Ridge waveguide based transitionless mode conversion structure

Abstract

This application provides a transitionless mode conversion structure based on a ridge waveguide, including a waveguide shell, an input ridge waveguide segment, a metal carrier, a matching joint, a bonding wire, and an output microstrip line. The metal carrier is disposed outside the narrow side of the input ridge waveguide segment, forming a coupling gap with the narrow side, and is electrically connected to the waveguide shell. The matching joint is disposed on one side of the metal carrier and spaced apart from it, with the arrangement direction of the matching joint and the metal carrier perpendicular to the arrangement direction of the input ridge waveguide segment and the metal carrier. One end of the bonding wire is connected to the metal carrier, and the other end is connected to the output microstrip line, which has a grounded metal layer. This transitionless mode conversion structure based on a ridge waveguide eliminates the need for complex transition structures such as microstrip probes or fins. The input ridge waveguide segment and the output microstrip line can be arranged in the same direction, offering advantages such as simple structure, small width, and ease of planar integration.

Description

Technical Field

[0001] This application relates to the field of microwave technology, and in particular to a transitionless mode conversion structure based on a ridge waveguide. Background Technology

[0002] Single-ridge waveguides possess advantages such as wide operating bandwidth, long cutoff wavelength (facilitating miniaturization), and low characteristic impedance (easy to match), making them widely used in microwave system design. In radio frequency (RF) system design, RF modules tend towards simplicity, integration, and miniaturization, requiring signal transmission paths to be as short as possible to ensure low-loss transmission. In microwave transmission design, the mode-switching structure between the waveguide and microstrip line is a crucial component for signal transmission, especially in broadband high-frequency applications. The width and performance of the mode-switching structure between the ridge waveguide and microstrip line directly affect RF integration and signal transmission efficiency.

[0003] Currently, there are two main approaches to achieving mode switching between ridge waveguides and microstrip lines, but each has its own inherent shortcomings that are difficult to overcome.

[0004] The first approach is to achieve mode conversion using a microstrip probe. This scheme places the microstrip probe within a ridge waveguide to convert the TE10 mode to the TEM mode. Depending on the placement method, the microstrip probe can be categorized into E-plane probes and H-plane probes. Taking the E-plane probe as an example, the probe direction is parallel to the electric field direction within the waveguide. Excited through electrical coupling, its impedance exhibits capacitive characteristics. Therefore, a high-impedance inductive microstrip line needs to be connected in series with the probe design to cancel the imaginary part of the impedance matching. Then, a quarter-wavelength impedance transformer is used to match it to a 50-ohm microstrip line. The main drawbacks of this approach are: firstly, in engineering implementation, differences in the assembly position between the microstrip probe and the ridge waveguide significantly affect the mode conversion efficiency, leading to deterioration of the input standing wave ratio and increased signal transmission loss; secondly, the signal transmission direction of the ridge waveguide is typically 90° to the signal transmission direction of the microstrip line, increasing the width of the mode conversion structure and hindering module miniaturization; and thirdly, the entire conversion structure requires a complex transition design (high-impedance line, quarter-wavelength transformer, etc.), increasing design difficulty and footprint.

[0005] The second method involves mode switching via microstrip fins. The waveguide-microstrip fin-50-ohm microstrip line is a quasi-planar switching structure. It smoothly transitions the TE10 mode in the waveguide to the TEM mode in the microstrip line by gradually rotating the electromagnetic field through the microstrip fin structure. The advantage of this approach is that the TE10 mode propagation direction and the microstrip line propagation direction can remain in the same horizontal direction. However, its disadvantages include the complexity of the microstrip fin structure itself, high requirements for fabrication technology, and the still relatively large width of the entire switching structure, which is not conducive to system miniaturization.

[0006] It is important to note that the techniques described in this section are not necessarily those previously conceived or adopted. Unless otherwise specified, no technique described in this section should be assumed to be prior art simply because it is included in this section. Similarly, unless otherwise specified, the issues mentioned in this section should not be considered to be recognized in any prior art. Summary of the Invention

[0007] This application provides a transition-free mode conversion structure based on a ridge waveguide, which aims to solve the technical problem that the existing ridge waveguide and microstrip line require complex transition structures such as microstrip probes or fins, which leads to increased design complexity and width.

