PCB mainboard signal constraint structure suitable for waveguide signal feed-in, waveguide transmission line, waveguide antenna radar and automobile

Abstract

The utility model provides a PCB main board signal constraint structure suitable for waveguide signal feed-in and a waveguide transmission line. The PCB main board signal constraint structure is characterized in that a grounding coplanar waveguide and a substrate integrated waveguide are respectively formed on a PCB main board; one end of the grounding coplanar waveguide is used for being connected with a radio frequency chip, the other end of the grounding coplanar waveguide is connected with the substrate integrated waveguide, a grounding hole used for restraining signal transmission is formed in the PCB mainboard, and the grounding hole is located in the edge of a signal transmission channel formed by the grounding coplanar waveguide and the substrate integrated waveguide; the substrate integrated waveguide provides a first area, and the grounding holes are distributed at the tail end of the first area; wherein the first area comprises the arrangement position of the coupling slot. According to the utility model, signal transmission is guided through the grounding hole, and a radio frequency signal is converted into an electric field signal fed perpendicular to the bottom surface of the waveguide H surface through the conversion structure, so that the problems of signal guide from a radio frequency chip signal to the waveguide and transmission mode conversion are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of waveguide structures, and particularly, to a signal constraint structure of a PCB main board suitable for waveguide signal feeding and a waveguide transmission line. Background Art

[0002] With the rapid development of wireless communication technology, microwaves and millimeter waves have gradually come into people's view and play an important role in the communication field.

[0003] Currently, in the application of vehicle-mounted millimeter-wave radars, waveguide antennas have received increasing attention due to their advantages such as low loss and high isolation; in the application of the 76-81 GHz frequency band of vehicle-mounted radars, since the technology of new radio frequency chips with waveguide ports is not yet mature, using existing radio frequency chips for waveguide connection has become an effective way to apply waveguide antennas in vehicle-mounted radars.

[0004] However, how to guide the radio frequency signal to be converted into a signal suitable for feeding at the bottom end of the H-plane of the waveguide has become a key problem. Summary of the Utility Model

[0005] Aiming at the defects in the prior art, the purpose of the utility model is to provide a signal constraint structure of a PCB main board suitable for waveguide signal feeding and a waveguide transmission line.

[0006] According to a signal constraint structure of a PCB main board suitable for waveguide signal feeding provided by the utility model, it includes: a PCB main board, on which a grounded coplanar waveguide and a substrate integrated waveguide are respectively formed;

[0007] One end of the grounded coplanar waveguide is used to connect to a radio frequency chip, the other end of the grounded coplanar waveguide is connected to the substrate integrated waveguide, and grounding holes for constraining signal transmission are arranged on the PCB main board, and the grounding holes are located at the edge of the signal transmission channel formed by the grounded coplanar waveguide and the substrate integrated waveguide;

[0008] The substrate integrated waveguide provides a first region, and the grounding holes are also distributed at the end of the first region;

[0009] Wherein, the first region includes the setting position of a coupling slot.

[0010] Preferably, a coupling slot is arranged in the first region, and the coupling slot generates a signal fed perpendicular to the bottom surface of the H-plane of the waveguide.

[0011] Preferably, the PCB main board includes a PCB top surface, a dielectric layer, and a PCB bottom surface stacked in sequence, and the PCB top surface and the PCB bottom surface are metallized layers;

[0012] A feeder is provided on the top surface of the PCB. One end of the feeder is used to connect to a radio frequency chip. Slots are provided on both sides of the feeder on the top surface of the PCB, and the grounding holes are located outside the slots; the feeder, the slots, and the grounding holes are combined to form a grounded coplanar waveguide;

[0013] The combination of the top surface of the PCB, the bottom surface of the PCB, and the grounding holes forms a substrate integrated waveguide.

[0014] Preferably, a signal transmission bottom surface is further formed on the top surface of the PCB main board, and the signal transmission bottom surface is used to connect to a single-layer waveguide structure to form the H-plane bottom surface of the waveguide structure.

[0015] Preferably, the coupling slot is formed by removing metallization on the metal top surface of the substrate integrated waveguide. The coupling slot is provided at the end of the substrate integrated waveguide and is aligned with the center of the substrate integrated waveguide along the center line;

[0016] The shape of the coupling slot is H-shaped, inclined slot-shaped, circular, annular, cross-shaped, or V-shaped.

[0017] Preferably, between the grounded coplanar waveguide and the substrate integrated waveguide on the PCB main board, the width of the feeder gradually increases, the width of the slots on both sides remains unchanged but the lateral spacing gradually increases, and the lateral spacing of the grounding holes on both sides gradually increases, forming a waveguide transition section.

