Dual-band filter

Abstract

The dual-band filter comprises a feed layer, a ground layer and a dielectric substrate, the dielectric substrate is arranged between the feed layer and the ground layer, the dielectric substrate is provided with a first conductive structure and a second conductive structure, the first conductive structure is electrically connected with the feed layer and the ground layer, and the second conductive structure is electrically connected with the ground layer. The second conductive structure is electrically connected with the feed layer and the ground layer to change the electric field formed by the first conductive structure. The second conductive structure is added in the resonant cavity, and the electric field distribution is changed by using the disturbance effect of the second conductive structure on the electric field, so that the dual-band filtering function is realized, the overall size of the filter is reduced, and the overall design of the filter is simplified.

Description

Technical Field

[0001] This application relates to the field of Internet of Things (IoT) technology, and in particular to a dual-band filter. Background Technology

[0002] Dual-band filters are widely used electronic devices that can process signals across multiple frequency bands simultaneously. In related technologies, dual-band filters typically employ cascaded multiple single-frequency resonant cavities, leading to increased filter size and issues such as crosstalk between cavities and poor isolation between passbands. Furthermore, these technologies often utilize multilayer low-temperature co-fired ceramics or precision metal waveguides, resulting in high manufacturing difficulty and cost. Summary of the Invention

[0003] In view of this, this application provides a dual-band filter that uses a single resonant cavity to achieve dual-band filtering function, simplifying the overall filter design.

[0004] In a first aspect, this application provides a dual-band filter, comprising: Feed layer; Strata; and A dielectric substrate is disposed between the feed layer and the ground layer. The dielectric substrate has a first conductive structure and a second conductive structure. The first conductive structure is electrically connected to the feed layer and the ground layer, and the second conductive structure is electrically connected to the feed layer and the ground layer to change the electric field formed by the first conductive structure.

[0005] In this embodiment, a resonant cavity is formed by the feed layer, the dielectric substrate, the ground layer, and a first conductive structure disposed in the dielectric substrate. The first conductive structure is used to constrain the propagation of electromagnetic waves within the SIW resonant cavity to form a stable electric field. By adding a second conductive structure to the resonant cavity, the electric field is disturbed by the second conductive structure, changing the transverse electric mode (TE mode) of the electric field. This causes the TE mode to separate into at least two electromagnetic modes with different resonant frequencies, forming a first passband and a second passband. This achieves dual-band filtering, reduces the overall size of the filter, and simplifies the overall filter design.

[0006] In some embodiments of this disclosure, the first conductive structure encloses a predetermined area, and the second conductive structure is disposed within the predetermined area.

[0007] In this embodiment, the predetermined area enclosed by the first conductive structure is the electric field distribution area, and the second conductive structure is specifically arranged in the predetermined area to directly disturb the electric field and avoid ineffective disturbance.

[0008] In some embodiments of this disclosure, the predetermined area is circular or polygonal.

[0009] In some embodiments of this disclosure, the predetermined region is a regular polygon, and the second conductive structure is arranged along at least one diagonal of the regular polygon.

[0010] In some embodiments of this disclosure, the predetermined region is rectangular, and the second conductive structure is arranged along one diagonal of the rectangle.

[0011] In this embodiment, the diagonal is the strong field region of the main mode electric field distribution in the cavity. Setting a second conductive structure on the diagonal can maximize the disturbance effect on the electric field.

[0012] In some embodiments of this disclosure, the first conductive structure includes a plurality of first metallized vias arranged at intervals between each other, and the second conductive structure includes a plurality of second metallized vias arranged at intervals between each other.

[0013] In this embodiment, metallized vias are used as perturbation structures to improve setup flexibility and simplify filter structure.

[0014] In some embodiments of this disclosure, a plurality of the second metallized vias are arranged linearly.

[0015] In this embodiment, multiple second metallized vias are arranged sequentially along a specific straight line direction within a predetermined area to form a linear perturbation array. By directionally enhancing the perturbation of the electric field in a specific direction, efficient separation of dual-frequency modes is achieved.

[0016] In some embodiments of this disclosure, the plurality of second metallized vias include a central via and side vias located on both sides of the central via, wherein the cross-sectional area of ​​the central via is larger than the cross-sectional area of ​​the side vias.

[0017] In this embodiment, the large cross-sectional area of ​​the central via can generate strong disturbances in the strong field peak region, while the small cross-sectional area of ​​the side vias generates weak disturbances in the medium field strength region, thus achieving precise adaptation to the strong field gradient.

[0018] In some embodiments of this disclosure, the cross-sectional area of ​​the side via decreases in the direction away from the central via.

[0019] In this embodiment, the cross-sectional area of ​​the side via gradually decreases along the direction away from the central via, which is synchronized with the attenuation law of the electric field strength from the center to the edge, so as to achieve precise adaptation to disturbances in electric field regions of different intensities.

[0020] In some embodiments of this disclosure, the plurality of second metallized vias include a central via and side vias located on both sides of the central via, wherein the distance between the central via and its adjacent side via is greater than the distance between adjacent side vias.

[0021] In some embodiments of this disclosure, the number of side vias on both sides of the central via is the same.

