Vertical transition structure of millimeter wave radar

Abstract

The utility model relates to the technical field of millimeter waves, in particular to a vertical transition structure of a millimeter wave radar. Comprising a waveguide cavity, a grounding coplanar waveguide and a rectangular waveguide which are sequentially arranged from bottom to top, the grounding coplanar waveguide comprises a dielectric substrate, a grounding coplanar waveguide transmission structure and a communication groove, the grounding coplanar waveguide transmission structure and the communication groove are arranged on the dielectric substrate, the waveguide cavity and the rectangular waveguide are communicated through the communication groove, an impedance conversion structure is arranged in the waveguide cavity, and the impedance conversion structure is arranged in the waveguide cavity. The head end of the impedance conversion structure is connected with the tail end of the grounding coplanar waveguide transmission structure, and the tail end of the impedance conversion structure is located under the communication groove. According to the utility model, the metalized rectangular waveguide is directly processed on the dielectric plate, the influence of dielectric constants and thicknesses of different laminated layers in the dielectric plate on high-frequency performance under a high-frequency condition is not considered, the design steps are simplified, and the signal transmission efficiency is greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of millimeter waves, in particular to a vertical transition structure of a millimeter wave radar. Background Art

[0002] In the field of automotive millimeter-wave radar technology, more and more manufacturers have turned from microstrip antennas to waveguide antennas in order to improve the performance of their own radars. As a "bridge" connecting the radar transceiver chip and the waveguide antenna, traditional chip flipping often uses vertical via technology to achieve interconnection. This technology needs to consider the PCB board layer stacking, dielectric constant and dielectric loss, and the PCB stacking should not be too thick. Under high-frequency conditions, too thick multi-layer boards will lead to greater signal transmission loss, increased drilling difficulty, and the corresponding RF performance will be greatly reduced, affecting the overall performance indicators of the radar. Summary of the invention

[0003] The utility model provides a vertical transition structure of a millimeter wave radar, which is used for reducing the transmission loss between a radar chip and an antenna.

[0004] The technical solution of the utility model is as follows: a vertical transition structure of a millimeter wave radar, comprising: a waveguide cavity, a grounded coplanar waveguide and a rectangular waveguide arranged in sequence from bottom to top, the grounded coplanar waveguide comprising a dielectric substrate, a grounded coplanar waveguide transmission structure arranged on the dielectric substrate and a connecting groove, the connecting groove connects the waveguide cavity and the rectangular waveguide, an impedance transformation structure is arranged in the waveguide cavity, the head end of the impedance transformation structure is connected to the end of the grounded coplanar waveguide transmission structure, and the end of the impedance transformation structure is located directly below the connecting groove.

[0005] Furthermore, the grounded coplanar waveguide transmission structure includes a metallized through hole array and a microstrip line on the dielectric substrate, the microstrip line is located on the lower surface of the dielectric substrate, and the end of the microstrip line is connected to the head end of the impedance transformation structure.

[0006] Furthermore, the metallized through hole array includes two rows of symmetrically distributed multiple metallized through holes and multiple metallized through holes distributed in a C-shape on three sides of the connecting groove, and the microstrip line is located between the two rows of symmetrically distributed multiple metallized through holes.

[0007] Furthermore, the diameter of the metallized through hole is 0.2 mm, and the spacing between adjacent metallized through holes is 0.4 mm.

[0008] Furthermore, metal layers are provided on both the upper and lower surfaces of the dielectric substrate, and the microstrip line is spaced apart from the metal layer on the lower surface of the dielectric substrate.

[0009] Furthermore, the impedance transformation structure includes a first impedance transformation segment, a second impedance transformation segment and a third impedance transformation segment, the top end of the first impedance transformation segment is connected to the end of the grounded coplanar waveguide transmission structure, the bottom end of the first impedance transformation segment is connected to the head end of the second impedance transformation segment, the tail end of the second impedance transformation segment is connected to the middle of the third impedance transformation segment, and the third impedance transformation segment is located directly below the center of the rectangular waveguide.

[0010] Furthermore, the second impedance transformation section and the third impedance transformation section are both rectangular parallelepiped structures, and the second impedance transformation section and the third impedance transformation section have the same height.

[0011] Furthermore, the second impedance transformation section has a length of 1.55 mm and a width of 0.28 mm, and the third impedance transformation section has a length of 0.8 mm and a width of 0.2 mm.

