Microstrip-to-waveguide structure, waveguide antenna and radar

Abstract

The utility model provides a microstrip-to-waveguide structure, a waveguide antenna and a radar, and the structure comprises a waveguide transmission line which is located in the waveguide antenna, the waveguide transmission line is provided with a waveguide opening on the side wall of the waveguide antenna, and the waveguide opening is provided with a preset size structure with a long side and a short side; the micro-strip feeder line is arranged on the PCB substrate, and the end part of the micro-strip feeder line extends into the projection from a first short edge of the projection of the waveguide opening on the PCB substrate; and the nail bed structure comprises a plurality of nail beds, one end of each nail bed is connected to the outer side of the waveguide opening, and the other end of each nail bed is connected or in clearance fit with the PCB substrate. According to the utility model, the nail bed design structure is utilized, the microstrip matching waveguide conversion is carried out in cooperation with the microstrip feeder line, and the broadband low-reflection low-loss performance is realized. The microstrip feed line is fed in from the short side, so that the microstrip feed line is shortened, the waveguide transmission line is lengthened, the transmission loss is reduced on the whole, and meanwhile, the occupied area of a PCB (Printed Circuit Board) substrate is smaller.

Description

[0001] This application claims the following patent application as a prior application based on priority:

[0002] Application number: 202311089688.0

[0003] Application date: 2023-08-28

[0004] Application name: Microstrip to waveguide structure, waveguide antenna and radar Technical Field

[0005] The utility model relates to the technical field of antennas, and in particular to a microstrip-to-waveguide structure, a waveguide antenna and a radar. Background Art

[0006] At present, mainstream manufacturers of automotive radar RF chips (especially 76-81GHz frequency band), such as Texas Instruments, NXP, and Infineon, are vigorously promoting a new generation of SOC chips with waveguide transmission ports. Such chips use waveguide interfaces for electrical signal transmission and match waveguide transmission antennas, and are recognized by the industry as a new generation of solutions for radar RF transmission and reception. Due to many restrictions, it is difficult for most domestic radar manufacturers to obtain the supply of such chips in the short term and apply them to the development of new generation radar products. In this case, the development of suitable waveguide transmission antennas in advance has become a necessary technical reserve, so that after the supply problem of the new generation of waveguide radar chips is solved, the development and application of waveguide radar products can be quickly cut in. Therefore, using the microstrip transmission solution of the existing radar RF chip and designing a waveguide antenna feeding method from microstrip to waveguide has become the key to solving this problem.

[0007] The traditional transmission structure design of microstrip to waveguide is to insert a microstrip feeder line along the side of the waveguide perpendicular to the narrow side or wide side at the end of the rectangular waveguide, feed a signal of appropriate frequency into the microstrip feeder line, and then stimulate an electrical signal that can be transmitted along the waveguide transmission line, which plays the role of switching and transmission. Figure 1 This is a typical microstrip-to-waveguide structure design. In this typical microstrip-to-waveguide structure design, the microstrip feeder is set on the PCB board and connected to the RF chip. At the same time, the microstrip feeder is inserted into the end of the waveguide cavity. This design has the following defects:

[0008] 1) It is impossible to completely separate the microstrip and waveguide transmission lines in space, which is not conducive to the separate design of the waveguide antenna and the RF PCB board, and is not conducive to the use of existing microstrip RF chips to match the waveguide antenna;

[0009] 2) The insertion structure design needs to maintain a certain gap, which may lead to risks such as energy leakage and significant insertion loss;

[0010] 3) The insertion structure design and assembly are difficult, the production efficiency is low, and product consistency is difficult to ensure. Utility Model Content

[0011] In view of the defects in the prior art, the purpose of the utility model is to provide a microstrip-to-waveguide structure, a waveguide antenna and a radar.