[0022] In some embodiments of this disclosure, there is one central via, and each side of the central via has two side vias.

[0023] In some embodiments of this disclosure, the first conductive structure includes a plurality of first metallized vias arranged at intervals from each other, and the predetermined area enclosed by the plurality of first metallized vias is rectangular; The second conductive structure includes a plurality of second metallized vias arranged at intervals from each other, the plurality of second metallized vias being arranged at intervals from each other along one diagonal of the rectangle; The spacing between two adjacent first metallized vias located at the middle of the first side of the rectangle and the spacing between two adjacent first metallized vias located at the middle of the second side of the rectangle are greater than the spacing between the remaining adjacent first metallized vias, and the first side and the second side are opposite to each other.

[0024] In some embodiments of this disclosure, the feed layer is provided with at least one slot extending along the thickness direction of the feed layer.

[0025] In this embodiment, the current path of the feed layer is changed by the slot, which further disturbs the electric field distribution in the cavity and helps the second conductive structure to achieve more precise mode control.

[0026] In some embodiments of this disclosure, the projections of the trench and the second conductive structure onto the stratum do not overlap. This avoids electric field interference between the trench and the first and second conductive structures.

[0027] In some embodiments of this disclosure, the groove is a strip groove or includes a plurality of through holes arranged linearly at intervals between each other.

[0028] In some embodiments of this disclosure, the first conductive structure includes a plurality of first metallized vias arranged at intervals from each other, and the predetermined area enclosed by the plurality of first metallized vias is rectangular; The second conductive structure includes a plurality of second metallized vias arranged at intervals from each other, the plurality of second metallized vias being arranged at intervals from each other along one diagonal of the rectangle; The slot is a strip-shaped slot or includes multiple through holes arranged linearly at intervals, and the slot is arranged along the other diagonal of the rectangular projection of the rectangle on the feed layer.

[0029] In this embodiment, the slot is arranged on the diagonal, forming a complementary disturbance direction with the diagonal distribution of the first conductive structure, which can fully cover the electric field distribution in different regions of the cavity.

[0030] In some embodiments of this disclosure, the slots are two in number and arranged symmetrically with respect to the center of the rectangular projection. This symmetrical arrangement ensures the symmetry of the electric field perturbation on the surface of the feed layer.

[0031] In some embodiments of this disclosure, the ground layer, the feed layer, and the dielectric substrate are all generally rectangular.

[0032] By employing the above technical solution, this application provides a dual-band filter, comprising: a feed layer, a ground layer, and a dielectric substrate. The dielectric substrate is disposed between the feed layer and the ground layer, and has a first conductive structure and a second conductive structure. The first conductive structure electrically connects the feed layer and the ground layer to change the electric field formed by the first conductive structure. In this solution, the feed layer, the dielectric substrate, the ground layer, and the first conductive structure disposed in the dielectric substrate together enclose a resonant cavity. The first conductive structure is used to constrain the propagation of electromagnetic waves within the SIW resonant cavity to form a stable electric field within the SIW resonant cavity. By adding a second conductive structure to the resonant cavity, the electric field is disturbed by the second conductive structure, changing the transverse wave mode of the electric field, causing the transverse wave mode to separate into at least two electromagnetic modes with different resonant frequencies, thereby forming a first passband and a second passband, thus realizing the dual-band filtering function, reducing the overall size of the filter, and simplifying the overall filter design.

[0033] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A schematic diagram of a dual-band filter provided in an embodiment of this disclosure; Figure 2A layered schematic diagram of a dual-band filter provided in an embodiment of this disclosure; Figure 3 This is a first schematic diagram of a dielectric substrate provided in an embodiment of the present disclosure; Figure 4 This is a third schematic diagram of a dielectric substrate provided in an embodiment of the present disclosure; Figure 5 This is a fourth schematic diagram of a dielectric substrate provided in an embodiment of the present disclosure; Figure 6 This is a fifth schematic diagram of a dielectric substrate provided in an embodiment of this disclosure; Figure 7 This is a first schematic diagram of the feed layer provided in an embodiment of the present disclosure; Figure 8 A schematic diagram of the first and second sides provided for embodiments of this disclosure; Figure 9 Another schematic diagram of a dual-band filter provided in an embodiment of this disclosure; Figure 10 Another layered schematic diagram of a dual-band filter provided in an embodiment of this disclosure; Figure 11 This is a second schematic diagram of the feed layer provided in an embodiment of the present disclosure; Figure 12 This is a third schematic diagram of the feed layer provided in an embodiment of the present disclosure; Figure 13 A schematic diagram illustrating the bonding between the feed layer and the dielectric substrate provided in an embodiment of this disclosure; Figure 14 This is a schematic diagram of parameter markings for a dielectric substrate provided in an embodiment of the present disclosure; Figure 15 A schematic diagram of parameter markings for the feed layer provided in an embodiment of this disclosure; Figure 16 A schematic diagram of the strata provided in the embodiments of this disclosure; Figure 17 Electric field diagram of the resonant cavity provided in the embodiments of this disclosure; Figure 18 This is a schematic diagram showing the effect of different second metallization via diameters on scattering parameters provided in the embodiments of this disclosure; Figure 19 This is a schematic diagram showing the effect of different slot lengths on scattering parameters provided in an embodiment of the present disclosure; Figure 20 A schematic diagram of the simulation results of scattering parameters provided in the embodiments of this disclosure; Figure 21 A schematic diagram of the bonding between the dielectric substrate and the feed layer in the cascaded resonant cavity provided in this embodiment of the present disclosure; Figure 22Another schematic diagram illustrating the simulation results of scattering parameters provided in the embodiments of this disclosure; Figure label: 100 - Feed layer; 200 - Ground layer; 300 - Dielectric substrate; 310 - First conductive structure; 320 - Second conductive structure; 330 - Predetermined area; 311 - First metallized via; 321 - Second metallized via; 322 - Center via; 323 - Side via; 110 - Input feed line; 120 - Output feed line; 101 - First groove; 101a - Bottom surface of first groove 101; 102 - Second groove; 102a - Bottom surface of second groove 101; 111 - First spacer; 121 - Second spacer; 331 - First side; 332 - Second side; 130 - Groove; 400 - Electromagnetic field coupling region. Detailed Implementation