[0008] To achieve the above objectives, this application provides a ridge waveguide-based transition-mode conversion structure, which includes: waveguide housing, The input ridge waveguide segment is located inside the waveguide housing; A metal carrier plate is disposed inside the waveguide housing and located outside the narrow side of the input ridge waveguide section. A coupling gap is formed between the metal carrier plate and the narrow side of the input ridge waveguide section. The metal carrier plate is electrically connected to the waveguide housing. Radio frequency energy in the input ridge waveguide section can be coupled to the metal carrier plate through the coupling gap. The metal carrier plate is used to convert spatial electromagnetic fields into conduction current. A matching section is disposed inside the waveguide housing and located on one side of the metal carrier plate. The matching section and the metal carrier plate are arranged opposite each other at a distance. The arrangement direction of the matching section and the metal carrier plate is defined as a first direction. The arrangement direction of the input ridge waveguide segment and the metal carrier plate, as well as the transmission direction of the radio frequency signal in the input ridge waveguide segment, are defined as a second direction. The first direction and the second direction are perpendicular to each other. Bonding wires are disposed inside the waveguide housing, with one end of the bonding wires electrically connected to the metal carrier plate; and An output microstrip line is disposed inside the waveguide housing. The output microstrip line is equipped with a ground metal layer, and the other end of the bonding wire is electrically connected to the output microstrip line.

[0009] Optionally, the output microstrip lines are arranged along the second direction.

[0010] Optionally, the matching section is spaced apart from the metal carrier plate to form a parallel capacitor, and the relative area and relative spacing between the matching section and the metal carrier plate are matched to the inductance settings of the bonding wire.

[0011] Optionally, the relative area between the matching section and the metal carrier plate is a preset fixed value, and the spacing between the matching section and the metal carrier plate in the first direction is set to match the capacitance of the parallel capacitor with the inductance of the bonding wire.

[0012] Optionally, the end face of the mating section facing the metal carrier plate is circular, and the ratio of the radius of the end face of the mating section to the width of the metal carrier plate in the second direction is 0.4 to 0.6.

[0013] Optionally, the ratio of the end face radius of the mating section to the width of the metal carrier plate in the second direction is 0.45 to 0.55.

[0014] Optionally, the first direction is the height direction of the input ridge waveguide segment, and the extension direction of the coupling slot is parallel to the wide side of the input ridge waveguide segment; the position of the metal carrier plate in the first direction can be adjusted to change the position of the coupling slot, thereby adjusting the amount of radio frequency energy coupling.

[0015] Optionally, the position of the metal carrier plate in the second direction is a preset fixed value, and the vertical distance between the center position of the coupling gap and the bottom end of the narrow sidewall of the input ridge waveguide section is 0.4 to 0.6 times the height of the narrow sidewall of the input ridge waveguide section.

[0016] Optionally, the vertical distance between the center of the coupling slot and the bottom end of the narrow sidewall of the input ridge waveguide segment is 0.45 to 0.55 times the height of the narrow sidewall of the input ridge waveguide segment.

[0017] Optionally, the ridge waveguide-based transitionless mode conversion structure further includes: A dielectric substrate is disposed inside the waveguide housing, and the metal carrier plate, the matching section and the output microstrip line are all disposed on the dielectric substrate.

[0018] This application utilizes a ridge waveguide-based transition-mode conversion structure, achieving electromagnetic field to conduction current conversion solely through the coupling gap between the input ridge waveguide segment and the metal carrier. The current is then directly output to the microstrip line via bonding wires, significantly simplifying the structural design and reducing manufacturing complexity. Furthermore, the matching section and the metal carrier are arranged along a first direction, while the input ridge waveguide segment and the metal carrier are arranged along a second direction, with the first and second directions perpendicular to each other. This results in a compact overall layout, facilitating miniaturized integration of the RF module. This application achieves mode conversion between the ridge waveguide and the microstrip line, enabling miniaturization of the RF module while maintaining excellent broadband matching performance, thus addressing the broadband matching requirements of ridge waveguide mode conversion in miniaturized applications.

