A millimeter wave radar module

Abstract

The application discloses a millimeter wave radar module in the technical field of radars, which comprises a millimeter wave radar circuit board integrated with an antenna on a mainboard, a metal frame and a shell, the metal frame covers the millimeter wave radar circuit board, the centers of the metal frame and the millimeter wave radar circuit board coincide, the upper and lower ends of the metal frame are in contact with the inner side of the shell and the upper surface of the mainboard respectively, the cross section of the metal frame is a rectangular structure, the long side size of the inner cavity of the metal frame is 2X=2*0.7lambda~2*0.9lambda, the short side size is Y=0.5X~0.8X, lambda is the wavelength of the radar wave, and the thickness of the metal frame is greater than or equal to 2mm. The application adds a metal frame with a proper size in the space between the product shell and the millimeter wave radar circuit board, the radar signal can be constrained and shaped by the shielding effect of the metal frame on the periphery of the millimeter wave radar circuit board, the interference of the shell or other components on the radar beam is avoided, the original clearance constraint condition is broken, the shell size is reduced, and the miniaturization and lightness of the product are realized.

Description

Technical Field

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

[0002] A millimeter-wave radar module typically consists of a millimeter-wave radar circuit board and an antenna. The module is mounted on top of the mainboard and protected by a casing, which acts as a radome for the antenna. A certain distance must be maintained between the antenna and the radome, and the radome must also meet specific thickness requirements to ensure optimal ranging performance and sensing capabilities of the millimeter-wave radar.

[0003] The optimal distance between the antenna and the inner surface of the radome helps to minimize the reflection effects caused by the radome. This effect is minimized when the electromagnetic wave reflected back to the antenna is in phase with the transmitted wave. Therefore, the ideal distance is an integer multiple of half a wavelength in air, which can be calculated using the following formula:

[0004]

[0005]

[0006] Where D is the distance from the antenna to the inner surface of the radome, and n is a positive integer. Let λ be the wavelength in air, and c be the speed of light in a vacuum. The center frequency at which the radar operates.

[0007] The thickness of an radome is typically determined based on factors such as the radar's operating frequency, radome material, and manufacturing process. In practical applications, the radome thickness not only determines the strength of the radar components but also influences radar performance. Therefore, when designing a radome, it is necessary to comprehensively consider both radar performance and practical application requirements to select an appropriate thickness. Ideally, the radome thickness should be an integer multiple of half the wavelength of the dielectric medium corresponding to the radar's actual operating frequency. This ensures that the radome becomes "almost transparent" within the expected frequency range. Therefore, the radome thickness can be calculated using the following formula:

[0008]

[0009]

[0010] Where T is the radome wall thickness, and n is a positive integer. where λ is the wavelength in the medium and c is the speed of light in a vacuum. The center frequency of radar operation. is the relative permittivity of the radome material.

[0011] For millimeter-wave radar antennas, besides the radome, the installation environment is also crucial. An unsuitable environment can severely impact the antenna's radiation performance, thereby affecting the radar's detection performance and accuracy. Conversely, a good installation environment can reduce interference from the surrounding environment. Therefore, millimeter-wave radar requires a good clearance area.

[0012] Based on the above calculation formula, for a 24GHz millimeter-wave radar, taking a PC material (dielectric constant 2.8) radome as an example, the ideal radome design and clearance area must meet the following requirements:

[0013] (1) Spacing between radar and radome (product housing): D≥6.25mm;

[0014] (2) Antenna radome (product casing) thickness: T=3mm;

[0015] (3) The minimum distance between the edge of the radar's clearance area and the radar shall not be less than 6.25 mm.

[0016] These three constraints are difficult to fully meet in the increasingly miniaturized and thinner design trends of electronic products. When the airspace conditions are not met, the performance of millimeter-wave radar cannot be fully utilized, affecting the end-product experience. Summary of the Invention

[0017] To overcome the shortcomings of existing millimeter-wave radars, such as the large clearance area required, the technical problem to be solved by this invention is to provide a millimeter-wave radar module that can reduce the clearance area.

