Microstrip-to-coplanar waveguide feed structure and structure parameter debugging method thereof

Abstract

The invention relates to a microstrip-to-coplanar waveguide feed structure and a structure parameter debugging method thereof, and belongs to the technical field of high-frequency communication. The microstrip-to-coplanar waveguide feed structure comprises a microstrip line, wherein the output end of the microstrip line is provided with a broadening structure; the input end of the coplanar waveguide is provided with a narrowing structure; the plurality of conduction structures are arranged in a coupling area between the broadening structure and the narrowing structure, are arranged in a [shape, and are used for connecting a grounding layer and guiding part of electromagnetic waves to be transmitted to the lower part of the structure along the vertical direction; the electric conductor is arranged below the conduction structure and is used for reflecting the electromagnetic waves guided and transmitted by the conduction structure; wherein the structure size cooperation and the relative position relation among the microstrip line, the coplanar waveguide, the conduction structure and the conductor are optimally set to form an auxiliary coupling path in a target frequency band, and the auxiliary coupling path is used for guiding part of electromagnetic signals to act on the coplanar waveguide after being reflected, so that the impedance matching performance is optimized, and the transmission loss is reduced.

Description

Technical Field

[0001] The present invention relates to the field of high-frequency communication technologies, and in particular, to a microstrip-to-coplanar waveguide feeding structure and a method for debugging its structural parameters. Background Art

[0002] In radio frequency systems in the millimeter-wave band, common forms of transmission lines mainly include microstrip lines (MicrostripLine) and coplanar waveguides (Coplanar Waveguide, CPW). Microstrip line structures are widely used in planar circuits due to their simple process and easy integration, while coplanar waveguides have gradually attracted attention in high-frequency systems due to their advantages of good electromagnetic compatibility and low radiation loss. In actual engineering, it is often necessary to connect microstrip lines and coplanar waveguides to construct an efficient and stable feeding path. However, due to significant differences in electromagnetic field distribution, impedance characteristics, and mode structures between the two transmission structures, traditional transition structure designs are difficult to achieve good impedance matching, and are prone to introducing large reflection losses and spatial radiation, thereby affecting the transmission performance of the entire system.

[0003] Currently, some technical solutions attempt to alleviate the discontinuity caused by the structural transition by setting broadening or narrowing structures between the microstrip line and the coplanar waveguide, and arranging metal structures such as vias in the connection area to achieve grounding or electromagnetic guidance. However, these structures often only play an auxiliary supporting role, and their role in the electromagnetic coupling path is limited, and they cannot form an effective reflection control and auxiliary signal path. In addition, there is a lack of optimized design for the coupling area between the end of the microstrip line and the starting section of the coplanar waveguide in the structural layout, and the synergistic relationship between the conduction structure and the reflection structure is not fully utilized, resulting in problems of large transmission losses or limited bandwidth in the operating frequency band of the system. Especially in the millimeter-wave band, the signal wavelength is short, the structural size is small, and the sensitivity to processing errors and structural design is significantly increased. If the transition structure design is unreasonable, it is extremely easy to cause ineffective radiation or reverse reflection of electromagnetic wave energy, seriously affecting signal integrity. In addition, traditional conduction structures are usually arranged in a linear or grid form, and their shielding or guiding functions are relatively single, and it is difficult to meet the requirement of constructing an auxiliary coupling path in the vertical direction.

[0004] Therefore, how to construct a high-performance transition structure with low reflection, low loss, and compact structure between the microstrip line and the coplanar waveguide, improve impedance matching, and optimize the overall transmission performance is an urgent problem to be solved in the current microstrip-to-coplanar waveguide feeding structure technology. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a microstrip-to-coplanar waveguide feeding structure, aiming to solve the problem that it is difficult to achieve a high-performance transition with low reflection, low loss, and compact structure between the microstrip line and the coplanar waveguide in the prior art, improve the coupling efficiency and signal integrity of the system in the millimeter-wave frequency band, and meet the growing technical requirements for compact and high-performance radio frequency systems.

[0006] In a possible implementation manner, a microstrip-to-coplanar waveguide feeding structure is provided, including: a microstrip line, a broadening structure is provided at the output end of the microstrip line; a coplanar waveguide, a narrowing structure is provided at the input end of the coplanar waveguide; a plurality of conduction structures are arranged in the coupling region between the broadening structure and the narrowing structure, and the conduction structures are arranged in a C shape, and are used to connect the ground layer and guide part of the electromagnetic wave to be transmitted vertically to the lower part of the structure; a conductor is arranged below the conduction structure and is used to reflect the electromagnetic wave guided and transmitted by the conduction structure; wherein, the structural dimensions and relative position relationships among the microstrip line, the coplanar waveguide, the conduction structure and the conductor are optimized and set to form an auxiliary coupling path within the target frequency band, and the auxiliary coupling path is used to guide part of the electromagnetic signal to act on the coplanar waveguide after reflection, so as to realize the signal superposition transmission of the main coupling path and the auxiliary path, and optimize the impedance matching performance and reduce the transmission loss.

[0007] In a possible implementation manner, the input section of the microstrip line is a standard 50Ω transmission line, and a broadening section is provided at the output end; the output section of the coplanar waveguide is a standard 50Ω transmission line, a narrowing section is provided at the input end, and is connected to the microstrip line by a coupling method.

[0008] In a possible implementation manner, the conductor is a metal closed structure, which is arranged below the conduction structure and is used to reflect the electromagnetic wave guided and transmitted by the conduction structure, and controls the phase of the reflected wave by adjusting the size or height of the reflection surface of the conductor, so as to optimize the impedance matching performance of the coplanar waveguide.

[0009] In a possible implementation manner, the coplanar waveguide is arranged on a flexible substrate, and a 90° bending structure in space is formed by bending the flexible substrate, which is used to realize the turning transmission of electromagnetic signals in the vertical direction.

[0010] In a possible implementation manner, the microstrip-to-coplanar waveguide feeding structure includes two transition structures from the microstrip line to the coplanar waveguide, and a coplanar waveguide bending section connecting the two, so as to realize dual-end symmetric feeding or signal output.

[0011] In a possible implementation, the flexible substrate is used to support the spatial bending structure of the coplanar waveguide, and a turning path consistent with the vertical direction is formed by the bending of the flexible substrate.

[0012] In a possible implementation, the conduction structure is arranged in a C-shaped layout, forming an equivalent electromagnetic shielding surface within the target frequency band to reduce the spatial radiation in the transition region.

[0013] In a possible implementation, the conduction structure includes one or more vias, and the multiple vias can enhance the electromagnetic coupling performance and reduce the manufacturing cost.

[0014] In a possible implementation, a reflection cavity is arranged inside the conductor, and the reflection cavity is a metal cavity for reflecting the electromagnetic wave guided and transmitted by the conduction structure.