[0019] It should be understood that the description in this section is not intended to identify key or essential features of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0020] The accompanying drawings exemplify embodiments and form part of the specification, working together with the textual description to explain exemplary implementations of the embodiments. The drawings shown are for illustrative purposes only and do not limit the scope of the claims. Throughout the drawings, the same reference numerals refer to similar but not necessarily identical elements.

[0021] Figure 1 This is a perspective view of an embodiment of the transitionless mode conversion structure based on a ridge waveguide in this application; Figure 2 for Figure 1 The front view of the embodiment shown; Figure 3 for Figure 1 Top view of the embodiment shown; Figure 4 for Figure 1 The simulation results of the embodiment shown are illustrated.

[0022] Explanation of reference numerals in the attached figures: Detailed Implementation

[0023] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] In the description of the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. The term "multiple" means two or more, unless otherwise explicitly specified. The term "comprising" indicates the presence of the described feature, whole, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or sets thereof. The term "and / or" describes the relationship between related objects, indicating that three relationships may exist. For example, A and / or B may include three cases: A existing alone, A and B existing simultaneously, and B existing alone. The character " / " generally indicates that the related objects before and after are in an "or" relationship.

[0026] Unless otherwise defined, all technical terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art; the terms used in the embodiments of this application are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "comprising" and "including", and any variations thereof, in the specification, claims and the foregoing description of the drawings of this application are intended to cover non-exclusive inclusion.

[0027] Furthermore, terms such as "exemplary," "for example," and "optional" are used to indicate illustrative purposes. Any technical solution described by the above terms in the embodiments of this application should not be construed as being more preferred or advantageous than other technical solutions. Specifically, these terms are intended to present the relevant technical concepts in terms of specific implementation methods.

[0028] like Figures 1 to 3 As shown, this application provides a ridge waveguide-based transitionless mode conversion structure 1, which is a miniaturized ridge waveguide transitionless conversion structure. The ridge waveguide-based transitionless mode conversion structure 1 includes a waveguide shell 11, an input ridge waveguide segment 12, a metal carrier 13, a matching section 14, a bonding wire 15, and an output microstrip line 16.

[0029] The waveguide housing 11 can be made of a metallic material (such as aluminum alloy, copper alloy, or Kovar alloy) through precision machining. The inner wall surface of the waveguide housing 11 can be plated with gold or silver to reduce conductor loss. The interior of the waveguide housing 11 forms a closed cavity, which is used to accommodate the input ridge waveguide section 12, the metal carrier plate 13, the matching section 14, the bonding wire 15, and the output microstrip line 16, and at the same time provides electromagnetic shielding and mechanical support.

[0030] The input ridge waveguide section 12 is located inside the waveguide housing 11. The input ridge waveguide section 12 can be a standard rectangular single-ridge waveguide structure; however, it is not limited to this and can also be a single-ridge waveguide structure of other types. The input ridge waveguide section 12 includes a wide side 121 and a narrow side 122, the dimensions of which are determined according to the operating frequency band. One end of the input ridge waveguide section 12 is a radio frequency signal input port, and the other end is either closed or connected to a matched load.

[0031] A metal carrier plate 13 is disposed inside the waveguide housing 11 and located outside the narrow side 122 of the input ridge waveguide section 12. The metal carrier plate 13 can be made of the same metal material as the waveguide housing 11 (or a different material), and its thickness is adapted to its operating frequency band. A coupling slot is formed between the metal carrier plate 13 and the narrow side 122 of the input ridge waveguide section 12. This coupling slot is parallel to the wide side 121 of the input ridge waveguide section 12, and the length and width of the coupling slot are designed according to the required coupling amount.

