CN112072222A - Ceramic dielectric waveguide filter with transmission zero - Google Patents
Ceramic dielectric waveguide filter with transmission zero Download PDFInfo
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- CN112072222A CN112072222A CN202010921239.8A CN202010921239A CN112072222A CN 112072222 A CN112072222 A CN 112072222A CN 202010921239 A CN202010921239 A CN 202010921239A CN 112072222 A CN112072222 A CN 112072222A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/2002—Dielectric waveguide filters
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/207—Hollow waveguide filters
- H01P1/208—Cascaded cavities; Cascaded resonators inside a hollow waveguide structure
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Abstract
The invention discloses a ceramic dielectric waveguide filter with transmission zero, comprising: the size of the at least two resonant cavities is determined according to the transmission characteristics required by the filter, the input end and the output end of the filter are respectively located in the preset range of two different resonant cavities on the filter, at least one coupling structure is arranged on the surface of the filter, the coupling structure is arranged above the at least two resonant cavities, and each coupling structure comprises two metal coupling points and a metal wire, wherein the two metal coupling points are respectively arranged in the preset range of the two different resonant cavities, and the metal wire is connected with the two metal coupling points. The embodiment of the invention discloses a ceramic dielectric waveguide filter with transmission zero, which has a simple structure and can improve the production efficiency of the ceramic dielectric waveguide filter.
Description
Technical Field
The embodiment of the invention relates to the filter technology, in particular to a ceramic dielectric waveguide filter with transmission zero.
Background
Ceramic dielectric waveguide filters are increasingly used in wireless communication devices due to their compact size, low insertion loss and high power capability. Ceramic dielectric waveguide filters often require at least one transmission zero in both the low-end and high-end bands of the operating passband to improve near-end rejection performance. The out-of-band rejection performance of the filter can also be improved by increasing the number of resonant cavities of the filter, but the increase of the number of resonant cavities increases the volume of the filter. At present, a common structure for realizing the transmission zero point is to form blind holes with different thicknesses on a ceramic dielectric body to realize capacitive or inductive coupling, but the structure has the defect that the difficulty in processing the thinner blind holes and metalizing the inner parts of the blind holes is higher. There are also references to the implementation of zero loading by opening holes in the sides of the filter and adding metal probes between different resonators, but this configuration is currently difficult to implement.
In summary, the transmission zero structure of the existing ceramic dielectric waveguide filter is difficult to process, which affects the production efficiency of the ceramic dielectric waveguide filter.
Disclosure of Invention
The invention provides a ceramic dielectric waveguide filter with transmission zero, provides a ceramic dielectric waveguide filter with transmission zero with simple structure, and can improve the production efficiency of the ceramic dielectric waveguide filter.
In a first aspect, an embodiment of the present invention provides a ceramic dielectric waveguide filter with a transmission zero, including: at least two resonant cavities;
the sizes of the at least two resonant cavities are determined according to the transmission characteristics required by the filter;
the input end and the output end of the filter are respectively positioned in the preset range of two different resonant cavities on the filter;
the surface of the filter is provided with at least one coupling structure, the coupling structure is arranged above the at least two resonant cavities, and each coupling structure comprises two metal coupling points and a metal wire, wherein the two metal coupling points are respectively arranged in a preset range of the two non-adjacent resonant cavities, and the metal wire is connected with the two metal coupling points.
In a possible implementation manner of the first aspect, the coupling structures include capacitive coupling structures, and each capacitive coupling structure includes two metal coupling disks respectively disposed in a predetermined range above two non-adjacent resonant cavities and a metal wire connecting the two metal coupling disks.
In a possible implementation manner of the first aspect, the position and the depth of the transmission zero of the filter are changed by adjusting the size of the metal coupling disc and the length of the metal wire of each capacitive coupling structure.
In a possible implementation manner of the first aspect, the coupling structures include inductive coupling structures, each inductive coupling structure includes two inductive coupling points respectively disposed in a preset range beside two non-adjacent resonant cavities and a metal wire connecting the two inductive coupling points, and each inductive coupling point includes an inductive coupling probe or a metallized blind via penetrating into the filter.
In a possible implementation manner of the first aspect, the position and the depth of the transmission zero of the filter are changed by adjusting the size and the depth of the metal coupling point and the length of the metal wire of each inductive coupling structure.
