A waveguide antenna structure and antenna array for millimeter wave radar

Abstract

This invention provides a waveguide antenna structure and antenna array for millimeter-wave radar, comprising a waveguide cavity and a waveguide fabrication structure disposed on the waveguide cavity. The waveguide fabrication structure is composed of a first waveguide fabrication structure and a second waveguide fabrication structure joined together. The bottom surface of the first waveguide fabrication structure is connected to the top surface of the waveguide cavity, and the bottom surface of the second waveguide fabrication structure is connected to the top surface of the first waveguide fabrication structure, with the centers of the first and second waveguide fabrication structures aligned. The waveguide fabrication structure is composed of two layers of fabrication structures joined together, with the upper part being one layer and the lower part being another. Both the columnar first waveguide fabrication structure and the stepped second waveguide fabrication structure are relatively simple and easy to manufacture, achieving lower manufacturing difficulty and a smaller array spacing on the basis of a double-layer structure, thereby achieving a larger unambiguous angle.

Description

Technical Field

[0001] This invention relates to the field of waveguide antennas, and more particularly to a waveguide antenna structure and antenna array for millimeter-wave radar. Background Technology

[0002] Millimeter-wave radar is a sensor that uses electromagnetic waves in the millimeter-wave frequency band for target detection and environmental perception. It has wide applications in the field of intelligent driver assistance systems, such as rear cross traffic alert (RCTA), forward cross traffic alert (FCTA), lane change assist (LCA), adaptive cruise control (ACC), blind spot detection (BSD), and forward collision warning (FCW). Furthermore, millimeter-wave radar can operate in all weather conditions, unaffected by adverse weather conditions such as fog, rain, or snow, providing stable and reliable perception data. Its performance directly impacts the safety and reliability of intelligent driver assistance systems.

[0003] With the rapid development and increasing penetration of intelligent assisted driving in recent years, the requirements for the reliability and safety of intelligent assisted driving are becoming increasingly stringent. Millimeter-wave radar, as one of the key sensors in assisted driving systems, is also constantly improving its detection range and resolution performance. Currently, conventional millimeter-wave radars generally use microstrip antenna arrays. This approach suffers from high feeder losses and low isolation between adjacent feeders and between the feeder and the antenna, leading to mutual coupling interference between channels, which in turn reduces antenna radiation performance and causes antenna pattern distortion. To mitigate these effects of microstrip antennas, the industry has proposed replacing them with waveguide antenna technology. Especially now that radar chips have implemented LOP (Low-Input Parcel) packaging technology, LOP packaging can directly design the RF signal transmission and reception interfaces as waveguide ports, enabling the chip's electromagnetic wave signals to be directly transmitted to the waveguide antenna through the waveguide structure. This significantly improves transmission loss, and the waveguide transmission of electromagnetic waves significantly reduces the impact of the transmission line on antenna radiation performance. Therefore, waveguide antennas can significantly improve the performance of millimeter-wave radar.

[0004] Current waveguide antenna technology solutions in the industry include multi-layer and two-layer structures. Multi-layer structures are relatively complex and costly, and it is difficult to control consistency in mass production. While two-layer structures simplify the structure and reduce the difficulty and cost of mass production, they impose more constraints on waveguide transmission lines and antenna design. Although existing technologies have achieved two-layer structures, the structure is still very complex and difficult to implement through conventional processing methods. At the same time, the way the waveguide feed line is fed in the middle of the antenna radiating array results in a large antenna width, making it impossible to achieve a small array spacing when assembling the antenna array. This will result in a relatively small angular unambiguity range for the radar, which may not meet system requirements.

[0005] Therefore, there is an urgent need for a waveguide antenna structure and antenna array for millimeter-wave radar to improve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a waveguide antenna structure and antenna array for millimeter-wave radar, which can achieve lower processing difficulty on the basis of a double-layer structure, while achieving a smaller array spacing and a larger unambiguous angle.

[0007] In a first aspect, the present invention provides a waveguide antenna structure for millimeter-wave radar, comprising a waveguide cavity and a waveguide fabrication structure disposed on the waveguide cavity; the waveguide fabrication structure is formed by splicing a first waveguide fabrication structure and a second waveguide fabrication structure; the bottom surface of the first waveguide fabrication structure is connected to the top surface of the waveguide cavity, the bottom surface of the second waveguide fabrication structure is connected to the top surface of the first waveguide fabrication structure, and the centers of the first waveguide fabrication structure and the second waveguide fabrication structure are aligned.

