Dielectric isolation structure and dielectric filter thereof

Abstract

The present invention is applicable to the technical field of dielectric filters, and provides a dielectric isolation structure, including at least one pair of adjacent first dielectric resonators and second dielectric resonators, wherein the first dielectric resonator is provided with a pair of first frequency blind holes of TE102 mode, the second dielectric resonator is provided with a second frequency blind hole of TE101 mode, and at least one through groove and / or through hole for isolating the first dielectric resonator and the second dielectric resonator is provided between the first dielectric resonator and the second dielectric resonator. A dielectric filter is also proposed, including at least one dielectric isolation structure. Thus, the present invention achieves a good isolator effect between adjacent dielectric resonators on a single ceramic dielectric block, reduces processing costs, increases design stability, and improves reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of dielectric filters, and in particular to a dielectric isolation structure and a dielectric filter thereof. Background Art

[0002] Like traditional metal coaxial filters, dielectric filters often encounter situations where two adjacent resonators do not need to be coupled to each other, but there is always a small amount of coupling due to structural or positional factors, which is generally called parasitic coupling. Parasitic coupling usually deteriorates the frequency response of the original design, so it is necessary to minimize parasitic coupling in the design, or reduce the influence of parasitic coupling on frequency response by adjusting the filter topology.

[0003] There are two common methods to reduce parasitic coupling between two adjacent resonators:

[0004] 1. Placing two adjacent resonators on two separate ceramic dielectric blocks can physically isolate the two, thereby minimizing the parasitic coupling between the two. The disadvantage is that the number of ceramic blocks in the filter is increased, additional alignment requirements and welding processes are introduced in the assembly of the filter, and the cumulative tolerance of the design is increased, which increases the difficulty of filter production and debugging.

[0005] 2. For example, the existing Chinese patent CN109103553B discloses that two adjacent resonators are still arranged on the same ceramic dielectric block, and the through groove arranged between the two is used to isolate the mutual coupling. This method avoids the block division of the ceramic dielectric, but because the two resonators are physically connected by the connecting sections at both ends of the through groove, there will still be a certain mutual coupling, and its coupling bandwidth increases rapidly with the increase of the width of the connecting section. Considering the difficulty of processing and forming of the ceramic dielectric block and the structural strength, the width of the connecting section generally cannot be less than 1mm, so the parasitic coupling amount is higher in magnitude than method one, and the influence of parasitic coupling on the frequency response must be reduced by adjusting the topological structure of the filter, so the topological design of the filter is greatly restricted. When the width of the connecting section is narrow, its structural strength is lower than that of other parts of the dielectric block, and there may be a risk of breakage under ceramic firing or high and low temperature impact, which has high requirements for ceramic materials and firing processes.

[0006] In summary, the existing methods have many problems in practical use, so it is necessary to improve them. Summary of the invention

[0007] In view of the above-mentioned defects, the object of the present invention is to provide a dielectric isolation structure to achieve a good isolator effect between adjacent dielectric resonators on a single ceramic dielectric block, reduce processing costs, increase design stability and improve reliability.

[0008] In order to achieve the above-mentioned object, the present invention provides a dielectric isolation structure, comprising at least one pair of adjacent first dielectric resonators and second dielectric resonators, wherein the first dielectric resonator is provided with a pair of first frequency blind holes of TE102 mode, the second dielectric resonator is provided with a second frequency blind hole of TE101 mode, and at least one through groove and / or through hole for isolating the first dielectric resonator and the second dielectric resonator is provided between the first dielectric resonator and the second dielectric resonator.

[0009] According to the dielectric isolation structure, two first frequency blind holes are symmetrically distributed on the upper surface of the first dielectric resonator along the axis connecting the centers of the first dielectric resonator and the second dielectric resonator, and the diameters and depths of the two first frequency blind holes are correspondingly equal.

[0010] According to the dielectric isolation structure, the second frequency blind hole is arranged on a straight line connecting the centers of the first dielectric resonator and the second dielectric resonator.