In a possible implementation manner of the first aspect, an isolation structure is further included between the at least two resonant cavities, and the isolation structure includes a metal or metallization structure disposed between two adjacent resonant cavities.
In a possible implementation manner of the first aspect, the metal or metallization structure is a continuous metal or metallization structure, or the metal or metallization structure is a metal or metallization structure densely distributed in a dot shape.
In a possible implementation manner of the first aspect, an isolation layer is provided between the coupling structure and the isolation structure.
In a possible implementation form of the first aspect, the coupling structure has an isolation layer between the metallization layer of the filter surface and the coupling structure.
In a possible implementation manner of the first aspect, the at least one coupling structure includes one coupling structure, and a symmetry center of the one coupling structure is located within a preset range of a symmetry center of the filter.
In a possible implementation manner of the first aspect, the filter surface further includes a printed circuit board with metal layers covered on both sides, and a side of the printed circuit board facing the filter surface is open-circuited with a surrounding metal layer at a position corresponding to the coupling structure, or the printed circuit board is slotted at a position corresponding to the coupling structure.
In a possible implementation manner of the first aspect, a side of the printed circuit board facing the filter surface is provided with a pattern corresponding to the filter surface at a position except for the coupling structure, and the printed circuit board is provided with a connecting structure electrically communicating two metal layers at a position corresponding to an input end and an output end of the filter.
The ceramic dielectric waveguide filter with the transmission zero provided by the embodiment of the invention comprises: the size of the at least two resonant cavities is determined according to the transmission characteristics required by the filter, the input end and the output end of the filter are respectively located in the preset range of two different resonant cavities on the filter, the surface of the filter is provided with at least one coupling structure, the coupling structure is arranged above the at least two resonant cavities, each coupling structure comprises two metal coupling points and a metal wire, the metal coupling points are respectively arranged in the preset range of the two different resonant cavities, the metal wire is connected with the two metal coupling points, due to the fact that the at least one coupling structure is arranged on the surface of the filter, the ceramic dielectric waveguide filter with the transmission zero point is enabled to have the transmission zero point, the coupling structure arranged on the surface of the filter is simple to process, and the production efficiency of the ceramic dielectric waveguide.
Drawings
FIG. 1 is a schematic diagram of the transmission and return loss characteristics of a conventional ceramic dielectric waveguide filter;
fig. 2 is a schematic structural diagram of a ceramic dielectric waveguide filter having transmission zeros according to an embodiment of the present invention;
fig. 3A and 3B are schematic structural diagrams of another ceramic dielectric waveguide filter with transmission zeros according to an embodiment of the present invention;
fig. 4A and 4B are schematic structural diagrams of another ceramic dielectric waveguide filter with transmission zeros according to an embodiment of the present invention;
fig. 5A and 5B are schematic structural diagrams of another ceramic dielectric waveguide filter with transmission zeros according to an embodiment of the present invention;
FIG. 6 is a graph showing the transmission and return loss characteristics of the ceramic dielectric waveguide filter with transmission zeroes of FIGS. 5A and 5B;
FIG. 7 is a schematic diagram of the transmission and return loss characteristics of a ceramic dielectric waveguide filter with transmission zeroes with the addition of a symmetrical coupling structure;
fig. 8A and 8B are schematic structural diagrams of another ceramic dielectric waveguide filter with transmission zeros according to an embodiment of the present invention;
fig. 9A and 9B are schematic structural diagrams of another ceramic dielectric waveguide filter with transmission zeros according to an embodiment of the present invention;
fig. 10A and 10B are schematic structural diagrams of another ceramic dielectric waveguide filter with transmission zeros according to an embodiment of the present invention;
fig. 11 is a schematic structural diagram of another ceramic dielectric waveguide filter with transmission zeros according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
The ceramic dielectric waveguide filter is designed and manufactured by utilizing the characteristics of low loss, high dielectric constant, small frequency temperature coefficient and thermal expansion coefficient, high power bearing and the like of a dielectric ceramic material. The ceramic dielectric waveguide filter is composed of a plurality of ladder-shaped circuits which are longitudinally connected in series or in parallel with a plurality of long resonators, and each resonator can also be called a resonant cavity. The ceramic dielectric waveguide filter can comprise a plurality of resonant cavities, and the higher the number of the resonant cavities of the ceramic dielectric waveguide filter is, the better the out-of-band rejection performance of the filter is. Fig. 1 shows a transmission characteristic curve and a return loss characteristic curve of a conventional ceramic dielectric waveguide filter, and fig. 1 is a schematic diagram of the transmission characteristic curve and the return loss characteristic curve of the conventional ceramic dielectric waveguide filter. As shown in fig. 1, S11 is the return loss characteristic curve of the conventional ceramic dielectric waveguide filter, and S12 is the transmission characteristic curve of the conventional ceramic dielectric waveguide filter. As can be seen from fig. 1, the transmission performance of the conventional ceramic dielectric waveguide filter is suppressed more gradually outside the band.
