Millimeter wave gap waveguide adjustable filter and communication system

Abstract

The invention discloses a millimeter wave gap waveguide adjustable filter and a communication system. The millimeter wave gap waveguide adjustable filter comprises a bottom metal plate, an upper metal plate and a coupling combined metal convex body structure, combined metal convex bodies which are periodically arranged are arranged on the two sides of the bottom metal plate, a channel is formed between the combined metal convex bodies which are periodically arranged on the two sides, the upper metal plate is a smooth metal plate, the multiple sets of coupling combined metal convex body structures are arranged on the upper metal plate through sliding metal rods, and the multiple sets of coupling combined metal convex body structures are located in the channel. The bottom metal plate and the upper metal plate are arranged in parallel at an interval of d to form a non-contact gap structure, and a plurality of resonant cavities are formed between the bottom metal plate and the upper metal plate. The design of a full-tuning adjustable filter with adjustable center frequency and adjustable bandwidth is realized in a millimeter wave band.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave gap waveguides, and in particular relates to a gap waveguide tunable filter and a communication system. Background Art

[0002] Gap waveguide technology has become a research hotspot in the field of filter design due to its superior high-frequency characteristics. Gap waveguides use the air gaps between metal waveguides to effectively reduce signal loss, and are particularly suitable for millimeter-wave and higher frequency working environments. In the millimeter-wave / terahertz frequency band, electromagnetic energy is highly concentrated in the air gap for propagation, which not only suppresses the conductor loss caused by the skin effect, but also gets rid of the high-frequency dielectric loss limitation of the dielectric material, significantly improving the signal transmission efficiency. Compared with traditional metal cavities or microstrip line structures, this technology forms an equivalent "field constraint fence" through a precisely designed electromagnetic band grid, which can localize the electromagnetic field without a physical metal wall, so that the filter still has excellent high-frequency selectivity and stopband suppression capabilities in a miniaturized size. At the same time, the all-metal modular design enhances the environmental robustness of the device. Compared with traditional waveguides, gap waveguide filters can achieve efficient signal filtering in a smaller volume and are widely used in high-frequency radar systems, 5G communications, satellite communications and other fields.

[0003] As the spectrum becomes increasingly tight, the demand for flexible and adjustable filters is gradually increasing. Especially in dynamically changing wireless environments, adjustable filters that can adjust frequency characteristics according to actual needs and provide more efficient signal processing and more precise filtering effects become particularly important.

[0004] The gap waveguide filter in the prior art is usually fixed in frequency and cannot flexibly adjust the operating frequency according to system requirements. Therefore, designing an adjustable filter that can not only utilize the excellent high-frequency characteristics of the gap waveguide but also adjust the frequency during operation has become a technical problem that needs to be solved urgently.

[0005] In the existing domestic technology, the Chinese patent with publication number CN116130906A discloses a gap waveguide filter with adjustable passband in the Ka band, but it only realizes adjustable bandwidth and the return loss S11 can only reach 10dB, and does not involve the tuning design of adjustable center frequency and fully tuned filter. Therefore, there is a lack of low-loss gap waveguide flange in the millimeter wave band. Summary of the invention

[0006] The present invention provides a novel millimeter-wave gap waveguide tunable filter to solve the problem of the inability to flexibly adjust the operating frequency in the above-mentioned millimeter-wave signal transmission, thereby meeting the requirements for fast and stable separation of different frequency signals in the communication system. The present invention provides a novel millimeter-wave gap waveguide tunable filter with the advantages of high operating frequency band, wide adjustment range, simple adjustment method, simple structure, etc.

[0007] To achieve the above-mentioned purpose, the present invention provides a millimeter-wave gap waveguide tunable filter, comprising a bottom metal plate, an upper metal plate and a coupled combined metal convex structure; periodically arranged combined metal convex bodies are arranged on both sides of the bottom metal plate, and a channel is formed between the periodically arranged combined metal convex bodies on both sides, the upper metal plate is a smooth metal plate, and multiple groups of coupled combined metal convex structures are arranged on the upper metal plate through sliding metal rods, and the multiple groups of coupled combined metal convex structures are located in the channel, the bottom metal plate and the upper metal plate are arranged in parallel with a spacing d to form a non-contact gap structure, and multiple resonant cavities are formed between the bottom metal plate and the upper metal plate.

[0008] Furthermore, the metal protrusions in the periodically arranged combined metal protrusions are all cuboids, and their sizes and structures are completely the same, and their lateral spacing and longitudinal spacing are the same.