[0015] In a possible implementation, a method for debugging the structural parameters of a microstrip-to-coplanar waveguide feeding structure is provided. The microstrip-to-coplanar waveguide feeding structure includes a microstrip line, a coplanar waveguide, a conduction structure, and a metal conductor arranged below the conduction structure. The method includes: determining a set of structural parameters, including the broadening dimension of the microstrip line, the narrowing dimension of the coplanar waveguide, the arrangement mode of the conduction structure, the aperture and pitch, and the dimension and relative position of the metal conductor; constructing a microstrip-to-coplanar waveguide feeding structure sample based on the structural parameters, and performing electromagnetic simulation or transmission performance test within the target frequency band to obtain the corresponding transmission loss result; judging whether the transmission loss meets the preset performance requirements; if the transmission loss meets the performance requirements, confirming the current structural parameters as the final structural configuration; if the transmission loss does not meet the performance requirements, performing at least one adjustment on the structural parameters, and repeating the above test and judgment steps based on the adjusted structural parameters until a combination of structural parameters that meets the performance requirements is obtained.

[0016] The additional aspects and advantages of the present invention will be partially given in the following description, partially will become obvious from the following description, or will be understood through the practice of the present invention. It has the following beneficial effects: The microstrip-to-coplanar waveguide feeding structure of the present invention sets a broadening structure at the output end of the microstrip line and a narrowing structure at the input end of the coplanar waveguide, so as to form a gradually changing impedance transition interface between the two different types of transmission lines in the coupling region, thereby constructing a main coupling path and realizing the basic energy transfer of electromagnetic signals from the microstrip line to the coplanar waveguide. Further, a number of conducting structures arranged in a C-shape are provided between the broadening structure and the narrowing structure. On the one hand, this conducting structure is used for electrical connection to the ground layer, and on the other hand, it constructs an energy transmission path in the vertical direction in the structural gap, guiding part of the electromagnetic waves in the main path to the lower part of the structure. At the same time, a conductor is arranged below the conducting structure to reflect the downward transmitted energy, making it return to the coupling region and act on the coplanar waveguide again to form an auxiliary coupling path. The structural dimensions and relative positions among the microstrip line, coplanar waveguide, conducting structure and conductor are set through collaborative optimization, so that the signals in the reflection path have specific phase and amplitude characteristics within the target frequency band, and can effectively interfere and superimpose with the signals in the main coupling path.

[0017] Through the above structure, on the basis of realizing direct coupling of the main path, the present invention adds an auxiliary coupling channel with independent structure and controllable path, effectively enhancing the signal injection efficiency, expanding the coupling bandwidth, and reducing the reflection coefficient of the coupling region. At the same time, the C-shaped arrangement of the conducting structure forms a shielding boundary on the plane, suppressing the spatial radiation in the millimeter wave band and contributing to improving the electromagnetic compatibility performance of the system. The overall structure is compact, the layout is clear, the cooperation of each component is clear, and it has good processing adaptability and high-frequency performance stability. Therefore, by constructing a cooperative transmission mechanism of the main coupling path and the auxiliary coupling path, and combining structural optimization and reflection regulation means, the present invention solves the problems of impedance mismatch, low energy coupling efficiency, large radiation loss, etc. existing between the microstrip line and the coplanar waveguide in the existing microstrip-to-coplanar waveguide feeding structure, and significantly improves the transmission performance and system reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic structural diagram of a microstrip-to-coplanar waveguide feeding structure provided by an embodiment of the present invention; Figure 2 It is an exploded view of a microstrip-to-coplanar waveguide feeding structure provided by an embodiment of the present invention; Figure 3 For Figure 2Enlarged view of area A

[0020] Description of reference numerals in the drawings: 100, microstrip line; 110, broadening structure; 200, coplanar waveguide; 210, narrowing structure; 300, conduction structure; 400, conductor; 500, flexible substrate; 600, reflection cavity Detailed implementation manners

[0021] For the purpose of making the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention

[0022] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention 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 therefore should not be construed as a limitation to the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more

[0023] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances

[0024] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention

[0025] Figure 1 Schematic diagram of a microstrip-to-coplanar waveguide feeding structure provided by an embodiment of the present invention; Figure 2 Exploded view of a microstrip-to-coplanar waveguide feeding structure provided by an embodiment of the present invention; Figure 3 is Figure 2 Enlarged view of area A in

[0026] In a possible implementation manner, the microstrip-to-coplanar waveguide feeding structure includes: a microstrip line 100, and a broadening structure 110 is arranged at an output end thereof; a coplanar waveguide 200, and a narrowing structure 210 is arranged at an input end thereof; a plurality of conducting structures 300 arranged in a C-shaped manner, which are arranged in a coupling region between the broadening structure 110 and the narrowing structure 210, and are used for connecting a ground layer and guiding part of electromagnetic waves to be transmitted vertically to below the structure; a conductor 400, which is arranged below the conducting structure 300 and is used for reflecting the electromagnetic waves guided and transmitted by the conducting structure 300; wherein, the structural dimensions and relative position relationships among the microstrip line 100, the coplanar waveguide 200, the conducting structure 300 and the conductor 400 are optimized and set to form an auxiliary coupling path within a target frequency band, and the auxiliary coupling path is used for guiding part of electromagnetic signals to act on the coplanar waveguide 200 after reflection, so as to realize the signal superposition transmission of the main coupling path and the auxiliary path, and optimize the impedance matching performance and reduce the transmission loss.

[0027] The concept of this implementation manner is based on the accurate modeling and design control of the electromagnetic coupling behavior between two heterogeneous transmission structures of the microstrip line 100 and the coplanar waveguide 200. The broadening structure 110 and the narrowing structure 210 are respectively located at the output end of the microstrip line 100 and the input end of the coplanar waveguide 200, and their core functions are to form a continuous impedance transition interface, reduce the instantaneous reflection at the starting point of coupling, and construct a main coupling path to realize the basic energy transfer. This basic structure ensures an initial performance basis with high efficiency and low reflection for the energy migration from the microstrip line 100 to the coplanar waveguide 200.

[0028] Furthermore, a plurality of conducting structures 300 arranged in a C-shaped manner are introduced between the above-mentioned main coupling path structures, which are clearly used for connecting the upper and lower ground layers. Its "C-shaped arrangement" clearly defines the arrangement manner of the conducting structure 300 on the plane, forms a directional and continuous geometric boundary, and has a spatial regulation effect on the electromagnetic behavior within the transmission path. Each conducting structure 300 guides the local electromagnetic field to be discharged vertically to below the structure through its open boundary, so that part of the energy breaks away from the main path and enters the auxiliary channel. In this auxiliary channel, the conductor 400 is arranged below the conducting structure 300 and is used for reflecting the downward-emitted electromagnetic waves and re-guiding them back to the input area of the coplanar waveguide 200 to form a reflection path. The phase and amplitude of the signal after reflection in this path are adjustable under the control of the structural parameters, and are synchronized in time domain and superimposed in frequency domain with the main path signal within the target frequency band.

[0029] Through the collaborative configuration of the above structure, the microstrip-to-coplanar waveguide feeding structure introduces a controllable reflection auxiliary path on the basis of the main coupling path. Without adding active devices to the system, it significantly expands the bandwidth of the coupling path, enhances the energy injection efficiency, and improves the impedance matching performance through the interference principle. At the same time, the U-shaped arranged conduction structure 300 forms an equivalent electromagnetic shielding surface in the planar region, effectively suppressing the spatial radiation leakage in the millimeter-wave band and improving the overall electromagnetic compatibility.

