and a waveguide cover disposed on the waveguide cavity;

[0008] The waveguide cavity is provided with multiple square openings, the waveguide cover is provided with multiple slots, and multiple coplanar waveguide microstrip lines are provided on both sides of the dielectric substrate. The coplanar waveguide microstrip lines are connected to the square openings, and the other side of the square openings is connected to the slots.

[0009] Furthermore, the dielectric plate includes a thick dielectric plate, and each side of the thick dielectric plate is provided with at least one thin dielectric plate.

[0010] Furthermore, the number of thin dielectric plates on both sides of the thick dielectric plate is the same.

[0011] Furthermore, the thick dielectric substrate is a radar chip module circuit board.

[0012] Furthermore, the waveguide cavity and the waveguide cover are made of plastic material with a metal electroplated surface.

[0013] Furthermore, the slits are arranged in a longitudinally equidistant pattern, with a longitudinal spacing of 0.5 wavelengths.

[0014] Furthermore, the number of gaps is greater than or equal to 10.

[0015] Furthermore, the waveguide cavity is provided with a boss, the waveguide cover is provided with a groove, and the boss is connected to the groove.

[0016] Furthermore, the waveguide cavity is provided with multiple rectangular slots and multiple square slots on both sides.

[0017] Furthermore, the antenna element is polygonal or circular.

[0018] As can be seen from the above technical solutions, the bidirectional millimeter-wave radar antenna provided in this application includes a dielectric substrate and antenna units respectively disposed on both sides of the dielectric substrate; the antenna unit includes a waveguide cavity and a waveguide cover disposed on the waveguide cavity; the waveguide cavity is provided with a plurality of square openings, the waveguide cover is provided with a plurality of slots, and a plurality of coplanar waveguide microstrip lines are disposed on both sides of the dielectric substrate, the coplanar waveguide microstrip lines are connected to the square openings, and the other side of the square openings is connected to the slots.

[0019] In practical applications, the antenna elements of the bidirectional millimeter-wave radar antenna adopt a waveguide slot array configuration, which can achieve broadband coverage of 77GHz-81GHz, including both 77GHz and 79GHz detection radar frequency bands, realizing high-precision radiation detection. The radar antenna has strong compatibility and a wide channel coverage angle. At the same time, the antenna elements of the bidirectional millimeter-wave radar antenna achieve bidirectional radiation through a double-sided configuration, realizing a 360° radiation coverage range. Attached Figure Description

[0020] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of an embodiment of a bidirectional millimeter-wave radar antenna according to this application;

[0022] Figure 2This is an exploded structural diagram of a bidirectional millimeter-wave radar antenna according to this application;

[0023] Figure 3 This is a simulation diagram of the bidirectional radiation effect of a bidirectional millimeter-wave radar antenna according to this application;

[0024] Figure 4 This is a schematic diagram of a dielectric substrate for a bidirectional millimeter-wave radar antenna according to this application;

[0025] Figure 5 This is a schematic diagram of the dielectric substrate structure of a bidirectional millimeter-wave radar antenna according to this application;

[0026] Figure 6 This is a schematic diagram of the waveguide cover of a bidirectional millimeter-wave radar antenna according to this application;

[0027] Figure 7 This is a schematic diagram of the other side of the waveguide cover of a bidirectional millimeter-wave radar antenna according to this application;

[0028] Figure 8 This is a schematic diagram of one side of the waveguide cavity of a bidirectional millimeter-wave radar antenna according to this application;

[0029] Figure 9 This is a schematic diagram of the other side of the waveguide cavity of a bidirectional millimeter-wave radar antenna according to this application;

[0030] Figure 10 The simulated radiation pattern of a bidirectional millimeter-wave radar antenna at 77 GHz according to this application;

[0031] Figure 11 The simulated radiation pattern of a bidirectional millimeter-wave radar antenna at 79 GHz according to this application is shown.

[0032] Figure 12 The image shows the S-parameter results of a bidirectional millimeter-wave radar antenna according to this application.

[0033] In the picture:

[0034] 1-Dielectric substrate, 11-Thick dielectric substrate, 12-Thin dielectric substrate, 2-Antenna element, 21-Waveguide top cover, 211-Square opening, 212-Boss, 213-Rectangular slot, 214-Square slot, 22-Waveguide cavity, 221-Gap, 222-Gutter. Detailed Implementation

[0035] To address the problems of low coverage frequency band, narrow bandwidth, high loss, low detection accuracy, and small coverage angle in existing radar antennas, this application provides a bidirectional millimeter-wave radar antenna.