[0009] Furthermore, the size, number and periodic spacing p of the metal protrusions of the periodically arranged combined metal protrusions are adjusted according to the designed operating frequency, size and order of the filter, and are closely surrounded on both sides of the designed filter.

[0010] Furthermore, the width and height of the resonant cavity are consistent with the standard waveguide port size of the filter operating frequency band, and the width and height of the corresponding resonant cavity are selected according to the frequency band of the designed filter; the resonant frequency of each resonant cavity is controlled only by controlling the length h of multiple resonant cavities, thereby controlling the center frequency of the filter, and the cavity resonant frequency is obtained according to the center frequency of the designed filter, thereby obtaining the initial cavity length, and after the cavity is connected, the lengths of different resonant cavities are adjusted according to the filter simulation results to meet the coupling.

[0011] Further, the spacing d between the bottom metal plate and the upper metal plate is smaller than a quarter wavelength corresponding to the operating frequency. Furthermore, sliding gaps are provided at both ends of the sliding metal rod, and the upper metal plate passes through the sliding gaps.

[0012] Furthermore, the coupled combined metal convex structure is set to two structures: a structure with no convex body in the middle and a full convex body structure. The structure with no convex body in the middle corresponds to stronger coupling, and the full convex body structure corresponds to weaker coupling. The corresponding structure is selected according to the coupling coefficient between each cavity of the designed filter and the external Q value.

[0013] Furthermore, the sizes of the multiple resonant cavities are changed by coupling the positions of the combined metal convex structures, and the coupling coefficients between the cavities are changed by controlling the distances between adjacent coupled combined metal convex structures.

[0014] Furthermore, the bottom metal plate and the upper metal plate are connected via waveguide flanges at both ends.

[0015] The present invention can also provide a high-frequency radar system, a 5G communication system or a satellite communication system, which adopts the above-mentioned millimeter-wave gap waveguide tunable filter.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The millimeter-wave gap waveguide tunable filter provided by the present invention realizes electromagnetic shielding through an electromagnetic bandgap structure in the form of a bottom metal plate and an upper metal plate, reduces electromagnetic leakage caused by an assembly gap, and reduces assembly sealing requirements; at the same time, the air gap of the electromagnetic bandgap structure provides conditions for the sliding of a coupled combined metal convex structure, and the sliding coupled combined metal convex structure realizes simple tuning of the filter; and a tunable filter design with adjustable center frequency, adjustable bandwidth, and full tuning is realized in the millimeter-wave band, and has the advantages of a wide adjustment range, a simple adjustment method, and a simple structure.

[0017] Furthermore, the periodically arranged metal structure generates an electromagnetic band gap in the set target frequency band, effectively suppressing the propagation of electromagnetic waves of the set target frequency. The symmetry of the lateral and longitudinal spacing makes this band gap consistent in multiple directions. The symmetrical spacing and repeated structure can achieve uniform distribution of heat and avoid local hot spots. Compared with the traditional rectangular waveguide filter, the metal protrusions and air gaps on both sides of the millimeter-wave gap waveguide tunable filter replace the closed metal thick wall, allowing heat to escape from both sides, which is suitable for applications with higher operating frequencies and higher power capacity density.

[0018] Furthermore, the size (such as height and width) and periodic spacing p of the periodically arranged metal protrusions directly affect the frequency range of their electromagnetic shielding band gap. By adjusting the size, the center frequency and stopband range of the filter's operating frequency band can be accurately included, and electromagnetic leakage to both sides can be suppressed in the filter's operating frequency band; its periodic spacing p controls the electromagnetic coupling strength between the metal protrusions. Reducing p can enhance coupling and widen the filter bandwidth; increasing p can reduce parasitic coupling and reduce in-band insertion loss; dynamically adjusting the arrangement of the convex array according to the filter size can maximize the use of the edge area in a limited space and avoid volume redundancy of other matching structures or transition structures. It is suitable for miniaturized RF systems and reduces electromagnetic losses.

[0019] Furthermore, the resonant cavity is consistent with the size of the standard waveguide port, ensuring a continuous impedance transition of the electromagnetic wave from the waveguide to the cavity, significantly reducing interface reflection and thus reducing insertion loss; matching the standard waveguide size can suppress the excitation of higher-order modes, ensuring the single-mode working state of the main mode, and avoiding passband distortion caused by parasitic resonance; when the waveguide port is consistent with the cavity size, the electromagnetic field is distributed more evenly, reducing local overheating.