[0030] In addition, the overall structure design fully considers the manufacturing feasibility and system integration requirements. The functions of each sub-structure are clearly partitioned, and it supports implementation in a standard PCB or multi-layer packaging environment. Key geometric parameters such as the length of the widened section, the number of conduction structures 300, and the distance between the conductor 400 and the conduction structure 300 can be quantitatively optimized through electromagnetic simulation tools to ensure that the signals in the reflection path meet the interference conditions without damaging the system stability.

[0031] It is worth noting that the conduction structure 300 still maintains the U-shaped arrangement feature, and the detailed parameters such as the arrangement spacing, the opening orientation, the via hole size and number can be finely adjusted according to the characteristics of the target frequency band to optimize the electromagnetic performance. The conductor 400 can be made of different materials and have different reflection surface shapes to meet the requirements for reflection phase and intensity at different frequencies.

[0032] In a possible implementation manner, the microstrip-to-coplanar waveguide feeding structure includes a microstrip line 100 and a coplanar waveguide 200. The input section of the microstrip line 100 is designed as a standard 50Ω characteristic impedance transmission line to ensure impedance-consistent connection with the RF source, the front stage of the circuit, or other standard interface modules, thereby reducing interface reflection and signal loss. The output end of the microstrip line 100 is constructed as a widened section. By gradually increasing the width of the transmission line, the electric field distribution at its output end is expanded, enhancing its radiation ability to the coupling region and thus improving the signal energy release efficiency. The geometric parameters of the widened section include the starting width, the ending width, and the gradient length, which can be optimized through simulation according to the target frequency, the substrate thickness, and the dielectric parameters to ensure that the radiation field characteristics match the input end of the coplanar waveguide 200.

[0033] The output section of the coplanar waveguide 200 also adopts a standard 50Ω characteristic impedance design, enabling it to maintain good impedance continuity when the signal is transmitted to the downstream antenna, receiving module, or other RF units, reducing energy reflection loss. Its input end is set as a narrowed section, and a local electromagnetic field focusing area is formed through the gradual contraction of the line width, making it more effective in receiving the electromagnetic energy radiated by the widened section of the microstrip line 100. This structure forms a gradual coupling interface in the coupling region, and the geometric configuration of the narrowed section (such as the contraction rate, the minimum line width, and the gradient form) can also be optimized through electromagnetic simulation to achieve the best coupling performance under different frequency bands and bandwidth conditions.

[0034] There is no physical welding or metal bridge connection in the structure between the microstrip line 100 and the coplanar waveguide 200. Instead, a non-contact coupling relationship is formed by arranging them in spatial proximity. This non-direct connection method not only avoids the interface reflection and thermal failure risks introduced by mechanical connections but also improves the flexibility and reliability of the structural design. Key coupling parameters such as the gap distance, relative arrangement, and relative height in the coupling region can all be used as optimization variables and adjusted according to the transmission performance requirements.

[0035] The above structure realizes a complete feed path design from a standardized input, a tapered coupling structure to a standardized output, which can effectively alleviate technical problems such as impedance discontinuity, low coupling efficiency, and high system integration complexity commonly existing in the feed structures in the millimeter-wave band. While improving the coupling efficiency and expanding the bandwidth coverage range, this structure also enhances the interconnection compatibility with existing radio frequency system modules through standardized design. The coordinated arrangement of the broadening structure 110 and the narrowing structure 210 provides a means to control the electric field distribution pattern and coupling strength, making the entire coupling process have better electromagnetic performance.

[0036] It is worth noting that the broadening section and the narrowing section can respectively adopt linear, logarithmic function, or multi-stage stepped tapered models, and the specific structural parameters can be flexibly set according to the target frequency band, substrate material characteristics, and manufacturing process accuracy. In addition, the standard impedance value can also be adjusted to non-50Ω matching values such as 55Ω or 60Ω under specific system conditions, provided that the impedance transition with other components in the system remains smooth and the reflection is minimized. This structure is also applicable to rigid PCBs, multi-layer circuit boards, and flexible substrate platforms, with good design universality, processing adaptability, and industrial engineering feasibility.

[0037] In a possible implementation, a conductor 400 is provided in the microstrip-to-coplanar waveguide feed structure. The conductor 400 is configured as a metal closed structure, located below the coupling region, and is directly opposite to the path guiding the electromagnetic energy transmission by the conduction structure 300. The conductor 400 is made of a high-conductivity metal material, preferably conventional microwave materials such as copper and aluminum, and the electroplated surface material can be selected according to the use environment to improve the reflection efficiency and corrosion resistance. Its structural form can be a closed metal box, a metal block with a cavity, or a conductor structure provided with a reflecting surface. The conductor 400 is in a fixed form in structure and does not include an adjustable mechanism. Its reflection surface size and relative height are set in the product design stage and remain unchanged during actual use.

[0038] The function of the conductor 400 is mainly to provide a reflection interface in the auxiliary coupling path. When electromagnetic waves are coupled and transmitted from the microstrip line 100 to the coplanar waveguide 200 through the broadening structure 110, part of the energy is dissipated in the coupling region and radiated downward from the structure through the U-shaped conduction structure 300. After this part of the energy is incident on the reflection surface of the conductor 400, it is reflected and returns to the coupling region of the coplanar waveguide 200, realizing the spatial superposition of the main path signal and the reflected signal. Since the position of the conductor 400 relative to the coupling structure is the key factor affecting the phase of the reflected wave, its design size and height need to be determined by simulation according to the wavelength and the expected phase difference within the target frequency band to ensure that the reflected signal is consistent with the main path signal in the time domain and realize the coherent enhancement of the reflected signal.

[0039] To ensure the stability of the reflection wave interference effect, the conductor 400 in this structure cannot be mechanically adjusted after the design is completed. This design ensures the structural certainty of the reflection path, which is beneficial to the long-term stability of the system operating point under high-frequency conditions and simplifies the assembly and debugging processes. The phase difference of the signal in the reflection path is jointly determined by the distance between the conductor 400 and the conduction structure 300, the electromagnetic wave propagation constant, and the reflection surface profile, and can be optimized through full-wave simulation tools in the design stage to ensure the effectiveness of the auxiliary coupling path.

[0040] This structure also exhibits good shielding performance in electromagnetic characteristics. The metal enclosed conductor 400 can prevent the leaked electromagnetic waves from entering the lower-layer structure of the system, effectively isolate the reverse electromagnetic interference between the microstrip line 100 and the coplanar waveguide 200, and improve the overall electromagnetic compatibility of the system. Especially in multi-layer PCBs, flexible circuits, or radio frequency modules with a high degree of system integration, this structure helps to maintain electromagnetic isolation between the upper and lower layers and avoid non-linear coupling between low-frequency and high-frequency signals.