[0032] The coupling slot can be implemented in various engineering forms. As a preferred option, the coupling slot can adopt a direct gap structure, where a uniform air gap is maintained between the metal carrier plate 13 and the narrow side 122 of the ridge waveguide. The width of the coupling slot is controlled by the installation position of the metal carrier plate 13, and the coupling amount is determined by both the width of the coupling slot and its height position on the narrow side 122. This scheme has a simple structure, low parasitic parameters, and is easy to manufacture. Alternatively, the coupling slot can adopt a dielectric-filled structure, where a certain thickness of dielectric material (such as polyimide, ceramic, or quartz) is filled into the gap between the metal carrier plate 13 and the narrow side 122. The dielectric layer provides support, insulation, or adjusts the equivalent coupling slot width, while simultaneously changing the equivalent dielectric constant of the coupling slot, thereby fine-tuning the coupling resonant frequency. The coupling slot can also adopt a stepped or grooved structure, where grooves or steps are machined on the sidewall of the narrow side 122 of the ridge waveguide, making the actual coupling path present a non-uniform cross-section to broaden the coupling bandwidth or achieve a specific coupling frequency response. In practical design, those skilled in the art can flexibly select or combine the above-mentioned coupling gap formation methods according to the operating frequency band, power capacity, processing cost and debugging requirements, and this application does not make specific limitations in this regard.

[0033] The metal carrier plate 13 is electrically connected to the waveguide housing 11. Specifically, the metal carrier plate 13 can be grounded to the waveguide housing 11 through multiple metallized vias, or it can be electrically connected to the waveguide housing 11 by conductive adhesive bonding or direct mechanical contact. The radio frequency energy input into the ridge waveguide section 12 is coupled to the metal carrier plate 13 through coupling slots, and the metal carrier plate 13 is used to convert the spatial electromagnetic field into conduction current.

[0034] The mating section 14 is disposed inside the waveguide housing 11 and located on one side of the metal carrier plate 13. The mating section 14 and the metal carrier plate 13 are disposed opposite each other at a distance. The mating section 14 can be made of the same metal material as the metal carrier plate 13 (or a different one). The mating section 14 can be machined into a cylindrical boss, that is, its end face facing the metal carrier plate 13 is circular. Of course, the mating section 14 can also be other shapes, without specific limitation. The mating section 14 can be directly formed on the dielectric substrate 17 or fixed as an independent part to the inner wall of the waveguide housing 11.

[0035] For ease of description, the arrangement direction of the mating section 14 and the metal carrier plate 13 is defined as the first direction (i.e., Figure 1 The vertical direction in the image corresponds to the height direction of the input ridge waveguide segment 12. The arrangement direction of the input ridge waveguide segment 12 and the metal carrier plate 13, as well as the transmission direction of the radio frequency signal within the input ridge waveguide segment 12, are defined as the second direction (i.e.,...). Figure 1 (Horizontal direction in the middle). The first direction and the second direction are perpendicular to each other.

[0036] In one embodiment, the matching section 14 is located below the metal carrier plate 13. Here, "below" means that along the first direction (i.e., the height direction of the input ridge waveguide segment 12), the matching section 14 is located on the side of the metal carrier plate 13 closer to the bottom inner wall of the waveguide housing 11. Since the first direction is defined as the arrangement direction of the matching section 14 and the metal carrier plate 13, and the first direction is perpendicular to the second direction (signal transmission direction), the matching section 14 is arranged perpendicular to the signal transmission direction and directly below the metal carrier plate 13. This arrangement ensures that the matching section 14 does not occupy additional space in the second direction, and the electric field direction of the parallel capacitor formed between the matching section 14 and the metal carrier plate 13 is distributed along the first direction, which is orthogonal to the compensation path of the inductive component introduced by the bonding line 15, thus avoiding mutual interference. In addition, the lower location of the matching section 14 facilitates the adjustment of the distance between the matching section 14 and the metal carrier plate 13 by means of an adjustment mechanism (such as a set screw or a shim) at the bottom of the waveguide housing 11, thereby achieving online matching optimization.

[0037] The bonding wire 15 (specifically, a gold wire bonding wire) is located inside the waveguide housing 11. One end of the bonding wire 15 is electrically connected to the metal carrier 13 via thermo-ultrasonic ball bonding or wedge bonding, and the other end is electrically connected to the signal line of the output microstrip line 16. The length and arch height of the bonding wire 15 are determined according to the actual layout to avoid short circuits.

[0038] The output microstrip line 16 is disposed inside the waveguide housing 11 and includes a signal conductor strip on the dielectric substrate 17 and a ground metal layer on the back (not shown). The ground metal layer can be tightly bonded to the waveguide housing 11 using conductive adhesive or soldering. The other end of the bonding wire 15 is connected to the signal conductor strip end of the output microstrip line 16. The characteristic impedance of the output microstrip line 16 is designed as the system impedance, and its conductor strip width is calculated based on the dielectric constant and thickness of the dielectric substrate 17.