[0018] Preferably, the grounding holes are arranged in a single row or multiple rows; there is one row or multiple rows of grounding holes at the end of the substrate integrated waveguide for closing.

[0019] A waveguide transmission line according to the present invention includes the PCB main board signal constraint structure suitable for waveguide signal feeding.

[0020] A waveguide antenna radar according to the present invention includes the waveguide transmission line.

[0021] An automobile according to the present invention includes the waveguide antenna radar.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. In the present invention, signals are guided to be transmitted in a signal transmission channel composed of a grounded coplanar waveguide and a substrate integrated waveguide through grounding holes. Through a conversion structure composed of a grounded coplanar waveguide, a substrate integrated waveguide, and a coupling slot, radio frequency signals are converted into electric field signals fed perpendicular to the H-plane bottom surface of the waveguide, solving the problems of signal guiding from a radio frequency chip to a waveguide and transmission mode conversion.

[0024] 2. By providing a waveguide transition section with a gradually increasing lateral spacing, the present utility model facilitates the gradual transition of the signal transmission mode from a grounded coplanar waveguide to a substrate integrated waveguide, reduces adverse effects such as reflection and loss, and ensures the transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects, and advantages of the present utility model will become more apparent from the following detailed description of non - restrictive embodiments read in conjunction with the accompanying drawings:

[0026] Figure 1 is a schematic diagram of a traditional waveguide transmission line;

[0027] Figure 2 is a schematic diagram of a traditional waveguide transmission line with EH conversion;

[0028] Figure 3 is a perspective view of a millimeter - wave radar waveguide antenna with a single - layer waveguide structure disclosed by the present utility model;

[0029] Figure 4 is a top view of a millimeter - wave radar waveguide antenna with a single - layer waveguide structure disclosed by the present utility model;

[0030] Figure 5 is a schematic diagram of the matching between the waveguide antenna and the PCB main board disclosed by the present utility model;

[0031] Figure 6 is a top view of the signal feeding structure disclosed by the present utility model;

[0032] Figure 7 is a cross - sectional view of the grounded coplanar waveguide disclosed by the present utility model;

[0033] Figure 8 is a cross - sectional view of the waveguide transition section disclosed by the present utility model;

[0034] Figure 9 is a cross - sectional view of the substrate integrated waveguide disclosed by the present utility model;

[0035] Figure 10 is an example diagram of different shapes of the coupling slot disclosed by the present utility model;

[0036] Figure 11 is an example diagram of the shielding wall solution disclosed by the present utility model;

[0037] Figure 12 is a schematic diagram of the S - parameter of the embodiment of the present utility model;

[0038] Figure 13 is a perspective exploded view of a practical case of a 4T4R single - layer waveguide structure antenna of the present utility model.

[0039] Description of the reference numerals:

[0040] Detailed implementation manners

[0041] The present utility model will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present utility model, but do not limit the present utility model in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several changes and improvements can still be made. These all belong to the protection scope of the present utility model.

[0042] The respective functional surfaces of a typical waveguide are as Figure 1 shown. The conventional feeding method from a PCB main board to a waveguide is usually to set a patch probe parallel to the end face of the waveguide, or to use a feeding probe protruding into the waveguide cavity perpendicular to the bottom surface of the H-plane of the waveguide; since the PCB main board is usually parallel to the waveguide transmission direction, these feeding methods all require setting feeding components protruding from the PCB surface on the PCB, resulting in problems of complex structure and difficult processing and assembly.

[0043] Another relatively mainstream feeding method is as Figure 2 shown. This feeding method adds an EH conversion structure at the end of the transverse waveguide, so that the waveguide extends out an end face with a downward direction, which is parallel and aligned with the patch probe set on the PCB main board to form a feeding structure. This feeding method has problems such as complex waveguide structure, requiring multiple-layer structures during plastic molding, high assembly process requirements, and high costs.

[0044] The present utility model provides a waveguide antenna with a single-layer structure. Referring to Figures 3 - 11 shown, it includes a PCB main board 1 and a waveguide antenna 2.

[0045] The PCB main board 1 includes a PCB top surface 11, a dielectric layer 12, and a PCB bottom surface 13. Among them, the PCB top surface 11 and the PCB bottom surface 13 are metallized layers, and the dielectric layer 12 is made of a high-frequency PCB material suitable for the 76 - 81 GHz frequency band, with a thickness of 5 - 10 mil.