[0041] In typical application scenarios, this structural design can be widely used in the following fields: (1) In a low sidelobe beam antenna, by reasonably designing the position of the conductor 400, beam optimization and sidelobe suppression can be achieved, improving the directivity and radiation efficiency of the antenna; (2) In a broadband feeding structure, the auxiliary reflection of the conductor 400 can play a frequency compensation role, enabling the system to maintain a relatively consistent coupling response at multiple frequency points; (3) In an integrated millimeter-wave module in a limited space, the conductor 400 can work in coordination with the packaging structure, taking into account reflection regulation and structural stability, and improving the overall consistency and environmental robustness of the system construction.

[0042] This structure has the following comprehensive advantages: (1) Its reflection regulation behavior is based on physical structure design without the participation of active devices, enhancing the reliability and manufacturing consistency of the system; (2) The parameters are adjustable in design and the size is fixed during use, ensuring the repeatability of the reflection path and the long-term controllability of the system performance; (3) The materials used are common and the structural form is simple, facilitating large-scale mass production; (4) It can be embedded in the existing millimeter-wave radio frequency link as a customizable coupling module, which is conducive to system standardization and platform design.

[0043] Through the above implementation manners, it can be seen that the conductor 400 not only undertakes the energy reflection function in the traditional sense, but also participates in the system-level electromagnetic regulation at the structural level. Its setting position, size and reflection behavior form a synergistic effect with the main coupling path, significantly improving the system impedance matching accuracy and coupling efficiency, while maintaining good system structural compactness and process realizability, providing a structural optimization means with engineering value for high-frequency communication systems.

[0044] In a possible implementation manner, the coplanar waveguide 200 is disposed on the flexible substrate 500. The flexible substrate 500 is made of a dielectric material with high-frequency performance and good mechanical bendability. It is preferably an SF202 non-adhesive double-sided flexible copper clad laminate, and its typical electrical parameters are a relative dielectric constant of 3.2 and a loss tangent of 0.007, which is suitable for low-loss and high-fidelity signal transmission in the millimeter-wave band. By designing the flexible substrate 500 to form a 90° bending structure in space in the coupling region, the coplanar waveguide 200 can be re-arranged in the vertical direction, thereby realizing the direction conversion of the signal path in the three-dimensional space and meeting the structural requirements for vertical turning transmission in the scenarios of module interlayer connection or space jump connection.

[0045] This structure combines the flexible substrate 500 with a rigid substrate to form a double-layer PCB system. The microstrip line 100 is disposed on the upper rigid substrate, and the coplanar waveguide 200 is disposed on the lower flexible substrate 500. The two are physically connected through an upper and lower pressing process, and the structural stability is provided by a fixed support layer. The flexible substrate 500 has a pre-set bending path before forming. Its bending radius and bending angle (such as 90°) are optimized according to the minimum bending tolerance and stress distribution of the material to ensure that the conductor pattern does not break or have microcracks during the bending process, and at the same time avoid impedance mismatch or reflection enhancement caused by local stretching / compression.

[0046] The coplanar waveguide 200 conductor pattern arranged on the flexible substrate 500 penetrates the entire bending region, and the geometric symmetry between the transmission strip line and the grounding metal edge line is maintained in the design, so as to ensure the consistency of the electromagnetic field distribution and the continuity of the path impedance before and after the bending structure. In order to further control the spatial radiation behavior of electromagnetic waves in the bending region, a U-shaped metallized via array is provided on both sides of the coplanar waveguide 200. The vias are connected to the upper and lower grounding layers through a through structure to form an equivalent electromagnetic closed path within the bending structure. Preferably, the via aperture is set to 0.2 mm and the via pitch is 0.35 mm. This parameter configuration has been verified by simulation to achieve effective electromagnetic coupling suppression and shielding performance in the 30-50 GHz frequency band.

[0047] The arrangement of the U-shaped vias combined with the controllable deformation characteristics of the flexible substrate 500 can suppress electromagnetic leakage in the bending region without increasing the structural complexity, and stabilize the mode field pattern in the transmission path, improving the signal integrity and frequency-domain response consistency of the overall structure in the spatial turning state. Such a closed grounding structure is convenient for reducing electromagnetic interference between wiring layers in a high-density packaging environment and optimizing the overall electromagnetic compatibility of the system.

[0048] While the overall structure realizes a 90° spatial turn of the signal path, it maintains the high-efficiency transmission characteristics in the millimeter-wave frequency band. Compared with the traditional methods of realizing spatial interlayer connection through jumpers, soldered connectors or metal bridge structures, this structure has simplified process and compact size, avoiding the stability problems of mechanical contact points, and is helpful to improve system reliability and mass production consistency.

[0049] In practical applications, this structure is particularly suitable for a variety of typical high-frequency system integration scenarios. For example, in a three-dimensional packaging structure, it can be used for the vertical connection of antenna modules to achieve spatial coupling between the antenna array board surface and the lower-layer feeder, significantly compressing the module thickness and improving the packaging integration; in millimeter-wave chip packaging, this structure can be used for the heterogeneous interconnection between the chip lead microstrip line 100 and the bottom or side coplanar waveguide 200 to adapt to the wiring requirements of chip flip-chip packaging or stacked structures; in vehicle-mounted radar modules, it can be used as a vertical wiring unit connecting different-level PCBs to meet the reliability requirements in high-vibration and high-density environments; in addition, this structure can also be used as an alternative to flexible RF cables for flexible transition connection between antennas and circuit boards, with lower loss and higher assembly flexibility compared with traditional semi-rigid cables; in millimeter-wave test fixtures or probe platforms, this structure can effectively realize the spatial extraction of probe signals to form a compact and low-reflection test interface, which is helpful to improve test accuracy and structural compatibility.

[0050] In a possible implementation, the microstrip-to-coplanar waveguide feeding structure includes two transition structures from the microstrip line 100 to the coplanar waveguide 200, and a bent section of the coplanar waveguide 200 connecting these two transition structures. On the basis of meeting the signal transmission function, this structure takes into account multiple system design requirements such as the adjustment of the path direction, the construction of a symmetric structure, and the adaptation of the spatial layout, and is applicable to millimeter-wave communication and radio frequency systems with high integration and wide bandwidth requirements.

[0051] The transition structures from the two microstrip lines 100 to the coplanar waveguide 200 respectively undertake the input and output functions. The microstrip line 100 adopts a standard 50Ω characteristic impedance, and a broadening structure 110 is designed at the end to increase the electromagnetic radiation area and enhance the coupling ability; the input end of the coplanar waveguide 200 is provided with a narrowing section to form a tapered impedance interface in the structure, so as to improve the absorption efficiency of the radiation energy of the microstrip line 100. The technical effect of this structural combination is to achieve a smooth energy transfer from the microstrip line 100 to the coplanar waveguide 200, reduce the reflection coefficient and expand the transmission bandwidth, which is beneficial to solving problems such as reflection interference and insufficient coupling efficiency caused by sudden changes in the transmission structure, and is particularly applicable to communication modules with high frequencies and strict signal integrity requirements.