In order to make the filtering performance of the ceramic dielectric waveguide filter better, transmission zeros are usually required to be disposed at the low-end frequency band and the high-end frequency band of the operating passband to improve the near-end rejection performance, that is, two sides of the transmission passband of the ceramic dielectric waveguide filter have points at which the transmission performance is sharply reduced. The scheme for realizing the transmission zero point of the existing ceramic dielectric waveguide filter is difficult to realize and is difficult to apply on a large scale.
Therefore, the embodiment of the invention provides the ceramic dielectric waveguide filter with the transmission zero point, the transmission zero point appears outside the band of the ceramic dielectric waveguide filter by arranging the coupling structure on the ceramic dielectric waveguide filter, and the coupling structure is low in processing difficulty and easy to realize.
Fig. 2 is a schematic structural diagram of a ceramic dielectric waveguide filter having a transmission zero according to an embodiment of the present invention, and fig. 2 is a top view, as shown in fig. 2, the ceramic dielectric waveguide filter (hereinafter, also referred to as a filter) having a transmission zero structure according to the embodiment includes:
in the present embodiment, 8 resonant cavities 201 are taken as an example, and the 8 resonant cavities 201 are arranged in two rows, but the number of resonant cavities in the ceramic dielectric waveguide filter with a transmission zero provided in the embodiment of the present invention is not limited thereto, as long as the ceramic dielectric waveguide filter with a transmission zero has two or more resonant cavities, which is within the scope of the embodiment of the present invention.
The size of each resonant cavity 201 is determined according to the transmission characteristics required by the filter, and the main performance parameters of the ceramic dielectric waveguide filter of the transmission zero point include the center frequency of the pass band, the bandwidth of the pass band, the out-of-band cut-off frequency, the in-band insertion loss, the return loss, the stop band rejection degree and the like. The main performance parameters of the filter depend on the number and arrangement of the resonant cavities and the size of each resonant cavity. Designing the size, number and arrangement of the resonant cavities of the ceramic dielectric waveguide filter according to the performance parameters of the filter is a conventional technical means for those skilled in the art, and is not described in detail in the embodiments of the present invention.
The filter is further provided with an input end 202 and an output end 203, the input end 202 and the output end 203 are respectively located in a preset range of two different resonant cavities 201 on the filter, that is, after a signal to be filtered is input into one resonant cavity 201 of the filter from the input end 202, the signal passes through each resonant cavity 201 in sequence and is finally output through the output end 203, so that the purpose of filtering is achieved. The input end 202 and the output end 203 may respectively correspond to one resonant cavity 201, and perform signal coupling with the corresponding resonant cavity through different coupling modes. The input 202 and the output 203 may be located on the upper surface or the side surface of the filter, and are coupled to the corresponding resonant cavities 201 by capacitive coupling or inductive coupling. The signal coupling mode of the input end and the output end of the ceramic dielectric waveguide filter can adopt any one of the existing coupling modes. In the embodiment of the present invention, the input end 202 and the output end 203 are located on the upper surface of the filter, and are described as an example of signal coupling with the corresponding resonant cavities.
