Millimeter wave radar

Abstract

The millimeter wave radar comprises a radome, a wave absorbing structure, a 3D waveguide and a circuit board, the radome is provided with an installation cavity, and the wave absorbing structure, the 3D waveguide and the circuit board are all fixed in the installation cavity and are attached in sequence; the 3D waveguide is provided with a plurality of waveguide radiation ports, the circuit board is provided with a radio frequency chip and a plurality of microstrip waveguide conversion structures, each microstrip waveguide conversion structure is connected with the radio frequency chip through a microstrip line, and the waveguide radiation ports are in one-to-one correspondence with the microstrip waveguide conversion structures. The 3D waveguide is fixed to the circuit board and covers the radio frequency chip and the microstrip waveguide conversion structures, and at least part of each microstrip waveguide conversion structure is located in the projection of the waveguide radiation port corresponding to the microstrip waveguide conversion structure in the plane where the circuit board is located. The millimeter wave radar provided by the invention has the characteristics of ground clutter suppression, high signal intensity, high angle measurement precision and low cost.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and more specifically to a millimeter wave radar. Background Art

[0002] The current vehicle-mounted millimeter-wave radar beam is a symmetrical beam. Because it is installed at a relatively short distance from the ground, the ground clutter reflects a large amount of energy, which in turn affects the radar's detection of other targets. Therefore, a millimeter-wave radar that suppresses ground clutter and has high radar accuracy is needed. Summary of the invention

[0003] The object of the present invention is to provide a millimeter wave radar which has the characteristics of suppressing ground clutter, high signal strength, high angle measurement accuracy and low cost.

[0004] Based on the above purpose, the present invention provides a millimeter wave radar, including a radome, an absorbing structure, a 3D waveguide and a circuit board, the radome having an installation cavity, the absorbing structure, the 3D waveguide and the circuit board are all fixed in the installation cavity and sequentially fitted; the 3D waveguide is provided with a plurality of waveguide radiation ports, the circuit board is provided with a radio frequency chip and a plurality of microstrip waveguide conversion structures, each of the microstrip waveguide conversion structures is connected to the radio frequency chip through a microstrip line, each waveguide radiation port corresponds to each microstrip waveguide conversion structure one by one, the 3D waveguide is fixed to the circuit board and covers the radio frequency chip and each microstrip waveguide conversion structure, and at least a portion of each of the microstrip waveguide conversion structures is located within the projection of the waveguide radiation port corresponding to the microstrip waveguide conversion structure on the plane where the circuit board is located.

[0005] Furthermore, the wave absorbing structure is attached to a surface of the 3D waveguide away from the circuit board and is located below each waveguide radiation port.

[0006] Furthermore, a plurality of positioning posts are provided on the surface of the 3D waveguide that is bonded to the circuit board, a plurality of positioning holes are provided on the circuit board, each positioning post corresponds to each positioning hole one by one, and the positioning posts are inserted into the corresponding positioning holes to position the 3D waveguide and the circuit board.

[0007] Furthermore, a heat dissipation groove is provided on a surface of the 3D waveguide that is bonded to the circuit board, and a projection of the heat dissipation groove on the plane where the circuit board is located and a projection of the RF chip on the plane where the circuit board is located at least partially overlap.

[0008] Furthermore, a heat dissipation element is provided in the heat dissipation slot.

[0009] Furthermore, a glue groove is provided near each waveguide radiation port, and the glue groove is located on a side where the 3D waveguide is bonded to the circuit board, and the glue groove is used to fill with conductive glue to electrically connect the 3D waveguide to the circuit board.

[0010] Furthermore, the microstrip waveguide conversion structure includes a differential line, a first metal patch and a second metal patch, the microstrip line corresponding to the microstrip waveguide conversion structure is connected to the differential line, the differential line is connected to the first metal patch, the first metal patch and the second metal patch are arranged relatively to each other, and the gap between the first metal patch and the second metal patch forms an electromagnetic coupling area; at least part of the differential line, the first metal patch and the second metal patch are all located within the projection of the waveguide radiation port on the plane where the circuit board is located.

[0011] Furthermore, the differential line is parallel to the length direction or width direction of the waveguide radiation port.

[0012] Furthermore, the microstrip line is connected to the differential line through a balun.

[0013] Furthermore, the aperture of the waveguide radiation port is a uniform aperture, a stepped aperture or a trapezoidal aperture.

