Miniaturized wide-stop-band SIW filter for 5G / 6G communication application

Abstract

The invention discloses a miniaturized wide-stop-band SIW filter applied to 5G / 6G communication, and belongs to the technical field of microwaves. Comprising a first metal layer, a second dielectric layer, a third metal layer, a fourth dielectric layer, a fifth metal layer, a sixth dielectric layer, a seventh metal layer, an eighth dielectric layer, a ninth metal layer, at least one metal perturbation hole and a plurality of metal through holes, wherein the first metal layer to the fifth metal layer jointly form two one-eighth mold cavities, the fifth metal layer to the ninth metal layer jointly form two one-eighth mold cavities, and the fifth metal layer serves as a common metal layer, is provided with two coupling windows and is used for achieving coupling of the one-eighth mold cavity in the upper layer and the one-eighth mold cavity in the lower layer. Through an innovative cavity structure and a coupling mechanism, miniaturization of the filter is realized, the stop band width is widened, the suppression capability on out-of-band interference signals is enhanced, and the filter has the advantage of relatively low insertion loss.

Description

Technical Field

[0001] The present invention relates to a miniaturized wide-stopband substrate integrated waveguide (SIW) filter for 5G / 6G communication applications, belonging to the field of microwave technology. Background Art

[0002] In today's era of rapid technological advancement, 5G / 6G communication systems are being built and expanded at an unprecedented pace, placing stringent demands on the performance of RF microwave components. As a core component in RF transceiver front-end systems, the performance of filters directly determines the quality of system signal transmission. As communication technology continues to advance toward higher speeds, larger capacity, and lower latency, the modern information industry's expectations for RF microwave components are increasingly focused on features such as small size, high performance, and ease of integration. Filters are no exception.

[0003] Currently, existing filters have numerous deficiencies in size, bandwidth, and stopband performance, making them unable to meet the urgent demands of 5G / 6G communication systems for miniaturization, high integration, and out-of-band interference resistance. In terms of size, some traditional filters are relatively large due to limitations in structural design and manufacturing processes. This takes up excessive space within communication equipment, where space is at a premium. This not only increases the overall size and weight of the equipment, but also hinders its miniaturization and portability.

[0004] In terms of bandwidth performance, the passband and stopband performance of many existing filters is unsatisfactory. The passband bandwidth is too narrow to meet the multi-band, high-speed data transmission requirements of 5G / 6G communication systems, resulting in low signal transmission efficiency and affecting the user communication experience. For example, in some scenarios requiring simultaneous transmission of multiple frequency band signals, narrow passband filters will limit the number and speed of signal transmissions, causing communication problems such as lag and delay. Poor stopband performance means that out-of-band interference signals cannot be effectively suppressed. These interference signals can easily mix into the useful signal, reducing signal quality and reliability, and interfering with the normal operation of the communication system.

[0005] Based on the quarter-mode folded substrate integrated waveguide (FSIW) cavity structure (with the advantage of miniaturization), such as Figure 1 As shown in , the SIW is folded twice along the central symmetry plane, which can reduce the circuit area to one-fourth of the original without affecting the transmission performance of the waveguide. Figure 2 As shown in the figure, the quarter-mode folded SIW cavity contains three layers of metal and two layers of dielectric, wherein the third layer is a square patch, whose edges are connected to metal pillars on both sides to form a quarter-mode. Then, after replacing the square patch with a triangular patch, a one-eighth cavity I is obtained. Then, a gap is further etched in the triangular patch to obtain a one-eighth cavity II. Figure 3As shown, the filter based on the above structure also has the problem of insufficient passband and stopband.

[0006] In summary, in order to meet the development needs of 5G / 6G communication systems and their diverse application scenarios, there is an urgent need for a new filter design scheme that can achieve breakthroughs in size, bandwidth, and stopband performance, solve the many problems existing in existing filters, and provide strong support for the continuous advancement of communication technology. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention provides a miniaturized wide-stopband SIW filter for 5G / 6G communication applications. The present invention effectively solves the above-mentioned technical difficulties through innovative cavity structure and coupling mechanism. Among them, based on the one-eighth mode resonant cavity, the miniaturization of the filter is achieved (0.29λg×0.29λg); combined with high-frequency harmonic suppression technology, the stopband width is widened (20dB@3.73f0), and the ability to suppress out-of-band interference signals is enhanced; miniaturized SIW multi-cavity multi-mode coupling is adopted to flexibly control the 3dB passband bandwidth (16.4%), and the insertion loss is low (1.54dB), which can ensure the efficient transmission of the target frequency band signal. The present invention has the performance characteristics of miniaturization, wide passband and wide stopband, and provides a practical engineering solution for the miniaturization, high integration and out-of-band anti-interference needs of 5G / 6G communication systems.