On the surface of the filter, there are coupling structures 204, and the number of the coupling structures 204 may be one or more, and two coupling structures 204 are taken as an example in this embodiment. Each coupling structure 204 is disposed above the resonant cavity 201, and each coupling structure 204 includes two metal coupling points 205 respectively disposed in a predetermined range of two different resonant cavities 201 and a metal line 206 connecting the two metal coupling points 205. The two metal coupling points 205 of each coupling structure 204 need to be located within a predetermined range of two different resonant cavities 201, where the predetermined range may be a range of a circle with the position of the resonant cavity 201 as a center and a radius as a predetermined range. After the metallized coupling structure 204 is disposed within the predetermined range of the resonant cavity 201, the coupling structure 204 will affect the transmission performance of the adjacent resonant cavity 201, so as to generate a transmission zero on the transmission characteristic curve of the filter. By adjusting the sizes of the metal coupling point 205 and the metal line 206 in the coupling structure 204, the position and depth of the transmission zero of the filter can be changed.
In addition, optionally, an isolation structure 207 is further included between the resonant cavities 201, and the isolation structure 207 includes a metal or metallization structure disposed between two adjacent resonant cavities 201. The isolation structures 207 serve to reduce unwanted coupling between different resonators 201. The more portions are isolated between adjacent resonators 201, i.e., the longer the length of the isolation structure 207, the weaker the coupling capability between adjacent resonators 201. For example, the isolation structure 207 between the resonators 201 corresponding to the input 202 and the output 203 is longest in the figure, so as to avoid signal coupling between the resonators 201 corresponding to the input 202 and the output 203.
The metal or metallization structure in the isolation structure 207 may be a continuous metal or metallization structure, or the metal or metallization structure may be a metal or metallization structure densely distributed in dots, and the metal or metallization structure densely distributed in dots approximates a complete metal or metallization structure. Wherein, the metallization structure between the adjacent resonant cavities 201 may be a metallization groove between the adjacent resonant cavities 201.
Further, after the filter is provided with the isolation structure 207, the coupling structure 204 in the filter needs to be isolated from the isolation structure 207, that is, an isolation layer 208 is provided. The purpose of isolation layer 208 is to avoid an electrical connection between coupling structure 204 and isolation structure 207. When the isolation structure 207 is located at the filter surface, there needs to be a portion of the filter surface between the isolation structure 207 and the coupling structure 204 where the metallization is removed. When the isolation structure 207 is located inside the filter, for example a metallization trench, it is also possible to have a non-metallized window between the isolation structure 207 and the isolation structure 204 above. In summary, the isolation layer 208 needs to be such that there is no electrical connection between the isolation structure 207 and the coupling structure 204.
Further, an isolation layer 210 is also required between the coupling structure 204 and the metallization 209 of the filter surface. Generally, the surface of the filter is metallized completely, and has a metallization layer 209, so that the coupling structure 204 and the metallization layer 209 on the surface of the filter need to be isolated from each other to avoid affecting the performance of the coupling structure 204. The isolation between the coupling structure 204 and the metallization 209 of the filter surface, i.e. the isolation layer 210 between the coupling structure 204 and the metallization 209 of the filter surface, is achieved by removing a ring of metallization between the coupling structure 204 and the metallization 209 of the filter surface.
The ceramic dielectric waveguide filter with the transmission zero provided by the embodiment of the invention comprises: the size of the at least two resonant cavities is determined according to the transmission characteristics required by the filter, the input end and the output end of the filter are respectively located in the preset range of two different resonant cavities on the filter, the surface of the filter is provided with at least one coupling structure, the coupling structure is arranged above the at least two resonant cavities, each coupling structure comprises two metal coupling points and a metal wire, the metal coupling points are respectively arranged in the two different resonant cavities, the metal wire is connected with the two metal coupling points, the at least one coupling structure is arranged on the surface of the filter, so that the ceramic dielectric waveguide filter with the transmission zero point has the transmission zero point, the coupling structure arranged on the surface of the filter is simple to process, and the production efficiency of the ceramic dielectric waveguide filter can be improved.
The coupling structure in the ceramic dielectric waveguide filter with the transmission zero provided by the embodiment of the invention can be realized by two different forms, wherein one is a capacitive coupling structure, the other is an inductive coupling structure, and the capacitive coupling structure and the inductive coupling structure can be independently arranged or mixed, and the detailed description is respectively given below.