[0014] The millimeter wave radar of the present invention uses a 3D waveguide as an antenna, which can improve the radar signal strength and angle measurement accuracy; a microstrip line is used instead of a waveguide transmission line, which can reduce the waveguide processing cost; an absorbing structure is arranged below the waveguide radiation port of the 3D waveguide, which can absorb electromagnetic waves below the waveguide radiation port, thereby realizing an asymmetric beam of the radar and suppressing the influence of ground clutter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the structure of a millimeter wave radar according to an embodiment of the present invention;

[0016] Figure 2 is an exploded diagram of a millimeter wave radar according to an embodiment of the present invention;

[0017] Figure 3 A schematic diagram of the structure of a circuit board of a millimeter wave radar according to an embodiment of the present invention;

[0018] Figure 4 A schematic diagram of the relationship between the wave absorbing structure and the 3D waveguide according to an embodiment of the present invention;

[0019] Figure 5 This is a schematic structural diagram of a side of a 3D waveguide bonded to a circuit board according to an embodiment of the present invention;

[0020] Figure 6 is an enlarged schematic diagram of a microstrip waveguide conversion structure according to an embodiment of the present invention;

[0021] Figure 7 is a perspective view of a 3D waveguide and a circuit board according to an embodiment of the present invention;

[0022] Figure 8 FIG. 4 is a schematic diagram of the position relationship between the millimeter wave radar according to an embodiment of the present invention and the ground when in use. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0024] like Figure 1 , Figure 2 and Figure 3 As shown, an embodiment of the present invention provides a millimeter wave radar, including a radar cover 100, an absorbing structure 200, a 3D waveguide 300 and a circuit board 400. The radar cover 100 has an installation cavity 110, and the absorbing structure 200, the 3D waveguide 300 and the circuit board 400 are all fixed in the installation cavity 110 and sequentially attached; the 3D waveguide 300 is provided with a plurality of waveguide radiation ports 310, and the circuit board 400 is provided with a radio frequency chip 410 and a plurality of microstrip waveguide conversion structures 420, each of which is connected to a microstrip waveguide conversion structure 420 by a microstrip waveguide. The strip line 430 is connected to the RF chip 410, each waveguide radiation port 310 corresponds to each microstrip waveguide conversion structure 420 one by one, the 3D waveguide 300 is fixed to the circuit board 400 and covers the RF chip 410 and each microstrip waveguide conversion structure 420, and at least a part of each microstrip waveguide conversion structure 420 is located within the projection of the waveguide radiation port 310 corresponding to the microstrip waveguide conversion structure 420 on the plane where the circuit board 400 is located; the RF chip 410 is used to modulate the baseband signal to the millimeter wave frequency band and generate a transmission signal that meets the requirements. The transmitting signal is transmitted to the microstrip waveguide conversion structure 420 through the microstrip line 430, and then transmitted to the 3D waveguide 300 through the microstrip waveguide conversion structure 420, and transmitted outwardly by the 3D waveguide 300 to illuminate the target. The transmitting signal is reflected by the target to form a reflected signal, and the reflected signal is transmitted back to the RF chip 410 through the 3D waveguide 300, the microstrip waveguide conversion structure 420, and the microstrip line 430 in sequence, so that the RF chip 410 analyzes and processes the transmitting signal and the reflected signal to obtain specific information of the target, including distance, speed, direction, etc.; the 3D waveguide 300 is used to guide the electromagnetic wave to propagate in a specific direction, reduce the loss of the signal during the transmission process, and ensure that the signal can accurately reach the target area; the microstrip waveguide conversion structure 420 is used to convert the microstrip signal into a waveguide signal or convert the waveguide signal into a microstrip signal (that is, to realize the conversion between the microstrip signal and the waveguide signal), so as to ensure the effective coupling of the electromagnetic energy between the two transmission media, while minimizing the reflection and loss to a maximum extent, so as to achieve efficient and stable signal transmission.

[0025] In some embodiments, each microstrip waveguide conversion structure 420 and its corresponding waveguide radiation port 310, and the microstrip line 430 between the microstrip waveguide conversion structure 420 and the RF chip 410 are formed as a transmission channel or a receiving channel of the RF chip 410, so that the RF chip 410 has multiple transmission channels and multiple receiving channels. Exemplarily, the millimeter wave radar includes 8 microstrip waveguide conversion structures 420 and 8 microstrip waveguide conversion structures 420, which together form 4 transmission channels and 4 receiving channels. The 4 transmission channels and 4 receiving channels can be virtualized into 16 channels using time division multiplexing technology, thereby improving the data transmission rate and spectrum efficiency.

[0026] like Figure 4 As shown, in some embodiments, the absorbing structure 200 is attached to the side of the 3D waveguide 300 away from the circuit board 400 and is located below each waveguide radiation port 310 (i.e., the side closer to the ground when in use). The absorbing structure 200 can absorb electromagnetic waves below the waveguide radiation port 310 and reduce the energy of the lower half of its radiation field. When the millimeter wave radar is in use, the bottom of the waveguide radiation port 310 can be made closer to the ground, thereby suppressing ground clutter through the absorbing structure 200.