[0037] The embodiments of this application will now be described in more detail with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0038] Embodiments of this disclosure are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting this disclosure.

[0039] This disclosure is not exhaustive, but merely illustrative of some embodiments, and is not intended to limit the scope of protection of this disclosure. Unless otherwise specified, each step in a particular embodiment can be implemented as an independent embodiment, and the steps can be arbitrarily combined. For example, a solution after removing some steps in a particular embodiment can also be implemented as an independent embodiment, and the order of the steps in a particular embodiment can be arbitrarily interchanged. Furthermore, the optional implementation methods in a particular embodiment can be arbitrarily combined; moreover, the embodiments can be arbitrarily combined, for example, some or all steps of different embodiments can be arbitrarily combined, and a particular embodiment can be arbitrarily combined with the optional implementation methods of other embodiments.

[0040] In each of the disclosed embodiments, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of the embodiments are consistent and can be referenced by each other. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0041] The terminology used in the embodiments of this disclosure is for the purpose of describing particular embodiments only and is not intended to limit the scope of this disclosure.

[0042] In this disclosure, unless otherwise stated, elements expressed in the singular form, such as "a," "an," "the," "the," "the," "the," "the," "the," "this," etc., can mean "one and only one," or "one or more," "at least one," etc. For example, when using articles such as "a," "an," "the," etc. in translation, the noun following the article can be understood as either a singular or a plural expression.

[0043] With the continuous development of modern wireless communication technology, especially in the field of wireless communication represented by 5G communication and IoT devices, high-performance, highly integrated, multi-band, and miniaturized radio frequency front-end devices have become a challenge.

[0044] A dual-band filter is a widely used electronic device that can process signals in multiple frequency bands simultaneously, allowing signals in two specific frequency bands to pass through with no or low attenuation, while suppressing all signals outside of those two frequency bands.

[0045] The essence of a filter is to achieve frequency selection by utilizing the resonance effect. By designing a resonant unit with a specific structure, the target frequency band signal resonates with the resonant unit, thus passing through smoothly. Signals in non-target frequency bands are reflected or absorbed because they do not meet the resonance condition.

[0046] In related technologies, most dual-band filters are implemented by cascading multiple single-frequency resonant cavities, resulting in increased size and problems such as signal crosstalk between multiple cavities and poor isolation between passbands. In addition, related technologies often rely on multilayer low-temperature co-fired ceramic or precision metal waveguide processes, which makes the overall circuit fabrication difficult and costly, making it difficult to meet the large-scale deployment requirements of IoT devices.

[0047] In view of the shortcomings and deficiencies of current dual-band filters, such as single frequency band, poor scalability, and complex manufacturing, this disclosure provides a multi-mode high-performance dual-band filter. Figure 1 This is a schematic diagram of a dual-band filter provided in an embodiment of this disclosure. Figure 2 This is a layered schematic diagram of a dual-band filter provided in an embodiment of this disclosure. (See attached diagram.) Figure 1 and Figure 2 As shown, the dual-band filter includes a feed layer 100, a ground layer 200, and a dielectric substrate 300. The dielectric substrate 300 is disposed between the feed layer 100 and the ground layer 200. The dielectric substrate 300 has a first conductive structure 310. The first conductive structure 310 electrically connects the feed layer 100 and the ground layer 200.

[0048] A closed space is formed by the feed layer 100, the ground layer 200, the dielectric substrate 300, and the first conductive structure 310. The first conductive structure 310 forms the boundary of this closed space in a direction perpendicular to the feed layer 100 or the ground layer 200, creating an equivalent sidewall to constitute a substrate integrated waveguide (SIW) resonant cavity. The first conductive structure 310 is used to confine the propagation of electromagnetic waves within the SIW resonant cavity to form a stable electric field. For ease of description, this stable electric field is referred to as the first electric field.

[0049] like Figure 2 As shown, the dielectric substrate 300 also includes a second conductive structure 320. The second conductive structure 320 electrically connects the feed layer 100 and the ground layer 200 to change the first electric field. For example, the second conductive structure 320 perturbs the first electric field, changing the transverse electric mode (TE mode) of the first electric field, causing the TE mode to separate into at least two electromagnetic modes with different resonant frequencies, thereby forming a first passband and a second passband.