Fig. 3A and fig. 3B are schematic structural diagrams of another ceramic dielectric waveguide filter with a transmission zero according to an embodiment of the present invention, where fig. 3A is a top view and fig. 3B is a side view, and in the filter according to the embodiment, the coupling structure is a capacitive coupling structure. As shown in fig. 3A and 3B, 8 coupling cavities 301, input terminals 302 and output terminals 303, and two capacitive coupling structures 304 are shown in this embodiment.
Each capacitive coupling structure 304 includes two metal coupling plates 305 respectively disposed above two different resonant cavities 304 and a metal line 306 connecting the two metal coupling plates 305. The two metal coupling plates 305 of each capacitive coupling structure 304 need to be located above two different resonant cavities 301 respectively, and may be within a preset range directly above or above the resonant cavities 301. Each capacitive coupling structure 304 is equivalently located between two or more resonant cavities 301, and each capacitive coupling structure 304 is equivalently formed by adding a capacitor between two or more resonant cavities 301, so that the purpose of changing the transmission performance of the resonant cavities 301 can be achieved. The shape of the metal coupling disc 305 is not limited, and may be, for example, circular, square, diamond, oval, or irregular. The two metal coupling pads 305 of each capacitive coupling structure 304 may be the same or different. The shape of the metal line 306 connecting the two metal coupling plates 305 is also not limited, and may be, for example, a straight line, a broken line, or an arbitrary curved line. Each capacitive coupling structure 304 may be symmetrically or asymmetrically disposed about the center of the filter.
After the metallization of the filter surface, a demetallization process may be performed around the metal coupling pads 305 and the metal lines 306 in order to isolate the capacitive coupling structure 304 from the metallization of the filter surface. In addition, when the filter surface has the isolation structure 307, isolation is also required between the isolation structure 307 and the capacitive coupling structure 304. For example, as shown in fig. 3A, the isolation structure 307 on the surface of the filter and the capacitive coupling structure 304 are demetallized, and as shown in fig. 3B, a non-metalized window 308 is formed between the isolation structure 307 and the capacitive coupling structure 304 inside the filter. In addition, there may be an isolation layer 310 between the capacitive coupling structure 304 and the metallization 209 of the filter surface.
By adjusting the size of the metal coupling plate 305 of the capacitive coupling structure 304 and the length of the metal wire 306, the position and depth of the transmission zero of the filter can be changed.
Fig. 4A and 4B are schematic structural diagrams of another ceramic dielectric waveguide filter with transmission zeros according to an embodiment of the present invention, where fig. 4A is a top view and fig. 4B is a side view, and in the filter according to the embodiment, the coupling structure is an inductive coupling structure. As shown in fig. 4A and 4B, 8 coupling cavities 401, input 402 and output 403, and two inductive coupling structures 404 are shown in this embodiment.
Each inductive coupling structure 404 comprises two inductive coupling points 405 respectively arranged near two different resonant cavities 404 and a metal wire 406 connecting the two inductive coupling points 405, said inductive coupling points 405 comprising inductive coupling probes or metallized blind holes going deep inside said filter. The two inductive coupling points 405 of each inductive coupling structure 404 need to be located within a predetermined range beside two different resonant cavities 404. Each inductive coupling structure 404 is equivalently located between two or more resonant cavities 401, and each inductive coupling structure 404 is equivalently formed by adding an inductor between two or more resonant cavities 401, so that the purpose of changing the transmission performance of the resonant cavities 401 can be achieved. The inductive coupling point 405 may be an inductive coupling probe or a metalized blind via penetrating into the filter, and may have any shape, such as a circle, a square, a diamond, an ellipse, or an irregular shape. The two inductive coupling points 405 of each inductive coupling structure 404 may be the same or different. The shape of the metal line 406 connecting the two inductive coupling points 405 is also not limited, and may be, for example, a straight line, a broken line or an arbitrary curve. Each inductive coupling structure 404 may be symmetrically or asymmetrically disposed about the center of the filter.
After the metallization of the filter surface, in order to isolate the inductive coupling structure 404 from the metallization of the filter surface, a demetallization process may be performed around the inductive coupling point 405 and the metal line 406. In addition, when the filter surface has the isolation structure 407, isolation is also required between the isolation structure 407 and the inductive coupling structure 404. For example, in fig. 4A, the isolation structures 407 on the surface of the filter are demetallized from the inductive coupling structures 404, and in fig. 4B, the isolation structures 407 in the interior of the filter have non-metallized windows 408 between them and the inductive coupling structures 404. In addition, there may be an isolation layer 410 between the inductive coupling structure 404 and the metallization layer 409 of the filter surface.