[0052] The bent section of the coplanar waveguide 200 connecting the above two ends is a key component unit of this structure at the spatial wiring level. This section can be designed as a structural path approximately in the shape of a C, U, or S according to the system wiring requirements. Among them, the C-shaped path is suitable for device wiring avoidance or spatial turning wiring; the U-shaped path is often used to form a symmetric feeding channel to improve the phase balance of the system; the S-shaped path is used for electrical length compensation or path delay equalization, which is particularly common in differential channel systems. These path forms are not limitations of the structure itself, but wiring forms flexibly selected according to the actual functional objectives of the system and the physical structure of the package.

[0053] The bent section is a continuous metal conductor layout structure, which can be arranged on a flexible substrate 500 or a rigid dielectric substrate. During the wiring process, the continuity of the path impedance is maintained by means of fillet processing, width gradient control, etc., to suppress the reflection peaks and in-band fluctuations caused by path bending. Its technical effect is to achieve the redirection of the high-frequency signal path direction, electrical length control, and physical layer symmetry construction, which is beneficial to engineering requirements such as system-level path management, antenna array phase control, and structural coupling between modules, and significantly improves the routability and system performance consistency of the radio frequency system under integrated conditions.

[0054] In the implementation scenario of the flexible structure, the bent section can construct a three-dimensional spatial path structure to realize signal extraction or module jump connection between different packaging layers. For example, in the packaging of radio frequency SoC chips and the interposer structure between packaging layers, the flexible bent section can avoid wire bonding across layers, improve connection reliability and simplify the process path. To further improve the signal integrity of the bent section under high-frequency transmission, an equidistant U-shaped metallized ground via array is arranged on both sides of the coplanar waveguide 200 in this section. This array penetrates the upper and lower ground planes to form an effective electromagnetic closed boundary, which is used to limit lateral radiation leakage and field distortion, and enhance the mode consistency and shielding performance of the transmission path.

[0055] The dimensions, path shape, electrical length of the above-mentioned bent section, and the dielectric material used are optimized by means of full-wave simulation and other means in the structural design stage, so that it is phase-consistent and impedance-matched with the rest of the system within the target frequency band, thereby forming a high-frequency transmission path with low loss, high consistency, and high stability in the entire structure.

[0056] In specific applications, this structure is suitable for the following typical scenarios: (1) In a dual-fed array antenna, it realizes symmetric excitation of the coplanar waveguide 200 signal, reducing the main lobe offset and sidelobe non-uniformity of the array; (2) In a millimeter-wave packaging module, it is used for spatial jump connection between different functional chips or between a chip and an antenna; (3) In a differential transmission system, the electrical lengths of the two paths are adjusted through U-shaped or S-shaped bent sections to ensure signal phase synchronization; (4) In a heterogeneous-layer PCB packaging structure, it provides a configurable path turn to avoid space overlap and improve the layout freedom of the module; (5) In the design of integrated radar modules and high-speed interconnection interfaces, it realizes high-reliability path control under high-bandwidth and high-density connections.

[0057] In a possible implementation manner, the flexible substrate 500 not only serves as the carrier of the coplanar waveguide 200, but also realizes the turning of the high-frequency signal path in the spatial direction through its own bendable characteristics. This function mainly relies on the coordinated cooperation of the mechanical properties of the flexible dielectric material itself and the structural design to form a path structure in the vertical direction for connecting high-frequency modules at different heights or different wiring planes.

[0058] The flexible substrate 500 is preferably made of a non-adhesive double-sided flexible copper-clad material, such as SF202, which has good mechanical flexibility and dimensional stability while meeting the requirements of high-frequency low-loss transmission. The coplanar waveguide 200 conductor pattern is arranged on the flexible substrate 500, including the middle signal wire and the grounding strips on both sides. The pattern is formed by photolithography and etching processes, and the layout is continuous and the edges are regular. In the design stage, a dedicated turning area is planned on the flexible substrate 500, which will withstand spatial bends of 90° or other angles to guide the coplanar waveguide 200 from the horizontal plane to the vertical direction to realize the spatial transition between modules.

[0059] This structural bend is not achieved by additional components, but by the thermocompression or shaping process of the flexible substrate 500 itself. Its greatest advantage lies in maintaining the continuity of the conductor pattern, eliminating the uncertain contact points caused by soldering, connectors, etc., thereby ensuring the stability of impedance matching. Especially in the millimeter-wave band, any discontinuity between interfaces may cause significant reflection and transmission losses, and this structure avoids this problem through an integrated transmission path.

[0060] To maintain the electrical performance of the bent area, key parameters such as the conductor line width of the coplanar waveguide 200, the transition of the turning angle, and the bending radius are controlled in the design. For example, a transition curve instead of a right angle can be used at the corner to avoid electric field concentration; the line width can be slightly increased or decreased to balance the geometric asymmetry caused by the bend; the dielectric layer thickness is adjusted to the optimal electrical length state according to simulation analysis. These measures together ensure that the waveform is maintained, the phase is stable, and the energy is concentrated when the signal passes through the bent area.

[0061] In addition, to suppress the leakage of high-frequency fields at the bent edge, a U-shaped metallized via array is set on both sides of the signal line. This array vertically penetrates the flexible substrate 500 and connects the upper and lower ground layers to form a local closed loop. Arranged equidistantly and uniformly in structure, it acts like a guardrail for the electromagnetic channel, playing a role in stabilizing the field pattern and suppressing interference for high-frequency signals. Especially in modules with limited space, this grounding structure helps maintain the electromagnetic compatibility of the system and prevent local resonance.

[0062] This flexible path structure forms a natural transition between different system layers, eliminating the use of traditional connectors such as micro coaxial cables, elastic probes, or three-dimensional soldering bridges, which not only improves the assembly efficiency but also enhances the structural stability. It is particularly suitable for highly integrated communication modules. For example, it can establish a direct channel between the upper part of the antenna package and the plane where the main control chip is located, or provide signal jumps between multiple array units in a phased array structure.

[0063] The flexible substrate 500 and the rigid substrate can also be combined into a composite structure. The microstrip line 100 is arranged on the rigid layer, coupled into the coplanar waveguide 200 in the flexible layer, and then bent into the vertical direction. This structural configuration has excellent spatial adaptation capabilities and can handle complex path planning under different-layer wiring, high-density packaging, and three-dimensional packaging architectures. System designers can use it as a highly integrated and low-loss spatial interconnection means and widely apply it to millimeter-wave communication terminals, packaged antenna modules, the front end of radar systems, and chip-level packaging interconnections.

[0064] Through parameter control in the design stage and process assurance in the forming stage, this structure can achieve stable reflection control, path equalization, and phase consistency within the target frequency band. Its characteristics of integration, low interference, and high mechanical stability make it highly practical in modern radio frequency systems.

[0065] In a possible implementation, the conduction structure 300 in the microstrip-to-coplanar waveguide feeding structure adopts a C-shaped arrangement in the coupling region. Essentially, through geometric layout in a two-dimensional plane, multiple metallized vias are arranged in a specific opening direction to form a local boundary-type enclosure structure. The "C-shaped" is not a change in the shape of the via body, but a geometric combination of its arrangement. In the design, an array of three-sided enclosures is preferentially arranged along the periphery of the coupling region, and the fourth side remains open to maintain the coupling efficiency between paths.

