Simple millimeter wave microstrip waveguide transition structure and waveguide tube preparation process

Abstract

The application relates to the technical field of waveguides, and particularly discloses a novel simple millimeter wave microstrip waveguide transition structure and a preparation process of a waveguide, which comprises a printed component, a waveguide, a metal base, metal screws and a positioning pin, the printed component is fixedly connected with the metal base and located above the metal base, the waveguide is fixedly connected with the printed component and located above the printed component, the metal screws penetrate through the waveguide, the printed component and the metal base, and the positioning pin penetrates through the waveguide, the printed component and the metal base in sequence. The microstrip line to the strip line conversion effectively reduces the transmission loss and the influence of medium radiation, the strip line transition to the microstrip probe is adopted to couple and excite the rectangular microstrip antenna, the transmission direction of the electromagnetic field is changed from the tangent direction to the normal direction, the microstrip antenna and the waveguide end matching are adopted to realize the low-loss energy transmission.

Description

Technical Field

[0001] This invention relates to the field of waveguide technology, and in particular to a simple millimeter-wave microstrip waveguide transition structure and its fabrication process. Background Technology

[0002] Currently, with the rapid development of millimeter-wave technology, the application of monolithic microwave integrated circuits (MMICs) is becoming increasingly widespread, and electromagnetic waves need to be transmitted in media of different forms and materials.

[0003] However, in current engineering applications, the main issues for microstrip waveguide transitions are: internal stepped ridge waveguide transitions, which are complex in structure, require a lot of debugging, and have high processing costs; microstrip fin waveguide transitions, which have low processing yields due to their proximity to the dielectric edge; and microstrip coupling probe transitions, which have relatively simple structures but face challenges in millimeter-wave frequency assembly processes and require high positioning accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a simple millimeter-wave microstrip waveguide transition structure and waveguide fabrication process, aiming to solve the technical problems of existing engineering methods for microstrip waveguide transitions, such as internal stepped ridge waveguide transitions, which are complex in structure, require a large amount of debugging, and have high processing costs; microstrip fin waveguide transitions, which have low processing yield due to their proximity to the dielectric edge; and microstrip coupling probe transitions, which have relatively simple structures but are difficult to assemble at millimeter-wave frequencies and require high positioning accuracy.

[0005] To achieve the above objectives, the present invention employs a simple millimeter-wave microstrip waveguide transition structure, comprising a printed component, a waveguide, a metal base, a metal screw, and a positioning pin. The printed component is fixedly connected to the metal base and is located above the metal base. The waveguide is fixedly connected to the printed component and is located above the printed component. The metal screw passes through the waveguide, the printed component, and the metal base. The positioning pin passes through the waveguide, the printed component, and the metal base in sequence.

[0006] The printed circuit board assembly includes an upper printed circuit board assembly, a lower printed circuit board assembly, and a middle printed circuit board. The lower printed circuit board assembly is disposed above the metal base, the middle printed circuit board is disposed above the lower printed circuit board assembly, the upper printed circuit board assembly is disposed above the middle printed circuit board, and the waveguide is disposed above the upper printed circuit board assembly.

[0007] The lower printed circuit board assembly includes a lower printed circuit board, a first copper layer, and a second copper layer. The first copper layer is fixedly connected to the lower printed circuit board and is located below the lower printed circuit board. The second copper layer is fixedly connected to the lower printed circuit board and is located above the lower printed circuit board.

[0008] The upper printed circuit board assembly includes an upper printed circuit board and a third copper layer. The upper printed circuit board is fixedly connected to the middle printed circuit board and is located above the middle printed circuit board. The third copper layer is fixedly connected to the upper printed circuit board and is located above the upper printed circuit board.

[0009] The lower printed circuit board, the first copper layer, the second copper layer, the upper printed circuit board, the third copper layer, and the middle printed circuit board each have two through holes, and the aforementioned through holes are connected to form two metal vias.

[0010] This invention also provides a fabrication process for a waveguide, comprising the following steps:

[0011] The inner cavity of the waveguide is formed by slow wire cutting, which improves the machining accuracy of the inner cavity. The machining accuracy can reach 0.01mm, and the surface roughness can reach Ra=0.8μm.

[0012] The waveguide is milled using a shaped flange, and the rectangular opening that mates with the outer cavity of the waveguide is formed by slow wire cutting. Drilling is performed using a drilling jig to ensure the positioning accuracy of the pin holes.