[0008] The specific technical solutions adopted in the present invention are as follows:

[0009] A miniaturized wide-stopband SIW filter for 5G / 6G communication applications, characterized in that it includes a first metal layer, a second dielectric layer, a third metal layer, a fourth dielectric layer, a fifth metal layer, a sixth dielectric layer, a seventh metal layer, an eighth dielectric layer, a ninth metal layer, at least one metal perturbation hole, and a plurality of metal through-holes, which are stacked in sequence from top to bottom; wherein the metal perturbation hole is located on the diagonal of the filter, penetrates all dielectric layers from the first metal layer downward and is connected to the ninth metal layer; all metal through-holes penetrate all dielectric layers and metal layers from the first metal layer downward and are connected to the ninth metal layer; the first metal layer, the second dielectric layer, the third metal layer, the fourth dielectric layer, and the fifth metal layer together constitute two one-eighth cavities, and the fifth metal layer, the sixth dielectric layer, the seventh metal layer, the eighth dielectric layer, and the ninth metal layer together constitute two one-eighth cavities; the fifth metal layer, as a common metal layer, is provided with two coupling windows for achieving coupling between the upper one-eighth cavity and the lower one-eighth cavity.

[0010] Preferably, the coupling window is a trapezoidal coupling window.

[0011] Preferably, the third metal layer is two isosceles triangular metal patches symmetrically distributed along the diagonal line; the seventh metal layer is two isosceles triangular metal patches symmetrically distributed along the diagonal line; that is, the upper one-eighth mold cavity and the lower one-eighth mold cavity are both one-eighth mold cavity I.

[0012] Preferably, a proportionally reduced triangular groove is provided in the middle of the isosceles triangular metal patch in the third metal layer or the seventh metal layer; that is, the upper one-eighth mold cavity or the lower one-eighth mold cavity is improved to one-eighth mold cavity II.

[0013] Preferably, a coplanar waveguide input port and a coplanar waveguide output port are provided on the first metal layer.

[0014] Preferably, a section of a meandering microstrip line with the same structure is loaded at each of the coplanar waveguide input port and the coplanar waveguide output port to increase the coupling between the source and the load.

[0015] Preferably, the filter is prepared using a high temperature co-fired ceramic (HTCC) process.

[0016] Preferably, all dielectric layers are made of Al2O3 material with a thickness of 0.1 mm, a relative dielectric constant of 9.8 and a loss tangent of 0.0002.

[0017] The present invention has the following beneficial effects:

[0018] First, miniaturization. Based on a one-eighth mode folded SIW cavity structure, this invention effectively reduces the filter size while meeting performance indicators, meeting the high-integration requirements of modern communication systems. Compared with some existing filters, it has a significant size advantage.

[0019] Second, excellent out-of-band suppression capability. The present invention introduces a transmission zero by loading a meandering microstrip line and a metal perturbation hole to suppress high-frequency harmonics, thereby widening the stopband width, more effectively suppressing out-of-band interference signals, and improving the anti-interference performance of the communication system.

[0020] Third, good passband performance. The present invention adopts miniaturized SIW multi-cavity multi-mode coupling technology to achieve a wide 3dB passband bandwidth and low insertion loss, ensuring accurate screening and efficient transmission of target frequency band signals.

[0021] Fourth, process advantages: The present invention adopts the HTCC process and combines it with specific dielectric layer materials to improve the overall performance and integration of the filter, providing strong support for the miniaturization design of 5G / 6G communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1An exploded view of a conventional quarter-mold folded SIW cavity is shown to illustrate the basic structure of the folded SIW cavity.

[0023] Figure 2 The middle layers of three traditional folded SIW cavities are shown, where (a) is a quarter cavity, (b) is a one-eighth cavity I, and (c) is a one-eighth cavity II, reflecting the structural differences of different mode cavities.

[0024] Figure 3 The electric field distributions of three traditional folded SIW cavities are demonstrated, intuitively presenting the electric field distribution characteristics of cavities in different modes.

[0025] Figure 4 An exploded view of the fourth-order bandpass filter structure in an embodiment is shown.

[0026] Figure 5 The top view of each metal layer in the fourth-order bandpass filter structure in the embodiment is shown, where (a) is the first metal layer, (b) is the third metal layer, (c) is the fifth metal layer, and (d) is the seventh metal layer, clearly showing the structural layout of each layer of the filter.

[0027] Figure 6 The topology of a fourth-order bandpass filter is shown, which helps to understand the coupling mechanism of the filter.