[0011] According to the dielectric isolation structure, at least one of the through slots and / or the through holes is symmetrically perpendicular to a center line connecting the first dielectric resonator and the second dielectric resonator.

[0012] According to the dielectric isolation structure, the widths of at least two dielectric connection sections of the through slot and / or the through hole connected between the first dielectric resonator and the second resonator are equal.

[0013] According to the dielectric isolation structure, the dielectric isolation structure is a ceramic dielectric block.

[0014] According to the dielectric isolation structure, the dielectric isolation structure is a rectangular block structure.

[0015] A dielectric filter is also provided, characterized in that it comprises the above dielectric isolation structure.

[0016] According to the dielectric filter, there are two dielectric isolation structures, which are distributed up and down and provided with a pair of input and output ports, and the first dielectric resonator and the second dielectric resonator are distributed adjacent to the input and output ports.

[0017] According to the dielectric filter, the operating frequency of the dielectric filter is 2.6 GHz.

[0018] The dielectric isolation structure of the present invention changes the working mode of one of the adjacent dielectric resonators from TE101 mode to TE102 mode by setting a pair of frequency blind holes, and the other resonator maintains a single frequency blind hole, and the working mode is the loaded TE101 mode. The two resonators are isolated by setting one or more through slots or through holes symmetrical along the axis connecting the centers of the two resonators. Due to the axial symmetry of the magnetic field distribution of the TE102 mode resonator along the axis connecting the centers of the two resonators, the coupling generated by the ceramic dielectric connecting sections on both sides of the axis is the same in size and opposite in polarity, and cancels each other, thereby reducing the parasitic coupling between the two resonators to a minimum. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a commonly used isolation structure of an existing traditional single ceramic dielectric block;

[0020] Figure 2 It is a schematic diagram of the three-dimensional structure of the dielectric isolation structure according to the first embodiment of the present invention;

[0021] Figure 3 It is a schematic diagram of a top view of the dielectric isolation structure according to the first embodiment of the present invention;

[0022] Figure 4 A schematic diagram of the magnetic field direction of the dielectric isolation structure according to the first embodiment of the present invention;

[0023] Figure 5 A schematic diagram showing a comparison of coupling bandwidths of the dielectric isolation structure of the first embodiment of the present invention and the existing traditional structure at different connection section widths;

[0024] Figure 6 It is a three-dimensional structural schematic diagram of a dielectric filter including the dielectric isolation structure described in the first embodiment of the present invention;

[0025] Figure 7 A topological schematic diagram of a dielectric filter including the dielectric isolation structure described in the first embodiment of the present invention;

[0026] Figure 8 A frequency response curve of the dielectric filter of the present invention including the dielectric isolation structure described in the first embodiment;

[0027] Fig. 9 It is a structural schematic diagram of the dielectric isolation structure according to the second embodiment of the present invention;

[0028] Fig.10 It is a structural schematic diagram of a dielectric isolation structure according to a third embodiment of the present invention;

[0029] Fig.11 It is a structural schematic diagram of the dielectric isolation structure described in the fourth embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] See also Figure 1 The isolation structure between the existing traditional dielectric resonators is a ceramic dielectric block 1, which includes two dielectric resonators, namely the first dielectric resonator 21 and the second dielectric resonator 22. The center of the upper surface of each dielectric resonator is provided with a frequency blind hole, namely the first frequency blind hole 31 and the second frequency blind hole 32, so that the resonator works in the TE101 mode. The working frequency of each resonator can be adjusted by adjusting the diameter and depth of the frequency blind hole. An isolation slot 4 is provided in the middle of the two dielectric resonators, which runs through the ceramic dielectric block. A dielectric connection section 5 is reserved at each end of the isolation slot 4, so that the two resonators are kept in the same ceramic dielectric block; the surface of the entire ceramic dielectric block including the blind hole and the slot is covered with a conductive coating, and a high conductivity metal layer such as copper plating or silver plating is usually used to reduce the insertion loss of the filter; because the middle area with a strong electromagnetic field is separated by the isolation slot 4, only a small amount of mutual coupling generated by the dielectric connection section 5 remains between the two resonators, thereby realizing the basic isolation of the two resonators while being physically connected and electrically. This method avoids the segmentation of the ceramic medium, but because the two resonators are physically connected by the connecting sections at both ends of the through slot, there is still a certain degree of mutual coupling, and the coupling bandwidth increases rapidly with the increase of the width of the connecting section.

