A microstrip line to waveguide conversion structure for millimeter-wave communication

Abstract

This invention provides a microstrip line-to-waveguide conversion structure for millimeter-wave communication. The conversion structure includes a printed circuit board (PCB) assembly and a rectangular waveguide assembly. The PCB assembly is used to bond with the rectangular waveguide assembly. The rectangular waveguide assembly includes pin slots and waveguide cavities. The opening of the waveguide cavity is located at the bottom of the pin slot. The PCB assembly has a pin slot on the side bonded to the PCB assembly, and multiple pins are evenly distributed in the pin slot. The PCB assembly has a probe metal layer on the side bonded to the rectangular waveguide assembly. The probe metal layer includes an outer metal plate and a probe plate. The outer metal plate has a window, and the probe plate is disposed within the window. The shape of the waveguide cavity opening corresponds to the window. When the PCB assembly is used to bond with the rectangular waveguide assembly, the opening of the waveguide cavity is positioned opposite to the window.

Description

Technical Field

[0001] This invention relates to the field of millimeter-wave communication technology, and in particular to a microstrip line to waveguide conversion structure for millimeter-wave communication. Background Technology

[0002] With the increasing demand for millimeter-wave applications, the connection between different transmission lines is becoming increasingly important. Rectangular waveguides, due to their low-loss characteristics, are widely used in millimeter-wave circuits, and the transition from microstrip lines to rectangular waveguides is crucial for the efficient interconnection of RF chips and millimeter-wave feed networks. However, in millimeter-wave communication, the microstrip line-to-waveguide transition structure, as a key component connecting the RF chip and the feed network, requires extremely high assembly precision. Even minute assembly errors can significantly impact the connection between the RF chip and the feed network.

[0003] Meanwhile, in vibration environments, printed circuit boards require greater thickness to enhance their mechanical strength and prevent damage from impacts. While there has been considerable research progress on microstrip line to rectangular waveguide conversion technology, current technologies struggle to address the challenges of efficient transmission and broadband matching in millimeter-wave communication under vibration conditions. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a microstrip line to waveguide conversion structure for millimeter-wave communication to eliminate or improve one or more defects existing in the prior art.

[0005] One aspect of the present invention provides a microstrip line to waveguide conversion structure for millimeter-wave communication, the conversion structure comprising a printed circuit board assembly and a rectangular waveguide assembly, the printed circuit board assembly being used to attach to the rectangular waveguide assembly;

[0006] The rectangular waveguide assembly includes a pin slot and a waveguide cavity. The opening of the waveguide cavity is located at the bottom of the pin slot. The rectangular waveguide assembly has a pin slot on the side that is in contact with the printed circuit board assembly. A plurality of pins are evenly arranged in the pin slot.

[0007] The printed circuit board assembly has a probe metal layer on the side that is in contact with the rectangular waveguide assembly. The probe metal layer includes an outer metal plate and a probe plate. The outer metal plate has a window, and the probe plate is disposed within the window.

[0008] The shape of the waveguide cavity opening corresponds to the window opening. When the printed circuit board assembly is used to fit with the rectangular waveguide assembly, the opening of the waveguide cavity is arranged opposite to the window opening.

[0009] The above-described solution suppresses electromagnetic wave leakage between the dielectric substrate and the printed circuit board (PCB) assembly by incorporating a choke coil, achieving efficient electromagnetic wave transmission. The buried via coaxial structure of the PCB assembly allows for flexible adjustment of the PCB thickness, enhancing its mechanical strength and addressing the issue of PCB damage under vibration. Periodically arranged metal pins around the waveguide port resolve electromagnetic wave leakage and impedance mismatch issues caused by assembly errors under millimeter-wave high-frequency conditions, achieving high-tolerance matching between the microstrip line and the waveguide.

[0010] In some embodiments of the present invention, the printed circuit board assembly is provided with a microstrip line layer, a first transition metal layer, a first choke layer, a second choke layer, a second transition metal layer, and a probe metal layer extending from the microstrip line layer toward the probe metal layer. A first dielectric substrate is disposed between the microstrip line layer and the first transition metal layer. A first adhesive layer is disposed between the first transition metal layer and the first choke layer. A second dielectric substrate is disposed between the first choke layer and the second choke layer. A second adhesive layer is disposed between the second choke layer and the second transition metal layer. A third dielectric substrate is disposed between the second transition metal layer and the probe metal layer.