[0050] In this dual-band filter, the first passband and the second passband are two different frequency ranges that allow signals to pass through with low loss. For example, the first passband is 14-15 GHz and the second passband is 18-19 GHz. Therefore, this dual-band filter can only allow signals with frequencies in the 14-15 GHz and 18-19 GHz ranges to pass through. It is understood that this application does not limit the specific values ​​of the frequency ranges of the first and second passbands.

[0051] In order to form the first electric field, such as Figure 3 As shown, the first conductive structure 310 includes a plurality of first metallized vias 311 arranged at intervals.

[0052] The first metallized via 311 can be a through hole extending along the thickness direction of the dielectric substrate 300, used to form an equivalent metal sidewall to constrain the propagation of electromagnetic waves in the SIW resonant cavity to form a first electric field.

[0053] In order to change the first electric field, such as Figure 3 As shown, the second conductive structure 320 includes a plurality of second metallized vias 321 arranged at intervals.

[0054] The second metallized via 321 can be a through-hole extending along the thickness direction of the dielectric substrate 300, used to disturb the first electric field. According to the function (disturb the electric field) and shape (columnar in the SIW resonant cavity) of the second metallized via 321, the second metallized via 321 can also be called a micro-perturbation metal pillar.

[0055] In some embodiments, through-holes can be formed on the dielectric substrate 300 along its thickness direction. A metal layer is then formed around the inner wall of the through-hole, thereby forming a first metallized via 311 and a second metallized via 321. Various feasible implementations of the metal layer material are possible. For example, the metal layer can use copper, copper-based gold plating, copper-based silver plating, or other metal materials. Various feasible implementations of the metal layer thickness are also possible. For example, the metal layer thickness can be 15~35 μm. It is understood that both the material and thickness of the metal layer can be set according to actual needs, and this application does not limit them.

[0056] To enhance the perturbation effect of the first electric field, such as Figure 3 As shown, in some embodiments, a first conductive structure 310 encloses a predetermined region 330, and a second conductive structure 320 is arranged within the predetermined region 330. The predetermined region 330 enclosed by the first conductive structure 310 is the electric field distribution region of the first electric field. The second conductive structure 320 is specifically arranged within this predetermined region 330, which can directly disturb the first electric field and avoid ineffective disturbance.

[0057] The shape of the predetermined region 330 can be varied. In some embodiments, the shape of the predetermined region 330 can be circular or... Figure 3 The polygon shown can be a rectangle, a square, a hexagon, etc. This application does not limit the shape of the polygon.

[0058] For example, the first conductive structure 310 includes a plurality of first metallized vias 311, which are arranged in a ring to enclose predetermined regions 330 of different shapes. Figure 3 As shown, multiple first metallized vias 311 are arranged in a rectangle, and the predetermined area 330 enclosed is rectangular.

[0059] Understandably, in practical applications, the arrangement of multiple first metallized vias 311 can be changed according to requirements such as electric field distribution, process adaptation, and function, so as to select and enclose a predetermined area 330 of different shapes.

[0060] Within the predetermined region 330 enclosed by the first conductive structure 310, the second conductive structure 320 can be arranged in various ways. The second conductive structure 320 can be positioned at the center of the predetermined region 330. If the predetermined region 330 is a regular polygon, the second conductive structure 320 can be arranged along at least one diagonal of the regular polygon.

[0061] By placing the second conductive structure 320 in the strong field region of the first electric field, such as placing it on the diagonal and / or center, the disturbance effect on the first electric field can be maximized, achieving efficient electric field disturbance and avoiding ineffective disturbance in the weak field region.

[0062] For example, the second conductive structure 320 includes a plurality of second metallized vias 321, which are arranged in a predetermined region 330 enclosed by the first conductive structure 310. Figure 3 As shown, for the predetermined area 330, which is rectangular, a plurality of second metallized vias 321 are arranged along one diagonal of the rectangle.

[0063] To alter the first electric field, the dimensions, spacing, and other settings of the second metallized via 321 can be varied. The details of the settings for the second metallized via 321 are described below with reference to the accompanying drawings.

[0064] like Figure 3 As shown, in some embodiments, multiple second metallized vias 321 are arranged linearly. The multiple second metallized vias 321 are sequentially arranged along a specific straight line direction within a predetermined region 330 to form a linear perturbation array. By directionally enhancing the perturbation of the electric field in a specific direction, efficient separation of dual-frequency modes is achieved.

[0065] like Figure 4 As shown, in some embodiments, the plurality of second metallized vias 321 include a central via 322 and side vias 323 located on both sides of the central via 322, wherein the cross-sectional area of ​​the central via 322 is larger than the cross-sectional area of ​​the side vias 323.

[0066] The central via 322 is a second metallized via 321 located at the center of the dielectric substrate 300, and the side vias 323 are located on both sides of the central via 322 along a direction parallel to the ground plane 200. The large cross-sectional area of ​​the central via 322 is designed for the strong field peak region, which can generate strong perturbations, while the small cross-sectional area of ​​the side vias 323 is designed for the medium field strength region, which can generate weak perturbations, thus achieving precise adaptation to the strong field gradient.