[0032] Figure 2-Figure 3 The dielectric isolation structure 11 described in the first embodiment of the present invention is shown, including at least a pair of adjacent first dielectric resonators 201 and second dielectric resonators 202. The first dielectric resonator 201 is provided with a pair of first frequency blind holes of TE102 mode, namely blind hole 302 and blind hole 303, so as to change its working mode from TE101 mode to TE102 mode. TE mode refers to a propagation mode in which the longitudinal component of the electric field in the propagation direction of the electromagnetic wave is zero and the longitudinal component of the magnetic field is not zero; the second dielectric resonator 202 is provided with a second frequency blind hole 301 of TE101 mode, and a through slot 40 for isolating the first dielectric resonator 201 and the second dielectric resonator 202 is provided in the middle of the first dielectric resonator 201 and the second dielectric resonator 202. At this time, the magnetic field of the first dielectric resonator 201 surrounds the two frequency blind holes and is also symmetrically distributed along the axis connecting the centers of the two resonators, see Figure 4Due to the axial symmetry of the magnetic field distribution of the TE102 mode resonator along the line connecting the centers of the two resonators, the coupling generated by the ceramic dielectric connecting sections on both sides of the axis is of the same magnitude and opposite polarity, which cancel each other out, thereby minimizing the parasitic coupling between the two resonators and achieving a good isolator effect between adjacent dielectric resonators on a single ceramic dielectric block.

[0033] In order to ensure that two magnetic fields of equal strength and opposite directions can be generated, the two first frequency blind holes of the present embodiment are symmetrically distributed on the upper surface of the first dielectric resonator 201 along the axis connecting the centers of the first dielectric resonator 201 and the second dielectric resonator 202, and the diameters and depths of the two first frequency blind holes are correspondingly equal; that is, the diameters of the blind holes 302 and the blind holes 303 are equal and the depths are also equal. The second frequency blind hole 301 is arranged on the straight line connecting the centers of the first dielectric resonator 201 and the second dielectric resonator 202, so that the coupling intensity between the second frequency blind hole 301 and the two first frequency blind holes is equal, and the polarities are opposite, which just cancel each other out.

[0034] In this embodiment, a through slot 40 is provided, and the through slot 40 is symmetrically perpendicular to the center line of the first dielectric resonator 201 and the second dielectric resonator 202; the two dielectric resonators on one dielectric block are isolated by the through slot 40. The dielectric isolation structure 11 is a ceramic dielectric block, and of course, it can also be other dielectric materials in other embodiments. The dielectric isolation structure 11 is a rectangular block structure, or it can also be other shapes in other embodiments.

[0035] Furthermore, the widths of the two dielectric connection sections 50 connected between the through slot 40 and the first dielectric resonator 201 and the second dielectric resonator 202 are equal. Unlike the conventional structure in which the parasitic coupling between the two dielectric resonators increases rapidly with the increase of the width of the dielectric connection section 50, the parasitic coupling in the dielectric isolation structure 11 of the present invention is not sensitive to the increase of the width of the dielectric connection section 50. As long as the widths of the upper and lower dielectric connection sections 50 remain the same, the two couplings with the same strength and opposite polarity remain in a state of cancellation, so that the total parasitic coupling can always be kept close to zero. Figure 5 The existing traditional isolation structure is usually in a dilemma about the width design of the dielectric connection section, and it is necessary to find a good balance between parasitic coupling and ceramic structure strength, and even it is necessary to repeatedly change the topology design of the entire filter. However, the isolation structure proposed by the present invention has a coupling bandwidth of parasitic coupling kept at a level close to zero and is basically not affected by the width of the dielectric connection section 50, which not only greatly improves the frequency selection performance and design flexibility of the dielectric filter, but also improves the structural strength and reliability of the dielectric filter.

