A broadband filtering coupler based on SSPPs of a ridge waveguide
Patent Information
- Application Number
- CN202611417927.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-14
- Publication Date
- 2026-10-16
AI Technical Summary
[0006]本发明旨在解决现有技术中滤波耦合器带宽窄、功率容量有限、以及脊波导SSPPs器件未能实现滤波与耦合功能一体化集成的技术问题，提供一种兼具宽带滤波与3 dB耦合功能、高功率容量和紧凑结构的集成化器件方案
[0017] 1. For the first time, the integrated filtering and coupling functions of a ridge waveguide SSPPs structure have been achieved.
Smart Images
Figure CN122931279A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wireless communication technology, and in particular to a broadband filter coupler based on ridge waveguides (SSPPs). Background Technology
[0002] With the large-scale commercialization of 5G communication technology and the system deployment of 6G communication technology, the demand for high power capacity and high integration in radio frequency (RF) front-end systems is becoming increasingly urgent. Filters, as key components in the RF front-end for suppressing out-of-band interference and selecting useful signals, directly affect the system's selectivity. 3 dB couplers, as core components for power distribution and combining, are indispensable in scenarios such as transmit link power combining, receive link signal distribution, and antenna feed networks. Integrating filters and 3 dB couplers into a single unit not only eliminates inter-port cascade losses and mismatches but also effectively reduces system size and improves overall integration, which is of great significance for meeting the miniaturization and high-performance requirements of future communication systems.
[0003] Existing filter couplers mostly employ microstrip line or rectangular waveguide structures. Microstrip line structures have limited power capacity, and rectangular waveguide filter couplers primarily achieve filtering through resonant cavity coupling, resulting in generally narrow operating bandwidths. To extend the bandwidth, multiple resonant cavities typically need to be cascaded, leading to a significant increase in device size.
[0004] To address the aforementioned issues, this study focuses on the implementation of broadband filters. Research has shown that surface plasmon polaritons (SSPPs) offer strong field confinement and tunable dispersion, making them ideal for constructing broadband filters. For example, a broadband bandpass filter was designed by etching an inverted T-shaped groove on the central ridge of a ridge waveguide to create an SSPP structure. In coupler design, the SSPP structure was combined with a slow-wave folded ridge half-mode substrate integrated waveguide (FRHMSIW) and applied to the miniaturization design of a 3 dB coupler. However, none of the above studies integrated filtering and coupling functions into the same structure. In practical RF front-end systems, this results in increased system size and insertion loss, as well as the need for additional matching networks.
[0005] Compared to rectangular waveguides, ridge waveguides offer a wider single-mode operating bandwidth and a lower cutoff frequency, along with higher power capacity. They enable broadband operation while maintaining miniaturization, making them an indispensable transmission form in future wireless communication systems. Therefore, there is an urgent need to design a broadband filter coupler based on a ridge waveguide structure to achieve integrated filtering and coupling functions, while simultaneously meeting the requirements of broadband, high power capacity, and a compact structure. Summary of the Invention
[0006] The present invention aims to solve the technical problems of narrow bandwidth and limited power capacity of existing filter couplers, as well as the failure of ridge waveguide SSPPs devices to achieve integrated filtering and coupling functions, and provides an integrated device solution that combines broadband filtering and 3 dB coupling functions, high power capacity and compact structure.
[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:
[0008] A broadband filtering coupler based on ridge waveguides (SSPPs) includes a cavity, a metal ridge, a periodic SSPP structure, a coupling aperture, and an SMA port.
[0009] The cavity is an air cavity, surrounded by a shell, and electromagnetic waves are transmitted within the cavity; grating structures are disposed on both sides of the cavity;
[0010] The metal ridge is disposed inside the cavity, and the ridge extends longitudinally along the cavity to form a ridge waveguide transmission line structure.
[0011] The SSPPs structure consists of several periodic grooves etched longitudinally at intervals on the ridge of the ridge waveguide, and the periodic grooves are arranged longitudinally along the ridge waveguide to form SSPPs transmission segments.
[0012] The coupling aperture is located below the ridge waveguide of the main transmission line and is used to achieve coupling between the main transmission line and the secondary transmission line.
[0013] The ports include an input port, a through port, a coupling port, and an isolation port located at both ends of the metal cavity; the input port and the through port are located at both ends of the ridge waveguide of the main transmission line, and the coupling port and the isolation port are located at both ends of the secondary transmission line.