[0046] A feeder line 111 is provided on the PCB top surface 11. One end of the feeder line 111 is connected to the signal pin of the radio frequency chip to receive or feedback electromagnetic signals; slots 115 are provided on both sides of the feeder line 111 on the PCB top surface 11, and grounding holes 116 with appropriate sizes and spacings are provided outside the slots 115. The grounding holes 116 are in good electrical connection with the PCB top surface 11 and the PCB bottom surface 13 respectively. The feeder line 111, the slots 115, and the grounding holes 116 are combined to form a grounded coplanar waveguide.

[0047] The grounding vias 116 extend away from the RF chip, with the lateral spacing gradually increasing. They combine with the PCB top surface 11 and the PCB bottom surface 13 to form a substrate integrated waveguide 113. One or more rows of grounding vias 116 are closed at the end of the substrate integrated waveguide 113, forming a substrate integrated waveguide 113 with a closed end. The grounding vias 116 can be single-row or multi-row to meet the performance requirements of good grounding and signal shielding.

[0048] Between the grounded coplanar waveguide and the substrate integrated waveguide 113 section, the width of the feeder 111 gradually increases, and the widths of the slots 115 on both sides remain unchanged but the lateral spacing gradually increases, forming a waveguide transition section 112 between the grounded coplanar waveguide and the substrate integrated waveguide 113.

[0049] There are differences in the lateral widths of the grounded coplanar waveguide and the substrate integrated waveguide 113, that is: the grounded coplanar waveguide is smaller, and the substrate integrated waveguide 113 is larger; by setting the waveguide transition section 112 with a gradually increasing spacing, the grounded coplanar waveguide and the substrate integrated waveguide 113 can be effectively connected; the gradually increasing spacing is beneficial for the signal transmission mode to gradually transition from the grounded coplanar waveguide to the substrate integrated waveguide 113, reducing adverse effects such as reflection and loss, and ensuring the transmission efficiency.

[0050] The substrate integrated waveguide 113 provides a first region, and the grounding vias 116 are also distributed at the end of the first region; wherein, the first region includes the setting position of the coupling slot 114, and the end of the first region is the end of the substrate integrated waveguide 113. A coupling slot 114 is arranged in the first region, and the coupling slot 114 generates a signal fed perpendicular to the bottom end of the waveguide H-plane bottom surface.

[0051] In the area of the PCB top surface 11 located in the substrate integrated waveguide 113, a non-metallized or de-metallized coupling slot 114 is arranged; the coupling slot 114 is arranged at the end of the substrate integrated waveguide 113 and is aligned with the substrate integrated waveguide 113 along the center line; an electric field perpendicular to the waveguide H-plane is excited through the coupling slot 114, thereby coupling the energy of the baseband integrated waveguide into the waveguide. The shape of the coupling slot 114 can be in forms such as H-shaped, oblique slot-shaped, circular, annular, cross-shaped, V-shaped, etc., without limitation here, as long as it can stimulate the mode conversion from the substrate integrated waveguide 113 to the waveguide. By adjusting the local dimensions of the shape, the reflection and impedance matching of the conversion can be improved, and then the transmission efficiency can be enhanced.

[0052] Refer to Figure 10 As shown, the coupling slot 114 can be set in a variety of different shapes. In the Figure 10 shown coupling slot 114 (the shaded part in the figure), a is H-shaped, b is oblique slot-shaped, c is cross-shaped, d is V-shaped, e is circular, and f is annular.

[0053] The waveguide antenna 2 includes: a waveguide top layer 21, a shielding wall 22, a magnetic conductor 24, and a slot antenna 23.

[0054] The waveguide top layer 21 is the main component of the waveguide antenna 2, and the shielding wall 22 and the magnetic conductor 24 are arranged below it; the shielding wall 22 and the magnetic conductor 24 are combined with the waveguide top layer 21 to form two E-plane sides, an H-plane top surface, and two end end surfaces of the waveguide cavity. A signal transmission bottom surface 117 is also formed on the top surface of the PCB main board 1, and the signal transmission bottom surface 117 covers the waveguide cavity and constitutes the H-plane bottom surface of the waveguide cavity, thus forming a complete waveguide cavity.

[0055] The end feed port 26 of the waveguide cavity located at the H-plane bottom surface covers the coupling slot 114. As Figure 5 shown, a feed port 26 for signals to enter the waveguide antenna from the coupling slot 114 is formed on the H-plane bottom surface of the waveguide cavity. The coupling slot 114 and the feed port 26 are centered and aligned along the signal transmission direction. The coupling slot 114 maintains an appropriate distance from the end face of the end feed port 26 of the waveguide H-plane bottom surface to ensure excellent coupling efficiency. The extending direction of the waveguide cavity is parallel to the PCB main board 1. Among them, both the H-plane top surface and the H-plane bottom surface of the waveguide cavity are parallel to the PCB main board 1.