[0066] From the perspective of the electromagnetic structure, this arrangement form has important physical effects. First, under high-frequency operating conditions, especially in the millimeter-wave frequency band (such as 24 GHz, 28 GHz, 60 GHz), the electromagnetic wave wavelength is short, the field changes rapidly, and the transmission path is extremely sensitive to boundary perturbations. In the coupling region between the traditional microstrip and the coplanar waveguide 200, due to factors such as structural transformation and impedance discontinuity, there are often spatial leakage radiation and edge scattering. The C-shaped arrangement forms local current loops through the vias and the upper and lower ground layers, which can construct equivalent electromagnetic closed boundaries on both sides of the transmission path, forming a lateral restriction on the signal energy, thereby effectively suppressing the out-of-field expansion in the coupling region.

[0067] Second, from the perspective of mode distribution, the C-shaped enclosure area of the vias has an absorption and reflection effect on dipole-type leakage waves or higher-order modes, enabling the main mode energy to be concentrated and transmitted along the designed direction. This is particularly crucial in the packaging environment or in the heterogeneous layer structure within the module, which can prevent the transmitted energy from coupling to adjacent paths or reverse interference sources. This structure has triple attributes of grounding, shielding, and boundary regulation in function, far exceeding the single action mode of conventional linear arrangements or grid-arranged vias.

[0068] The structure is fully compatible with the standard PCB process path. The vias used in the C-shaped arrangement are formed by laser drilling or mechanical drilling, and are metallized by electroplating or chemical deposition to connect the upper and lower ground layers. Its arrangement form is generated by a layout graphics design tool, and the arrangement spacing, opening direction, and coverage area can be adjusted according to the target frequency and coupling bandwidth parameters in the design stage. Usually, the arrangement density should ensure that there is at least one conduction point within every λg / 10 (λg is the substrate guided wavelength at the operating frequency) to maintain the continuous boundary effect. During the simulation process, three-dimensional full-wave simulation software (such as HFSS, CST) can be used to perform electric field distribution, S-parameter analysis, and spatial radiation modeling to ensure that the structure arrangement achieves the expected performance within the target frequency band.

[0069] Compared with the traditional conduction structure 300 (such as uniform grid arrangement or linear array), the C-shaped arrangement has a more definite electromagnetic directivity control ability. Although the grid arrangement has an all-round shielding ability, it has a large interference on the transmission mode and may introduce reflection peaks; the linear arrangement has strong directivity, but poor field closing ability, and it is easy to form a high field gradient at the edge of the structure. The C-shaped arrangement provides an open coupling edge while the three-sided boundary of it has a restrictive effect on energy, taking into account the structural balance between coupling efficiency and radiation suppression.

[0070] This structure has a wide adaptability in actual systems. For example, applying a C-shaped conduction array in the coupling structure of the coplanar waveguide 200 and the microstrip line 100 can effectively reduce the reverse radiation power in the coupling area, improve the far-field consistency and near-field mode stability of the system; in the integrated antenna design, the C-shaped boundary shields the leakage waves outside the main lobe direction of the antenna, which helps to control the sidelobe characteristics; in the high-frequency jump connection channel between packaging modules, this structure can limit the path coupling to adjacent control lines, low-frequency channels or ground slots to prevent high-frequency crosstalk.

[0071] In various application environments such as multi-layer board wiring, millimeter-wave antenna feeding, space jumpers in module packaging, and high-speed I / O design of system-on-chip, the C-shaped arrangement conduction structure 300 shows good engineering adaptability and signal integrity improvement effect. Especially in system designs with high requirements for electromagnetic compatibility, radiation interference control and near-field consistency, as an active suppression mechanism at the structural level, it has obvious functional advantages and practicality.

[0072] In summary, through the C-shaped conduction arrangement design at the structural level, this specific implementation realizes the effective regulation of the electromagnetic behavior at the boundary of the coupling region. Its structure is clear, the action mechanism is distinct, and the implementation path is mature. It not only has obvious technical functional effects, but also can be applied at the engineering level in various high-frequency communication systems, providing a promotable boundary shielding solution for microwave structure design in the millimeter-wave field.

[0073] In a possible implementation, the conduction structure 300 in the microstrip-to-coplanar waveguide feeding structure includes one or more metallized vias, and these vias are arranged along the coupling path between the widened region of the microstrip line 100 and the narrowed region of the coplanar waveguide 200. Each via penetrates between the upper and lower ground layers, constituting an electrical connection channel between structural layers and also a boundary constraint element in the high-frequency electromagnetic path. Design parameters such as the number, arrangement density, and position distribution of the vias can be simulated and optimized according to the electromagnetic wave propagation characteristics of the target frequency band to construct a composite conduction structure 300 with both good grounding continuity and electromagnetic constraint ability.

[0074] In this structure, the setting of "multiple vias" not only helps to improve the equivalent low impedance performance of the ground plane under high-frequency conditions and avoid ground potential fluctuations caused by single-point grounding, but also constructs a local electromagnetic boundary through multi-point arrangement in space to limit the unintended propagation of high-frequency energy outside the coupling area. In terms of electromagnetic behavior, this via array can be approximated as a periodic metal structure in the millimeter-wave frequency band. It has significant flux closure effect and lateral field strength limitation on the action path, which helps to improve the purity of the main transmission mode and reduce energy leakage and structural resonance caused by high-order mode coupling.

[0075] From the perspective of structural mechanism, this conductive structure 300 can be regarded as a "structural barrier" in the electromagnetic field, and its working principle can be compared to the restriction of the waveguide wall on the mode distribution. When multiple vias are equidistantly arranged on both sides of the coupling path, an electromagnetic reflection interface can be formed outside the coupling area, so that the main energy is confined within the expected coupling path, avoiding spatial radiation and uneven coupling caused by the open structure. At the same time, since the structural parameters of the via can be flexibly adjusted, its reflection phase and impedance characteristics at a specific frequency can also be designed to minimize reflection interference to the main signal, while maintaining the impedance matching of the main path while enhancing the boundary constraint.

[0076] In terms of manufacturing, the conductive structure 300 is fully compatible with traditional PCB and package board processes. The conductive holes can be formed by mechanical drilling, laser drilling, copper deposition, and electroplating. The structure has high processing accuracy and a mature and stable process path. The structure can be templated in standard design tools (such as Altium, Cadence, and Mentor) through a multi-point ground hole module, and can be optimized in conjunction with conventional RF simulation tools (such as HFSS and CST) to achieve a comprehensive balance between structural performance and process cost.