[0014] The working principle of this invention is as follows:
[0015] The signal enters the ridge waveguide main transmission line from the input port. The SSPPs structure selectively filters electromagnetic waves, allowing signals within the passband frequency range to pass through with low loss, while effectively suppressing signals within the stopband frequency range. The filtered signal propagates along the ridge waveguide to the coupling region, where a portion of the signal power is coupled to the secondary transmission line via the coupling structure and output from the coupling port; the remaining signal continues to propagate along the main transmission line and is output from the through port. By adjusting the size of the coupling aperture, the output power of the coupling port and the through port are made equal (i.e., 3 dB coupling), achieving equal power distribution. The isolation port is an isolation terminal and theoretically has no signal output.
[0016] The present invention has the following beneficial effects:
[0017] 1. For the first time, the integrated filtering and coupling functions of a ridge waveguide SSPPs structure have been achieved.
[0018] Existing research on ridge waveguide-based SSPPs mainly focuses on individual filter or coupler designs, lacking a technical solution that integrates filtering and coupling functions into a single ridge waveguide SSPPs structure. This invention integrates the SSPPs filtering structure and the 3 dB coupling structure within the same ridge waveguide cavity, simultaneously achieving bandpass filtering and equal power distribution on a single device. This eliminates the need for cascading independent devices, effectively reducing system connection losses and mismatch. This technical advantage is achieved through two key features: etching periodic rectangular blocks in the middle section of the ridge waveguide to form the SSPPs structure and placing coupling holes at the bottom of the ridge waveguide.
[0019] 2. Broadband operating characteristics
[0020] This invention employs a ridge waveguide as the transmission line, offering a wider single-mode operating band compared to traditional rectangular waveguides. Furthermore, the introduction of SSPPs (Special Selective Polarized Pulse Filters) allows for independent control of the upper and lower cutoff frequencies of the passband by adjusting the depth of the periodic grooves, achieving a broadband bandpass filtering response. The filter coupler of this invention also possesses broadband operating capability. This technical advantage is directly attributable to the combined features of the "ridge waveguide structure" and the "tunable dispersion of the SSPPs structure."
[0021] 3. Compact structure
[0022] This invention integrates filtering and coupling functions into a single cavity, eliminating the space occupied by cascaded ports and matching networks compared to schemes that use separate filters and couplers. The integrated design of this invention further reduces the device size. This technical advantage is directly derived from the technical feature of "integrating filtering and coupling functions into the same ridge waveguide SSPPs structure".
[0023] 4. Flexible design and controllable bandwidth
[0024] In this invention, the dispersive characteristics of the SSPPs structure can be flexibly controlled by adjusting the depth, width, and period of the groove, and the passband bandwidth can be tuned according to actual needs. This technical effect is directly brought about by the technical feature that "the geometric parameters of the periodic groove are easy to adjust for dispersion".
[0025] The filter coupler ultimately implemented in this invention achieves a low input return loss (|S) within the 4 GHz-4.6 GHz range. 11 Both are better than 16 dB, and the port isolation (|S) is better than 16 dB. 41 The performance is also better than 15.7 dB, with amplitude imbalance within the band within ± 0.5 dB. Suppression is better than 20 dB in the frequency range of 4.7 GHz to 7.6 GHz. Attached Figure Description
[0026] Figure 1The diagram shows the overall structure of the broadband filter coupler based on ridge waveguide SSPPs of the present invention; (a) is an exploded view; (b) is an actual structural diagram.
[0027] Figure 2 for Figure 1 A schematic diagram of the longitudinal section structure of the broadband filter coupler shown.
[0028] Figure 3 The effect of grating structure on the low cutoff frequency of filter passband;
[0029] Figure 4 This is a dispersion curve diagram of the SSPPs structure in this invention;
[0030] Figure 5 The above is a simulation curve of the S-parameters of the broadband filter coupler of the present invention.
[0031] Figure 6 This is a schematic diagram showing the specific dimensions of the broadband filter coupler based on ridge waveguide SSPPs of the present invention. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, this invention adopts the following technical solution.
[0033] like Figure 1 As shown in (a) and (b), this embodiment provides a broadband filter coupler based on ridge waveguide SSPPs, including a cavity 1, a ridge 2, a coupling hole 3, and four ports. The cavity 1 is an air cavity, which is surrounded by an aluminum alloy, so that the two cavities 1 form two independent structures. The cavity 1 has a length of 62.8 mm, a width of 35.7 mm, and a height of 18.9 mm.