[0011] In some embodiments of the present invention, the printed circuit board assembly further includes a first through-hole extending from a first dielectric substrate to a third dielectric substrate.

[0012] In some embodiments of the present invention, the first choke coil layer and the second choke coil layer have the same structure. The first choke coil layer and the second choke coil layer include a first ring, a second ring and a plurality of outer branches. The first ring is disposed inside the second ring. The plurality of outer branches are evenly disposed and connected to the outer periphery of the first ring. One end of the outer branch is connected to the outer periphery of the first ring and the other end extends toward the inner side of the second ring.

[0013] In some embodiments of the present invention, the first through hole passes through the center of the first ring of the first choke layer and the second choke layer.

[0014] In some embodiments of the present invention, a plurality of third through holes are provided between the first choke coil layer and the second choke coil layer, and the plurality of third through holes are evenly distributed along the first ring and the second ring, extending from above the first ring and the second ring of the first choke coil layer to below the first ring and the second ring of the second choke coil layer.

[0015] In some embodiments of the present invention, the microstrip layer is a metal strip, one end of which is disposed on one side of the printed circuit board assembly along its length, and the other end of which extends to the port of the first through hole.

[0016] In some embodiments of the present invention, the printed circuit board assembly further includes a second through-hole extending from the upper surface of the second transition metal layer to the lower surface of the probe metal layer, and a plurality of the second through-holes are provided along the edge of the window in the probe metal layer.

[0017] In some embodiments of the present invention, the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are all made of RO 3003 material, and the first adhesive layer and the second adhesive layer are both made of FR 28 material.

[0018] In some embodiments of the present invention, the thickness of the second dielectric substrate is greater than the thickness of the first dielectric substrate or the third dielectric substrate.

[0019] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and will also become apparent in part to those skilled in the art upon studying the text, or may be learned by practice of the invention. The objects and other advantages of the invention will become apparent from the description and the accompanying drawings.

[0020] Those skilled in the art will understand that the objectives and advantages achievable with the present invention are not limited to those specifically described above, and that the above and other objectives achievable with the present invention will become clearer from the following detailed description. Attached Figure Description

[0021] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, are not intended to limit the scope of the invention.

[0022] Figure 1 This is a perspective view of the overall structure of the microstrip line to waveguide conversion structure applied to millimeter-wave communication in this scheme;

[0023] Figure 2 This is a schematic diagram showing the overall structure of the microstrip line to waveguide conversion structure applied to millimeter-wave communication in this scheme.

[0024] Figure 3 This is a schematic diagram of the printed circuit board assembly for this solution;

[0025] Figure 4 This is a top view of the printed circuit board assembly for this solution;

[0026] Figure 5 This is a schematic diagram of the microstrip layer in this scheme;

[0027] Figure 6 This is a schematic diagram of the first dielectric substrate of this scheme;

[0028] Figure 7 This is a schematic diagram of the first or second transition metal layer in this scheme;

[0029] Figure 8 This is a schematic diagram of the cross-section of the first or second choke layer in this scheme;

[0030] Figure 9 This is a schematic diagram of the second dielectric substrate in this scheme;

[0031] Figure 10 This is a schematic diagram of the third dielectric substrate in this solution;

[0032] Figure 11 This is a schematic diagram of the probe metal layer in this scheme;

[0033] Figure 12 This is a cross-sectional perspective view of the printed circuit board assembly in this solution;

[0034] Figure 13 This is a perspective view of the rectangular waveguide assembly in this scheme;

[0035] Figure 14 A schematic diagram of the simulation results of the printed circuit board assembly and rectangular waveguide assembly under the condition of no gaps and no misalignment in this scheme;

[0036] Figure 15 A schematic diagram of the simulation results for the printed circuit board assembly and rectangular waveguide assembly of this scheme under the assembly conditions of 0.1mm gap and 0.35mm misalignment along the X and Y axes;

[0037] Figure 16 This is a schematic diagram of the field distribution at the gap between the printed circuit board assembly and the rectangular waveguide assembly in this solution.