[0008] Optionally, the first waveguide fabrication structure is a cylindrical cavity, and the cross-section of the first waveguide fabrication structure is rectangular, with the length direction of the rectangle being the same as the length direction of the waveguide cavity.

[0009] Optionally, all four corners of the rectangle are rounded chamfers.

[0010] Optionally, the second waveguide fabrication structure is a stepped cavity, and the cross-section of the second waveguide fabrication structure gradually decreases from the top surface to the bottom surface.

[0011] Optionally, the second waveguide fabrication structure is a cavity with a three-step shape, and steps are respectively provided on two opposite sides of the second waveguide fabrication structure in the width direction of the waveguide cavity; and / or the shape of the cross section is rectangular.

[0012] Optionally, the waveguide fabrication structure is two or more, and is evenly spaced on the waveguide cavity, forming a straight line of waveguide slots, with the distance between the centers of adjacent waveguide slots being half a wavelength.

[0013] Optionally, the waveguide cavity extends forward in a curved shape along its length.

[0014] The beneficial effects of this invention are as follows: A waveguide cavity and a waveguide fabrication structure disposed on the waveguide cavity are provided; the waveguide fabrication structure is formed by splicing a first waveguide fabrication structure and a second waveguide fabrication structure; the bottom surface of the first waveguide fabrication structure is connected to the top surface of the waveguide cavity, and the bottom surface of the second waveguide fabrication structure is connected to the top surface of the first waveguide fabrication structure, with the centers of the first and second waveguide fabrication structures aligned. The waveguide fabrication structure is formed by splicing the first and second waveguide fabrication structures vertically, with the upper part being one layer of fabrication structure and the lower part being another layer of fabrication structure. The columnar first waveguide fabrication structure and the stepped second waveguide fabrication structure are both relatively simple and easy to fabricate, achieving lower fabrication difficulty on the basis of a double-layer structure. Simultaneously, it enables side-feeding of the waveguide antenna radiating element, significantly reducing the antenna width and achieving a smaller array spacing, thereby achieving a larger unambiguous angle.

[0015] Secondly, the present invention provides a waveguide antenna array for millimeter-wave radar, the antenna array comprising M input channels and N output channels connected by waveguide transmission cavities, wherein M and N are positive integers, each channel comprising a first conversion structure, a second conversion structure, and any possible combination of the waveguide antenna structures described in the first aspect; the second input interface of the second conversion structure is used to receive radio frequency signals; the second output interface of the second conversion structure is connected to the waveguide antenna structure through the first conversion structure.

[0016] Optionally, the first conversion structure includes a first conversion waveguide cavity; the top surface of the first conversion waveguide cavity is a plane; one side of the first conversion waveguide cavity protrudes outward to form a first input interface, and the opposite side of the first conversion waveguide cavity protrudes outward to form a first output interface; the short side of the first input interface is horizontal and the long side is vertical; the long side of the first output interface is horizontal and the short side is vertical, and the size of the first output interface is the same as the size of the input interface of the waveguide cavity of the waveguide antenna structure; the first input interface is used to connect with the second output interface.

[0017] Optionally, the second conversion structure is based on LOP packaging and includes a second conversion waveguide cavity; one side of the second conversion waveguide cavity protrudes outward to form a second input interface, and the other side of the second conversion waveguide cavity, perpendicular to the first side, protrudes outward to form a second output interface; the top surface of the second output interface is higher than the top surface of the second input interface.

[0018] For the beneficial effects of the second aspect mentioned above, please refer to the description of the first aspect mentioned above. Attached Figure Description

[0019] Figure 1A schematic diagram of the overall structure of a waveguide antenna structure for millimeter-wave radar provided in an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the overall structure of the first conversion structure provided in an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of the return loss of the first conversion structure provided in an embodiment of the present invention;

[0022] Figure 4 A schematic diagram of the insertion loss of the first conversion structure provided in an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the overall structure of the second conversion structure provided in an embodiment of the present invention;

[0024] Figure 6 A performance diagram of the second conversion structure provided in an embodiment of the present invention;

[0025] Figure 7 A schematic diagram of the overall structure of a waveguide antenna array for millimeter-wave radar provided in an embodiment of the present invention;

[0026] Figure 8 for Figure 7 A three-dimensional diagram of the specific fabrication structure of the waveguide antenna array shown.