[0027] In some embodiments, the upper and lower surfaces of the radome are both planes, and the side walls are perpendicular to the upper and lower surfaces. The side walls are connected to the upper and lower surfaces through arc surfaces, which helps to reduce the secondary radiation of the signal, thereby improving the signal stability and penetration, so as to reduce the impact on the radar signal.

[0028] In some embodiments, the aperture of the waveguide radiation port 310 is a uniform aperture, a stepped aperture, or a trapezoidal aperture.

[0029] like Figure 5 As shown, in some embodiments, a plurality of positioning posts 320 are provided on the surface of the 3D waveguide 300 that is in contact with the circuit board 400, and a plurality of positioning holes 440 are provided on the circuit board 400. Each positioning post 320 corresponds to each positioning hole 440 one by one, and the positioning posts 320 can be inserted into the corresponding positioning holes 440 to achieve positioning between the 3D waveguide 300 and the circuit board 400.

[0030] In some embodiments, a heat dissipation groove 330 may be further provided on the surface of the 3D waveguide 300 that is bonded to the circuit board 400. The projection of the heat dissipation groove 330 on the plane where the circuit board 400 is located and the projection of the RF chip 440 on the plane where the circuit board 400 is located at least partially overlap. A heat dissipation element (such as heat dissipation glue or heat dissipation paste) is provided in the heat dissipation groove 330 to achieve thermal conduction between the RF chip 440 and the 3D waveguide 300, so that the heat of the RF chip 440 can be transferred outward through the 3D waveguide 300, thereby increasing the thermal conductivity of the millimeter wave radar.

[0031] In some embodiments, a glue groove 340 is provided near each waveguide radiation port 310. The glue groove 340 is located on the side where the 3D waveguide 300 and the circuit board 400 are bonded. The glue groove 340 is used to fill with conductive glue to fix and electrically connect the 3D waveguide 300 and the circuit board 400, thereby increasing the conductivity between the 3D waveguide 300 and the circuit board 400.

[0032] In some embodiments, the 3D waveguide 300 may be provided with a plurality of first screw holes 350, and the circuit board 400 may be provided with a plurality of second screw holes 450, each first screw hole 350 corresponds to each second screw hole 450 one by one, and the first screw hole 350 and the corresponding second screw hole 450 are aligned with each other so that screws can be passed through the first screw hole 350 and the second screw hole 450 to fix the 3D waveguide 300 and the circuit board 400 together.

[0033] like Figure 6 As shown, in some embodiments, the microstrip waveguide conversion structure 420 includes a differential line 421, a first metal patch 422, and a second metal patch 423. The differential line 421 is connected to the first metal patch 422. The first metal patch 422 and the second metal patch 423 are arranged opposite to each other, and the gap between the two forms an electromagnetic coupling region. The differential line 421 is also connected to the microstrip line 430 corresponding to the microstrip waveguide conversion structure 420. At least part of the differential line 421, the first metal patch 422, and the second metal patch 423 are all located within the projection of the waveguide radiation port 310 on the plane where the circuit board 400 is located (such as Figure 7 As shown); when the microstrip signal of the microstrip line 430 is transmitted to the microstrip waveguide conversion structure 420, it will first be converted into a differential signal. After the differential signal is transmitted to the first metal patch 422, a current will be generated on the first metal patch 422. The electromagnetic field generated by the current will interact with the second metal patch 423 and induce an electromagnetic field matching the waveguide mode. This electromagnetic field is then transmitted through the waveguide, thereby realizing the conversion of the microstrip signal to the waveguide signal; similarly, when the waveguide signal enters the electromagnetic coupling region, a current will be generated on the second metal patch 423. The electromagnetic field generated by the current will interact with the first metal patch 422, thereby forming a mode matching the differential line 421 after passing through the first metal patch 422. This mode is transmitted to the microstrip line 430 through the differential line 421, thereby realizing the conversion of the waveguide signal to the microstrip signal.

[0034] In some embodiments, efficient signal conversion and good impedance matching between the microstrip line and the waveguide can be achieved by adjusting the size of the first metal patch 422 and the second metal patch 423 and the gap between the two. For example, the length and width of the first metal patch 422 and the second metal patch 423 can be determined according to the operating frequency, the waveguide mode and the characteristic impedance of the microstrip line. It is necessary to ensure that their size can support the required electromagnetic wave mode and achieve good matching with the microstrip line. The gap width between the two metal patches is an important factor affecting the strength of electromagnetic coupling. A narrower gap can usually enhance the coupling of the electromagnetic field, thereby improving the conversion efficiency. However, a too narrow gap may increase the difficulty and cost of processing and may cause structural instability. Therefore, it is necessary to select an appropriate gap width while meeting the performance indicators.

[0035] In some embodiments, the differential line 421 may be parallel to the length direction of the waveguide radiation port 310 , thereby effectively improving the working bandwidth of the microstrip waveguide conversion structure 420 . In other embodiments, the differential line 421 may also be parallel to the width direction of the waveguide radiation port 310 .