[0034] like Figure 2 As shown, the ridge 2 is disposed inside the cavity 1 and extends longitudinally along the cavity. The ridge 2 is a solid structure made of aluminum alloy and is fixed to the aluminum alloy outside the cavity 1 by screws, thus maintaining a gap between the top of the ridge 2 waveguide and the top surface of the cavity 1, forming a ridge waveguide transmission line structure. The width of the ridge 2 waveguide is 8.57 mm and the height is 16.4 mm. The ridge 2 waveguide adopts a single-ridge structure, which has a wider single-mode operating bandwidth and a lower cutoff frequency compared to a rectangular waveguide.
[0035] The coupling hole 3 is located between the two cavities 1. In this embodiment, the coupling hole 3 is rectangular, 30 mm long and 9 mm wide. The coupling hole 3 is located in the strong field region directly below the ridge 2. By adjusting the size of the coupling hole 3, the coupling degree can be controlled by 3 dB. By designing the geometric parameters of the coupling hole 3, the output power of the coupling port 6 and the through port 5 are made equal, achieving equal power distribution.
[0036] The four ports are the input port 4, through port 5, coupling port 6, and isolation port 7 of the filter coupler.
[0037] The grating structure 8 is disposed on both sides of the cavity 1. The grating structure 8 is a periodic metal protrusion disposed along the side wall of the cavity. By increasing the length of the protrusion... The low cutoff frequency of the filter coupler passband can be adjusted. The protrusion of grating 81 is 12 mm long and 3 mm wide. The protrusion of grating 82 is 8 mm high and 3 mm wide. Grating 82 is symmetrically distributed along grating 81. Figure 3 The variation of the low cutoff frequency of the filter coupler as the length of grating 81 is given.
[0038] like Figure 2 As shown, the SSPPs structure 9 consists of several periodic grooves etched longitudinally at intervals on the ridge 2. Figure 2 As shown, in this embodiment, the grooves are rectangular grooves 91, arranged at equal intervals along the longitudinal direction of ridge 2. The depth of the rectangular grooves 91 is 14.2 mm, and the width is 1.8 mm. The periodic grooves arranged along the longitudinal direction of ridge 2 constitute an SSPPs transmission section. The SSPPs structure 9 has the characteristics of strong field constraint and adjustable dispersion. By adjusting the geometric parameters such as the depth, width, and period of the rectangular grooves 91, the dispersion characteristics of the SSPPs structure 9 can be controlled, thereby flexibly adjusting the passband range of the filter coupler. The SSPPs structure 9 is respectively set in the middle section and the two end sections of ridge 2. The middle section is a uniform SSPPs structure, that is, the geometric parameters of the rectangular grooves 91 are consistent; the two end sections are gradient SSPPs transition structures 92. The depth of the gradient SSPPs transition structure 92 increases gradually from the end to the middle. The transition structure has two levels of gradient, with the first level groove depth being 10.9 mm and the second level groove depth being 7.9 mm. The gradient SSPPs transition structure 92 achieves smooth impedance matching from the standard ridge waveguide to the SSPPs transmission section, reducing reflection loss in the passband.
[0039] The ports include an input port 4, a through port 5, a coupling port 6, and an isolation port 7 located at both ends of the cavity 1. Each port is an SMA type coaxial connector, with its inner conductor extending into the cavity and connecting to the ridge 2.
[0040] The working process of this embodiment is as follows:
[0041] The signal enters the main transmission line from input port 4. The tapered SSPPs transition structure 92 smoothly transitions the signal from the standard ridge waveguide mode to the SSPPs transmission mode. The SSPPs structure 9 is used to implement filtering, effectively suppressing signals in the stopband frequency range and achieving bandpass filtering.
[0042] The filtered signal propagates to the coupling region. Coupling aperture 3 couples a portion of the signal power from the main transmission line to the secondary transmission line, outputting from coupling port 6; the remaining signal continues to propagate along the main transmission line, outputting from through port 5. By designing the size of coupling aperture 3, the output power of coupling port 6 and through port 5 are made equal (i.e., 3 dB coupling), achieving equal power distribution. Isolation port 7 is an isolation terminal and theoretically has no signal output.