[0077] In practical application, the conductive structure 300 is suitable for a variety of high-frequency transmission demand scenarios, especially in complex structures that require high bandwidth, low crosstalk, and high density, showing good engineering adaptability. Specifically, in the high-frequency module packaging structure, multiple conductive holes are used for field shape control in the transition zone from microstrip to coplanar waveguide 200, reducing on-chip coupling interference and improving port connection stability; in the antenna feed array, the conductive holes are arranged on both sides of the feed path to form an equivalent reflection boundary, which is used to stabilize the main beam direction and effectively suppress sidelobe leakage; in the package-level jumper interconnection application, the conductive hole group forms a continuous ground barrier to achieve a smooth transition from the microstrip path to the underlying coplanar waveguide 200; in the multi-channel differential structure, the conductive hole array can be used as a magnetic isolation belt between channels to limit the electromagnetic crosstalk path and improve the anti-interference ability between systems; at the same time, in the high-density interconnection platform, the conductive hole structure can also serve as both mechanical support and thermal channel, assisting in achieving thermal management and stress balance in the multi-layer structure.

[0078] In summary, in this embodiment, a plurality of vias are arranged in the coupling region to form a composite conduction structure 300, which has multiple functions such as electrical grounding, electromagnetic boundary constraint, and structural stability. In a millimeter-wave high-frequency structure, it not only improves the energy focusing and propagation efficiency of the main path, but also improves the overall radiation suppression and signal integrity control of the structure. It has a clear design basis, a verifiable physical mechanism, and high manufacturing adaptability, and is suitable for popularization and application in high-integration scenarios with strict electromagnetic performance requirements in radio frequency systems.

[0079] In a possible embodiment, a reflection cavity 600 is arranged inside a conductor 400 in a microstrip-to-coplanar waveguide feeding structure. The reflection cavity 600 is a closed or semi-closed metal cavity, which is specifically used to reflect the electromagnetic waves guided and leaked by the conduction structure 300. In this embodiment, the structure of the conductor 400 for realizing the auxiliary reflection function is not limited to a simple metal closed surface, but a metal reflection cavity 600 with the characteristics of a spatial cavity is constructed inside it. The cavity is formed by opening a hollow structure inside the material of the conductor 400 and adopting a box-shaped configuration with five closed sides and one open side, so that the electromagnetic waves leaking from the upper conduction path form a standing wave distribution inside the cavity, thereby enhancing the energy reverse coupling efficiency while controlling the reflection phase. The cavity body is made of a highly conductive material, typically copper or aluminum material plated with silver on the surface, and its inner wall is smoothed to reduce reflection loss. The opening part of the cavity directly corresponds to the layout area of the conduction structure 300, ensuring that the received electromagnetic energy is incident on the inner reflection surface of the cavity in its main propagation direction and forms a predictable reflection path. Since the depth, height, and lateral expansion dimensions of the cavity can be used as design variables, its equivalent electrical length determines the phase of the reflected wave when it returns to the coplanar waveguide 200 path. Therefore, the interference characteristics of the reflected wave relative to the main coupled wave can be controlled by the structural parameters.

[0080] To achieve effective phase superposition within a specific frequency band, the internal dimensions of the cavity are usually designed to be an integer multiple of 1 / 4 or 1 / 2 of the operating wavelength, or the position distribution of the standing wave enhancement points is obtained through simulation optimization, so that the returned signal forms a constructive interference with the main signal in terms of phase. The opening form of the cavity can be partially shielded or quasi-open designed according to the conduction array structure, so as to reduce the bandwidth narrowing caused by the overly ideal closed structure while ensuring the reflection efficiency. In some variants, low-dielectric-constant and low-loss materials, such as PTFE films or dielectric foam materials, can also be added inside the cavity to adjust the equivalent electrical length and quality factor Q value of the cavity, and further refine the reflection bandwidth and frequency response curve. In addition, the reflection cavity 600 body is integrated below the conductor 400 as a physical structure and can share part of the metal boundary with the original grounding structure in the system, without occupying additional vertical space, and is suitable for use in high-integration packaging scenarios.

[0081] The reflection cavity 600 forms a three-dimensional cooperative reflection mechanism with the broadening structure 110, the narrowing structure 210, and the conduction array above the coupling region, so that part of the released signal returns through the reflection cavity 600 and acts on the coplanar waveguide 200 region, improving the utilization rate of auxiliary energy outside the main path. This structure has stronger frequency domain control ability compared with the implementation method that only uses metal plane reflection, and is particularly suitable for application requirements with strict frequency characteristics, high sensitivity to rapid changes, or prominent bandwidth compression problems. In a microwave communication module, a millimeter-wave band antenna feeding system, or a high-speed radio frequency transceiver channel, the reflection cavity 600 can effectively compensate for the non-uniform energy distribution caused by impedance gradient in the main path and provide an in-band flattening function, with obvious engineering value and system integration advantages.

[0082] The present invention also discloses a method for debugging structural parameters of a microstrip-to-coplanar waveguide feeding structure. The microstrip-to-coplanar waveguide feeding structure includes a microstrip line 100, a coplanar waveguide 200, a conduction structure 300, and a metal conductor 400 disposed below the conduction structure 300. The method includes: Determine a set of structural parameters, including the broadening size of the microstrip line 100, the narrowing size of the coplanar waveguide 200, the arrangement mode of the conduction structure 300, the aperture and spacing, as well as the size and relative position of the metal conductor 400; Construct a microstrip-to-coplanar waveguide feeding structure sample based on the structural parameters, and perform electromagnetic simulation or transmission performance test within the target frequency band to obtain the corresponding transmission loss results; Judge whether the transmission loss meets the preset performance requirements; If the transmission loss meets the performance requirements, confirm the current structural parameters as the final structural configuration; If the transmission loss does not meet the performance requirements, make at least one adjustment to the structural parameters, and repeat the above test and judgment steps based on the adjusted structural parameters until a combination of structural parameters that meets the performance requirements is obtained.

[0083] In this embodiment, to ensure that the microstrip-to-coplanar waveguide feeding structure has good matching performance and low transmission loss within the target frequency band, a set of methods based on structural parameter debugging is systematically established. Starting from the physical design of the structure, combining electromagnetic simulation analysis and measured feedback optimization, this method realizes the quantitative setting of key structural dimensions and forms a complete parameter optimization closed-loop. The structure includes a microstrip line 100, a coplanar waveguide 200, a U-shaped conduction structure 300, and a metal conductor 400 below it. The debugging process uses "the lowest insertion loss and the best return loss matching in the target frequency band" as the performance index.

[0084] The first step of parameter debugging is the extraction of key structural variables. By analyzing the energy evolution process of the electromagnetic path, the following core geometric parameters are determined: the starting width W1, the ending width W2, and the gradual change length L1 of the widened section of the microstrip line 100; the starting width W3, the narrowest section width W4, and the narrowing length L2 of the narrowed section of the coplanar waveguide 200; the aperture D (0.2 - 0.4 mm), the pitch P (0.3 - 0.6 mm), and the arrangement pattern (linear, C-shaped, or array type) of the vias; the dimensions of the conductor 400 including the lateral width A, the depth B, and the height H (0.8 - 2.5 mm), and whether the reflection cavity 600 is provided with its internal opening structure (such as an eccentric opening or a centrally symmetric structure). These parameters directly determine the electrical length, impedance continuity, reflection phase control ability, and spatial electromagnetic energy distribution boundary of the main / auxiliary coupling paths.