[0038] Figure 17 This is a schematic diagram of the field distribution at the first and second choke layers of this scheme.

[0039] Explanation of reference numerals in the attached figures

[0040] The technical solution of the present invention can be more clearly understood and explained through the above description of the reference numerals in the accompanying drawings and in conjunction with the embodiments of the present invention.

[0041] 1. Printed circuit board assembly; L6. Probe metal layer; 111. Outer metal plate; 112. Probe board; 113. Window; 2. Rectangular waveguide assembly; 21. Pin slot; 22. Waveguide cavity; L1. Microstrip line layer; V1. First via; 141. First ring; 142. Second ring; 143. Outer stub; V3. Third via; V2. Second via; L2. First transition metal layer; L3. First choke layer; L4. Second choke layer; L5. Second transition metal layer. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. Here, the illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention.

[0043] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0044] Numerous research achievements exist in microstrip line to rectangular waveguide transition technology. Existing technology one proposes an online E-plane microstrip probe to waveguide transition structure. This proposed through-hole transition structure consists of a waveguide T-junction with two short-circuit branch waveguides of a quarter-wavelength difference and a microstrip line-fed probe aligned with the main waveguide. However, this structure suffers from high assembly precision and susceptibility to PCB damage under vibration. Existing technology two proposes a transition structure operating in the millimeter-wave band from microstrip to the H-plane of a rectangular waveguide. However, this structure also suffers from high assembly precision and susceptibility to PCB damage under vibration. Existing technology three proposes a low-loss horizontal transition structure between a rectangular dielectric waveguide and a microstrip line in the W-band. This transition structure consists of a microstrip line, a ridge waveguide, a dielectric-filled waveguide, a conical horn, and a rectangular dielectric waveguide. However, this structure also suffers from high assembly precision and susceptibility to PCB damage under vibration. Existing technology four proposes a microstrip line to waveguide transition method for monolithic millimeter-wave integrated circuit packaging. This method uses a pair of anti-symmetrical rectangular probes, arranged on both sides of the substrate within the E-plane waveguide, with the probe tips close to the sides of the waveguide and their roots overlapping. This helps to gradually rotate the coupled electric field from the waveguide into the microstrip. However, this structure has the disadvantages of high assembly precision and susceptibility of the printed circuit board to vibration. Existing technology five proposes a novel broadband transition from microstrip to waveguide using a via-less choke structure. It utilizes a simple rectangular patch to convert the quasi-TEM mode of the microstrip line to the TE10 mode of the waveguide, introducing multiple open stubs instead of vias to suppress power leakage. However, this structure also suffers from susceptibility of the printed circuit board to vibration. Moreover, to date, no microstrip line to rectangular waveguide transition structure has been proposed to address the issues of printed circuit board rigidity and high assembly precision in millimeter-wave communication under vibration. The structure of this solution fills this gap.

[0045] like Figure 1 , 2 As shown in Figures 4 and 13, this invention proposes a microstrip line to waveguide conversion structure for millimeter-wave communication. The conversion structure includes a printed circuit board assembly and a rectangular waveguide assembly, wherein the printed circuit board assembly is used to attach to the rectangular waveguide assembly.

[0046] The rectangular waveguide assembly includes a pin slot and a waveguide cavity. The opening of the waveguide cavity is located at the bottom of the pin slot. The rectangular waveguide assembly has a pin slot on the side that is in contact with the printed circuit board assembly. A plurality of pins are evenly arranged in the pin slot.

[0047] like Figure 11 As shown, the printed circuit board assembly has a probe metal layer on the side that is in contact with the rectangular waveguide assembly. The probe metal layer includes an outer metal plate and a probe plate. The outer metal plate has a window, and the probe plate is disposed within the window.

[0048] The shape of the waveguide cavity opening corresponds to the window opening. When the printed circuit board assembly is used to fit with the rectangular waveguide assembly, the opening of the waveguide cavity is arranged opposite to the window opening.