[0012] A microstrip-to-waveguide structure provided by the utility model includes:

[0013] A waveguide transmission line 1 is located in a waveguide antenna 2, wherein the waveguide transmission line 1 has a waveguide opening 4 on a side wall of the waveguide antenna 2, and the waveguide opening 4 has a preset long side and short side size structure;

[0014] A microstrip feed line 6 is arranged on a PCB substrate 7, and an end portion thereof extends from a first short side of a projection of the waveguide opening 4 on the PCB substrate 7 into the projection;

[0015] The nail bed structure includes a plurality of nail beds 5 , one end of each nail bed 5 is connected to the outside of the waveguide opening 4 , and the other end is connected to or gap-fitted with the PCB substrate 7 .

[0016] Furthermore, the nail bed 5 is located on other sides of the projection except the first short side.

[0017] Further, the waveguide antenna 2 is made of a conductive metal material, or a non-conductive material with a metal film coated on the inner and outer surfaces;

[0018] The outer surface of the nail bed 5 is plated with a metal film.

[0019] Furthermore, the number of the bed of nails structures is the same as the number of the waveguide openings 4 and they correspond one to one.

[0020] Further, the first short side is 0.7 mm-1.6 mm;

[0021] The center spacing between the nail beds 5 is 1mm-1.5mm;

[0022] The height of the nail bed 5 is 0.7 mm-1.2 mm.

[0023] Furthermore, there are multiple waveguide transmission lines 1 and microstrip feed lines 6, and they correspond one to one.

[0024] Portions of the plurality of microstrip feed lines 6 feeding into the first short side are arranged side by side along a first direction, and the first direction is a direction parallel to the short side of the waveguide opening 4 .

[0025] Furthermore, the distance between the nail bed 5 and the PCB substrate 7 is 0 mm-0.5 mm.

[0026] Furthermore, the microstrip feed line 6 coincides with a center line of the first short side, and an end of the microstrip feed line 6 is located at the center of the projection.

[0027] A waveguide antenna provided by the utility model comprises the microstrip-to-waveguide structure.

[0028] A radar provided by the utility model includes the waveguide antenna.

[0029] Compared with the prior art, the utility model has the following beneficial effects:

[0030] 1) The microstrip-to-waveguide structure provided by the utility model separates the PCB microstrip feeder and the waveguide antenna in structure, which facilitates the application of waveguide antenna technology on the existing microstrip RF chip;

[0031] 2) The microstrip-to-waveguide structure provided by the utility model includes a gap waveguide structure, which effectively reduces the loss in conversion and transmission;

[0032] 3) The microstrip-to-waveguide structure provided by the utility model effectively reduces the precision requirements for parts manufacturing errors and assembly errors due to the use of gap waveguide structure and separation design, which is more conducive to improving product manufacturing efficiency and quality stability;

[0033] 4) The utility model solves the problem that when there is no supply of the latest generation of waveguide RF chips, the existing microstrip RF chips can be used to match the design of waveguide antennas, thereby effectively improving the detection performance of the radar.

[0034] 5) The utility model solves the current situation that microstrip antennas need to rely on large areas of foreign high-frequency PCB boards, effectively reduces the use area of ​​high-frequency boards, and greatly improves the cost of radar, especially in the application field of 4D imaging radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0036] Figure 1 Schematic diagram of the traditional microstrip-to-waveguide structure;

[0037] Figure 2 , Figure 3 It is a perspective view of the structure of two microstrip waveguides of the utility model;

[0038] Figure 4 It is a cross-sectional view of the utility model;

[0039] Figure 5 The figure is a schematic diagram of a waveguide antenna with a microstrip-to-waveguide structure of the utility model. DETAILED DESCRIPTION

[0040] The utility model is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the utility model, but do not limit the utility model in any form. It should be pointed out that for those of ordinary skill in the art, several changes and improvements can be made without departing from the concept of the utility model. These all belong to the protection scope of the utility model.

[0041] Example 1

[0042] like Figure 2 , Figure 3 As shown, this embodiment discloses a microstrip-to-waveguide structure suitable for the 70Ghz-90Ghz frequency band, including: a waveguide transmission line 1, a microstrip feed line 6 and a bed of nails structure.