[0036] In some embodiments, the microstrip line 430 can be connected to the differential line 421 through a balun to achieve broadband matching of the microstrip line 430 and the differential line 421 with low loss. Balun refers to a balanced-unbalanced converter, which is a three-port passive device. Its essence is to achieve mutual conversion between balanced signals (differential signals) and unbalanced signals (single-ended signals) through mutual coupling of inductor coils.

[0037] In some embodiments, the portion of the circuit board 400 where the microstrip line 430 is located is a high-frequency board, and the rest is a common FR4 board (ie, fiberglass board).

[0038] In some embodiments, the radome 100 is composed of two detachable parts to facilitate installation and removal of the absorbing structure 200 , the 3D waveguide 300 and the circuit board 400 therein.

[0039] like Figure 8 As shown, when the millimeter wave radar is in use, the plane where the circuit board 400 is located is perpendicular to the ground (XY plane) 500, that is, the circuit board 400 is located in the YZ plane, and the absorbing structure 200 is located below the waveguide radiation port 310, so that the absorbing structure 200 is closer to the ground 500.

[0040] The millimeter wave radar of the embodiment of the present invention uses the 3D waveguide 300 as an antenna, which can improve the radar signal strength and angle measurement accuracy; the microstrip line 430 is used instead of the waveguide transmission line, which can reduce the waveguide processing cost; the wave absorbing structure 200 is arranged below the waveguide radiation port 310 of the 3D waveguide 300, which can absorb the electromagnetic waves below the waveguide radiation port 310, thereby realizing an asymmetric beam of the radar and suppressing the influence of ground clutter.

[0041] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A millimeter wave radar, characterized in that: It includes a radome, an absorbing structure, a 3D waveguide and a circuit board, the radome has an installation cavity, the absorbing structure, the 3D waveguide and the circuit board are all fixed in the installation cavity and fitted in sequence; the 3D waveguide is provided with a plurality of waveguide radiation ports, the circuit board is provided with a radio frequency chip and a plurality of microstrip waveguide conversion structures, each of the microstrip waveguide conversion structures is connected to the radio frequency chip through a microstrip line, each waveguide radiation port corresponds to each microstrip waveguide conversion structure one by one, the 3D waveguide is fixed to the circuit board and covers the radio frequency chip and each microstrip waveguide conversion structure, and at least a portion of each microstrip waveguide conversion structure is located within the projection of the waveguide radiation port corresponding to the microstrip waveguide conversion structure on the plane where the circuit board is located.

2. The millimeter wave radar according to claim 1, characterized in that: The wave absorbing structure is attached to a surface of the 3D waveguide away from the circuit board and is located below each waveguide radiation port.

3. The millimeter wave radar according to claim 1, characterized in that: A plurality of positioning posts are provided on one surface of the 3D waveguide that is bonded to the circuit board, and a plurality of positioning holes are provided on the circuit board. Each positioning post corresponds to each positioning hole one by one, and the positioning posts are inserted into the corresponding positioning holes to position the 3D waveguide and the circuit board.

4. The millimeter wave radar according to claim 1, characterized in that: A heat dissipation groove is provided on the surface of the 3D waveguide that is bonded to the circuit board, and the projection of the heat dissipation groove on the plane where the circuit board is located and the projection of the radio frequency chip on the plane where the circuit board is located at least partially overlap.

5. The millimeter wave radar according to claim 4, characterized in that: A heat dissipation element is arranged in the heat dissipation groove.

6. The millimeter wave radar according to claim 1, characterized in that: A glue groove is provided near each waveguide radiation port, and the glue groove is located on a side where the 3D waveguide is attached to the circuit board. The glue groove is used to fill with conductive glue to electrically connect the 3D waveguide to the circuit board.

7. The millimeter wave radar according to claim 1, characterized in that: The microstrip waveguide conversion structure includes a differential line, a first metal patch and a second metal patch. The microstrip line corresponding to the microstrip waveguide conversion structure is connected to the differential line, the differential line is connected to the first metal patch, the first metal patch and the second metal patch are arranged opposite to each other, and the gap between the first metal patch and the second metal patch forms an electromagnetic coupling area; at least part of the differential line, the first metal patch and the second metal patch are all located within the projection of the waveguide radiation port on the plane where the circuit board is located.

8. The millimeter wave radar according to claim 7, characterized in that: The differential line is parallel to the length direction or the width direction of the waveguide radiation port.

9. The millimeter wave radar according to claim 7, characterized in that: The microstrip line is connected to the differential line through a balun.

10. The millimeter wave radar according to claim 1, characterized in that: The aperture of the waveguide radiation port is a uniform aperture, a stepped aperture or a trapezoidal aperture.

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