[0043] like Figure 6 As shown in the figure, the specific dimensions of the broadband filter coupler based on ridge waveguide SSPPs in this application are illustrated in the table below:
[0044]
[0045] like Figure 3 As shown, by reducing the length of the grating structure 82 The signal power S coupled to port 6 31 The gradually decreasing low cutoff frequency indicates that the bandwidth of the filter coupler is gradually increasing. Therefore, the bandwidth of the filter coupler can be adjusted by modifying this structure.
[0046] like Figure 4 As shown, by reducing the depth h1 of the rectangular slot 91, the dispersion characteristics of the SSPPs structure 9 can be changed, thereby increasing the high cutoff frequency of the filter coupler.
[0047] In summary, by adjusting the size of the grating structure 82 and the rectangular slot 91, the low and high cutoff frequencies of the filter coupler can be changed independently. Compared with other structures, it has flexibility, controllability, and is easy to achieve broadband.
[0048] Figure 5 The final performance of the filter coupler is shown, S 11 This represents the signal power reflected to port 4, S 21 This represents the signal power directly connected to port 5, S 31 This represents the signal power coupled to port 6, S 41 This indicates the signal power to port 7. Figure 5 (a) shows that the filtering characteristics of the filter coupler are better than 20 dB in the frequency range of 4.7 GHz - 7.6 GHz. Figure 5(b) shows the coupling characteristics of the filter coupler in the range of 4 GHz - 4.6 GHz, with input return loss (|S 11 Both are better than 16 dB, and the port isolation (|S) is better than 16 dB. 41 |) It is also better than 15.7 dB, with an amplitude imbalance within the band of ± 0.5 dB.
[0049] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A broadband filter coupler based on ridge waveguide SSPPs, characterized in that, Includes cavities, metal ridges, SSPPs periodic structures, coupling holes, and SMA ports; The cavity is an air cavity, surrounded by a shell, and electromagnetic waves are transmitted within the cavity; grating structures are disposed on both sides of the cavity; The metal ridge is disposed inside the cavity, and the ridge extends longitudinally along the cavity to form a ridge waveguide transmission line structure. The SSPPs structure consists of several periodic grooves etched longitudinally at intervals on the ridge of the ridge waveguide, and the periodic grooves are arranged longitudinally along the ridge waveguide to form SSPPs transmission segments. The coupling aperture is located below the ridge waveguide of the main transmission line and is used to achieve coupling between the main transmission line and the secondary transmission line. The ports include an input port, a through port, a coupling port, and an isolation port located at both ends of the cavity; the input port and the through port are located at both ends of the ridge waveguide of the main transmission line, and the coupling port and the isolation port are located at both ends of the secondary transmission line.
2. A broadband filter coupler based on ridge waveguide SSPPs according to claim 1, characterized in that, The groove is a rectangular groove.
3. A broadband filter coupler based on ridge waveguide SSPPs according to claim 1, characterized in that, By adjusting the depth, width, and period of the groove, the dispersion characteristics of the SSPPs structure can be controlled, thereby adjusting the bandwidth of the filter coupler.
4. A broadband filter coupler based on ridge waveguide SSPPs according to claim 1, characterized in that, The SSPPs structures are respectively disposed in the middle section and both ends of the ridge waveguide. The middle section is a uniform SSPPs structure, and the two ends are gradient SSPP transition structures. The groove depth of the gradient SSPP transition structure decreases gradually from the middle to both sides to achieve impedance matching from the standard ridge waveguide to the SSPP transmission section.
5. A broadband filter coupler based on ridge waveguide SSPPs according to claim 1, characterized in that, The degree of coupling can be controlled by adjusting the size of the coupling hole.
6. A broadband filter coupler based on ridge waveguide SSPPs according to claim 1, characterized in that, Each port is a coaxial connector, with its inner conductor extending into the cavity and connecting to the ridge waveguide.
7. A broadband filter coupler based on ridge waveguide SSPPs according to claim 1, characterized in that, The cavity and ridge are made of aluminum alloy.
8. A broadband filter coupler based on ridge waveguide SSPPs according to claim 1, characterized in that, The grating structure consists of periodic metal protrusions arranged along the sidewall of the cavity.
9. A broadband filter coupler based on ridge waveguide SSPPs according to claim 8, characterized in that, The bandwidth of the filter coupler can be adjusted by changing the length of the grating structure.
10. A broadband filter coupler based on ridge waveguide SSPPs according to claim 1, characterized in that, The ridge is a solid structure that is fixed to the outer shell of the cavity with screws.