[0027] Figure 9 for Figure 7 A top view of the specific fabrication structure of the waveguide antenna array shown.

[0028] Figure 10 for Figure 7 A side view of the specific fabrication structure of the waveguide antenna array shown.

[0029] Figure 11-14 for Figure 7 The diagram shows the performance of the waveguide antenna array.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Waveguide antenna structure;

[0032] 11. Waveguide cavity;

[0033] 121. First waveguide fabrication structure one; 122. First waveguide fabrication structure two; 123. First waveguide fabrication structure three; 124. First waveguide fabrication structure four;

[0034] 131. Second waveguide fabrication structure one; 132. Second waveguide fabrication structure two; 133. Second waveguide fabrication structure three; 134. Second waveguide fabrication structure four;

[0035] 2. First conversion structure;

[0036] 21. First input interface; 22. First output interface;

[0037] 3. Second conversion structure;

[0038] 31. Second input interface; 32. Second output interface;

[0039] 4. Waveguide antenna array. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.

[0041] The technical solutions of the embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the embodiments of the present invention, the terminology used in the following embodiments is for the purpose of describing specific embodiments only and is not intended to limit the present invention. The singular expressions “a,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise. It should also be understood that in the following embodiments of the present invention, “at least one” and “one or more” refer to one or more (including two). The term “and / or” is used to describe the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character “ / ” generally indicates that the preceding and following related objects are in an “or” relationship.

[0042] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of the invention. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," and "in still other embodiments" appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless otherwise specifically emphasized. The term "connection" includes both direct and indirect connections, unless otherwise stated. "First" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0043] In embodiments of the present invention, "exemplarily" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design described as "exemplarily" or "for example" in embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or design solutions. Rather, the use of "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0044] like Figure 1 As shown, the present invention provides a waveguide antenna structure 1 for millimeter-wave radar, including a waveguide cavity 11 and a waveguide fabrication structure disposed on the waveguide cavity 11; the waveguide fabrication structure is formed by splicing a first waveguide fabrication structure and a second waveguide fabrication structure; the bottom surface of the first waveguide fabrication structure is connected to the surface of the waveguide cavity 11, and the bottom surface of the second waveguide fabrication structure is connected to the top surface of the first waveguide fabrication structure, and the centers of the first waveguide fabrication structure and the second waveguide fabrication structure are aligned. The waveguide fabrication structure is formed by splicing the first waveguide fabrication structure and the second waveguide fabrication structure vertically, with the upper part being a single fabrication structure and the lower part being another fabrication structure. The columnar first waveguide fabrication structure and the stepped second waveguide fabrication structure are both relatively simple and easy to fabricate, achieving lower fabrication difficulty on the basis of a double-layer structure. At the same time, it realizes the side-feeding method of the waveguide antenna radiating element, significantly reducing the antenna width, enabling smaller array spacing, and thus achieving a larger unambiguous angle.

[0045] In some embodiments, the first waveguide fabrication structure (first waveguide fabrication structure one 121, first waveguide fabrication structure two 122, first waveguide fabrication structure three 123, first waveguide fabrication structure four 124) is a cylindrical cavity, and the cross-section of the first waveguide fabrication structure is rectangular. The length direction of the rectangle is the same as the length direction of the waveguide cavity 11. This basic structural design shows significant system compatibility advantages in practical applications. The length direction of the rectangle is consistent with the length direction of the waveguide cavity 11, which can ensure the stability of the electromagnetic wave transmission mode and reduce mode distortion caused by abrupt changes in cross-section.

[0046] In some specific embodiments, the four corners of the rectangle are all rounded chamfers. By designing the corners of the column to be rounded, the accumulation of edge field strength can be effectively suppressed, and low-loss transmission of electromagnetic energy can be achieved.

[0047] In some other embodiments, the second waveguide fabrication structure (second waveguide fabrication structure one 131, second waveguide fabrication structure two 132, second waveguide fabrication structure three 133, second waveguide fabrication structure four 134) is a stepped cavity, and the cross-section of the second waveguide fabrication structure gradually decreases from the top surface to the bottom surface.