[0036] Figure 6The dielectric filter of the present invention including the dielectric isolation structure 11 described in the first embodiment is shown. The working frequency of the dielectric filter is 2.6 GHz. The dielectric filter includes two dielectric isolation structures 11, which are distributed up and down and are provided with a pair of input and output ports 60. The first dielectric resonator 201 and the second dielectric resonator 202 are distributed adjacent to the input and output ports 60. As shown in the figure, the dielectric filter is composed of two upper and lower ceramic dielectric blocks, each of which contains five dielectric resonators, and a frequency blind hole is provided at the center of the surface of each dielectric resonator. Among them, the two resonators on the ceramic dielectric block one near the input and output ports 60 are adjacent, and the parasitic coupling between the two has a greater influence on the frequency response of the entire filter. Therefore, two frequency blind holes 302 and 303 symmetrically arranged along the central axis of the dielectric block are arranged on the surface of one of the dielectric resonators, so that its working mode is TE102 mode, and the other dielectric resonator maintains a single frequency blind hole 301, and the working mode is TE101 mode. Compared with the existing traditional isolation structure, the isolation structure proposed by the present invention can provide better isolation effect, smaller parasitic coupling, and higher ceramic structure strength. Figure 8 The figure shows the simulated frequency response curve of the dielectric filter and the comparison with the simulation curve of the existing traditional isolation structure. It can be seen that the parasitic coupling between the two resonators at the input and output ends is greatly reduced after adopting the isolation structure, the out-of-band suppression performance on both sides of the working frequency band is significantly improved, and the frequency selection performance is greatly improved.

[0037] Fig. 9 The dielectric isolation structure 12 of the second embodiment of the present invention is shown, comprising at least one pair of adjacent first dielectric resonators 201 and second dielectric resonators 202, the first dielectric resonator 201 is provided with a pair of first frequency blind holes of TE102 mode, which are blind holes 302 and blind holes 303 with equal diameters and widths, respectively, and the second dielectric resonator 202 is provided with a second frequency blind hole 301 of TE101 mode; the difference from the above embodiment is that two through slots 41 for isolating the first dielectric resonator 201 and the second dielectric resonator 202 are provided between the first dielectric resonator 201 and the second dielectric resonator 202 in this embodiment, the two through slots 41 are symmetrically perpendicular to the center line of the first dielectric resonator 201 and the second dielectric resonator 202, and the widths of the three dielectric connection sections of the two through slots 41 connected between the first dielectric resonator 201 and the second dielectric resonator 202 are equal.

[0038] Fig.10The dielectric isolation structure 13 of the third embodiment of the present invention is shown, comprising at least one pair of adjacent first dielectric resonators 201 and second dielectric resonators 202, the first dielectric resonator 201 is provided with a pair of first frequency blind holes of TE102 mode, which are blind holes 302 and blind holes 303 with equal diameters and widths, respectively, and the second dielectric resonator 202 is provided with a second frequency blind hole 301 of TE101 mode; the difference from any of the above embodiments is that four through holes 42 for isolating the first dielectric resonator 201 and the second dielectric resonator 202 are arranged between the first dielectric resonator 201 and the second dielectric resonator 202 in this embodiment, the four through holes 42 are symmetrically distributed and perpendicular to the center line of the first dielectric resonator 201 and the second dielectric resonator 202, and the widths of the five dielectric connection sections of the two through holes 42 connected between the first dielectric resonator 201 and the second dielectric resonator 202 are equal.