[0043] The waveguide transmission line 1 is located in the waveguide antenna 2. The waveguide transmission line 1 has a waveguide opening 4 on the side wall of the waveguide antenna 2. The waveguide opening 4 has a preset long side and short side size structure. The waveguide antenna 2 is a hollow pipe structure. The pipe wall (boundary) restricts the form of the electromagnetic wave in the pipe. The electromagnetic wave is transmitted in the pipe by total reflection. The microstrip feed line 6 can generate an alternating electromagnetic field that can excite the long side of the waveguide antenna 2 in the waveguide antenna 2 through appropriate size settings, thereby forming an electromagnetic wave that can be transmitted in the waveguide transmission line 1.

[0044] The microstrip feed line 6 is arranged on the PCB substrate 7, and the end portion extends from the first short side / first long side of the projection of the waveguide opening 4 on the PCB substrate 7 into the projection. The nail bed structure includes a plurality of nail beds 5, one end of the nail bed 5 is connected to the outside of the waveguide opening 4, and the other end is connected to or gap-fitted with the PCB substrate 7. The waveguide transmission line 1 is designed for use in a design with the same or similar dimensions as the standard waveguide cross-section, with the long side being 2.2mm-2.8mm and the short side being 0.7mm-1.6mm. Figure 4 As shown, the basic material of the waveguide antenna 2 is a good electrical conductor (such as metal aluminum alloy, copper alloy, etc.), or a plastic material and the inner and outer surfaces are coated with a metal film 3, and the outer surface of the nail bed 5 can also be coated with a metal film 3.

[0045] The bed of nails structure can prevent or reduce electromagnetic waves from escaping from the gap between the PCB substrate 7 and the waveguide antenna 2. In order to facilitate the entry of the microstrip feeder 6, the bed of nails structure is connected around the outside of the other sides except the first short side / first long side, and the microstrip feeder 6 coincides with the center line of the first short side / first long side and enters the center of the projection. The bottom surface of the bed of nails structure and the top surface of the PCB substrate 7 maintain a gap fit with a nominal value of 0mm-0.5mm; the bed of nails structure is composed of multiple nail beds 5 with a diameter of 0.4mm-0.8mm and a height of 0.7mm-1.2mm, which are periodically arranged around the opening 4 at a center spacing of 1mm-1.5mm. The surface of the bed of nails structure can also be plated with a metal film.

[0046] Example 2

[0047] like Figure 5 As shown, the utility model provides a waveguide antenna, including the microstrip to waveguide structure of Example 1, which is suitable for the 76Ghz-81Ghz frequency band and can match the existing traditional microstrip radio frequency chips, bringing the feasibility of developing the next generation of waveguide antenna radar to radar manufacturers.

[0048] The design of the waveguide antenna 2 includes a waveguide transmission line 1, a bed of nails structure and a slot antenna subarray 21. The basic material is a good electrical conductor (such as metal aluminum alloy, copper alloy, etc.), or a plastic material with a metal film coated on the surface.

[0049] Two or more microstrip feed lines 6 are designed to be perpendicular to the short side direction of the waveguide opening 4 and aligned in the center of the opening 4, and are mounted on the PCB substrate 7. The microstrip feed lines 6 can generate an alternating electromagnetic field that can excite the long side of the waveguide transmission line 1 in the waveguide cavity through appropriate size settings, thereby forming electromagnetic waves that can be transmitted in the waveguide transmission line 1. The number of microstrip feed lines 6 is determined according to the chip specifications and radar performance requirements, and is integrated on the PCB substrate 7 through the PCB printing process. The microstrip feed lines 6 can be designed in a variety of size specifications, which are not limited here.

[0050] Two or more bed-of-nails structures are designed and arranged around the waveguide opening 4, and the bottom surface thereof and the top surface of the PCB substrate 7 maintain a nominal clearance fit of 0 mm-0.5 mm; the bed-of-nails structure is composed of multiple cylinders with a diameter of 0.4 mm-0.8 mm and a height of 0.7 mm-1.2 mm, which are periodically arranged around the opening 4 at intervals of 1 mm-1.5 mm between the centers. The number of bed-of-nails structures is the same as the number of microstrip feed lines 6 and slot antenna subarrays, and the position of the bed-of-nails structure is determined according to the position of the microstrip feed line 6.