[0048] In some specific embodiments, the second waveguide fabrication structure is a cavity with three stepped layers. Steps are provided on two opposite sides of the second waveguide fabrication structure along the width direction of the waveguide cavity 11. This three-step design is not only easy to fabricate, but the gradual decrease in size from top to bottom of the three steps also reduces the cross-section of the entire second waveguide fabrication structure, creating a highly efficient impedance transformation structure. This structure can smoothly transition the impedance of the standard waveguide to free-space impedance, improving the antenna's transmission efficiency. Furthermore, the selection of step positions allows for precise control of the electromagnetic field distribution at the waveguide opening, improving the antenna's anti-interference capability and signal purity. Together, these factors ensure that the final fabricated waveguide antenna structure 1 has a more compact structure and better array performance, while reducing sidelobe levels and improving antenna stability. In other specific embodiments, the cross-section is rectangular. The waveguide antenna structure 1, comprising a cylindrical first waveguide fabrication structure and a three-step stepped second waveguide fabrication structure, achieves a series-feed configuration with very low sidelobe levels and a compact antenna size.

[0049] In other embodiments, the number of waveguide fabrication structures is two or more, and they are evenly spaced on the waveguide cavity 11, arranged in a straight line as waveguide slots, with the distance between the centers of adjacent waveguide slots being half a wavelength. For example, as shown... Figure 1As shown, there are four waveguide fabrication structures, which are evenly spaced on the waveguide cavity 11. Along the length of the waveguide cavity 11, waveguide slots are arranged in a straight line, and the distance between the centers of adjacent waveguide slots is about half a wavelength (if the dimensional tolerance of all slots can be stably controlled within ±0.01mm). The four radiating elements are sequentially excited by traveling waves inside the waveguide, which not only achieves a compact longitudinal dimension, but also makes the entire antenna structure exhibit excellent comprehensive performance of high gain, low sidelobes, and small size.

[0050] In some specific embodiments, the waveguide cavity 11 extends forward in a curved shape along its length.

[0051] The advantages of the waveguide antenna structure 1 of this invention are that it achieves lower manufacturing difficulty based on a double-layer structure, and can be manufactured using conventional methods. It enables side-feeding of the waveguide antenna radiating elements, significantly reducing the antenna width and allowing for smaller array spacing, thereby achieving a larger unambiguous angle.

[0052] Based on the waveguide antenna structure 1 described above for millimeter-wave radar, as follows: Figure 2 , Figure 5 , Figure 7-10 As shown, the present invention also provides a waveguide antenna array 4 for millimeter-wave radar. The antenna array includes M input channels and N output channels connected via waveguide transmission cavities, where M and N are positive integers. Each channel includes a first conversion structure 2, a second conversion structure 3, and the aforementioned waveguide antenna structure 1 for millimeter-wave radar. The second input interface 31 of the second conversion structure 3 is used to receive radio frequency signals. The second output interface 32 of the second conversion structure 3 is connected to the waveguide antenna structure 1 via the first conversion structure 2. For example, as... Figure 7 As shown, both M and N are 4, meaning that the waveguide antenna array 4 has 4 input channels and 4 output channels.

[0053] In some embodiments, such as Figure 2 As shown, the first conversion structure 2 includes a first conversion waveguide cavity; the top surface of the first conversion waveguide cavity is a plane; one side of the first conversion waveguide cavity protrudes outward to form a first input interface 21, and the opposite side of the first conversion waveguide cavity protrudes outward to form a first output interface 22; the short side of the first input interface 21 is horizontal and the long side is vertical; the long side of the first output interface 22 is horizontal and the short side is vertical, and the size of the first output interface 22 is the same as the size of the input interface of the waveguide cavity 11 of the waveguide antenna structure 1; the first input interface 21 is used to connect with the second output interface 32. Figure 3 and Figure 4As shown, based on the return loss and insertion loss of the first conversion structure 2, it can be seen that the bandwidth and loss of this conversion structure are both relatively good.

[0054] In other embodiments, the second conversion structure 3 is based on a LOP package and includes a second conversion waveguide cavity; one side of the second conversion waveguide cavity protrudes outward to form a second input interface 31, and another side of the second conversion waveguide cavity perpendicular to the first side protrudes outward to form a second output interface 32; the top surface of the second output interface 32 is higher than the top surface of the second input interface 31. Figure 6 As shown, the second conversion structure 3 based on LOP packaging not only realizes the waveguide transmission of electromagnetic wave signals between the chip, PCB, and waveguide antenna, but also has superior performance and is easy to process.