[0018] The technical solution adopted by this invention to solve its technical problem is:

[0019] A millimeter-wave radar module includes a millimeter-wave radar circuit board located on a motherboard and an antenna integrated on the millimeter-wave radar circuit board, as well as a housing covering the millimeter-wave radar circuit board. It also includes a metal frame with open top and bottom sides, which encloses the millimeter-wave radar circuit board with their centers coinciding. The top and bottom ends of the metal frame contact the inner side of the housing and the upper surface of the motherboard, respectively. The metal frame has a rectangular cross-section, with a long side dimension of 2X = 2*0.7λ ~ 2*0.9λ and a short side dimension of Y = 0.5X ~ 0.8X, where λ is the wavelength of the radar wave, and the thickness H of the metal frame is ≥ 2mm.

[0020] Furthermore, the thickness T of the outer shell is ≥1mm, and the distance D between the outer shell and the millimeter-wave radar circuit board is 2~3mm.

[0021] Furthermore, the inner cavity of the metal frame is rectangular.

[0022] Furthermore, one end of the metal frame is fixed to the motherboard, and the other end abuts against the outer casing; or one end is fixed to the outer casing, and the other end abuts against the motherboard.

[0023] Furthermore, the metal frame is fixed to the motherboard or casing by means of adhesive bonding, screw connection, or snap-fit ​​connection.

[0024] Furthermore, the metal frame is made of aluminum, copper, or iron.

[0025] The beneficial effects of this invention are: by adding a metal frame in the space between the product casing and the millimeter-wave radar circuit board, the shielding effect of the metal frame on the periphery of the millimeter-wave radar circuit board can be used to constrain and shape the radar signal, thereby avoiding interference from the casing or other components to the radar beam. This allows for overcoming the original clearance conditions, reducing the size of the casing, and achieving miniaturization and thinning of the product. Attached Figure Description

[0026] Figure 1 This is a main sectional view of the present invention;

[0027] Figure 2 This is a side sectional view of the present invention.

[0028] The diagram is labeled as follows: 1-Main board, 2-Millimeter-wave radar circuit board, 3-Casing, 4-Metal frame, 5-Antenna. Detailed Implementation

[0029] The invention will be further described below with reference to the accompanying drawings.

[0030] It should be noted that if this invention uses directional terms such as up, down, left, right, front, and back, these are for describing the relative positions of components and are not specific references to the absolute positions of related components or the relationships between them. They are only used to explain the relative positional relationships and movements of components in a specific posture. If the specific posture changes, the directional indication will also change accordingly. If this invention uses terms related to quantity such as "many," "multiple," or "several," these specifically refer to two or more.

[0031] like Figure 1 , Figure 2As shown, the millimeter-wave radar module provided by the present invention includes a millimeter-wave radar circuit board 2 located on a motherboard 1, an antenna 5 integrated on the millimeter-wave radar circuit board 2, and a housing 3 covering the millimeter-wave radar circuit board 2. It also includes a metal frame 4 with open upper and lower sides. The metal frame 4 covers the millimeter-wave radar circuit board 2 inside, and the centers of the two coincide. The upper and lower ends of the metal frame 4 are in contact with the inner side of the housing 3 and the upper surface of the motherboard 1, respectively. The cross-section of the metal frame 4 is a rectangular structure, and its inner cavity has a long side dimension of 2X = 2*0.7λ~2*0.9λ, a short side dimension of Y = 0.5X~0.8X, where λ is the wavelength of the radar wave, and the thickness H of the metal frame 4 is ≥ 2mm.

[0032] This invention primarily utilizes a metal frame 4, motherboard 1, and outer casing 3 to form a metal cavity structure to enclose the millimeter-wave radar circuit board 2. The metal cavity effectively beamforms the radar waves transmitted and received by the millimeter-wave radar circuit board 2. By appropriately setting the size and thickness of the metal cavity, the beamwidth of the radar waves can be adjusted, thereby regulating the coverage area of ​​the millimeter-wave radar. Since the millimeter-wave radar circuit board 2 is typically rectangular, to save space, the metal frame 4 is preferably also rectangular, meaning the inner cavity of the metal frame 4 is cuboid. Theoretical analysis and numerous experiments have shown that, to achieve the beamforming effect, the longer side dimension of the inner cavity of the metal frame 4 should be 2X, where the theoretical range of X is λ / 2 < X < λ. In practical design, a frequency offset margin needs to be reserved, therefore X is taken as 0.7λ~0.9λ. The theoretical value of the shorter side dimension is Y = λ / 2. To balance power and size, and to meet the FOV requirements of the radar in practical applications, Y is taken as 0.5X~0.8X. Taking a 24G radar module as an example, the wavelength of 24GHz is 12.5mm, and the calculated X = 8.75mm~11.25mm and Y = 4.375mm~9mm. Figure 1 , Figure 2 The middle part is a single Rx or Tx unit. In order to balance the performance of the two units, the Rx and Tx parts overlap. Therefore, the long side needs to be 2X=17.5mm~22.5mm, and the short side needs to be selected in the range of 4.375mm~9mm according to the actual radar FOV requirements to achieve the purpose of beamforming.