[0049] In the specific implementation process, by reasonably designing the dimensions of the rectangular metal waveguide structure, the rectangular waveguide assembly is a stepped gradient waveguide, consisting of a blade-shaped waveguide at the opening of the waveguide cavity and two-stage rectangular waveguides in the waveguide cavity. At the same time, metal pins are periodically arranged in the pin slots to further enlarge the waveguide opening, thereby achieving high tolerance matching between the microstrip probe of the probe metal layer and the rectangular waveguide assembly.

[0050] The above-described solution suppresses electromagnetic wave leakage between the dielectric substrate and the printed circuit board (PCB) assembly by incorporating a choke coil, achieving efficient electromagnetic wave transmission. The buried via coaxial structure of the PCB assembly allows for flexible adjustment of the PCB thickness, enhancing its mechanical strength and addressing the issue of PCB damage under vibration. Periodically arranged metal pins around the waveguide port resolve electromagnetic wave leakage and impedance mismatch issues caused by assembly errors under millimeter-wave high-frequency conditions, achieving high-tolerance matching between the microstrip line and the waveguide.

[0051] like Figure 3 As shown, Figure 3 (a) is a schematic diagram of the overall printed circuit board assembly, as shown below. Figure 3 (b) A schematic diagram of the structure of each layer of the printed circuit board assembly. In some embodiments of the present invention, the printed circuit board assembly extends from the microstrip line layer towards the probe metal layer, and is provided layer by layer with a microstrip line layer, a first transition metal layer, a first choke layer, a second choke layer, a second transition metal layer, and a probe metal layer. A first dielectric substrate is disposed between the microstrip line layer and the first transition metal layer, such as... Figure 6 As shown, a first adhesive layer is disposed between the first transition metal layer and the first choke layer, a second dielectric substrate is disposed between the first choke layer and the second choke layer, a second adhesive layer is disposed between the second choke layer and the second transition metal layer, and a third dielectric substrate is disposed between the second transition metal layer and the probe metal layer.

[0052] like Figure 7 , 9 As shown in 10 and 12, in some embodiments of the present invention, the printed circuit board assembly further includes a first through-hole extending from a first dielectric substrate to a third dielectric substrate.

[0053] like Figure 8 As shown, in some embodiments of the present invention, the first choke coil layer and the second choke coil layer have the same structure. The first choke coil layer and the second choke coil layer include a first ring, a second ring and a plurality of outer branches. The first ring is disposed inside the second ring. The plurality of outer branches are evenly disposed and connected to the outer periphery of the first ring. One end of the outer branch is connected to the outer periphery of the first ring and the other end extends toward the inner side of the second ring.

[0054] like Figure 8 As shown, in some embodiments of the present invention, the first through hole passes through the center of the first ring of the first choke layer and the second choke layer.

[0055] like Figure 9 and 12 As shown, in some embodiments of the present invention, a plurality of third through holes are provided between the first choke coil layer and the second choke coil layer. The plurality of third through holes are evenly distributed along the first ring and the second ring, extending from above the first ring and the second ring of the first choke coil layer to below the first ring and the second ring of the second choke coil layer.

[0056] In the specific implementation process, by reasonably designing the size of the annular buried via structure, i.e. the third through hole, a metal ring is placed outside the first and second choke layers of the printed circuit board metal layer to wrap it. At the same time, annular buried vias are distributed on the metal rings of the first and second choke layers to suppress electromagnetic leakage generated by the holeless choke structure and the buried via coaxial structure.

[0057] Specifically, the rectangular waveguide assembly and the probe metal layer of the printed circuit board assembly are tightly bonded together.

[0058] By adopting the above scheme, the structure of two choke coils can replace metal buried vias to suppress electromagnetic wave leakage between the dielectric substrates through a rationally designed choke coil structure. Multiple third vias are provided between the first and second choke coil layers. Through a rationally designed buried via coaxial structure, the first vias penetrate the printed circuit board, connecting the microstrip line layer and the probe metal layer. The third vias are arranged in a ring-shaped pattern between the first and second choke coil layers of the printed circuit board. Since only metal buried vias and metal through-holes exist between the first and second choke coil layers, the thickness of the printed circuit board can be controlled by adjusting the thickness of the dielectric substrate between the first and second choke coil layers.