[0067] For example, such as Figure 4 As shown, there is one central via 322, and the number of side vias 323 on both sides of the central via 322 is the same, with two side vias 323 on each side. Both the central via 322 and the side vias 323 are circular, and the diameter of the central via 322 is [diameter missing]. R c The diameter of the side through holes 323 on both sides is R 1, R c > R 1.

[0068] In some embodiments, the cross-sectional area of ​​the side via 323 decreases in the direction away from the central via 322. The cross-sectional area of ​​the side via 323 decreases progressively in the direction away from the central via 322.

[0069] For example, such as Figure 5 As shown, there is one central via 322, and each side of the central via 322 has two side vias 323. Both the central via 322 and the side vias 323 are circular, and the diameter of the central via 322 is [diameter missing]. R c The diameters of the two side vias 323 are respectively R 2. R 3, R c > R 2> R 3.

[0070] The cross-sectional area of ​​the second metallized via 321 gradually decreases from the center to the edge, which is synchronized with the attenuation law of the electric field strength from the center to the edge, so as to achieve precise adaptation to disturbances in electric field regions of different intensities.

[0071] like Figure 6 As shown, in some embodiments, the spacing between the central via 322 and its adjacent side via 323 is... t 1 is greater than the spacing between adjacent side vias 323 t 2. The spacing between adjacent side vias 323 decreases in the direction away from the central via 322, and the spacing between adjacent side vias 323 is reduced from... t 2 decreased to t 3.

[0072] Based on the electric field gradient characteristics of strong at the center and weak at the edges, the electric field disturbance effect is improved by optimizing the spacing distribution of the second metallized via 321.

[0073] To achieve signal transmission, in some embodiments, the feed layer 100 includes an input feed line 110 and an output feed line 120 to realize the input of the signal to be filtered and the output of the filtered signal. For example... Figure 7 As shown, along a direction parallel to the ground layer 200, the surface of the feed layer 100 has a first groove 101 extending in a first direction and a second groove 102 extending in a second direction. An input feed line 110 extending in the second direction is disposed on the bottom surface 101a of the first groove 101. A first gap 111 exists between the input feed line 110 and the inner wall of the first groove 101. An output feed line 120 extending in the first direction is disposed on the bottom surface 102a of the second groove 102. A second gap 121 exists between the output feed line 120 and the inner wall of the second groove 102. The first direction and the second direction are opposite.

[0074] In some embodiments, such as Figure 8 As shown, the first conductive structure 310 includes a plurality of first metallized vias 311 arranged at intervals from each other, and the predetermined area 330 enclosed by the plurality of first metallized vias 311 is rectangular. The spacing between two adjacent first metallized vias 311 located at the middle of the first side 331 of the rectangle is... M 1 and the spacing between two adjacent first metallized vias 311 located at the middle of the second side 332 of the rectangle. M 2. The spacing between the remaining adjacent first metallized vias 311 is greater than the spacing between the other two vias. P The first side 331 and the second side 332 are opposite to each other.

[0075] It is understood that the first side 331 and the second side 332 are the sides where the projections of the input feed line 110 and the output feed line 120 are located on the dielectric substrate 300, respectively. The spacing between two adjacent first metallized vias 311 located in the middle of the first side 331 of the rectangle. M 1 and the spacing between two adjacent first metallized vias 311 located at the middle of the second side 332 of the rectangle. M 2. The spacing can be set according to the dimensions of the first groove 101 and the second groove 102. The above spacing setting can avoid short circuits caused by direct contact between the input feed line 110, the output feed line 120 and the first conductive structure 310.

[0076] To enhance the perturbation effect of the first electric field, in some embodiments, such as Figure 9 , Figure 10 , Figure 11 As shown, the feed layer 100 is provided with at least one groove 130 extending along the thickness direction of the feed layer 100.

[0077] The slot 130 is positioned within the projection area of ​​the predetermined region 330 onto the feed layer 100. The projections of the slot 130, the first conductive structure 310, and the second conductive structure 320 onto the ground layer 200 do not overlap. This avoids electric field interference between the slot 130 and the first and second conductive structures 310 and 320. By altering the current path of the feed layer 100 through the slot 130, the electric field distribution within the cavity is further agitated, assisting the second conductive structure 320 in achieving more precise mode control.

[0078] The groove 130 can have various shapes. For example... Figure 11 As shown, groove 130 is a strip-shaped groove that can continuously cut the surface current path inside the cavity along a specific direction, thereby improving the disturbance effect. The strip-shaped groove can be rectangular, elliptical, or other shapes, and this application does not limit it in this regard.

[0079] like Figure 12 As shown, the groove 130 may also include multiple through holes arranged linearly at intervals. More precise electromagnetic field control can be achieved through the perturbation of these linearly arranged through holes.

[0080] like Figure 11 , Figure 12 As shown, in some embodiments, a plurality of slots 130 are arranged symmetrically with respect to the center of the projected region of the predetermined region 330 on the feed layer 100. This symmetrical arrangement ensures the symmetry of the electric field perturbation on the surface of the feed layer 100.