[0036] See Figure 1This is a schematic diagram of an embodiment of a bidirectional millimeter-wave radar antenna according to this application. See also... Figure 2 This is an exploded structural diagram of a bidirectional millimeter-wave radar antenna according to this application. The bidirectional millimeter-wave radar antenna includes: a dielectric substrate 1 and antenna units 2 respectively disposed on both sides of the dielectric substrate 1; the antenna unit 2 includes a waveguide cavity 21 and a waveguide cover 22 disposed on the waveguide cavity 21; the waveguide cavity 21 is provided with a plurality of square openings 211, the waveguide cover 22 is provided with a plurality of slots 221, and a plurality of coplanar waveguide microstrip lines 3 are disposed on both sides of the dielectric substrate 1, the coplanar waveguide microstrip lines 3 are connected to the square openings 211, and the other side of the square openings 211 is connected to the slots 221.

[0037] Specifically, in this embodiment, the antenna element 2 is disposed on the outside of the dielectric substrate 1 and corresponds to the coplanar waveguide microstrip line 3 on the dielectric substrate 1. The coplanar waveguide microstrip line 3 is used to propagate radar antenna signals, and the radar signals are propagated outward through the antenna element 2. The antenna part includes the antenna element 2, which adopts a waveguide slot array configuration, enabling broadband coverage of 77GHz-81GHz, including both 77GHz and 79GHz detection radar frequency bands, achieving high-precision radiation detection, strong radar antenna compatibility, and a wide channel coverage angle. The antenna element 2 achieves bidirectional radiation through its double-sided configuration. See [link to relevant documentation]. Figure 3 The image shows a simulation of the bidirectional radiation effect of a bidirectional millimeter-wave radar antenna according to this application. Because the two antenna elements 2 are thin, structurally symmetrical, and located on both sides of the radar antenna body, they can form a bidirectional radar antenna propagation. At the same time, the antenna elements 2 are located around the radar antenna body with a large clearance, which allows the radar antenna body to achieve a bandwidth channel that is unmatched by unidirectional microstrip antennas with a relatively small thickness. Moreover, the flat design of the antenna elements 2 allows for space reuse, making it easy to form a compact planar bidirectional propagation radar antenna array.

[0038] Figure 4 This is a schematic diagram of a dielectric substrate for a bidirectional millimeter-wave radar antenna according to this application.

[0039] In some embodiments of this application, the dielectric substrate 1 needs to transmit antenna signals of different intensities to both sides in actual operation. By changing the number of thin dielectric substrates 12 on both sides of the dielectric substrate 1, the required radiation signal units can be set, and the intensity of radiation can be controlled, thus improving the flexibility of radiation intensity adjustment. In this embodiment, the dielectric substrate 1 consists of two identical thin dielectric substrates 12 and one thick dielectric substrate 11. The thin dielectric substrate 12 is specifically model ROGERS RO3003 with a thickness of 0.127mm, and the thick dielectric substrate 11 is specifically model FR4 with a thickness of 1.5mm. The thin dielectric substrates 12 on both sides of the dielectric substrate 1 are mirrored and identical. Each side is provided with 4 feed lines, and each feed line ends with a coplanar waveguide microstrip line 3. In practical applications, the routing of the feed lines and the location of the coplanar waveguide microstrip line 3 are not unique and can be distributed according to actual needs or design.

[0040] Figure 5 This is a schematic diagram of the dielectric substrate structure of a bidirectional millimeter-wave radar antenna according to this application.

[0041] In some embodiments of this application, to flexibly adapt to certain special scenarios, the number of thin dielectric plates 12 on both sides of the thick dielectric plate 11 is different. In practice, different numbers of thin dielectric plates 12 are set on both sides according to operational needs, in order to adjust the radiation intensity of the radar antennas on both sides to adapt to the required radiation intensity in different operational scenarios. In this embodiment, the number of thin dielectric plates 12 on both sides of the thick dielectric plate 11 is the same. Setting the same number of thin dielectric plates 12 ensures that the signal strength propagated by the dielectric plate 1 is the same and uniform.

[0042] Preferably, the thick dielectric plate 11 is a radar chip module circuit board. In this embodiment, the thick dielectric plate 11 mainly serves as a structural support. In practical applications, in order to make the radar antenna layout more compact and integrated, the radar chip module circuit board can be placed in the position of the thick dielectric plate 1 instead. Therefore, the routing of the positive feedback circuit can be coordinated with the chip's PIN pin interface to achieve a flexible layout and compact structure.

[0043] Figure 6 This is a schematic diagram of the waveguide cover of a bidirectional millimeter-wave radar antenna according to this application.

[0044] Furthermore, the slits 221 are arranged in a longitudinally equidistant pattern, with a longitudinal spacing of 0.5 wavelengths.