[0028] Figure 7 The S parameters of the fourth-order bandpass filter simulation are displayed, which intuitively reflects the frequency response performance of the filter.

[0029] Explanation of the accompanying drawings: 1. First metal layer, 2. Second dielectric layer, 3. Third metal layer, 4. Fourth dielectric layer, 5. Fifth metal layer, 6. Sixth dielectric layer, 7. Seventh metal layer, 8. Eighth dielectric layer, 9. Ninth metal layer, 10. Metal through hole, 11. Metal perturbation hole, 12. Bent microstrip line, 13. Trapezoidal coupling window, 14. Triangular slot. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0031] In order to facilitate those skilled in the art to fully understand the technical solution of the present invention, the specific implementation methods of the present invention are now described in detail with reference to the accompanying drawings. It should be noted that the following examples are only used to illustrate the technical principles and implementation methods of the present invention, and do not constitute any limitation to the scope of protection of the present invention. Based on the basic principles of the present invention, any equivalent transformations or improvements made by those skilled in the art without paying creative labor should be included in the scope of protection of the present invention. In the specific description process, in order to avoid the redundant description of common knowledge affecting the understanding of the core technology of the present invention, some conventional technical details will be appropriately omitted.

[0032] The accompanying drawings of the embodiments of the present invention show schematic diagrams of the relevant structures. It should be noted that the illustrated contents are not drawn strictly to scale, some details are appropriately enlarged for clarity, and some non-critical details may be simplified. The functional areas, structural layers and their relative sizes and positional relationships shown in the figures are only schematic in nature. Reasonable deviations may exist in actual implementation due to process tolerances or technical conditions. Those skilled in the art can adaptively adjust the shape, size and spatial layout of the illustrated structure according to specific application requirements, and these reasonable variations should all fall within the scope of protection of the present invention.

[0033] This embodiment provides a miniaturized wide-stopband SIW filter for 5G / 6G communication applications. Figure 4 As shown, it includes a first metal layer, a second dielectric layer, a third metal layer, a fourth dielectric layer, a fifth metal layer, a sixth dielectric layer, a seventh metal layer, an eighth dielectric layer, a ninth metal layer, a metal perturbation hole and twenty metal through holes stacked in sequence from top to bottom.

[0034] The metal perturbation hole has a diameter of 0.211 mm, is located on the diagonal line of the filter, and the distance d5 between the center and the adjacent edge is 1.38 mm. It runs from the first metal layer downward through all dielectric layers to connect to the ninth metal layer.

[0035] The diameter of all metal through holes is 0.211 mm, and they penetrate all dielectric layers and metal layers from the first metal layer downward to connect to the ninth metal layer.

[0036] The first metal layer, the second dielectric layer, the third metal layer, the fourth dielectric layer and the fifth metal layer are square structures with a side length of L1 = 3.5 mm, and together constitute two one-eighth cavity I; wherein, a coplanar waveguide input port and a coplanar waveguide output port are provided on the first metal layer, and a section of bent microstrip line with the same structure is loaded at the ports of the coplanar waveguide input port and the coplanar waveguide output port to increase the coupling between the source and the load; the third metal layer is two isosceles triangular metal patches symmetrically distributed along the diagonal line.

[0037] The fifth metal layer, sixth dielectric layer, seventh metal layer, eighth dielectric layer and ninth metal layer are also square structures with a side length of L1 = 3.5 mm, and together constitute two one-eighth mold cavities II; among them, the seventh metal layer is two isosceles triangular metal patches symmetrically distributed along the diagonal, and a proportionally reduced triangular groove is provided in the middle.

[0038] The fifth metal layer serves as a common metal layer and is provided with two trapezoidal coupling windows for achieving coupling between the upper one-eighth mold cavity I and the lower one-eighth mold cavity II.

[0039] Specifically, if Figure 5 As shown, the dimensions in this embodiment are: L2=2.49mm, L3=1mm, s1=1.7mm, s2=0.28mm, s3=0.29mm, s4=1.1mm, s5=0.13mm, s6=3.14mm, s7=0.4mm, s8=0.1mm, s9=1.97mm, s 10 =0.15mm,s 11 =0.4mm, d1=1.7mm, d2=0.33mm, d3=0.44mm, d5=1.38mm, m1=0.48mm, m2=0.42mm, m3=2.23mm, m4=0.62mm, m5=0.4mm, m6=2.02mm.