[0059] like Figure 5 As shown, in some embodiments of the present invention, the microstrip layer is a metal strip, one end of which is disposed on one side of the printed circuit board assembly along its length, and the other end of which extends to the port of the first through hole.

[0060] In the specific implementation process, this solution achieves an input impedance of 50 ohms at the port where the metal strip of the microstrip layer is connected to the RF chip by reasonably designing the broadband of the microstrip line structure.

[0061] like Figure 10 and 12 As shown, in some embodiments of the present invention, the printed circuit board assembly further includes a second through-hole, which extends from the upper surface of the second transition metal layer to the lower surface of the probe metal layer, and a plurality of the second through-holes are provided along the edge of the window in the probe metal layer.

[0062] By adopting the above scheme, through reasonable design of the microstrip probe structure size, metal pattern design is performed on the probe metal layer of the printed circuit board metal layer, and blind via treatment of the second through hole is performed on the dielectric substrate between the probe metal layer and the second transition metal layer around the metal pattern. Electromagnetic waves are radiated and fed to the rectangular waveguide assembly through the probe metal layer.

[0063] In some embodiments of the present invention, the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are all made of RO 3003 material, and the first adhesive layer and the second adhesive layer are both made of FR 28 material.

[0064] In some embodiments of the present invention, the thickness of the second dielectric substrate is greater than the thickness of the first dielectric substrate or the third dielectric substrate.

[0065] To verify the theoretical correctness and the theoretical performance of the proposed microstrip line-waveguide conversion structure, this scheme designs a microstrip line-waveguide conversion structure with an operating frequency band of 59 GHz to 65 GHz. Simulation verification is performed on the microstrip line-waveguide conversion structure under gapless and misalignment-free assembly conditions. The simulation results are as follows: Figure 14 As shown; simulation verification was performed on the printed circuit board assembly and the rectangular waveguide assembly with a gap of 0.1mm, and the simulation results are as follows. Figure 15 As shown in (a), simulation results were obtained under assembly conditions with a 0.35mm misalignment along the X and Y axes. Figure 15 As shown in (b), under the condition of no gap and no misalignment in the assembly, the transmission coefficient of the microstrip line to waveguide conversion structure is >-1.6dB and the reflection coefficient is <-13dB; under the condition of 0.1mm gap and 0.35mm misalignment along the X and Y axes in the assembly, the transmission coefficient of the microstrip line to waveguide conversion structure is >-2.1dB and the reflection coefficient is <-10dB.

[0066] This solution provides a microstrip line-to-waveguide conversion structure and a waveguide conversion structure for millimeter-wave communication. By using a hole-free choke, electromagnetic wave leakage between the dielectric substrate is suppressed, achieving efficient electromagnetic wave transmission. The buried via coaxial structure allows for flexible adjustment of the printed circuit board thickness, improving the mechanical strength of the printed circuit board and solving the problem of PCB damage under vibration. Periodically arranged metal pins around the rectangular waveguide opening solve the problems of electromagnetic wave leakage and impedance mismatch caused by assembly errors under high-frequency millimeter-wave conditions, achieving high-tolerance matching between the microstrip line and the waveguide. This invention opens up new technical avenues for designing microstrip line-to-waveguide conversion structures and waveguide conversion structures for millimeter-wave communication.

[0067] In summary, to achieve efficient electromagnetic wave transmission between microstrip lines and waveguides, this solution employs a coaxial probe to feed the waveguide and suppresses electromagnetic wave leakage at the bonding layer through a rationally designed non-porous choke. Figure 17 As shown, this method achieves efficient electromagnetic wave transmission. By controlling the length of the buried via coaxial structure, the thickness of the printed circuit board (PCB) can be arbitrarily adjusted. An electromagnetic bandgap structure is formed between the periodic metal pins loaded around the metal waveguide port and the top metal of the PCB, achieving efficient transmission and broadband matching of the conversion structure even under high assembly errors. This solution solves the problem of requiring extremely high assembly precision for microstrip line-waveguide conversion structures in the traditional millimeter-wave band. Furthermore, this conversion structure is applicable to microstrip lines on PCBs of any thickness, greatly improving the mechanical strength of the PCB and providing a new design approach for realizing microstrip line-waveguide conversion structures in the millimeter-wave band.