[0081] like Figure 13 As shown, in some embodiments, the first conductive structure 310 includes a plurality of first metallized vias 311 arranged at intervals from each other, and the predetermined area 330 enclosed by the plurality of first metallized vias 311 is rectangular. The second conductive structure 320 includes a plurality of second metallized vias 321 arranged at intervals from each other, and the plurality of second metallized vias 321 are arranged at intervals from each other along one diagonal of the rectangle.

[0082] The slots 130 are two in number and symmetrically arranged with respect to the center of the rectangular projection, and the slots 130 are arranged along the other diagonal of the rectangular projection of the rectangle on the feed layer 100. The slots 130 are arranged on the diagonal, forming a complementary perturbation direction with the diagonal distribution of the second conductive structure 320, which can fully cover the electric field distribution in different regions of the cavity.

[0083] In some embodiments, the ground layer 200, the feed layer 100, and the dielectric substrate 300 are all generally rectangular. That is, the ground layer 200, the feed layer 100, and the dielectric substrate 300 are generally rectangular in shape, allowing for minor trimming of the edges due to feed line extension and installation positioning requirements.

[0084] In some embodiments, the dielectric substrate 300 is provided with one layer. The dual-band filter uses a single-layer printed circuit board (PCB) process to fabricate the dielectric substrate 300, avoiding interlayer alignment errors and electromagnetic interference caused by multi-layer dielectric substrates 300.

[0085] In some embodiments, the dielectric substrate 300 is made of polytetrafluoroethylene vinyl composite material, such as Rogers 5880 board, with a dielectric constant of 2.2, a loss tangent tanδ of 0.0009, and a thickness of 0.508 mm.

[0086] The following is based on Figure 9 , Figure 10 The presented dual-band filter illustrates the implementation of dual-band functionality. For example... Figure 10 , Figure 11 , Figure 14 , Figure 15 , Figure 16As shown, the dual-band filter includes a feed layer 100, a ground layer 200, and a dielectric substrate 300. The dielectric substrate 300 is disposed between the feed layer 100 and the ground layer 200, and has a plurality of first metallized vias 311 and five second metallized vias 321 arranged at intervals between each other. The predetermined area enclosed by the plurality of first metallized vias 311 is rectangular, and the five second metallized vias 321 are arranged at intervals along one diagonal of the rectangle.

[0087] The five second metallized vias 321 include a central via 322 and side vias 323 located on either side of the central via. There is one central via 322, and each side of the central via 322 has two side vias 323. The diameter of the central via 322 is... R c The diameter of the side through holes 323 on both sides is R 1, R c > R 1. The distance between the center via 322 and its adjacent side via 323 t 1 is greater than the spacing between adjacent side vias 323 t 2.

[0088] A square SIW resonant cavity is formed by a feed layer 100, a dielectric substrate 300, a ground layer 200, and multiple first metallized vias 311. Before disturbance through the five second metallized vias 321, three transverse wave modes exist within the square SIW resonant cavity: TE101 mode, TE102 mode, and TE201 mode. Figure 17 The diagram shows the electric field of a square SIW resonant cavity. By adding five second metallized vias 321 to the square SIW resonant cavity, the electric field distribution is disturbed by the five second metallized vias 321, altering the TE101, TE102, and TE201 modes, forming the first, second, and third electromagnetic modes, respectively. The first and second electromagnetic modes have similar electric field distributions and resonant frequencies, and can jointly form the first passband. The TE201 mode is significantly affected by the disturbed electric field distribution, resulting in a higher resonant frequency. The third electromagnetic mode forms the second passband independently.

[0089] In addition to adding five second metallized vias 321 for perturbation, in order to better control the frequency, such as Figure 15 As shown, two strip grooves 130 are arranged along the other diagonal of the rectangular projection of the rectangle on the stratum 200, and the two strip grooves 130 are arranged symmetrically with respect to the center of the rectangular projection.

[0090] The following section describes the effects of two perturbation methods, the second metallized via 321 and the slot 130, on the three transverse wave modes in a single cavity. Figure 18 and Figure 19 The curves show the effects of the diameter of the via 322 and the length of the slot 130 on the scattering parameters (S-Parameters), with the horizontal axis representing frequency and the vertical axis representing the absolute value of the transmission coefficient (|S21|).

[0091] Figure 18 , Figure 19 The effects of the diameter of the central via 322 and the length of the strip groove 130 on the frequency response of the transverse electromagnetic wave mode are shown respectively. Based on Figure 18 It can be seen that, with the diameter of the central via 322... Rc Increase Rc The diameters are 1.6mm, 2.0mm, and 2.4mm, respectively. The first passband shifts to higher frequencies, while the second passband has a relatively smaller impact. Meanwhile, simulation results from |S21| show that due to the electric field distribution characteristics of the first electromagnetic mode, the diameter of the second metallized via 321... Rc The increase of has a significant impact on the first transmission pole.