[0045] In some embodiments of this application, the waveguide cover 22 has four columns of slots 221 on its front side, with 10 slots 221 in each column. These slots 221 form the centerline of an offset array in the lateral direction. The lateral offset distance of each slot 221 is slightly different, determined according to the optimized dimensions of the final radar antenna. In this embodiment, the slots 221 are arranged at equal intervals in the longitudinal direction, with a longitudinal spacing of approximately 0.5 wavelengths. In other embodiments, the gap between the slots 221 is set to 0.1 wavelengths, resulting in a reduced actual test bandwidth. The gap affects the antenna bandwidth; a larger gap results in a wider bandwidth. The size of the slots 221 is designed according to the center frequency of the operating frequency band required for actual operation.

[0046] Furthermore, in some embodiments of this application, the waveguide cavity 21 and the waveguide cover 22 are made of plastic with a metal-plated surface. In actual production, the waveguide cavity 21 and the waveguide cover 22 are injection molded to form two integral parts, and metal is simultaneously electroplated onto the surface of the waveguide cavity 21 and the waveguide cover 22. Then, the waveguide cover 22 is placed on the waveguide cavity 21 and fixed with screws or other fastening methods. In other embodiments, the waveguide cavity 21 is made of metal, resulting in a heavy weight and high production cost, making it difficult to mass-produce. In contrast, the antenna unit 2 in this embodiment requires fewer components, has a simple structure, is easy to assemble, requires no welding, is easily automated, and has low production cost, making it suitable for large-scale, efficient production.

[0047] Figure 7 This is a schematic diagram of the other side of the waveguide cover of a bidirectional millimeter-wave radar antenna according to this application.

[0048] Figure 8 This is a schematic diagram of one side of the waveguide cavity of a bidirectional millimeter-wave radar antenna according to this application.

[0049] like Figure 7 and Figure 8 As shown, the waveguide cavity 21 is provided with a boss 212, and the waveguide cover 22 is provided with a groove 222, with the boss 212 connected to the groove 222. In this embodiment, the groove 222 is provided on one side of the waveguide cover 22, and the slot 221 array adopts a recessed design and is set in the groove 222 to better isolate the four slot 221 arrays, so that the electromagnetic waves can obtain better isolation performance in their respective cavity grooves 222. The boss 212 is designed on the contact surface between the waveguide cavity 21 and the waveguide cover 22 to fit the groove 222 of the waveguide cover 22, which is to better assemble and connect the waveguide cavity 21 and the waveguide cover 22.

[0050] Figure 9 This is a schematic diagram of the other side of the waveguide cavity of a bidirectional millimeter-wave radar antenna according to this application;

[0051] like Figure 9 As shown, the waveguide cavity 21 is also provided with multiple rectangular slots 213 and multiple square slots 214 on both sides. In order to reduce weight, the front of the cavity has non-through rectangular slots 213 and the back has non-through square slots 214, which not only satisfies the structural strength of the waveguide cavity 21, but also reduces the weight.

[0052] Furthermore, the antenna element 2 is polygonal or circular. In order to meet the structural requirements of the antenna element 2 under actual working conditions, the antenna element 2 can be set as polygonal or circular. In one embodiment of this application, the two antenna elements 2 have the same shape and can be square, rectangular, trapezoidal, triangular, circular, etc.

[0053] In summary, the bidirectional millimeter-wave radar antenna of this application embodiment not only enables bidirectional radiation but also has a planar structure and advantages such as small size, simple structure, wide bandwidth, and easy assembly into a planar array.

[0054] To enable those skilled in the art to better understand this application, a specific example from this application will be used for further explanation below.

[0055] like Figure 10 As shown, the simulated radiation pattern of a bidirectional millimeter-wave radar antenna at 77 GHz is presented in this application. When transmitting a 77 GHz signal through the aforementioned bidirectional millimeter-wave radar antenna, the gain coefficient of each antenna element 2 is greater than 11 dB, and the mutual coupling between two antenna elements 2 is less than 0.75 dB. The reflection coefficient is the ratio of the reflected wave to the incident wave; the smaller the reflected wave, the more energy the antenna radiates. Mutual coupling is the degree of coupling between antennas; the smaller the mutual coupling, the higher the signal stability. The radiation pattern of a 77 GHz radar antenna is used as an example for illustration. Due to the symmetrical antenna structure, only the elevation radiation pattern of the bidirectional millimeter-wave radar antenna at 77 GHz is given here.

