A ridge waveguide-strip line transition structure with integrated band-stop function

Abstract

The application provides a ridge waveguide-strip line transition structure with integrated band rejection function, and relates to the technical field of wireless communication. A local metal ridge discontinuity is introduced in the ridge waveguide, and the discontinuity area is electrically continuously reconstructed by using an embedded strip line, so that the radio frequency signal can be continuously transmitted between the ridge waveguide section and the strip line section along the same propagation direction, forming a transition transmission path composed of the ridge waveguide and the strip line in series. In the set 5.3-18.3 GHz operating frequency band, the transition structure can maintain good impedance matching and transmission characteristics, realizing wideband and low-reflection signal transmission. At the same time, by introducing a spur line structure on the strip line, a clear band rejection notch response can be formed at a specific frequency, so as to effectively suppress the target frequency signal on the basis of maintaining the wideband transmission characteristics.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, specifically to a ridge waveguide-stripline transition structure with integrated bandstop functionality. Background Technology

[0002] Waveguides, due to their high power carrying capacity and low transmission loss, are widely used in RF and microwave front-end modules of communication systems. Meanwhile, planar transmission lines such as microstrip lines and striplines play a crucial role in control circuits and system integration due to their excellent integration and low manufacturing cost. In practical communication systems, waveguides and planar transmission lines often need to be interconnected. For example, interconnection between waveguide feed lines and on-chip striplines, and signal transmission between waveguide ports and microstrip filter / amplifier modules, all involve waveguides and planar transmission lines. Therefore, achieving a high-performance transition structure between striplines and waveguides that combines low insertion loss and wideband transmission characteristics has become one of the key technologies in waveguide-planar circuit hybrid integration design.

[0003] Currently, various transition structures have been proposed in the existing technology field to achieve the connection and matching between waveguides and planar transmission lines. Among the existing transition technologies, E-plane probe technology has been widely used in the transition structure between waveguides and microstrip lines due to its relatively simple structure. However, its performance is quite sensitive to the probe's geometric parameters and installation position, making design optimization difficult. Furthermore, some implementation methods increase assembly complexity and may limit the integrated implementation of the waveguide cavity. Another common method is to use a multi-segment ridge waveguide impedance ladder to achieve the transition. This method can achieve a wider operating bandwidth, but its structure is more complex, posing significant challenges in manufacturing precision control and assembly consistency. In addition, slot-coupled transition structures have certain advantages in integration due to their inherent planar characteristics, but their bandwidth is usually limited. For some broadband or highly integrated designs, multi-layer dielectric or multi-metal layer structures are required, leading to complex manufacturing processes and higher costs. In practical engineering applications, the above-mentioned existing technical solutions generally require a trade-off between sacrificing structural compactness, manufacturing process complexity, or bandwidth and matching performance. Furthermore, since most schemes require repeated switching between waveguide modes (such as TE10) and planar transmission line modes (quasi-TEM), this back-and-forth mode switching process inevitably generates additional reflections and losses, affecting the overall transmission performance. Summary of the Invention

[0004] Therefore, this invention provides a ridge waveguide-stripline transition structure with integrated band-stop functionality to solve the above problems. This invention provides a ridge waveguide-stripline transition structure with integrated band-stop functionality, which avoids repeated mode switching and achieves broadband, low-reflection signal transmission. Simultaneously, a spur line structure is introduced into the stripline to achieve integrated band-stop functionality. Addressing the problems of complex mode switching processes, complex structures, and additional losses introduced by existing waveguide-planar transmission line transition structures, this invention proposes a structural form that achieves a smooth transition between the waveguide structure and the planar transmission line, thereby obtaining good impedance matching and transmission performance under broadband operating conditions, and improving the compactness and integrability of the structure.

[0005] The present invention provides a ridge waveguide-stripline transition structure with integrated bandstop function. The structure includes: a rectangular cavity, in which a metal ridge is disposed; and the metal ridge is provided with a discontinuous region that cuts off the metal ridge.

[0006] Furthermore, a dielectric substrate is disposed at the top of the discontinuous region, and a strip conductor is disposed on the dielectric substrate. Grooves with the same thickness as the dielectric substrate are provided at the metal ridges on both sides of the discontinuous region for embedding and fixing the dielectric substrate.

[0007] Furthermore, the strip conductor is provided with barbed wire.

[0008] Furthermore, the two ends of the metal ridge are fitted to the two ends of the rectangular cavity. The bottom of the metal ridge is fitted to the bottom of the rectangular cavity. Both the rectangular cavity and the metal ridge are made of aluminum.