[0013] The waveguide uses a non-standard thickness, increasing the waveguide wall thickness to 2mm. The waveguide openings at both ends are machined into rectangular stops to facilitate matching with the rectangular openings of irregular flanges. Vacuum brazing is then performed to reduce the deformation of the waveguide caused by welding.

[0014] The beneficial effects of the simplified millimeter-wave microstrip waveguide transition structure and waveguide fabrication process of the present invention are as follows: the microstrip line to stripline transformation effectively reduces transmission loss and the influence of dielectric radiation; the stripline to microstrip probe is used to couple and excite a rectangular microstrip antenna, so that the transmission direction of the electromagnetic field is changed from the tangential direction of the microstrip line to the normal direction; the microstrip antenna and waveguide termination matching is used to achieve low-loss energy transmission, and to reduce processing costs and defective products. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the simplified millimeter-wave microstrip waveguide transition structure of the present invention.

[0017] Figure 2This is a flowchart of the fabrication process steps of the waveguide of the present invention.

[0018] 1-Waveguide, 2-Metal base, 3-Metal screw, 4-Positioning pin, 5-Lower printed circuit board, 6-Middle printed circuit board, 7-Upper printed circuit board, 8-First copper layer, 9-Second copper layer, 10-Third copper layer, 11-Metal via. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] Please see Figure 1 This invention provides a simple millimeter-wave microstrip waveguide transition structure, including a printed component, a waveguide 1, a metal base 2, a metal screw 3, and a positioning pin 4. The printed component is fixedly connected to the metal base 2 and is located above the metal base 2. The waveguide 1 is fixedly connected to the printed component and is located above the printed component. The metal screw 3 passes through the waveguide 1, the printed component, and the metal base 2. The positioning pin 4 passes through the waveguide 1, the printed component, and the metal base 2 in sequence.

[0021] Furthermore, the printed circuit board assembly includes an upper printed circuit board assembly, a lower printed circuit board assembly, and a middle printed circuit board 6. The lower printed circuit board assembly is disposed above the metal base 2, the middle printed circuit board 6 is disposed above the lower printed circuit board assembly, the upper printed circuit board assembly is disposed above the middle printed circuit board 6, and the waveguide 1 is disposed above the upper printed circuit board assembly.

[0022] Furthermore, the lower printed circuit board assembly includes a lower printed circuit board 5, a first copper layer 8, and a second copper layer 9. The first copper layer 8 is fixedly connected to the lower printed circuit board 5 and is located below the lower printed circuit board 5. The second copper layer 9 is fixedly connected to the lower printed circuit board 5 and is located above the lower printed circuit board 5.

[0023] Furthermore, the upper printed circuit board assembly includes an upper printed circuit board 7 and a third copper layer 10. The upper printed circuit board 7 is fixedly connected to the middle printed circuit board 6 and is located above the middle printed circuit board 6. The third copper layer 10 is fixedly connected to the upper printed circuit board 7 and is located above the upper printed circuit board 7.

[0024] Furthermore, the lower printed circuit board 5, the first copper layer 8, the second copper layer 9, the upper printed circuit board 7, the third copper layer 10, and the middle printed circuit board 6 each have two through holes, and the aforementioned through holes are connected to form two metal vias 11.

[0025] In this invention, the upper printed circuit board 7 is laminated onto the lower printed circuit board 5 via the middle printed circuit board 6, and the metal via 11 penetrates the lower printed circuit board 5, the first copper layer 8, the second copper layer 9, the upper printed circuit board 7, the third copper layer 10, and the middle printed circuit board 6. The positioning pin 4 can achieve the purpose of positioning, and the metal screw 3 is installed and fixed on the metal base 2.

[0026] The metal via 11 effectively ensures the positioning accuracy of the positioning pin 4 assembly; the metal base 2, the metal via 11, and the positioning pin 4 are interference-fitted, serving as the positioning reference for the positioning pin 4; the positioning pin 4 is transition-fitted with the printed circuit board assembly and the waveguide 1, enabling layered positioning and effectively ensuring the assembly accuracy of each layer; the holes of the positioning pin 4 are designed to be evenly distributed around the circumference, ensuring the concentricity of the waveguide center and the microstrip center of the printed circuit board assembly, and the metal screws 3 are evenly distributed around the circumference for fixing, ensuring uniform force on the printed circuit board assembly and reducing the gaps in the pressing of each layer of the printed circuit board assembly;

[0027] The radio frequency signal is fed in through the microstrip line of the lower printed circuit board 5, then transformed from microstrip line to stripline, and transmitted to the microstrip probe. The rectangular microstrip antenna of the upper printed circuit board 7, which is coupled and excited, radiates energy and finally outputs through the waveguide 1, realizing the transition from microstrip to waveguide.