The position and depth of the transmission zero of the filter can be changed by adjusting the size and depth of the metal coupling point 405 of the inductive coupling structure 404 and the length of the metal line 406.
The capacitive coupling structures shown in fig. 3A and 3B and the inductive coupling structures shown in fig. 4A and 4B may be used separately or simultaneously. As shown in fig. 5A and 5B, fig. 5A and 5B are schematic structural diagrams of another ceramic dielectric waveguide filter with a transmission zero according to an embodiment of the present invention, where fig. 5A is a top view and fig. 5B is a side view, the filter provided in this embodiment includes two coupling structures, which are a capacitive coupling structure and an inductive coupling structure, respectively.
In this embodiment, 8 coupling cavities 501, input ends 502 and output ends 503, capacitive coupling structures 504, and inductive coupling structures 505 are shown. Specific structures of the capacitive coupling structure 504 and the inductive coupling structure 505 are shown in fig. 3A and 3B and fig. 4A and 4B. The capacitive coupling structure 504 includes a metal coupling plate 506 and a metal line 507, and the inductive coupling structure 505 includes an inductive coupling point 508 and a metal line 507.
In addition, in this embodiment, an isolation structure 509 may be further included, and the relationship between the isolation structure 509 and the capacitive coupling structure 504 and the inductive coupling structure 505 is also as shown in fig. 3A and 3B and fig. 4A and 4B. Window 510 is similar to window 308 and window 408.
After the filter simultaneously uses the capacitive coupling structure and the inductive coupling structure, zero points can appear on two sections of the passband of the filter. Fig. 6 is a diagram showing a transmission characteristic curve and a return loss characteristic curve of the ceramic dielectric waveguide filter having the transmission zero shown in fig. 5A and 5B. As shown in FIG. 6, S11-6 is the return loss characteristic curve, and S12-6 is the transmission characteristic curve. As can be seen from fig. 6, the ceramic dielectric waveguide filter having transmission zeros shown in fig. 5A and 5B has transmission zeros on both sides of the pass band, and two transmission zeros are also present on the left side of the pass band.
In addition, in the ceramic dielectric waveguide filter with the transmission zero provided by the embodiment of the invention, the coupling structure can be arranged symmetrically or asymmetrically about the center of the filter. If the symmetry center of the coupling structure is located within the preset range of the symmetry center of the filter, the coupling structure can be considered to be basically symmetrical relative to the filter, and therefore, the filter can have double-side transmission zero points no matter the coupling structure is a capacitive coupling structure or an inductive coupling structure. As shown in fig. 7, fig. 7 is a schematic diagram of transmission characteristic curves and return loss characteristic curves of a ceramic dielectric waveguide filter with transmission zeros with a symmetrical coupling structure added, where S11-7 is the return loss characteristic curve and S12-7 is the transmission characteristic curve. Fig. 7 is a schematic diagram of a ceramic dielectric waveguide filter corresponding to the schematic diagram of fig. 1, in which a symmetric capacitive coupling structure or an inductive coupling structure is added, and it can be seen from fig. 7 that, after a symmetric capacitive coupling structure or an inductive coupling structure is added to the filter, the return loss does not change much, and it can be seen from the transmission performance curve that a double-sided transmission zero point appears.
Fig. 8A and 8B are schematic structural diagrams of another ceramic dielectric waveguide filter with a transmission zero according to an embodiment of the present invention, where fig. 8A is a top view and fig. 8B is a side view, and in the filter according to the embodiment, the capacitive coupling structure is disposed in an asymmetric slanted manner. As shown in fig. 8A and 8B, 4 coupling cavities 801, input terminals 802 and output terminals 803, and capacitive coupling structures 804 are shown in this embodiment.
Two metal coupling plates 805 of the capacitive coupling structure 804 are respectively located near adjacent diagonal resonant cavities 801. The specific structure of the capacitive coupling structure 804 is the same as the capacitive coupling structure shown in fig. 3A and 3B, and is not described herein again. The capacitive coupling structure 804 further comprises a metal line 806 and the ceramic dielectric waveguide filter with transmission zeroes further comprises an isolation structure 807. Window 808 is similar to window 308.