[0092] based on Figure 19 It can be seen that as the length of the groove 130 increases... ll The continuous increase ll With diameters of 3.0mm, 4.0mm, and 5.0mm respectively, the second passband shifts to lower frequencies, while the first passband remains unaffected. This is because the diagonal linear slot 130 cuts the surface current of the third electromagnetic mode, increasing the electrical length of the current path and consequently lowering the resonant frequency of the third electromagnetic mode. Overall, the diameter of the second metallized via 321 is positively correlated with the center frequency of the first passband, while the length of the slot 130 is negatively correlated with the center frequency of the second passband. Adjusting the diameter of the second metallized via 321 allows for independent optimization of the first passband, and adjusting the length of the slot 130 allows for independent optimization of the second passband. These two perturbation methods enable flexible control of the passband of the dual-band filter.

[0093] Electromagnetic modeling of the above dual-band filter structure was performed, and after simulation and optimization, the structural parameters of the dual-band filter were obtained as shown in the table below:

[0094] Among them, such as Figure 14 , Figure 15 , Figure 16 As shown, W The length of the square SIW resonant cavity; W t The width of the interval (first interval 111, second interval 121) on both sides of the input feed line 110 and the output feed line 120; W mThe widths of the input feed line 110 and the output feed line 120; W 1 represents a 300mm width for the dielectric substrate; W 2 represents a stratum width of 200; ll The length of the groove is 130. l t The length of the interval (first interval 111, second interval 121) on both sides of the input feed line 110 and the output feed line 120; l m The lengths of the input feed line 110 and the output feed line 120; R c The diameter of the central via 322; R 1 represents the diameter of the side via 323; t 1 represents the distance between the center via 322 and the side via 323; t 2 represents the distance between adjacent side vias 323; P The distance between adjacent first metallized vias 311; D The diameter of the first metallized via 311.

[0095] Simulation results of scattering parameters of dual-band filter are as follows Figure 20 As shown. Figure 20 In the diagram, the horizontal axis represents frequency (GHz), and the vertical axis represents scattering parameters (dB). Sim.S11 represents the simulation results for the input reflection coefficient, and Sim.S21 represents the simulation results for the transmission coefficient. The center frequencies of the multimode dual-band filter are 14.58 GHz and 18.96 GHz, respectively. Two transmission poles are generated in the first passband due to the first and second electromagnetic modes, and one transmission pole is generated in the second passband due to the presence of the third electromagnetic mode. The 3dB relative bandwidths are 4.3% and 5%, respectively, and the insertion losses are 0.65 dB and 0.98 dB, respectively. The return loss in both passbands is better than 11 dB.

[0096] To improve the out-of-band rejection and passband edge steepness of the filter, a dual-band filter with a high roll-off rate is proposed based on the aforementioned single-cavity dual-band filter structure. This filter comprises multiple cascaded SIW resonant cavities. The synergistic effect of these multiple cavities enhances the filter's out-of-band rejection capability and improves the passband edge steepness.

[0097] In some embodiments, the SIW resonant cavity is formed by the feed layer 100, the dielectric substrate 300, and the ground layer 200. The output feed line 120 extends in a direction parallel to the ground layer 200. Multiple SIW resonant cavities are arranged sequentially along the extension direction of the output feed line 120. That is, multiple SIW resonant cavities are cascaded along the signal transmission path to improve filter selectivity and enhance stopband suppression.

[0098] In some embodiments, the second conductive structures 320 of two adjacent SIW resonant cavities are symmetrically arranged. This ensures that the electric field perturbation characteristics of adjacent cavities are consistent, thereby improving coupling stability.

[0099] For example, such as Figure 21 As shown, the dual-band filter comprises two cascaded square SIW resonant cavities. It can be understood that, as... Figure 15 As shown, a first gap 111 exists on both sides of the input feed line 110. A second gap 121 exists on both sides of the output feed line 120. This spacing structure keeps the input feed line 110 and the output feed line 120 spatially isolated from the surrounding feed layer 100 structure, preventing direct connection. On one hand, it achieves electrical isolation between the input feed line 110 and the output feed line 120 and other feed layer 100 structures, avoiding signal crosstalk or short circuits between the feed line signals and surrounding metal. On the other hand, by fixing the gap size, it maintains the characteristic impedance and transmission mode stability of the input feed line 110 and the output feed line 120. Simultaneously, for two adjacent cascaded SIW resonant cavities, along the signal transmission path, adjacent feed layers 100 are sequentially spliced ​​together. In two adjacent feed layers 100, the second gap 121 on the output feed line 120 side and the first gap 111 on the input feed line 110 side can be correspondingly spliced ​​together to form... Figure 21 The electromagnetic field coupling region 400 shown is used to transmit signals.

[0100] Electromagnetic modeling of the above dual-band filter structure was performed, and after simulation and optimization, the structural parameters of the dual-band filter were obtained as shown in the table below:

[0101] in, l a The length of the electromagnetic field coupling region; W a The width of the electromagnetic field coupling region; W b This represents the length of the two SIW resonant cavities after cascading.

[0102] Simulation results of scattering parameters of dual-band filter are as follows Figure 22 As shown, the center frequencies of the multimode dual-band filters are 14.7 GHz and 18.9 GHz, with insertion losses of 0.5 dB and 0.8 dB, respectively. The return losses in both passbands are better than 20 dB.