[0051] The waveguide transmission line 1 is designed to be used in designs with the same or similar cross-sectional dimensions as the standard waveguide, with the long side being 2.2mm-2.8mm and the short side being 0.7mm-1.6mm.

[0052] exist Figure 5 In the embodiment, a plurality of microstrip feed lines 6 are arranged side by side along a first direction to feed into the first short side of the waveguide transmission line 1, and the first direction is a direction parallel to the short side of the waveguide opening. Compared with the method of feeding from the long side, since the distance from the chip on the PCB to the waveguide antenna is certain, the structure of the present application makes the microstrip feed line shorter and the waveguide transmission line longer. Since the transmission loss of the waveguide transmission line is much smaller than the transmission loss of the microstrip feed line at the same length, the transmission loss is reduced as a whole, and the occupied PCB substrate area is smaller.

[0053] After computer software simulation calculations and actual sample testing, the results show that the design of the waveguide antenna is effective and feasible, and all indicators including bandwidth, reflection, loss, etc. meet the preset vehicle-mounted radar design requirements. Furthermore, the design of the waveguide antenna adopts a nail bed structure, which effectively reduces the loss of microstrip to waveguide, and reduces the assembly and matching accuracy requirements of the waveguide antenna and the PCB board, which is more conducive to improving production efficiency and product quality.

[0054] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0055] The above describes the specific embodiments of the present invention. It should be understood that the present invention 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 does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other at will.

Claims

1. A microstrip-to-waveguide structure, characterized in that: include: A waveguide transmission line (1) is located in a waveguide antenna (2), wherein the waveguide transmission line (1) has a waveguide opening (4) on a side wall of the waveguide antenna (2), and the waveguide opening (4) has a preset long side and short side size structure; A microstrip feed line (6) is arranged on a PCB substrate (7), and an end portion thereof extends from a first short side of a projection of the waveguide opening (4) on the PCB substrate (7) into the projection; The nail bed structure comprises a plurality of nail beds (5), one end of the nail bed (5) is connected to the outside of the waveguide opening (4), and the other end is connected to or gap-fitted with the PCB substrate (7).

2. The microstrip-to-waveguide structure according to claim 1, characterized in that: The nail bed (5) is located on other sides of the projection except the first short side.

3. The microstrip-to-waveguide structure according to claim 1, characterized in that: The waveguide antenna (2) is made of a conductive metal material, or a non-conductive material with a metal film coated on the inner and outer surfaces; The outer surface of the nail bed (5) is plated with a metal film.

4. The microstrip-to-waveguide structure according to claim 1, characterized in that: The number of the bed of nails structures is the same as that of the waveguide openings (4) and they correspond one to one.

5. The microstrip-to-waveguide structure according to claim 1, characterized in that: The first short side is 0.7mm-1.6mm; The center spacing between the nail beds (5) is 1mm-1.5mm; The height of the nail bed (5) is 0.7 mm-1.2 mm.

6. The microstrip-to-waveguide structure according to claim 1, characterized in that: The waveguide transmission lines (1) and the microstrip feed lines (6) are multiple in number and correspond one to one; The parts of the plurality of microstrip feed lines (6) feeding into the first short side are arranged side by side along a first direction, and the first direction is a direction parallel to the short side of the waveguide opening (4).

7. The microstrip-to-waveguide structure according to claim 1, characterized in that: The distance between the nail bed (5) and the PCB substrate (7) is 0 mm-0.5 mm.

8. The microstrip-to-waveguide structure according to claim 1, characterized in that: The microstrip feed line (6) coincides with the center line of the first short side, and the end of the microstrip feed line (6) is located at the center of the projection.

9. A waveguide antenna, characterized in that: The invention comprises the structure of the microstrip-to-waveguide according to claim 1.

10. A radar, characterized in that: Includes the waveguide antenna as claimed in claim 9.

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