Fig. 9A and 9B are schematic structural diagrams of another ceramic dielectric waveguide filter with transmission zeros according to an embodiment of the present invention, where fig. 9A is a top view and fig. 9B is a side view, and in the filter according to the embodiment of the present invention, the inductive coupling structure is disposed in an asymmetric slanted-span manner. As shown in fig. 9A and 9B, 4 coupling cavities 901, input ends 902 and output ends 903 and inductive coupling structures 904 are shown in this embodiment.
Two inductive coupling points 905 of the inductive coupling structure 904 are respectively located near the adjacent diagonal resonant cavities 901. The specific structure of the inductive coupling structure 904 is the same as the inductive coupling structure shown in fig. 4A and 4B, and is not described herein again. The inductive coupling structure 904 further comprises a metal line 906 and the ceramic dielectric waveguide filter with transmission zeroes further comprises an isolation structure 907. Window 908 is similar to window 408.
The slanted capacitive coupling structure and the slanted inductive coupling structure shown in fig. 8A and 8B and fig. 9A and 9B may be used alone or in combination.
In the ceramic dielectric waveguide filter with the transmission zero shown in the above embodiments, in each coupling structure, no matter the coupling structure is a capacitive coupling structure or an inductive coupling structure, two metal coupling points of each coupling structure may be respectively disposed in a preset range of a resonant cavity in which two signal transmission paths are not adjacent to each other. That is, the coupling structure is disposed between two non-adjacent resonators on the signal transmission path in the filter. For example, in the embodiment shown in fig. 3A and 3B, the signal transmission path of the filter is from the input end 302 to the output end 303, that is, the resonant cavities 301 corresponding to the input end 302 sequentially pass through the resonant cavities 301 in the clockwise direction, and finally reach the resonant cavities 301 corresponding to the output end 303, so that the resonant cavities 301 corresponding to the input end 302 and the resonant cavities 301 corresponding to the output end 303 are the resonant cavities whose signal transmission paths are not adjacent.
Of course, a coupling structure may be provided between adjacent resonators of two signal transmission paths. The resonant cavities in the ceramic dielectric waveguide filter are all coupled by adopting an inductive coupling mode, so that a capacitive coupling structure can be added between the adjacent resonant cavities of two signal transmission paths, the purpose of changing the transmission performance of the ceramic dielectric waveguide filter can be achieved, and the ceramic dielectric waveguide filter has a transmission zero point.
Fig. 10A and 10B are schematic structural diagrams of another ceramic dielectric waveguide filter with a transmission zero according to an embodiment of the present invention, where fig. 10A is a top view and fig. 10B is a side view, and in the filter according to the embodiment, a surface of the filter further includes a printed circuit board with double-sided metal layers. As shown in fig. 10A and 10B, the ceramic dielectric waveguide filter of the transmission zero provided in this embodiment further includes a printed circuit board 100 covering the surface of the filter on the basis of fig. 4A and 4B.
The printed circuit board 100 is covered with metal layers on both sides, wherein the side facing the filter surface is a lower metal layer 101, the side away from the filter surface is an upper metal layer 102, and the middle is an insulating medium 103, the dielectric constant of which is greater than 1. The metal layer of the lower metal layer 101 at the position corresponding to the coupling structure 304 is open-circuited with the surrounding metal layer, or the printed circuit board 100 is slotted at the position corresponding to the coupling structure 304. That is, the metal layer on the lower metal layer 101 of the printed circuit board is not electrically connected to the coupling structure, and remains in an open state. Specifically, a metal layer on the lower metal layer 101 at a position corresponding to the coupling structure 304 may be removed, or a hollow groove may be directly formed at a position corresponding to the coupling structure 304 on the printed circuit board 100, as shown in fig. 11, fig. 11 is a schematic structural diagram of another ceramic dielectric waveguide filter with a transmission zero according to an embodiment of the present invention, fig. 11 only shows a top view, and in fig. 11, the printed circuit board 100 has the hollow groove 104.