[0039] The output microstrip line 16 can be arranged along the second direction. Since the second direction simultaneously defines the arrangement direction of the input ridge waveguide section 12 and the metal carrier plate 13, as well as the transmission direction of the radio frequency signal within the input ridge waveguide section 12, the signal transmission direction of the output microstrip line 16 is consistent with the signal transmission direction of the input ridge waveguide section 12 when it extends along the second direction.

[0040] In the ridge waveguide-based transition-mode conversion structure 1 of this application, the input ridge waveguide segment 12, the metal carrier plate 13, the matching section 14, and the output microstrip line 16 are all arranged sequentially along the same axis. Compared with the traditional scheme that requires a quarter-wavelength converter or a vertical transition, the volume of the ridge waveguide-based transition-mode conversion structure 1 of this application is significantly reduced, which can meet the stringent requirements of RF modules for high integration and miniaturization. At the same time, the consistent input and output directions eliminate the need for additional bending or corner structures, reduce signal reflection and radiation loss, and facilitate broadband matching and cascading. In addition, the co-directional ports make testing, assembly, and docking with back-end circuits more convenient, improving engineering practicality.

[0041] The dielectric substrate 17 is disposed inside the waveguide housing 11 and can be made of a high-frequency dielectric material (such as a polytetrafluoroethylene (PTFE) substrate 17, a ceramic substrate 17, or a quartz substrate 17). The metal carrier plate 13, the matching node 14, and the output microstrip line 16 can all be fabricated on the surface of the dielectric substrate 17 using photolithography, electroplating, or etching processes. In embodiments where the output microstrip line 16 is arranged along a second direction, the metal carrier plate 13, the matching node 14, and the output microstrip line 16 are fabricated on the same surface of the dielectric substrate 17.

[0042] Please combine Figures 1 to 3 The working principle and design parameters of the ridge waveguide-based transitionless mode conversion structure 1 of this application will be introduced below.

[0043] The radio frequency energy in the input ridge waveguide segment 12 is transmitted to the metal carrier plate 13 through the coupling slot. The energy is concentrated in the coupling slot region, exciting the metal carrier plate 13 and making it act like a probe. The extension direction of the coupling slot is parallel to the wide side 121 of the input ridge waveguide segment 12, and its length and width are determined according to the operating frequency band and the required coupling amount. The normalized equivalent admittance of the coupling slot can be expressed as:

[0044] Where j is the imaginary unit, used to distinguish between the real and imaginary admittance of the coupling gap; The normalized parallel conductance characterizes the ability of the coupling slot to couple active power from the input ridge waveguide segment 12; The normalized parallel susceptance characterizes the reactive power storage properties of the coupling gap. When the coupling gap resonates, At this point, the coupling slot exhibits pure conductive characteristics, resulting in the highest coupling efficiency. The coupling strength of the coupling slot depends on its lateral position (the horizontal distance between the narrow side 122 of the input ridge waveguide segment 12 and the metal carrier plate 13) and its longitudinal position (the vertical distance between the bottom end of the narrow side 122 of the input ridge waveguide segment 12 and the bottom end of the metal carrier plate 13). Since the coupling slot is parallel to the wide side 121 of the input ridge waveguide segment 12, the cutting current is a lateral wall current, and the coupling strength is mainly determined by the height of the coupling slot.

[0045] The sidewall current distribution of the input ridge waveguide segment 12 is approximately cosine-shaped, with the current being largest near the center and smallest near the edges. Therefore, the normalized parallel conductance of the coupling gap between the input ridge waveguide segment 12 and the metal carrier plate 13 is... It can be approximated as:

[0046] In the formula: Let be the vertical distance (i.e., height position) from the center of the coupling slot to the bottom end of the narrow sidewall 122 of the input ridge waveguide segment 12, b be the height of the narrow sidewall 122 of the input ridge waveguide segment 12, and K be a constant related to the size of the input ridge waveguide segment 12, the width of the coupling slot, and the operating frequency, which can be extracted through analytical simulation. From this equation, it can be seen that by adjusting... It can effectively adjust the coupling amount of radio frequency energy, so that the signal is coupled to the metal carrier plate 13 with low loss.