[0056] Figure 11 As shown, this application discloses a simulated radiation pattern of a bidirectional millimeter-wave radar antenna at 79 GHz. Antenna element 2 mainly excites an electromagnetic field in both directions to propagate radar signals in both forward and reverse directions. The gain coefficient of antenna element 2 is greater than 11 dB, and the difference between the highest gain in the forward direction and the highest gain in the reverse direction is within 0.1 dB, which can achieve the 79 GHz frequency band. At the same time, antenna element 2 excites an electromagnetic field in both directions to propagate in both forward and reverse directions. In this way, the two antenna elements form bidirectional radiation in the plane, thus realizing the function of bidirectional radiation.

[0057] In summary, according to the embodiments of this application, a bidirectional millimeter-wave radar antenna, due to the relatively small thickness of the two antenna elements 2 and their approximately symmetrical structure, can propagate electromagnetic radiation in both positive and negative directions, thus forming bidirectional radiation. At the same time, the two antenna elements 2 and the feed matching circuit are placed vertically, thus forming radiation in two directions, thereby realizing the bidirectional radiation function of the antenna. Moreover, the antenna has a compact structure and has the advantages of small size, simple structure, wide bandwidth, and easy assembly into a planar array.

[0058] Figure 12 The diagram shows the S-parameter results of a bidirectional millimeter-wave radar antenna according to this application. The diagram shows that S11 < -10dB in the channel from 76.5GHz to 81.5GHz, indicating that the bidirectional millimeter-wave radar antenna of this application is working well and covers the two main radar frequency bands of 77GHz and 79GHz, enabling high-precision detection of small objects.

[0059] As can be seen from the above technical solutions, the bidirectional millimeter-wave radar antenna provided in this application includes: a dielectric substrate 1 and antenna units 2 respectively disposed on both sides of the dielectric substrate 1. The antenna unit 2 includes a waveguide cavity 21 and a waveguide cover 22 disposed on the waveguide cavity 21. The waveguide cavity 21 is provided with a plurality of square openings 211, the waveguide cover 22 is provided with a plurality of slots 221, and a plurality of coplanar waveguide microstrip lines 3 are disposed on both sides of the dielectric substrate 1. The coplanar waveguide microstrip lines 3 are connected to the square openings 211, and the other side of the square openings 211 is connected to the slots 221.

[0060] In practical applications, the antenna element 2 of this bidirectional millimeter-wave radar antenna adopts a waveguide slot array configuration, which can achieve broadband coverage of 77GHz-81GHz. The 77GHz and 79GHz detection radar frequency bands are both included, achieving high-precision radiation detection. The radar antenna has strong compatibility and a wide channel coverage angle. At the same time, the antenna element of this radar antenna achieves bidirectional radiation through a double-sided configuration, realizing a 360° radiation coverage range.

[0061] The present application has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present application. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and implementation methods of the present application without departing from the spirit and scope of the present application, and all such modifications and improvements fall within the scope of the present application.

Claims

1. A bidirectional millimeter-wave radar antenna, characterized in that, It includes a dielectric substrate (1) and antenna units (2) respectively disposed on both sides of the dielectric substrate (1); The antenna unit (2) includes a waveguide cavity (21) and a waveguide cover (22) disposed on the waveguide cavity (21); the waveguide cavity (21) is also provided with a plurality of square openings (211), and the waveguide cover (22) is provided with a plurality of slits (221). Multiple coplanar waveguide microstrip lines (3) are also provided on both sides of the dielectric substrate (1). The coplanar waveguide microstrip lines (3) are connected to the square opening (211), and the other side of the square opening (211) is connected to the slot (221). The dielectric plate (1) includes a thick dielectric plate (11), and each side of the thick dielectric plate (11) is provided with at least one thin dielectric plate (12). The thick dielectric plate (11) is a radar chip module circuit board; The waveguide cavity (21) and the waveguide cover (22) are made of plastic with a metal electroplated surface.

2. The bidirectional millimeter-wave radar antenna according to claim 1, characterized in that, The number of thin dielectric plates (12) on both sides of the thick dielectric plate (11) is the same.

3. The bidirectional millimeter-wave radar antenna according to claim 1, characterized in that, The slits (221) are arranged in a longitudinally equidistant pattern with a longitudinal spacing of 0.5 wavelengths.

4. A bidirectional millimeter-wave radar antenna according to claim 1, characterized in that, The number of the gaps (221) is greater than or equal to 10.

5. A bidirectional millimeter-wave radar antenna according to claim 1, characterized in that, The waveguide cavity (21) is provided with a boss (212), and the waveguide cover (22) is provided with a groove (222). The boss (212) is connected to the groove (222).

6. A bidirectional millimeter-wave radar antenna according to claim 1, characterized in that, The waveguide cavity (21) is also provided with multiple rectangular slots (213) and multiple square slots (214) on both sides.

7. A bidirectional millimeter-wave radar antenna according to claim 1, characterized in that, The antenna element (2) is polygonal or circular.

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