In addition, the printed circuit board 100 has a pattern corresponding to the filter surface at a position other than the coupling structure 304 on the side facing the filter surface, and the printed circuit board 100 has a connection structure 105 electrically communicating two metal layers, i.e., the upper metal layer 102 and the lower metal layer 101, at a position corresponding to the input end 302 and the output end 303 of the filter. The connection structure 105 connecting the upper metal layer 102 and the lower metal layer 101 may be a metalized via or other possible forms.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (13)
1. A ceramic dielectric waveguide filter having transmission zeroes, comprising: at least two resonant cavities;
the sizes of the at least two resonant cavities are determined according to the transmission characteristics required by the filter;
the input end and the output end of the filter are respectively positioned in the preset range of two different resonant cavities on the filter;
the surface of the filter is provided with at least one coupling structure, the coupling structure is arranged above the at least two resonant cavities, and each coupling structure comprises two metal coupling points and a metal wire, the two metal coupling points are respectively arranged in the preset ranges of the two different resonant cavities, and the metal wire is connected with the two metal coupling points.
2. The filter of claim 1, wherein the coupling structures comprise capacitive coupling structures, each capacitive coupling structure comprising two metal coupling plates disposed within a predetermined range above two different resonant cavities, and a metal line connecting the two metal coupling plates.
3. The filter of claim 2, wherein the position and depth of the transmission zero of the filter are changed by adjusting the size of the metal coupling plate and the length of the metal wire of each capacitive coupling structure.
4. The filter of claim 1, wherein the coupling structures comprise inductive coupling structures, each inductive coupling structure comprising two inductive coupling points respectively disposed within a predetermined range beside two different resonant cavities and a metal wire connecting the two inductive coupling points, the inductive coupling points comprising inductive coupling probes or metallized blind vias extending into the filter.
5. The filter of claim 4, wherein the position and depth of the transmission zero of the filter are changed by adjusting the size and depth of the metal coupling point and the length of the metal line of each inductive coupling structure.
6. The filter according to any one of claims 1 to 5, wherein the two metal coupling points of each coupling structure are respectively disposed within a predetermined range of two resonators which are not adjacent to each other in the signal transmission path.
7. A filter according to any one of claims 1 to 5, further comprising an isolation structure between the at least two resonant cavities, wherein the isolation structure comprises a metal or metallization structure disposed between two adjacent resonant cavities.
8. The filter according to claim 7, wherein the metal or metallization structure is a continuous metal or metallization structure, or wherein the metal or metallization structure is a densely populated metal or metallization structure of dots.
9. The filter of claim 7, wherein the coupling structure and the isolation structure have an isolation layer therebetween.
10. A filter according to any of claims 1 to 5, characterised in that an isolating layer is provided between the coupling structure and the metallised layer of the filter surface.
11. The filter according to any of claims 1-5, wherein the at least one coupling structure comprises a coupling structure, and a center of symmetry of the coupling structure is within a predetermined range of a center of symmetry of the filter.
12. A filter according to any of claims 1 to 5, wherein the filter surface further comprises a printed circuit board covered on both sides with metal layers, the side of the printed circuit board facing the filter surface being open-circuited to surrounding metal layers at a position corresponding to the coupling structure or being slotted at a position corresponding to the coupling structure.
13. The filter of claim 12, wherein a side of the printed circuit board facing the filter surface has a pattern corresponding to the filter surface at a location other than the coupling structure, and wherein the printed circuit board has a connection structure electrically communicating two metal layers at a location corresponding to an input and an output of the filter.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010921239.8A CN112072222A (en) | 2020-09-04 | 2020-09-04 | Ceramic dielectric waveguide filter with transmission zero |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010921239.8A CN112072222A (en) | 2020-09-04 | 2020-09-04 | Ceramic dielectric waveguide filter with transmission zero |
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| CN112072222A true CN112072222A (en) | 2020-12-11 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112952312A (en) * | 2021-01-26 | 2021-06-11 | 南京邮电大学 | Dual-mode dielectric waveguide filter with controllable transmission zero |
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2020
- 2020-09-04 CN CN202010921239.8A patent/CN112072222A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112952312A (en) * | 2021-01-26 | 2021-06-11 | 南京邮电大学 | Dual-mode dielectric waveguide filter with controllable transmission zero |
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