[0009] In operation, the radio frequency signal is input from one end of the ridge waveguide and propagates within the rectangular waveguide cavity along the axial direction of the metal ridge. Due to the introduction of the metal ridge, the electromagnetic field is more concentrated in the local region between the ridge and the adjacent conductor wall, allowing the dominant mode of this structure to exhibit quasi-TEM-like field distribution characteristics while maintaining the waveguide propagation nature. Based on this field pattern similarity, a smoother electromagnetic transition can be achieved between the ridge waveguide segment and the strip segment, avoiding the complex mode matching process required by traditional complex transition structures.

[0010] When the radio frequency signal propagates to the axial discontinuity region of the metal ridge, the original energy transmission path guided along the metal ridge is interrupted. At this time, the stripline transmission line arranged in the discontinuity region acts as an intermediate connecting segment to redirect the electromagnetic energy, allowing the energy to transition from the preceding ridge waveguide region to the stripline segment, and then reintroducing it into the subsequent metal ridge region after crossing the discontinuity, thereby achieving continuous signal transmission within this region.

[0011] In the above process, the stripline, composed of a dielectric substrate and a stripline conductor, is embedded inside a rectangular waveguide cavity. Its field distribution characteristics are well compatible with those of the adjacent ridge waveguide segments, which is beneficial for achieving smooth transmission of radio frequency signals. By rationally designing the height of the metal ridge and the linewidth of the stripline, the two are matched in terms of characteristic impedance, thereby reducing impedance abrupt changes introduced by structural changes, reducing reflection loss, and ensuring stable transmission of radio frequency signals over a wide frequency range.

[0012] Therefore, this invention reconstructs a continuous transmission path for radio frequency (RF) signals by introducing localized metallic ridge discontinuities in the ridge waveguide and bridging the discontinuities with embedded striplines. This allows the RF signal to propagate continuously in the same direction between the ridge waveguide segment and the stripline segment, forming a transitional transmission path composed of a ridge waveguide and a stripline connected in series. Within the defined operating frequency band of 5.3–18.3 GHz, this transitional structure maintains good impedance matching and transmission characteristics, achieving broadband, low-reflection signal transmission.

[0013] To verify the functional scalability and integration capability of the present invention, a spur-line structure was etched on the stripline transmission path, and its geometry was used to determine the corresponding resonant frequency. When the RF signal frequency approaches the resonant frequency of the spur-line, a significant resonant impedance effect is introduced, effectively suppressing the transmitted signal at that frequency, thereby forming a significant band-stop notch response in the overall transmission characteristics. By rationally designing the structural parameters of the spur-line, the present invention achieves a stable notch point at 8.9 GHz, while maintaining good transmission performance in other frequency bands.

[0014] The present invention has the following advantages over the prior art:

[0015] 1. This invention achieves continuous transmission between a three-dimensional waveguide structure and a planar transmission line by introducing an axial discontinuity on the metal ridge of the ridge waveguide and embedding a stripline as an intermediate connecting segment. Compared to the traditional waveguide-planar transmission line transition structure, this invention reduces complex mode conversion steps, which helps to reduce structural complexity and additional transmission loss. Simultaneously, by etching a spur-line structure on the embedded stripline, effective suppression of the target frequency is achieved.

[0016] 2. This invention features low insertion loss and wide bandwidth. Within a 13GHz frequency bandwidth of 5.3-18.3GHz, the insertion loss is less than 0.03 dB, and the return loss is greater than 15 dB. Therefore, the ridge waveguide-stripline transition circuit exhibits excellent impedance matching characteristics and transmission performance over a wide frequency range. Furthermore, by introducing a spur line structure into the stripline, a notch point is achieved at 8.9GHz, enabling selective suppression of specific frequency points while maintaining good broadband transmission characteristics. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 These are (a) a 3D structural schematic diagram, (b) a top view, and (c) a side view of the present invention;

[0019] Figure 2 The present invention is shown in (a) a 3D structural schematic diagram, (b) a top view and (c) a side view after the spur line is set;

[0020] Figure 3 This is a graph showing the S-parameter simulation results of this invention;

[0021] Figure 4 This is a simulation result of the S-parameters after setting the spur line according to the present invention.

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

[0023] 1. Rectangular cavity; 2. Metal ridge; 3. Strip conductor; 4. Dielectric substrate; 5. Discontinuity region; 6. Groove; 7. Spur line. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] This embodiment provides a ridge waveguide-stripline transition structure with integrated bandstop functionality, the structure of which is as follows: Figure 1The diagram shows a 3D structural diagram of a ridge waveguide-stripline transition structure, which comprises a ridge waveguide and a stripline. An axial discontinuity is introduced along the propagation direction on the metal ridge 2 of the ridge waveguide, and a stripline transmission line is arranged within this discontinuity region 5. The stripline serves as an intermediate connecting segment, connecting to the metal ridges 2 on both sides of the discontinuity region 5, thereby reconnecting the broken metal ridges 2 and forming an integrated composite transmission line structure. The rectangular cavity 1 and metal ridge 2 of the ridge waveguide are both made of aluminum, and the stripline is made of an RO4350B dielectric substrate 4 with a stripline conductor 3 laid on its surface.