[0103] In this embodiment, based on a traditional square SIW resonator, a second metallized via 321 (perturbation metal pillar) is added at the diagonal position to perturb the electric field in the square SIW resonator, thereby achieving dual-band performance. Furthermore, a slot 130 is added at the other diagonal position to better achieve frequency control. Simultaneously, the proposed square SIW resonator is scalable; to improve the passband roll-off rate, multiple square SIW resonators can be cascaded to achieve a high roll-off rate dual-band filter. Compared to traditional dual-band design methods, this method utilizes a single resonator to achieve dual-band filtering, reducing the overall filter size and simplifying the overall filter design compared to existing multi-cavity cascaded solutions.

[0104] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A dual-band filter, characterized in that, include: Feed layer (100); Strata (200); and A dielectric substrate (300) is disposed between the feed layer (100) and the ground layer (200). The dielectric substrate (300) is provided with a first conductive structure (310) and a second conductive structure (320). The first conductive structure (310) is electrically connected to the feed layer (100) and the ground layer (200), and the second conductive structure (320) is electrically connected to the feed layer (100) and the ground layer (200) to change the electric field formed by the first conductive structure (310).

2. The dual-band filter according to claim 1, characterized in that, The first conductive structure (310) encloses a predetermined area (330), and the second conductive structure (320) is arranged within the predetermined area (330).

3. The dual-band filter according to claim 2, characterized in that, The predetermined area (330) is circular or polygonal.

4. The dual-band filter according to claim 3, characterized in that, The predetermined region (330) is a regular polygon, and the second conductive structure (320) is arranged along at least one diagonal of the regular polygon.

5. The dual-band filter according to claim 4, characterized in that, The predetermined area (330) is rectangular, and the second conductive structure (320) is arranged along one diagonal of the rectangle.

6. The dual-band filter according to any one of claims 1-5, characterized in that, The first conductive structure (310) includes a plurality of first metallized vias (311) arranged at intervals from each other, and the second conductive structure (320) includes a plurality of second metallized vias (321) arranged at intervals from each other.

7. The dual-band filter according to claim 6, characterized in that, Multiple second metallized vias (321) are arranged in a linear fashion.

8. The dual-band filter according to claim 7, characterized in that, The plurality of second metallized vias (321) include a central via (322) and side vias (323) located on both sides of the central via (322), wherein the cross-sectional area of ​​the central via (322) is greater than the cross-sectional area of ​​the side vias (323).

9. The dual-band filter according to claim 8, characterized in that, The cross-sectional area of ​​the side via (323) decreases in the direction away from the central via (322).

10. The dual-band filter according to claim 7, characterized in that, The plurality of second metallized vias (321) include a central via (322) and side vias (323) located on both sides of the central via (322), wherein the distance between the central via (322) and its adjacent side via (323) is greater than the distance between adjacent side vias (323).

11. The dual-band filter according to claim 8, characterized in that, The number of side vias (323) on both sides of the central via (322) is the same.

12. The dual-band filter according to claim 11, characterized in that, There is one central via (322), and each side of the central via (322) has two side vias (323).

13. The dual-band filter according to claim 4, characterized in that, The first conductive structure (310) includes a plurality of first metallized vias (311) arranged at intervals from each other, and the predetermined area (330) enclosed by the plurality of first metallized vias (311) is rectangular; The second conductive structure (320) includes a plurality of second metallized vias (321) arranged at intervals from each other, the plurality of second metallized vias (321) being arranged at intervals from each other along one diagonal of the rectangle; The spacing between two adjacent first metallized vias (311) located in the middle of the first side of the rectangle and the spacing between two adjacent first metallized vias (311) located in the middle of the second side of the rectangle are greater than the spacing between the remaining adjacent first metallized vias (311), and the first side and the second side are opposite to each other.

14. The dual-band filter according to claim 1, characterized in that, The feed layer (100) is provided with at least one groove (130) extending along the thickness direction of the feed layer (100).

15. The dual-band filter according to claim 14, characterized in that, The projections of the groove and the second conductive structure (320) onto the stratum (200) do not overlap.

16. The dual-band filter according to claim 15, characterized in that, The groove (130) is a strip groove or includes multiple through holes arranged linearly at intervals between each other.

17. The dual-band filter according to claim 14, characterized in that, The first conductive structure (310) includes a plurality of first metallized vias (311) arranged at intervals from each other, and the predetermined area (330) enclosed by the plurality of first metallized vias (311) is rectangular; The second conductive structure (320) includes a plurality of second metallized vias (321) arranged at intervals from each other, the plurality of second metallized vias (321) being arranged at intervals from each other along one diagonal of the rectangle; The slot (130) is a strip slot or includes a plurality of through holes arranged linearly at intervals between each other, and the slot (130) is arranged along the other diagonal of the rectangular projection of the rectangle on the feed layer (100).

18. The dual-band filter according to claim 17, characterized in that, The slots (130) are two in number and are arranged symmetrically with respect to the center of the rectangular projection.

19. The dual-band filter according to claim 1, characterized in that, The ground layer (200), the feed layer (100), and the dielectric substrate (300) are all generally rectangular.

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