[0056] The bottom end face of the shielding wall 22 covers the grounding hole 116, and the grounding hole 116 is located outside the waveguide cavity; the inner side face of the shielding wall 22 is located between the side of the coupling slot 114 and the grounding hole 116.

[0057] In the design of the waveguide antenna 2, the fewer the number of waveguide layers, the simpler the manufacturing, the smaller the volume, and the lower the cost. Therefore, the optimal structure of the waveguide antenna 2 is a single layer. And the single-layer waveguide antenna 2 needs to use the metal top surface of the PCB main board 1 as the H-plane bottom surface of the waveguide. The single-layer structure is beneficial to the plastic molding of the waveguide antenna and the subsequent surface metallization process, and does not require additional connection processes such as welding or gluing, which is more conducive to the processing and assembly of the radar waveguide antenna, reduces the dimensional accuracy requirements, and saves the manufacturing cost.

[0058] The main characteristic requirement of waveguide feeding is that the electric field direction of the fed signal must be perpendicular to the waveguide H-plane (i.e., the long side plane). Since in the design of the single-layer waveguide conductor, the top surface of the PCB main board 1 is parallel and close to the bottom surface H-plane of the waveguide cavity, the electric field direction of the electromagnetic signal excited by the patch probe provided by the traditional microstrip design is necessarily parallel to the waveguide H-plane, thus unable to excite the waveguide transmission mode.

[0059] The utility model adopts signal conversion through coupling slots 114 on a substrate integrated waveguide 113, solving the problem of signal transmission from a PCB main board 1 to a single-layer waveguide antenna 2. The slot coupling principle is essentially a waveguide coupler. The basic structure of a waveguide coupler includes an input waveguide, an output waveguide, and a coupling component. When a microwave signal enters the coupling component from the input waveguide, the signal can be coupled to the output waveguide to achieve signal transmission and distribution.

[0060] At the other end of the waveguide cavity, multiple slot structures are provided to penetrate the top layer 21 of the waveguide, forming a waveguide slot antenna 23 for signal transmission and reception of the waveguide antenna 2. The number of slots of the slot antenna 23 is determined according to different antenna radiation performances. In vehicle-mounted radar applications, considering the size scale of the waveguide structure itself, generally 4 - 12 slots are set.

[0061] Refer to Figure 11 As shown, the internal dimensions of the waveguide cavity formed by the shielding wall 22 and the magnetic conductor 24 are set such that the ratio of the H-plane width to the E-plane height is 2:1 or a similar ratio, and it meets the transmission requirements of the 76 - 81 GHz frequency band; the shielding wall 22 can have one circle (shown as a in the figure), or two circles or multiple circles; the magnetic conductor 24 can be one circle, two circles or multiple circles, and the shielding wall 22 is arranged outside the magnetic conductor 24; the magnetic conductor 24 is one of geometric shapes such as periodically arranged cylinders, rectangular bodies, trapezoidal bodies, etc., and can be selected according to different technical requirements such as materials, processes, and isolation performance; a ridge structure 25 can be added as needed to form a ridged waveguide form. A ridge 25 is provided at the midline of the waveguide cavity below the top layer of the waveguide to form a ridged waveguide transmission line. The orthographic projection of the ridge 25 on the PCB main board 1 is staggered from the coupling slot 114, and the waveguide cavity is a cavity at the feeding port 26.

[0062] The material of the waveguide antenna 2 is a metal material or a plastic material with a metallized surface.

[0063] The connection between the waveguide antenna 2 and the PCB main board 11 is generally a fastening connection with a metal part or a plastic part. Among them, the shielding wall 22 and the magnetic conductor 24 can be closely connected or set with a gap to the PCB main board 1; the feeding port 26 at the end of the H-plane bottom surface of the waveguide cavity keeps an appropriate distance from the coupling slot 114 to excite signal coupling.

[0064] Refer to Figure 12 As shown, the waveguide antenna 2 structure disclosed by the utility model realizes an efficient conversion with a working frequency of 76 - 81 GHz, a -10 dB relative bandwidth of 12.16%, and a loss of -0.6 dB, and is applicable to vehicle-mounted radar applications. It can be seen from Figure 12 that the utility model realizes the feeding from the substrate integrated waveguide to the feeding port 26 at the end of the H-plane bottom surface of the waveguide, with high transmission efficiency.