[0020] Furthermore, after removing the middle convex body, the direct overlapping area of ​​the electromagnetic fields between adjacent resonant cavities increases, and a high coupling coefficient is achieved through edge field strength coupling, which is suitable for broadband filter design; the full convex body structure limits the field leakage between cavities through the electromagnetic shielding effect of the metal convex body, reduces the coupling coefficient, and is suitable for narrowband high-selectivity filters; in addition, the convex body structure can also serve as a heat sink fin, reducing the temperature rise of the cavity through the heat conduction path of the metal convex body. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solution in the present invention, the following briefly introduces the drawings required for use in the description of the invention; obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 The side cross-sectional view of the millimeter-wave gap waveguide tunable filter proposed by the present invention is schematically shown; Figure 2 The schematic diagram of the top cross-section of the millimeter-wave gap waveguide tunable filter (without the upper metal plate and the sliding metal rod) proposed by the present invention is shown; Figure 3 A perspective stereoscopic diagram of the millimeter wave gap waveguide tunable filter (without the combined metal convex body of the bottom metal plate) proposed by the present invention is schematically shown; Figure 4 a schematically shows a structure diagram of a millimeter-wave gap waveguide tunable filter proposed by the present invention, in which there is no convex structure in the middle of the coupled combined metal convex structure; Figure 4 b schematically shows a schematic structural diagram of a coupled combined metal convex structure and a full convex structure in the millimeter wave gap waveguide tunable filter proposed by the present invention; Figure 5 A schematic diagram showing the top-view cross-sectional structural relationship between a coupled combined metal convex structure and a plurality of resonant cavities in the millimeter-wave gap waveguide tunable filter proposed by the present invention is shown; Figure 6 The schematic diagram shows the simulation results of the millimeter wave gap waveguide tunable filter and the center frequency tunable filter proposed by the present invention; Figure 7 The schematic diagram shows the simulation results of the millimeter wave gap waveguide tunable filter and the bandwidth tunable filter proposed by the present invention; Figure 8 The schematic diagram shows the simulation results of the millimeter wave gap waveguide tunable filter and the fully tuned filter proposed in the present invention; In the attached drawings, 1-bottom metal plate, 2-upper metal plate, 3-coupled combined metal convex structure, 31-middle non-convex structure, 32-full convex structure, 4-periodically arranged combined metal convex, 5-resonant cavity. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The structural forms and arrangements described in the following specific examples are only used to concisely express the present invention. They are only examples and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings: Example 1, reference Figure 1 and Figure 2 The adjustable gap waveguide filter disclosed in the embodiment of the present invention comprises a bottom metal plate 1, an upper metal plate 2 and a coupled combined metal convex structure 3. Periodically arranged combined metal convex bodies 4 are arranged on both sides of the bottom metal plate 1, and a channel is formed between the periodically arranged combined metal convex bodies 4 on both sides; the upper metal plate 2 is a smooth metal surface, and the bottom metal plate 1 and the upper metal plate 2 are arranged in parallel with a spacing d to form a non-contact gap structure. The bottom metal plate 1, the upper metal plate 2, and the coupled combined metal convex structure 3 are connected to each other to obtain multiple resonant cavities 5 of the filter.

[0026] The width b and height a of each resonant cavity 5 are consistent with the standard waveguide port size of the filter operating frequency band. The width and height of the corresponding resonant cavity are selected according to the frequency band of the designed filter. The resonant frequency of each resonant cavity is controlled only by controlling the length h of multiple resonant cavities, thereby controlling the center frequency of the filter. The cavity resonant frequency is obtained according to the center frequency of the designed filter, thereby obtaining the initial cavity length. After the cavities are connected, the lengths of different resonant cavities are adjusted according to the filter simulation results to meet the coupling.

[0027] Example 2, as an optional structure, refer to Figure 4 , 180° bending structures are provided at both ends of the sliding metal rod 6, and a sliding gap is formed between the 180° bending structures and the body of the sliding metal rod 6. 90° bending structures can also be provided at both ends of the sliding metal rod 6, and screws or pins are provided on the 90° bending structures. The 90° bending structures and the 180° bending structures are integrally formed with the sliding metal rod 6.

[0028] Based on the above embodiments, Figure 3 The coupled metal convex structure 3 can be controlled to slide freely on the upper metal plate 2. The coupled metal convex structure 3 includes two rows of metal convex bodies, and the two rows of metal convex bodies can slide separately. By controlling the positions of the two rows of metal convex bodies, the length h of the resonant cavity 5 is changed, thereby changing the center frequency of the filter; by controlling the distance g between two adjacent rows of metal convex bodies, the coupling coefficient between the cavities is changed.