[0068] Those skilled in the art will understand that the exemplary components, systems, and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Whether implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention. When implemented in hardware, it can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this invention are programs or code segments used to perform the desired tasks. The programs or code segments can be stored in a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried in a carrier wave.

[0069] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0070] In this invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or in place of features of other embodiments.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations of the embodiments of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A microstrip-to-waveguide transition structure for millimeter wave communications, comprising: The conversion structure includes a printed circuit board assembly and a rectangular waveguide assembly, wherein the printed circuit board assembly is used to be bonded to the rectangular waveguide assembly; The rectangular waveguide assembly includes a pin slot and a waveguide cavity. The opening of the waveguide cavity is located at the bottom of the pin slot. The rectangular waveguide assembly has a pin slot on the side that is in contact with the printed circuit board assembly. A plurality of pins are evenly arranged in the pin slot. The printed circuit board assembly has a probe metal layer on the side that is in contact with the rectangular waveguide assembly. The probe metal layer includes an outer metal plate and a probe plate. The outer metal plate has a window, and the probe plate is disposed within the window. The printed circuit board assembly extends from the microstrip line layer toward the probe metal layer, and is provided with a microstrip line layer, a first transition metal layer, a first choke layer, a second choke layer, a second transition metal layer, and a probe metal layer in succession. A first dielectric substrate is disposed between the microstrip line layer and the first transition metal layer. A first adhesive layer is disposed between the first transition metal layer and the first choke layer. A second adhesive layer is disposed between the first choke layer and the second choke layer. A dielectric substrate is provided, a second adhesive layer is disposed between the second choke layer and the second transition metal layer, and a third dielectric substrate is disposed between the second transition metal layer and the probe metal layer; the printed circuit board assembly further includes a first through hole, the first through hole extending from the first dielectric substrate to the third dielectric substrate; the first choke layer and the second choke layer have the same structure, the first choke layer and the second choke layer include a first ring, a second ring and a plurality of outer branches, the first ring is disposed inside the second ring, the plurality of outer branches are uniformly connected to the outer periphery of the first ring, one end of the outer branch is connected to the outer periphery of the first ring, and the other end extends toward the inner side of the second ring; The shape of the waveguide cavity opening corresponds to the window opening. When the printed circuit board assembly is used to fit with the rectangular waveguide assembly, the opening of the waveguide cavity is arranged opposite to the window opening.

2. The microstrip-to-waveguide transition structure for millimeter-wave communication according to claim 1, wherein, The first through hole passes through the center of the first ring of the first choke layer and the second choke layer. 3.The microstrip-to-waveguide transition structure for millimeter-wave communication of claim 1, wherein, A plurality of third through holes are provided between the first choke coil layer and the second choke coil layer. The plurality of third through holes are evenly distributed along the first ring and the second ring, extending from above the first ring and the second ring of the first choke coil layer to below the first ring and the second ring of the second choke coil layer. 4.The microstrip-to-waveguide transition structure for millimeter-wave communication of claim 1, wherein, The microstrip layer is a metal strip, with one end of the metal strip disposed on one side of the printed circuit board assembly along its length, and the other end of the metal strip extending to the port of the first through hole. 5.The microstrip-to-waveguide transition structure for millimeter-wave communication of claim 1, wherein, The printed circuit board assembly further includes a second through-hole, which extends from the upper surface of the second transition metal layer to the lower surface of the probe metal layer, and multiple second through-holes are provided along the edge of the window in the probe metal layer.

6. The microstrip-to-waveguide transition structure for millimeter-wave communication according to any one of claims 1 to 5, wherein The first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are all made of RO 3003 material, and the first adhesive layer and the second adhesive layer are both made of FR 28 material.

7. The microstrip-to-waveguide transition structure for millimeter-wave communication according to any one of claims 1 to 5, wherein The thickness of the second dielectric substrate is greater than the thickness of the first dielectric substrate or the third dielectric substrate.

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