[0047] In one embodiment, the position of the metal carrier plate 13 in the second direction is set to a preset fixed value, that is, the horizontal position of the coupling slot remains constant relative to the narrow side 122 of the input ridge waveguide section 12, while the vertical distance from the center of the coupling slot to the bottom end of the sidewall of the narrow side 122 of the input ridge waveguide section 12 is... This serves as the main adjustable parameter for adjusting the coupling amount. When the vertical distance between the center of the coupling slot and the bottom end of the sidewall of the narrow side 122 of the input ridge waveguide segment 12 is 0.4 to 0.6 times (greater than or equal to 0.4 times and less than or equal to 0.6 times) the height of the narrow side 122 of the input ridge waveguide segment 12, that is... When the value is in the range of 0.4 to 0.6 times the height b of the narrow side 122, a good trade-off can be achieved between coupling efficiency and operating bandwidth.

[0048] Furthermore, when the vertical distance between the center of the coupling slot and the bottom end of the sidewall of the narrow side 122 of the input ridge waveguide segment 12 is 0.45 to 0.55 times the height of the narrow side 122 of the input ridge waveguide segment 12, that is, when... Limiting the coupling to 0.45b to 0.55b ensures sufficient coupling strength while significantly reducing the sensitivity of the coupling amount to machining tolerances and assembly errors, thereby improving the consistency of mass production. This application is not limited to the above range. It can also be 0.44b~0.58b, 0.49b~0.56b, 0.41b~0.54b, 0.51b~0.52b, or 0.48b~0.49b, etc.

[0049] When the vertical distance between the center of the coupling slot and the bottom end of the narrow sidewall 122 of the input ridge waveguide segment 12 is approximately 0.5 times the height of the narrow sidewall 122 of the input ridge waveguide segment 12, that is... When the value is approximately 0.5b, the coupling slot is located precisely in the region of maximum current density on the narrow sidewall 122 of the ridge waveguide (the peak position of the approximate cosine distribution). The coupling slot operates in a quasi-resonant state, and its normalized parallel conductance is... When the maximum value is reached, efficient coupling can be achieved with only a small coupling gap width, while the equivalent parallel susceptance of the coupling gap is also increased. It is approximately zero, and a low input VSWR can be obtained without additional tuning.

[0050] In the radio frequency path, bonding wire 15 introduces an inductive component, with an inductive reactance of:

[0051] In the formula, f is the operating frequency, and L is the equivalent inductance of the bonding wire 15 (which mainly depends on the length and diameter of the bonding wire 15). If this inductive component is not compensated, it will lead to impedance mismatch and increase signal reflection.

[0052] To offset the inductive component introduced by the bonding wire 15, this application provides a matching section 14 on the metal carrier 13 near one end of the bonding wire 15. A parallel capacitor is formed between the matching section 14 and the metal carrier 13, and its capacitive reactance is:

[0053] In the formula denoted as the dielectric constant of the dielectric substrate 17, A is the effective area between the mating section 14 and the metal carrier plate 13, and d is the distance between them (distance along the first direction).

[0054] Please see Figures 1 to 3In one embodiment, the relative areas of the matching section 14 and the metal carrier plate 13 are set to a preset fixed value, while the spacing between the matching section 14 and the metal carrier plate 13 in the first direction is set such that the capacitance of the parallel capacitor formed between them matches the inductance introduced by the bonding wire 15. For example, to achieve this matching relationship, please refer to [reference needed]. Figure 3 In this embodiment, the end face of the mating section 14 facing the metal carrier plate 13 is designed as a circle with a radius of R. Therefore, the effective area A between the mating section 14 and the metal carrier plate 13 is A = πR². At the same time, the width of the metal carrier plate 13 in the second direction is defined as W.

[0055] To ensure that the matching section 14 does not generate additional capacitive coupling components with the input ridge waveguide section 12, thus preventing impedance mismatch, the ratio of R to W must be appropriately selected. When the ratio of the end face radius of the matching section 14 to the width of the metal carrier plate 13 in the second direction is 0.4 to 0.6 (greater than or equal to 0.4 and less than or equal to 0.6), that is, when the R / W ratio is controlled within the range of 0.4 to 0.6, the electric field generated by the matching section 14 is mainly concentrated in the region directly opposite the metal carrier plate 13, while the leakage electric field to the sidewall of the input ridge waveguide section 12 is significantly reduced, thereby effectively avoiding the formation of parasitic capacitance.