[0065] Referring to Figure 13 As shown, in a specific embodiment provided by the present utility model, a practical case of a 4T4R single-layer waveguide structure transmission line is introduced, which includes a radio frequency chip and 8 single-layer waveguide antennas 2 connected to the radio frequency chip.

[0066] The present utility model provides a waveguide antenna radar, which adopts the above-mentioned waveguide transmission line of the present utility model. The present utility model also provides a vehicle, on which the above-mentioned waveguide antenna radar is installed.

[0067] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0068] The specific embodiments of the present utility model have been described above. It should be understood that the present utility model is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present utility model. Without conflict, the embodiments and features in the present application can be combined with each other arbitrarily.

Claims

1. A signal constraint structure for a PCB main board applicable to waveguide signal feeding, characterized in that Comprising: A PCB main board (1), on which a grounded coplanar waveguide and a substrate integrated waveguide (113) are respectively formed; One end of the grounded coplanar waveguide is used to connect to a radio frequency chip, the other end of the grounded coplanar waveguide is connected to the substrate integrated waveguide (113), and grounding holes (116) for restricting signal transmission are arranged on the PCB main board (1), and the grounding holes (116) are located at the edge of a signal transmission channel formed by the grounded coplanar waveguide and the substrate integrated waveguide (113); The substrate integrated waveguide (113) provides a first region, and the grounding holes (116) are also distributed at the end of the first region; Wherein, the first region includes the setting position of a coupling slot (114).

2. The signal constraint structure of the PCB main board applicable to waveguide signal feeding according to claim 1, characterized in that, A coupling slot (114) is arranged in the first region, and the coupling slot (114) generates a signal fed perpendicular to the bottom surface of the H-plane of the waveguide.

3. The signal constraint structure of the PCB main board applicable to waveguide signal feeding according to claim 1, characterized in that The PCB main board (1) includes a PCB top surface (11), a dielectric layer (12), and a PCB bottom surface (13) stacked in sequence, and the PCB top surface (11) and the PCB bottom surface (13) are metallized layers; A feeder line (111) is arranged on the PCB top surface (11), one end of the feeder line (111) is used to connect to a radio frequency chip, slots (115) are arranged on both sides of the feeder line (111) on the PCB top surface (11), and the grounding holes (116) are located outside the slots (115); the feeder line (111), the slots (115), and the grounding holes (116) are combined to form a grounded coplanar waveguide; The PCB top surface (11), the PCB bottom surface (13), and the grounding holes (116) are combined to form a substrate integrated waveguide (113).

4. The signal constraint structure of the PCB main board applicable to waveguide signal feeding according to claim 1, characterized in that A signal transmission bottom surface (117) is further formed on the top surface of the PCB main board (1), and the signal transmission bottom surface (117) is used to connect to a single-layer waveguide to form a waveguide cavity, and the signal transmission bottom surface (117) constitutes the bottom surface of the H-plane of the waveguide cavity.

5. The signal constraint structure of the PCB main board applicable to waveguide signal feeding according to claim 1, characterized in that, The coupling slot (114) is made by removing metallization on the metal top surface of the substrate integrated waveguide (113), the coupling slot (114) is arranged at the end of the substrate integrated waveguide (113), and is aligned with the center of the substrate integrated waveguide (113) along the center line; The shape of the coupling slot (114) is H-shaped, inclined slot-shaped, circular, annular, cross-shaped, or V-shaped.

6. The signal constraint structure of the PCB main board applicable to waveguide signal feeding according to claim 1, characterized in that Between the grounded coplanar waveguide and the substrate integrated waveguide (113) on the PCB main board (1), the width of the feeder line (111) gradually increases, the widths of the slots (115) on both sides remain unchanged but the lateral spacing gradually increases, and the lateral spacing of the grounding holes (116) on both sides gradually increases, forming a waveguide transition section (112).

7. The signal constraint structure of the PCB main board applicable to waveguide signal feeding according to claim 6, wherein The grounding holes (116) are arranged in a single row or multiple rows; one or more rows of grounding holes (116) are used to close the end of the substrate integrated waveguide (113).

8. A waveguide transmission line, characterized in that, Comprising the PCB main board signal constraint structure for waveguide signal feeding according to any one of claims 1 to 7.

9. A waveguide antenna radar, characterized in that, Comprising the waveguide transmission line according to claim 8.

10. A vehicle, characterized in that, Comprising the waveguide antenna radar according to claim 9.

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