[0012] Beneficial effects of the utility model: The utility model directly processes a metallized rectangular waveguide on a dielectric plate, and does not consider the influence of the dielectric constant and thickness of different laminates in the dielectric plate on the high-frequency performance under high-frequency conditions, simplifies the design steps, and greatly improves the signal transmission efficiency. At the same time, the waveguide cavity can also prevent electromagnetic leakage during propagation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the utility model.

[0014] Figure 2 It is a schematic diagram of the cross-sectional structure of the utility model.

[0015] Figure 3 It is a structural schematic diagram of the waveguide cavity in the utility model.

[0016] Figure 4 It is a bottom view schematic diagram of the utility model.

[0017] Figure 5 It is a top view schematic diagram of the utility model.

[0018] Figure 6 It is a simulation schematic diagram of the utility model.

[0019] Figure 7 It is a schematic diagram of the radar structure of the utility model. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. The described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0021] In an embodiment of the present utility model, Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 It is a structural schematic diagram provided according to a vertical transition structure of a millimeter wave radar of the utility model, such as Figure 1 As shown, the utility model comprises: a waveguide cavity 2, a grounded coplanar waveguide 1 and a rectangular waveguide 3 arranged in sequence from bottom to top,

[0022] like Figure 2 As shown, the grounded coplanar waveguide includes a dielectric substrate 11, a grounded coplanar waveguide transmission structure and a connecting slot 13 arranged on the dielectric substrate 11, the connecting slot 13 connects the waveguide cavity 2 and the rectangular waveguide 3, an impedance transformation structure 21 is arranged in the waveguide cavity 2, the head end of the impedance transformation structure 21 is connected to the end of the grounded coplanar waveguide transmission structure, and the end of the impedance transformation structure 21 is located directly below the connecting slot 13. The dielectric substrate is a PCB circuit board.

[0023] like Figure 4 and Figure 5 As shown, the grounded coplanar waveguide transmission structure includes a metallized through hole array and a microstrip line 15 on the dielectric substrate 11, the microstrip line 15 is located on the lower surface of the dielectric substrate, and the end of the microstrip line 15 is connected to the head end of the impedance transformation structure 21. The impedance of the microstrip line is 50Ω. One end of the microstrip line away from the impedance transformation structure 21 is connected to the radar transceiver chip.

[0024] The metallized through hole array includes two rows of symmetrically distributed multiple metallized through holes 14 and multiple metallized through holes 14 distributed in a C-shape on three sides of the connecting groove 13, and the microstrip line 15 is located between the two rows of symmetrically distributed multiple metallized through holes 14. The diameter of the metallized through hole 14 is 0.2 mm, and the spacing between adjacent metallized through holes 14 is 0.4 mm. Among them, the metallized through hole 14 is a grounding hole.

[0025] The upper and lower surfaces of the dielectric substrate 11 are both provided with metal layers 16, and the microstrip line 15 is spaced apart from the metal layer 16 on the lower surface of the dielectric substrate 11. The metal layer 16 may be a copper foil. The metallized through hole 14 connects the upper and lower metal layers, which is beneficial to reduce electromagnetic leakage and reduce the resonance effect caused by high frequency.

[0026] It should be noted that since there are metal layers above and below the dielectric substrate, in order to better show the arrangement of metallized vias, Figure 4 and Figure 5 In the figure, metallized vias are represented by dotted lines.

[0027] like Figure 3 As shown, the impedance transformation structure 21 includes a first impedance transformation segment 211, a second impedance transformation segment 212 and a third impedance transformation segment 213, the top of the first impedance transformation segment 211 is connected to the end of the grounded coplanar waveguide transmission structure, the bottom of the first impedance transformation segment 211 is connected to the head of the second impedance transformation segment 212, the tail of the second impedance transformation segment 212 is connected to the middle of the third impedance transformation segment 213, and the third impedance transformation segment 213 is located directly below the center of the rectangular waveguide 3.

[0028] The second impedance transformation section 212 and the third impedance transformation section 213 are both rectangular parallelepiped structures, and the second impedance transformation section 212 and the third impedance transformation section 213 are of equal height. The third impedance transformation section 213 is arranged in the same manner as the rectangular waveguide, and the center of the third impedance transformation section 213 and the bottom center of the rectangular waveguide are located on the same vertical line.