[0056] Furthermore, when the ratio of the end face radius of the mating section 14 to the width of the metal carrier plate 13 in the second direction is 0.45 to 0.55, that is, R / W is preferably 0.45 to 0.55, the distance between the edge of the mating section 14 and the edge of the metal carrier plate 13 is just right: it avoids insufficient facing area due to an excessively small radius, requiring the spacing d to be compressed to the process limit, and also avoids unnecessary edge radiation due to the lateral dimension of the mating section 14 exceeding the boundary of the metal carrier plate 13 due to an excessively large radius. The above range is further preferably 0.48 to 0.52. This application is not limited to the above range, and R / W can also be 0.44 to 0.58, 0.49 to 0.56, 0.41 to 0.54, 0.51 to 0.52, or 0.48 to 0.49, etc.

[0057] When the ratio of the end face radius of the matching section 14 to the width of the metal carrier plate 13 in the second direction is close to 0.5, that is, R / W is about 0.5, the facing area of ​​the matching section 14 and the metal carrier plate 13 is moderate, and the capacitance value of the parallel capacitor is most sensitive to the change of the spacing d. That is, a small adjustment of d can obtain a significant change in capacitance value, which greatly facilitates the tolerance control in actual debugging and mass production.

[0058] By setting the above proportions, this application only needs to adjust the spacing d parameter to accurately compensate for the inductance of the bonding wire 15, without repeatedly modifying the size or shape of the matching section 14, thereby simplifying the design process and reducing manufacturing costs. The resulting technical effects include: First, the parasitic coupling between the matching section 14 and the input ridge waveguide section 12 is suppressed to a negligible level, avoiding additional impedance discontinuities and helping to maintain a low VSWR across the entire frequency band; Second, the capacitance value of the parallel capacitor can be optimized online through precision mechanical tuning (e.g., fine-tuning screws or shims), allowing the same structure to adapt to drifts in the length of the gold wire or the parameters of the dielectric substrate 17 in different batches, improving product yield and consistency; Third, the circular end face structure of the matching section 14 is easy to process by planar photolithography or CNC milling, and there is no risk of sharp corner discharge, making it suitable for medium-power applications.

[0059] This application presents a ridge waveguide-based transition-mode conversion structure 1. Through the aforementioned structure and working principle, it achieves direct conversion from the TE10 mode of the input ridge waveguide segment 12 to the TEM mode of the output microstrip line 16, eliminating the need for complex transition networks such as microstrip probes, fin lines, or quarter-wavelength converters. The input ridge waveguide segment 12 and the output microstrip line 16 are arranged along the same horizontal direction (second direction), resulting in a compact overall structure and significantly reduced size. Simultaneously, the parallel capacitor introduced by the matching section 14 effectively compensates for the inductive component of the bonding wire 15, achieving excellent impedance matching over a wide bandwidth.

[0060] Please see Figure 4 The simulation results shown in the figure demonstrate that, within the frequency range of 26 GHz to 40 GHz, the return loss S11 of the ridge waveguide-based transition-mode conversion structure 1 of this application is ≤ -15 dB, fully verifying its broadband matching performance and miniaturization effect. Specifically, the return loss S11 is a core indicator characterizing the port impedance matching degree, defined as the logarithmic form of the ratio of reflected power to incident power. When S11 ≤ -15 dB, it indicates that the ridge waveguide-based transition-mode conversion structure 1 of this application has excellent signal transmission efficiency within the operating frequency band. In the ridge waveguide-based transition-mode conversion structure 1 of this application, the parallel capacitor introduced by the matching section 14 and the inductance of the bonding wire 15 achieve dynamic balance across the entire frequency band, eliminating the need for frequency-by-frequency tuning. Meanwhile, the simulation results were obtained under a compact structure in which the input ridge waveguide segment 12 and the output microstrip line 16 are arranged in the same direction (second direction), which verifies that the miniaturized design does not introduce additional reflections or resonances. This proves that the ridge waveguide-based transition mode conversion structure 1 of this application successfully maintains broadband low-reflection transmission characteristics while significantly reducing the size of the conversion structure, providing a reliable miniaturized solution for RF front-end integration in the millimeter-wave band.