[0028] Please see Figure 2 The present invention also provides a fabrication process for waveguide 1, which fabricates the simple millimeter-wave microstrip waveguide transition structure described above, comprising the following steps:

[0029] S1: The inner cavity of the waveguide 1 is formed by slow wire cutting, which improves the machining accuracy of the inner cavity. The machining accuracy can reach 0.01mm and the surface roughness can reach Ra=0.8μm.

[0030] S2: The waveguide 1 is milled using a special-shaped flange, and the rectangular opening that mates with the outer cavity of the waveguide 1 is formed by slow wire cutting. Drilling is performed using a drilling jig to ensure the positioning accuracy of the pin holes.

[0031] S3: The waveguide 1 adopts a non-standard thickness, increasing the waveguide wall thickness to 2mm, and machining the waveguide openings at both ends into rectangular stops to facilitate matching with the rectangular openings of the irregular flanges. Vacuum brazing is then performed to reduce the deformation of the waveguide 1 caused by welding.

[0032] Millimeter-wave bands require waveguide cavities with high precision and surface finish to reduce transmission loss. Simultaneously, waveguide flanges need to be fabricated with irregular structures to avoid interference between microstrip lines and mounting holes. Transformations from microstrip lines to striplines and from striplines to microstrip probes improve transmission efficiency. The microstrip probe couples and excites a rectangular microstrip antenna to rotate the electromagnetic field transmission direction by 90°. The structure where the printed circuit board assembly and waveguide are connected via positioning pins 4 is technologically mature, easy to process, and simple to assemble.

[0033] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A simple millimeter-wave microstrip waveguide transition structure, characterized in that, The device includes a printed component, a waveguide, a metal base, metal screws, and locating pins. The printed component is fixedly connected to the metal base and is located above the metal base. The waveguide is fixedly connected to the printed component and is located above the printed component. The metal screws pass through the waveguide, the printed component, and the metal base. The locating pins pass through the waveguide, the printed component, and the metal base in sequence. The printed circuit assembly includes an upper printed circuit board assembly, a lower printed circuit board assembly, and a middle printed circuit board. The lower printed circuit board assembly is disposed above the metal base, the middle printed circuit board is disposed above the lower printed circuit board assembly, the upper printed circuit board assembly is disposed above the middle printed circuit board, and the waveguide is disposed above the upper printed circuit board assembly. The lower printed circuit board assembly includes a lower printed circuit board, a first copper layer, and a second copper layer. The first copper layer is fixedly connected to the lower printed circuit board and is located below the lower printed circuit board. The second copper layer is fixedly connected to the lower printed circuit board and is located above the lower printed circuit board. The upper printed circuit board assembly includes an upper printed circuit board and a third copper layer. The upper printed circuit board is fixedly connected to the middle printed circuit board and is located above the middle printed circuit board. The third copper layer is fixedly connected to the upper printed circuit board and is located above the upper printed circuit board. The lower printed circuit board, the first copper layer, the second copper layer, the upper printed circuit board, the third copper layer, and the middle printed circuit board each have two through holes, and the above-mentioned through holes are connected to form two metal vias; The fabrication of waveguides using the aforementioned simplified millimeter-wave microstrip waveguide transition structure includes the following steps: The waveguide inner cavity is formed by slow wire cutting to improve the machining accuracy of the inner cavity. The machining accuracy is 0.01mm and the surface roughness is Ra=0.8μm. The waveguide is milled using a shaped flange, and the rectangular opening that mates with the outer cavity of the waveguide is formed by slow wire cutting. Drilling is performed using a drilling jig to ensure the positioning accuracy of the pin holes. The waveguide uses a non-standard thickness, increasing the waveguide wall thickness to 2mm. The waveguide openings at both ends are machined into rectangular stops to facilitate matching with the rectangular openings of irregular flanges. Vacuum brazing is then performed to reduce the deformation of the waveguide caused by welding.

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