[0039] Fig.11 The dielectric isolation structure 14 of the fourth embodiment of the present invention is shown, comprising at least one pair of adjacent first dielectric resonators 201 and second dielectric resonators 202, the first dielectric resonator 201 is provided with a pair of first frequency blind holes of TE102 mode, which are blind holes 302 and 303 with equal diameters and widths, respectively, and the second dielectric resonator 202 is provided with a second frequency blind hole 301 of TE101 mode; the difference from any of the above embodiments is that two half-open through slots 43 for isolating the first dielectric resonator 201 and the second dielectric resonator 202 are arranged between the first dielectric resonator 201 and the second dielectric resonator 202 in this embodiment, the two through slots 43 are symmetrically distributed and perpendicular to the center line of the first dielectric resonator 201 and the second dielectric resonator 202, and the width of a dielectric connection section between the first dielectric resonator 201 and the second dielectric resonator 202 connected by the two through slots 43 is equal.

[0040] The dielectric isolation structures of the second embodiment, the third embodiment and the fourth embodiment described above can also generate two magnetic fields of equal strength and opposite directions, which are coupled with the magnetic field in the dielectric resonator 21 through the dielectric connecting sections 5 on both sides, and the coupling amounts are equal in magnitude and opposite in polarity, which just cancel each other out, thereby achieving a good isolator effect between adjacent dielectric resonators on a single ceramic dielectric block.

[0041] A method including Fig. 9 or Fig.10 or Fig.11 A dielectric filter with a dielectric isolation structure.

[0042] In summary, the present invention achieves a good isolator effect between adjacent dielectric resonators on a single ceramic dielectric block, minimizes the amount of mutual coupling, and avoids the increased difficulty of assembly, welding and debugging caused by dielectric block division; the isolation effect is greatly improved compared with the existing traditional isolation structure, the coupling bandwidth between the two resonators is significantly reduced compared with the existing isolation structure, the influence of parasitic coupling on the frequency response of the filter is minimized, the frequency selection performance of the dielectric filter is improved, and the topology requirements of the filter during design are reduced, thereby increasing the flexibility of the design; the parasitic coupling in the structure basically does not change with the width of the dielectric connecting section between the two dielectric resonators, so the width of the connecting section can be appropriately increased compared with the existing design, and the structural strength of the entire dielectric block is enhanced, thereby greatly reducing the requirements for ceramic materials and firing processes, and also reducing the risk of dielectric filters breaking due to stress or temperature changes during firing, production, transportation and use, thereby improving the reliability of dielectric filters.

[0043] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A dielectric isolation structure, characterized in that: The invention comprises at least one pair of adjacent first dielectric resonators and second dielectric resonators, wherein the first dielectric resonator is provided with a pair of first frequency blind holes of TE102 mode, the second dielectric resonator is provided with a second frequency blind hole of TE101 mode, and at least one through slot and / or through hole for isolating the first dielectric resonator and the second dielectric resonator is provided between the first dielectric resonator and the second dielectric resonator; Two first frequency blind holes are symmetrically distributed on the upper surface of the first dielectric resonator along the axis connecting the centers of the first dielectric resonator and the second dielectric resonator, and the diameters and depths of the two first frequency blind holes are correspondingly equal; The second frequency blind hole is arranged on a straight line connecting the centers of the first dielectric resonator and the second dielectric resonator; At least one of the through slots and / or the through holes is symmetrically and perpendicularly disposed on a center line connecting the first dielectric resonator and the second dielectric resonator; The widths of at least two dielectric connection sections of the through groove and / or the through hole connected between the first dielectric resonator and the second dielectric resonator are equal.

2. The dielectric isolation structure according to claim 1, characterized in that: The dielectric isolation structure is a ceramic dielectric block.

3. The dielectric isolation structure according to claim 1, characterized in that: The dielectric isolation structure is a rectangular block structure.

4. A dielectric filter, characterized in that: The invention comprises a dielectric isolation structure as claimed in any one of claims 1 to 3.

5. The dielectric filter according to claim 4, characterized in that: The invention comprises two dielectric isolation structures, which are distributed up and down and provided with a pair of input and output ports, and the first dielectric resonator and the second dielectric resonator are distributed adjacent to the input and output ports.

6. The dielectric filter according to claim 4, characterized in that: The operating frequency of the dielectric filter is 2.6 GHz.

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