[0029] The height H of the first impedance transformation section 211 is 0.5 mm. The length L2 of the second impedance transformation section 212 is 1.55 mm, the width W2 is 0.28 mm, and the length L1 of the third impedance transformation section 213 is 0.8 mm, the width W1 is 0.2 mm.

[0030] The radar transceiver chip transmits the signal from the 50-ohm microstrip line 15 to the waveguide cavity 2 through the impedance transformation structure 21, and then transmits it out through the rectangular waveguide 3 on the PCB board. The inner surface of the rectangular waveguide on the PCB board needs to be metallized, and a circle of grounded metallized through holes needs to be set around it to prevent electromagnetic wave leakage.

[0031] like Figure 7 As shown in the figure, the surface of the radar transceiver chip is coated with thermal grease, which can directly transfer the heat to the radar box body, thereby improving the heat dissipation performance of the radar chip. The waveguide cavity is set in the sealed radar box body to prevent the leakage of electromagnetic signals during propagation. This structure can improve the heat dissipation performance of the product, and the sealed cavity can also prevent the leakage of electromagnetic signals during propagation.

[0032] like Figure 6 As shown in the figure, the horizontal axis represents frequency (GHz) and the vertical axis represents loss value (dB). The simulation results show that the bandwidth of the return loss of the two ports below -15dB is about 4GHz, and the loss is about 0.5dB. Compared with conventional vertical vias, the loss can be reduced by 50%.

[0033] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to examples, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A vertical transition structure of a millimeter wave radar, characterized in that: include: A waveguide cavity (2), a grounded coplanar waveguide (1) and a rectangular waveguide (3) are arranged in sequence from bottom to top, the grounded coplanar waveguide comprising a dielectric substrate (11), a grounded coplanar waveguide transmission structure arranged on the dielectric substrate (11) and a connecting groove (13), the connecting groove (13) connecting the waveguide cavity (2) and the rectangular waveguide (3), an impedance transformation structure (21) is arranged in the waveguide cavity (2), the head end of the impedance transformation structure (21) is connected to the end of the grounded coplanar waveguide transmission structure, and the end of the impedance transformation structure (21) is located directly below the connecting groove (13).

2. The vertical transition structure of the millimeter wave radar according to claim 1, characterized in that: The grounded coplanar waveguide transmission structure comprises a metallized through-hole array and a microstrip line (15) on the dielectric substrate (11); the microstrip line (15) is located on the lower surface of the dielectric substrate; and the end of the microstrip line (15) is connected to the head end of the impedance transformation structure (21).

3. The vertical transition structure of the millimeter wave radar as claimed in claim 2, characterized in that: The metallized through hole array comprises two rows of symmetrically distributed multiple metallized through holes (14) and a plurality of metallized through holes (14) distributed in a C-shape on three sides of the connecting groove (13), and the microstrip line (15) is located between the two rows of symmetrically distributed multiple metallized through holes (14).

4. The vertical transition structure of the millimeter wave radar as claimed in claim 2, characterized in that: The diameter of the metallized through hole (14) is 0.2 mm, and the spacing between adjacent metallized through holes (14) is 0.4 mm.

5. The vertical transition structure of the millimeter wave radar as claimed in claim 2, characterized in that: The upper and lower surfaces of the dielectric substrate (11) are both provided with a metal layer (16), and the microstrip line (15) is spaced apart from the metal layer (16) on the lower surface of the dielectric substrate (11).

6. The vertical transition structure of the millimeter wave radar according to claim 1, characterized in that: The impedance transformation structure (21) comprises a first impedance transformation section (211), a second impedance transformation section (212) and a third impedance transformation section (213); the top end of the first impedance transformation section (211) is connected to the end of the grounded coplanar waveguide transmission structure; the bottom end of the first impedance transformation section (211) is connected to the head end of the second impedance transformation section (212); the tail end of the second impedance transformation section (212) is connected to the middle of the third impedance transformation section (213); and the third impedance transformation section (213) is located directly below the center of the rectangular waveguide (3).

7. The vertical transition structure of the millimeter wave radar according to claim 6, characterized in that: The second impedance transformation section (212) and the third impedance transformation section (213) are both rectangular parallelepiped structures, and the second impedance transformation section (212) and the third impedance transformation section (213) are of the same height.

8. The vertical transition structure of the millimeter wave radar as claimed in claim 7, characterized in that: The second impedance transformation section (212) has a length of 1.55 mm and a width of 0.28 mm, and the third impedance transformation section (213) has a length of 0.8 mm and a width of 0.2 mm.

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