[0085] After parameter extraction, it enters the electromagnetic simulation stage. Use HFSS or CST software to establish a three-dimensional structure model. In the model, the widened section, the conduction area, the conductor 400, the reflection cavity 600, and the coplanar waveguide 200 structures are respectively set, and waveguide port excitation is loaded. Set the target frequency range (for example, 24 - 32 GHz), extract the S-parameter curve, and use S21 > -1.5 dB and S11 < -15 dB as the basic performance requirements. For the part with performance index deviation, adopt a single-factor analysis strategy, adjust the structural parameters item by item and compare their effects on the frequency-domain response. For example, when it is found that the insertion loss increases at the frequency band edge, the lateral dimension A of the reflection surface of the conductor 400 can be increased to enhance the broadband interference intensity of the reflected wave; if there are periodic fluctuations in the return loss curve, it is often because the via pitch P forms an interference frequency with the wavelength, and its periodicity needs to be fine-tuned.

[0086] During the simulation process, the field strength distribution and power flow direction are also monitored to observe whether there is standing wave superposition interference in the auxiliary coupling path. If it is found that there is mode distortion in the reflection cavity 600, the value of H or the opening size can be further adjusted to ensure the effective upward coupling of the reflected energy. At the same time, in the widened and narrowed section structures, if the electric field density is too concentrated, it indicates the existence of an impedance breakpoint, and the widened path can be changed to a non-linear (such as exponential) gradual change form to smooth the electric field expansion.

[0087] After the simulation is completed, three groups of optimized parameter combinations are selected for processing verification. The material used for processing is a double-layer structure composed of Rogers RO3003 rigid board and SF202 flexible layer. The vias are made by laser drilling process. The conductor 400 is a CNC machined aluminum block, and its surface is electroplated to enhance the reflection efficiency. The reflection cavity 600 is opened by a high-precision machining center to ensure the flatness of the inner wall and the consistency of the cavity. After the components are welded, an S-parameter measurement is carried out using a VNA (such as Keysight E8363B) with a millimeter-wave calibration fixture. The test frequency bands are the same, and S11 and S21 are recorded and compared with the simulation data. If the measured results match the simulation within the error range, it indicates that the parameter combination can be solidified; if the difference is significant, the material loss factor, the actual line width of the trace, and the assembly deviation in the simulation model are corrected in reverse, and the second round of closed-loop optimization is carried out.

[0088] This method is particularly suitable for the design scenarios of millimeter-wave transition structures with micro-structure combinations, significant path superposition effects, or sensitive boundary radiation. It has engineering advantages such as clear parameter design logic, strong operability, reliable closed-loop, and wide applicable frequency bands. In occasions such as package feeding, millimeter-wave transceiver modules, and package array wiring, the rapid parameter configuration can be completed according to this method, greatly reducing the trial production cycle and structural uncertainty, and having strong popularization value.

[0089] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0090] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A microstrip-to-coplanar waveguide feeding structure, characterized in that: Comprising: A microstrip line, with a broadening structure provided at the output end of the microstrip line; A coplanar waveguide, with a narrowing structure provided at the input end of the coplanar waveguide; A plurality of conduction structures, arranged in a C-shaped pattern in the coupling region between the broadening structure and the narrowing structure, for connecting to the ground layer and guiding part of the electromagnetic wave to be transmitted vertically downward to the structure below; A conductor, provided below the conduction structure, for reflecting the electromagnetic wave guided and transmitted by the conduction structure; Wherein, the structural dimension matching and relative position relationship among the microstrip line, the coplanar waveguide, the conduction structure and the conductor are optimized and set to form an auxiliary coupling path within the target frequency band, and the auxiliary coupling path is used to guide part of the electromagnetic signal to act on the coplanar waveguide after reflection, so as to realize the signal superposition transmission of the main coupling path and the auxiliary path, optimize the impedance matching performance and reduce the transmission loss.

2. The microstrip-to-coplanar waveguide feeding structure according to claim 1, wherein: The input section of the microstrip line is a standard 50Ω transmission line, and a broadening section is provided at the output end; the output section of the coplanar waveguide is a standard 50Ω transmission line, and a narrowing section is provided at the input end, and is connected to the microstrip line by a coupling method.

3. The microstrip-to-coplanar waveguide feeding structure according to claim 2, wherein: The conductor is a metal closed structure, provided below the conduction structure, for reflecting the electromagnetic wave guided and transmitted by the conduction structure, and controlling the phase of the reflected wave by adjusting the size or height of the reflecting surface of the conductor, so as to optimize the impedance matching performance of the coplanar waveguide.

4. The microstrip-to-coplanar waveguide feeding structure according to claim 1, wherein: The coplanar waveguide is provided on a flexible substrate, and a 90° bending structure in space is formed by the bending of the flexible substrate, for realizing the turning transmission of the electromagnetic signal in the vertical direction.

5. The microstrip-to-coplanar waveguide feeding structure according to claim 1, characterized in that: The microstrip-to-coplanar waveguide feeding structure includes two transition structures from the microstrip line to the coplanar waveguide, and a coplanar waveguide bending section connecting the two, so as to realize dual-end symmetric feeding or signal output.

6. The microstrip-to-coplanar waveguide feeding structure according to claim 4, characterized in that: The flexible substrate is used to support the spatial bending structure of the coplanar waveguide, and a turning path consistent with the vertical direction is formed by the bending of the flexible substrate.

7. The microstrip-to-coplanar waveguide feeding structure according to claim 1, characterized in that, The conduction structures are arranged in a C-shaped pattern, forming an equivalent electromagnetic shielding surface within the target frequency band, for reducing the spatial radiation in the transition region.

8. The microstrip-to-coplanar waveguide feeding structure according to claim 1, characterized in that, The conduction structure includes one or more vias, and the plurality of vias can enhance the electromagnetic coupling performance and reduce the manufacturing cost.

9. The microstrip-to-coplanar waveguide feeding structure according to claim 3, wherein A reflection cavity is arranged inside the conductor, and the reflection cavity is a metal cavity, for reflecting the electromagnetic wave guided and transmitted by the conduction structure.

10. A method for debugging structural parameters of a microstrip-to-coplanar waveguide feeding structure, the microstrip-to-coplanar waveguide feeding structure comprising a microstrip line, a coplanar waveguide, a conduction structure, and a metal conductor disposed below the conduction structure, characterized in that, Comprising: Determine a set of structural parameters, including the broadening size of the microstrip line, the narrowing size of the coplanar waveguide, the arrangement mode of the conduction structures, the aperture and spacing, and the size and relative position of the metal conductor; Construct a microstrip-to-coplanar waveguide feeding structure sample based on the structural parameters, and perform electromagnetic simulation or transmission performance test within the target frequency band to obtain the corresponding transmission loss result; Judge whether the transmission loss meets the preset performance requirements; If the transmission loss meets the performance requirements, confirm the current structural parameters as the final structural configuration; If the transmission loss does not meet the performance requirements, at least one adjustment is made to the structural parameters, and the above-mentioned test and judgment steps are repeated based on the adjusted structural parameters until a combination of structural parameters that meets the performance requirements is obtained.

Images