[0040] The topology of the fourth-order bandpass filter in the embodiment of the present invention is as follows: Figure 6 As shown, resonant nodes 1, 2, 3, and 4 are all one-eighth modes. Because the seventh layer etches triangular grooves on the isosceles triangular patch, the resonant frequencies of resonant nodes 3 and 4 are different from those of resonant nodes 1 and 2. Furthermore, in the horizontal direction, magnetic field coupling dominates resonant nodes 1 and 2 (or resonant nodes 3 and 4); in the vertical direction, electric field coupling dominates resonant nodes 1 and 3 (or resonant nodes 2 and 4). Furthermore, a curved microstrip line is added to increase the coupling between the source and the load. In summary, based on the above topology, multiple zeros can be generated out of band.

[0041] The fourth-order bandpass filter in the implementation case is simulated and calculated based on the finite element commercial electromagnetic simulation software ANSYS Electronics 2021R1. The results are as follows: Figure 7 shown.

[0042] refer to Figure 7 , the horizontal axis represents frequency, and the vertical axis represents S parameters. As can be seen from the simulation result graph, the center frequency f0 of the filter is 6.8GHz, the 3dB passband bandwidth is 16.4%, and the minimum insertion loss is 1.54dB, which can ensure the efficient transmission of the target frequency band signal. Moreover, the filter has two transmission poles and three transmission zeros, and the three zeros are located at 10.2GHz, 12.8GHz and 15.3GHz. At a frequency of 25.35GHz (3.73f0), the S21 level is lower than -20dB, indicating that the filter has a wide stopband and can effectively block interference signals.

[0043] In summary, the present invention proposes a substrate-integrated waveguide (SIW) filter design based on a high-temperature co-fired ceramic (HTCC) process. This design combines the high-Q characteristics of the SIW structure with the three-dimensional integration advantages of the HTCC process, achieving performance indicators of miniaturization (0.29λg × 0.29λg), wide passband (16.4%), and wide stopband (20dB@3.73f0), strongly supporting the miniaturization, high integration, and out-of-band interference mitigation requirements of 5G / 6G communication systems.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A miniaturized wide-stopband SIW filter for 5G / 6G communication applications, characterized in that: It includes a first metal layer, a second dielectric layer, a third metal layer, a fourth dielectric layer, a fifth metal layer, a sixth dielectric layer, a seventh metal layer, an eighth dielectric layer, a ninth metal layer, at least one metal perturbation hole and a plurality of metal through holes, which are stacked in sequence from top to bottom; wherein the metal perturbation hole is located on the diagonal of the filter, penetrates all dielectric layers from the first metal layer downward and is connected to the ninth metal layer; all metal through holes penetrate all dielectric layers and metal layers from the first metal layer downward and are connected to the ninth metal layer; the first metal layer, the second dielectric layer, the third metal layer, the fourth dielectric layer and the fifth metal layer together constitute two one-eighth mold cavities, and the fifth metal layer, the sixth dielectric layer, the seventh metal layer, the eighth dielectric layer and the ninth metal layer together constitute two one-eighth mold cavities; the fifth metal layer, as a common metal layer, is provided with two coupling windows for realizing the coupling between the upper one-eighth mold cavity and the lower one-eighth mold cavity.

2. A miniaturized wide-stopband SIW filter for 5G / 6G communication applications according to claim 1, characterized in that: The coupling window is a trapezoidal coupling window.

3. A miniaturized wide-stopband SIW filter for 5G / 6G communication applications according to claim 2, characterized in that: The third metal layer is composed of two isosceles triangle metal patches symmetrically distributed along a diagonal line; the seventh metal layer is composed of two isosceles triangle metal patches symmetrically distributed along a diagonal line.

4. A miniaturized wide-stopband SIW filter for 5G / 6G communication applications according to claim 3, characterized in that: A proportionally reduced triangular groove is provided in the middle of the isosceles triangular metal patch in the third metal layer or the seventh metal layer.

5. A miniaturized wide-stopband SIW filter for 5G / 6G communication applications according to claim 3 or 4, characterized in that: A coplanar waveguide input port and a coplanar waveguide output port are provided on the first metal layer.

6. A miniaturized wide-stopband SIW filter for 5G / 6G communication applications according to claim 5, characterized in that: The ports of the coplanar waveguide input port and the coplanar waveguide output port are respectively loaded with a section of a bent microstrip line with the same structure to increase the coupling between the source and the load.

7. A miniaturized wide-stopband SIW filter for 5G / 6G communication applications according to claim 6, characterized in that: The filter is prepared by adopting a high-temperature co-fired ceramic process.

8. A miniaturized wide-stopband SIW filter for 5G / 6G communication applications according to claim 7, characterized in that: All dielectric layers are made of Al2O3 material with a thickness of 0.1 mm, a relative dielectric constant of 9.8 and a loss tangent of 0.0002.

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