[0061] The above embodiments are only used to illustrate the present application and are not intended to limit it. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included within the protection scope of the present application.

Claims

1. A transition-free mode conversion structure based on a ridge waveguide, characterized in that, include: waveguide housing, The input ridge waveguide segment is located inside the waveguide housing; A metal carrier plate is disposed inside the waveguide housing and located outside the narrow side of the input ridge waveguide section. A coupling gap is formed between the metal carrier plate and the narrow side of the input ridge waveguide section. The metal carrier plate is electrically connected to the waveguide housing. Radio frequency energy in the input ridge waveguide section can be coupled to the metal carrier plate through the coupling gap. The metal carrier plate is used to convert spatial electromagnetic fields into conduction current. A matching section is disposed inside the waveguide housing and located on one side of the metal carrier plate. The matching section and the metal carrier plate are arranged opposite each other at a distance. The arrangement direction of the matching section and the metal carrier plate is defined as a first direction. The arrangement direction of the input ridge waveguide segment and the metal carrier plate, as well as the transmission direction of the radio frequency signal in the input ridge waveguide segment, are defined as a second direction. The first direction and the second direction are perpendicular to each other. A bonding wire is disposed inside the waveguide housing, and one end of the bonding wire is electrically connected to the metal carrier plate. as well as An output microstrip line is disposed inside the waveguide housing. The output microstrip line is equipped with a ground metal layer, and the other end of the bonding wire is electrically connected to the output microstrip line.

2. The transitionless mode conversion structure based on ridge waveguide according to claim 1, characterized in that, The output microstrip lines are arranged along the second direction.

3. The transitionless mode conversion structure based on ridge waveguide according to claim 1, characterized in that, The matching section forms a parallel capacitor with the metal carrier plate, and the relative area and relative spacing of the matching section and the metal carrier plate match the inductance setting of the bonding wire.

4. The transitionless mode conversion structure based on ridge waveguide according to claim 3, characterized in that, The relative area between the matching section and the metal carrier plate is a preset fixed value, and the spacing between the matching section and the metal carrier plate in the first direction is set to match the capacitance of the parallel capacitor with the inductance of the bonding wire.

5. The ridge waveguide-based transition-free mode conversion structure according to claim 3, characterized in that, The end face of the mating section facing the metal carrier plate is circular, and the ratio of the radius of the end face of the mating section to the width of the metal carrier plate in the second direction is 0.4 to 0.

6.

6. The ridge waveguide-based transition-free mode conversion structure according to claim 5, characterized in that, The ratio of the end face radius of the matching section to the width of the metal carrier plate in the second direction is 0.45 to 0.

55.

7. The ridge waveguide-based transition-free mode conversion structure according to claim 1, characterized in that, The first direction is the height direction of the input ridge waveguide segment, and the extension direction of the coupling slot is parallel to the wide side of the input ridge waveguide segment; the position of the metal carrier plate can be adjusted to change the position of the coupling slot, thereby adjusting the amount of radio frequency energy coupling.

8. The ridge waveguide-based transition-free mode conversion structure according to claim 7, characterized in that, The position of the metal carrier plate in the second direction is a preset fixed value, and the vertical distance between the center position of the coupling gap and the bottom end of the narrow sidewall of the input ridge waveguide section is 0.4 to 0.6 times the height of the narrow sidewall of the input ridge waveguide section.

9. The transitionless mode conversion structure based on a ridge waveguide according to claim 8, characterized in that, The vertical distance between the center of the coupling gap and the bottom end of the narrow sidewall of the input ridge waveguide is 0.45 to 0.55 times the height of the narrow sidewall of the input ridge waveguide.

10. The ridge waveguide-based transition-free mode conversion structure according to any one of claims 1-9, characterized in that, Also includes: A dielectric substrate is disposed inside the waveguide housing, and the metal carrier plate, the matching section and the output microstrip line are all disposed on the dielectric substrate.

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