[0055] The advantage of this embodiment of the invention lies in the design of the first conversion structure 2 and the second conversion structure 3, which achieves waveguide polarization conversion while ensuring a two-layer fabrication structure, enabling a compact layout of the waveguide transmission line and facilitating docking with the LOP package port. Figure 11-14 It can be seen that the waveguide antenna array 4 provided by the present invention has a gain and radiation pattern, and the antenna's -10dB bandwidth is greater than 5GHz, while the sidelobe level is less than -25dB, which is significantly better than the prior art.

[0056] When the waveguide antenna array 4 provided by the present invention is working, the radio frequency signal of the chip is received by the second input interface 31 of the second conversion structure 3 after passing through the cavity of the PCB, and reaches the second output interface 32 through the second conversion waveguide cavity shown. The radio frequency signal enters the first input interface 21 of the first conversion structure 2 from the second output interface 32, and enters the first output interface 22 of the first conversion structure 2 through the first conversion waveguide cavity, and then enters the waveguide cavity 11 of the waveguide antenna structure 1.

[0057] Although the embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. The above descriptions are merely embodiments of the present invention and do not limit the patent scope of the present invention. However, it should be understood that such modifications and variations fall within the scope and spirit of the present invention as set forth in the claims. Moreover, the present invention described herein may have other embodiments and can be implemented or realized in various ways. All equivalent transformations made based on the description and drawings of the present invention, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A waveguide antenna structure for millimeter-wave radar, characterized in that, Includes a waveguide cavity and a waveguide fabrication structure disposed on the waveguide cavity; The waveguide fabrication structure is composed of a first waveguide fabrication structure and a second waveguide fabrication structure. The first waveguide fabrication structure is a cylindrical cavity, and the second waveguide fabrication structure is a stepped cavity. The cross-section of the second waveguide fabrication structure gradually decreases from the top surface to the bottom surface. The bottom surface of the first waveguide fabrication structure is connected to the top surface of the waveguide cavity, the bottom surface of the second waveguide fabrication structure is connected to the top surface of the first waveguide fabrication structure, and the centers of the first waveguide fabrication structure and the second waveguide fabrication structure are aligned.

2. The waveguide antenna structure according to claim 1, characterized in that, The cross-section of the first waveguide fabrication structure is rectangular, and the length direction of the rectangle is the same as the length direction of the waveguide cavity.

3. The waveguide antenna structure according to claim 2, characterized in that, The rectangle has rounded chamfers at all four corners.

4. The waveguide antenna structure according to claim 1, characterized in that, The second waveguide fabrication structure is a cavity with three stepped layers. Steps are provided on two opposite sides of the second waveguide fabrication structure in the width direction of the waveguide cavity; and / or the cross-section is rectangular.

5. The waveguide antenna structure according to any one of claims 1-4, characterized in that, The waveguide fabrication structure consists of two or more pieces, which are evenly spaced on the waveguide cavity and arranged in a straight line as waveguide slots. The distance between the centers of adjacent waveguide slots is half a wavelength.

6. The waveguide antenna structure according to claim 5, characterized in that, The waveguide cavity extends forward in a curved shape along its length.

7. A waveguide antenna array for millimeter-wave radar, the antenna array comprising M input channels and N output channels connected by waveguide transmission cavities, wherein, M and N are positive integers, characterized in that each channel includes a first conversion structure, a second conversion structure, and a waveguide antenna structure as described in any one of claims 1 to 6; The second input interface of the second conversion structure is used to receive radio frequency signals; The second output interface of the second conversion structure is connected to the waveguide antenna structure through the first conversion structure.

8. The antenna array according to claim 7, characterized in that, The first conversion structure includes a first conversion waveguide cavity; The top surface of the first conversion waveguide cavity is a plane; one side of the first conversion waveguide cavity protrudes outward to form a first input interface, and the opposite side of the first conversion waveguide cavity protrudes outward to form a first output interface; The short side of the first input interface is horizontal and the long side is vertical; the long side of the first output interface is horizontal and the short side is vertical, and the size of the first output interface is the same as the size of the input interface of the waveguide cavity of the waveguide antenna structure. The first input interface is used to connect to the second output interface.

9. The antenna array according to claim 7, characterized in that, The second conversion structure is based on LOP packaging and includes a second conversion waveguide cavity; One side of the second conversion waveguide cavity protrudes outward to form a second input interface, and the other side of the second conversion waveguide cavity, which is perpendicular to the first side, protrudes outward to form a second output interface; The top surface of the second output interface is higher than the top surface of the second input interface.

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