[0029] refer to Figure 4 a. Figure 4 b. The coupled combined metal convex structure 3 is provided with two structures: a structure 31 without a convex body in the middle and a structure 32 with full convex bodies, that is, a plurality of metal convex bodies with no metal convex body in the center and symmetrical left and right are provided on the sliding metal rod 6 or a plurality of metal convex bodies are evenly arranged; the structure 31 without a convex body in the middle corresponds to a stronger coupling, and the structure 32 with full convex bodies corresponds to a weaker coupling, and the corresponding structure is selected according to the coupling coefficient between each cavity of the designed filter and the external Q value; it should be noted that the stronger coupling and the weaker coupling are the relative strengths of the two situations and do not involve quantitative description. The number of metal convex bodies in the structure 31 without a convex body in the middle and the structure 32 with full convex bodies is related to the cavity width of the corresponding frequency band and the size of the metal convex body.

[0030] The millimeter wave gap adjustable waveguide filter described in this embodiment uses a gap waveguide filter with a center frequency of f0 and a 20dB bandwidth of 500MHz as the center standard of the adjustable filter, and the insertion loss of the filter at the center frequency f0 is 0.3dB. Figure 5As shown, the millimeter-wave gap adjustable waveguide filter described in this embodiment is a third-order filter, plus an external coupling cavity, with a total of 5 cavities, namely a first external coupling cavity 51, a first filter cavity 52, a second filter cavity 53, a third filter cavity 54 and a second external coupling cavity 55; two groups of full convex structures 32 are arranged in the middle, and the spacing between the full convex structures 32 is the second spacing g23 and the third spacing g34 respectively, and two groups of middle non-convex structures 31 are arranged at both ends, and the spacing between the middle non-convex structures 31 is the first spacing g12 and the fourth spacing g45 respectively. The first spacing g12 of the two rows of metal convex bodies 311 on the middle non-convex body structure 31 controls the coupling between the first external coupling cavity 51 and the first filter cavity 52, and the fourth spacing g45 controls the coupling between the third filter cavity 54 and the second external coupling cavity 55; the second spacing g23 of the two rows of metal convex bodies 321 on the full convex body structure 32 controls the coupling between the first filter cavity 52 and the cavity 53, and the third spacing g34 controls the coupling between the second filter cavity 53 and the third filter cavity 54; and due to the symmetry of the filter, the first spacing g12 is equal to the fourth spacing g45, and the second spacing g23 is equal to the third spacing g34. Figure 6 As shown, the center frequency adjustment simulation comparison of this embodiment with the center standard filter as the reference is adjusted by 300MHz (the adjustment range is not limited to 300MHz), and the in-band insertion loss is better than 0.55dB, but the return loss is worsened by reducing the center frequency; Figure 7 As shown in FIG. 1 , the embodiment realizes partial bandwidth adjustment simulation comparison based on the central standard filter, and realizes filters with bandwidth reduced by 73MHz and bandwidth increased by 84MHz, respectively, indicating that the embodiment can maintain good transmission performance within a wider central frequency and bandwidth adjustment range. Figure 8 As shown, the embodiment uses the central standard filter as a reference to realize a partial simulation comparison of a fully tuned filter with adjustable center frequency and bandwidth, realizing a filter with a center frequency increased by 359MHz and a bandwidth reduced from 500MHz to 355MHz, indicating that the embodiment can achieve full tuning through a variety of adjustment methods to meet different requirements of signal separation in the communication system. The present invention provides a millimeter-wave gap waveguide tunable filter with the advantages of high operating frequency band, wide adjustment range, simple adjustment method, simple structure, etc.

[0031] Based on the above structure, the present invention can confirm the order and coupling coefficient of the adjustable filter according to the design parameter requirements. Different adjustable filters select different numbers and types of coupled combined metal convex structures 3 and resonant cavities 5 according to different orders and coupling coefficients. The sizes of multiple resonant cavities 5 are changed by the positions of the coupled combined metal convex structures 3, and the coupling coefficients between cavities are changed by controlling the distances between adjacent coupled combined metal convex structures 3. The middle non-convex structure 31 corresponds to a stronger coupling, and the full convex structure 32 corresponds to a weak coupling. The structure of the coupled combined metal convex structure 3 is selected according to the coupling coefficient between each cavity of the designed filter and the external Q value; the size, number and periodic spacing p of the metal convex bodies of the periodically arranged combined metal convex bodies 4 are adjusted according to the designed filter operating frequency, size and order.