[0027] Specifically, such as Figure 1 As shown, a metal ridge 2 is loaded within a rectangular cavity 1 with a length of 36.2 mm, a width of 12 mm, and a height of 8 mm. The metal ridge 2 has a length of 36.2 mm, a width of 5 mm, and a height of 7 mm. A 10.2 mm long discontinuous region is cut off in the middle of the metal ridge 2 along the propagation direction to embed a strip conductor 3 with a length of 10.2 mm and a width of 4 mm. The strip conductor 3 is mechanically supported by a dielectric substrate 4 with a length of 10.2 mm, a width of 5 mm, and a height of 0.2 mm. To facilitate assembly and ensure structural stability, grooves 6 with a height of 0.2 mm and a length of 1 mm are reserved at both ends of the discontinuous metal ridge 2 for embedding and fixing the dielectric substrate 4.

[0028] The parameters involved are: a = 12, b = 8, l = 36.2, l1 = 10.2, w1 = 4.1, s = 5, d = 1, h1 = 6.7, h2 = 6.9. (Unit: mm)

[0029] The operating frequency band of the transition structure described in this invention is set to 5.3–18.3 GHz. The height of the metal ridge 2 and the linewidth of the strip are designed according to the required characteristic impedance, and the impedance matching relationship is optimized and determined through electromagnetic simulation, thereby achieving stable transmission characteristics within the operating frequency band.

[0030] Figure 2 A 3D structural diagram of a ridge waveguide-stripline transition structure integrating bandstop functionality is shown. Figure 1 Based on the transition structure, the spur line 7 structure was introduced, and its structure and dimensions are as follows: Figure 4 As shown, l1 = 10.2 mm, l2 = 6.5mm, l3 = 5.5 mm, w1 = 4.1 mm, w2 = 2 mm, w3 = 0.5 mm.

[0031] Figure 3 The S-parameter simulation results of the ridge waveguide-stripline transition structure are presented. As shown in the figure, this transition structure achieves good impedance matching in the frequency range of 5.3–18.3 GHz, with an operating bandwidth of 13 GHz and a return loss better than 15 dB. Meanwhile, due to the relatively smooth electromagnetic transition between the ridge waveguide segment and the stripline segment, the structure maintains low insertion loss, all below 0.03 dB, over the widest range.

[0032] Figure 4 S-parameter simulation results of a ridge waveguide-stripline transition structure integrating bandstop functionality are presented. It can be seen that by introducing a spur line structure into the stripline, a significant notch response is generated at 8.9 GHz, with a suppression of -13 dB. These results demonstrate that the proposed transition structure not only possesses excellent broadband transmission performance but also exhibits good functional scalability and integration capabilities.

[0033] The transition structure integrating bandstop function described in this invention has a response point of 8.9GHz. The length and width of the spur line 7 are designed according to the required response point position and optimized through electromagnetic simulation to ensure that the structure forms a stable notch response at the target frequency and maintains good passband transmission performance.

[0034] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A ridge waveguide-stripline transition structure integrating bandstop functionality, characterized in that, include: A rectangular cavity (1) is provided with a metal ridge (2) inside the rectangular cavity (1); the metal ridge (2) is provided with an intermittent region (5) that cuts off the metal ridge (1).

2. The ridge waveguide-stripline transition structure with integrated bandstop function according to claim 1, characterized in that, The discontinuous region (5) is embedded with a dielectric substrate (4), and a strip conductor (3) is disposed on the dielectric substrate (4).

3. The ridge waveguide-stripline transition structure with integrated bandstop function according to claim 2, characterized in that, The metal ridges (2) on both sides of the discontinuous region (5) are provided with grooves (6) of the same thickness as the dielectric substrate (4) for embedding and fixing the dielectric substrate (4).

4. The ridge waveguide-stripline transition structure with integrated bandstop function according to claim 3, characterized in that, The strip conductor (3) is provided with barbed wire (7).

5. The ridge waveguide-stripline transition structure with integrated bandstop function according to claim 4, characterized in that, The two ends of the metal ridge (2) are attached to the two ends of the rectangular cavity (1).

6. The ridge waveguide-stripline transition structure with integrated bandstop function according to claim 5, characterized in that, The bottom of the metal ridge (2) is attached to the bottom of the rectangular cavity (1).

7. The ridge waveguide-stripline transition structure with integrated bandstop function according to claim 6, characterized in that, The rectangular cavity (1) and the metal ridge (2) are both made of aluminum.

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