[0033] After adding the metal frame 4, the thickness and clearance area of ​​the outer shell 3 no longer need to meet the original requirements. According to experimental verification, the thickness T of the outer shell 3 can be reduced to 1mm, the distance D between the outer shell 3 and the millimeter-wave radar circuit board 2 can be reduced to 2-3mm, and the distance between the inner wall of the metal frame 4 and the edge of the millimeter-wave radar circuit board 2 can be reduced to 2-3mm. Taking a 24G radar module with a PC material radome as an example, under the premise of achieving the same detection effect, the thickness of the outer shell 3 is 1mm, the distance between the outer shell 3 and the millimeter-wave radar circuit board 2 is 2mm, and the distance between the inner wall of the metal frame 4 and the edge of the millimeter-wave radar circuit board 2 is 2mm. Therefore, by adopting the solution of this invention, the thickness and size of the outer shell 3 can be significantly reduced, thereby achieving product miniaturization and thinning.

[0034] When installing the metal frame 4, one end of the metal frame 4 can be fixed to the main board 1, and the other end can abut against the outer casing 3; or one end can be fixed to the outer casing 3, and the other end can abut against the main board 1. Specific fixing methods can include adhesive bonding, screw connection, or clip connection. The material of the metal frame 4 can be ordinary aluminum, copper, or iron.

[0035] In summary, this invention can significantly reduce the clearance requirements of the millimeter-wave radar circuit board 2 by adding a metal frame 4 between the main board 1 and the outer casing 3 without adjusting the existing product structure. This makes it easier to ensure the ranging and sensing performance of the millimeter-wave radar in products with thin casings and small spaces.

Claims

1. A millimeter-wave radar module, comprising a millimeter-wave radar circuit board (2) located on a motherboard (1) and an antenna (5) integrated on the millimeter-wave radar circuit board (2), and a housing (3) covering the millimeter-wave radar circuit board (2), characterized in that: It also includes a metal frame (4) with open top and bottom sides. The metal frame (4) covers the millimeter-wave radar circuit board (2) inside, and the two coincide in center. The top and bottom ends of the metal frame (4) are in contact with the inner side of the outer shell (3) and the upper surface of the main board (1), respectively. The cross-section of the metal frame (4) is a rectangular structure. Its inner cavity has a long side dimension of 2X=2*0.7λ~2*0.9λ, a short side dimension of Y=0.5X~0.8X, where λ is the wavelength of the radar wave, and the thickness H of the metal frame (4) is ≥2mm.

2. The millimeter-wave radar module as described in claim 1, characterized in that: The thickness T of the outer shell (3) is ≥1mm, and the distance D between the outer shell (3) and the millimeter-wave radar circuit board (2) is 2~3mm.

3. A millimeter-wave radar module as described in claim 1, characterized in that: The inner cavity of the metal frame (4) is rectangular.

4. A millimeter-wave radar module as described in claim 1, characterized in that: One end of the metal frame (4) is fixed to the motherboard (1), and the other end abuts against the outer shell (3); or one end is fixed to the outer shell (3), and the other end abuts against the motherboard (1).

5. A millimeter-wave radar module as described in claim 4, characterized in that: The metal frame (4) is fixed to the motherboard (1) or the outer shell (3) by means of adhesive, screw connection or snap connection.

6. A millimeter-wave radar module as described in claim 1, characterized in that: The metal frame (4) is made of aluminum, copper or iron.

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