[0032] In summary, the present invention provides a millimeter-wave gap waveguide tunable filter, comprising a bottom metal plate 1, an upper metal plate 2 and a coupled combined metal convex structure 3; periodically arranged combined metal convex bodies 4 are arranged on both sides of the bottom metal plate 1, and a channel is formed between the periodically arranged combined metal convex bodies 4 on both sides, the upper metal plate 2 is a smooth metal plate, and multiple groups of coupled combined metal convex structures 3 are slidably arranged on the upper metal plate 2; multiple groups of coupled combined metal convex structures 3 are arranged on the upper metal plate 2 through sliding metal rods 6, and multiple groups of coupled combined metal convex structures 3 are located in the channel, the bottom metal plate 1 and the upper metal plate 2 are arranged in parallel with a spacing d to form a non-contact gap structure, and multiple resonant cavities 5 are formed between the bottom metal plate 1 and the upper metal plate 2; the coupled combined metal convex structure can slide on the upper metal plate to change the resonant frequency of the multiple resonant cavities and the coupling between the cavities. The millimeter-wave gap waveguide tunable filter provided by the present invention has a high operating frequency band, a wide adjustment range, a simple adjustment method, and a simple structure; and realizes a tunable filter design with adjustable center frequency, adjustable bandwidth, and full tuning in the millimeter-wave band.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, such as adjusting the size of the metal protrusions, changing the shape of the nail bed, selecting the number, size and arrangement of the filter cavities, selecting the coupling metal protrusion structure, selecting different mechanical position control methods, etc. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A millimeter wave gap waveguide tunable filter, characterized in that: The invention comprises a bottom metal plate (1), an upper metal plate (2) and a coupled combined metal convex structure (3); periodically arranged combined metal convex bodies (4) are arranged on both sides of the bottom metal plate (1); a channel is formed between the periodically arranged combined metal convex bodies (4) on both sides; the upper metal plate (2) is a smooth metal plate; a plurality of groups of coupled combined metal convex structures (3) are arranged on the upper metal plate (2) via sliding metal rods (6); the plurality of groups of coupled combined metal convex structures (3) are located in the channel; the bottom metal plate (1) and the upper metal plate (2) are arranged in parallel at a spacing d to form a non-contact gap structure; and a plurality of resonant cavities (5) are formed between the bottom metal plate (1) and the upper metal plate (2).

2. The millimeter wave gap waveguide tunable filter according to claim 1, characterized in that: The metal protrusions in the periodically arranged combined metal protrusions (4) are all rectangular parallelepipeds, and their sizes and structures are completely the same, and their lateral spacing and longitudinal spacing are the same.

3. The millimeter wave gap waveguide tunable filter according to claim 2, characterized in that: The size, number and periodic spacing p of the metal protrusions of the periodically arranged combined metal protrusions (4) are adjusted according to the operating frequency, size and order of the designed filter, and are closely surrounded on both sides of the designed filter.

4. The millimeter wave gap waveguide tunable filter according to claim 1, characterized in that: The widths and heights of the multiple resonant cavities (5) are consistent with the standard waveguide opening dimensions of the corresponding working frequency band of the filter, and the width and height of the corresponding resonant cavity (5) are selected according to the frequency band of the designed filter.

5. The millimeter wave gap waveguide tunable filter according to claim 1, characterized in that: The distance d between the bottom metal plate (1) and the upper metal plate (2) is less than a quarter wavelength corresponding to the operating frequency.

6. The millimeter wave gap waveguide tunable filter according to claim 1, characterized in that: Sliding gaps are provided at both ends of the sliding metal rod (6), and the upper metal plate (2) passes through the sliding gaps.

7. The millimeter wave gap waveguide tunable filter according to claim 1, characterized in that: The coupled combined metal convex structure (3) is provided with two structures: a structure without a convex body in the middle (31) and a structure with a full convex body (32); the structure without a convex body in the middle (31) corresponds to a stronger coupling, and the structure with a full convex body (32) corresponds to a weaker coupling, and the corresponding structure is selected according to the coupling coefficient between each cavity of the designed filter and the external Q value.

8. The millimeter wave gap waveguide tunable filter according to claim 7, characterized in that: The sizes of the plurality of resonant cavities (5) are changed by coupling the positions of the combined metal convex structures (3), and the coupling coefficients between the cavities are changed by controlling the distances between adjacent coupled combined metal convex structures (3).

9. The millimeter wave gap waveguide tunable filter according to claim 1, characterized in that: The bottom metal plate (1) and the upper metal plate (2) are connected via waveguide flanges at both ends.

10. A communication system, characterized in that: For a high-frequency radar system, a 5G communication system or a satellite communication system, a millimeter-wave gap waveguide tunable filter as described in any one of claims 1 to 9 is used.

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