Dielectric filter

Abstract

The present invention provides a dielectric filter, which includes at least one first resonator operating in the TE102 mode and at least one second resonator operating in the TE101 mode; the top surface and the bottom surface of the first resonator respectively include a symmetric top surface center and a bottom surface center; a pair of first tuning blind holes are symmetrically arranged on the top surface of the first resonator with respect to the top surface center; a bottom blind hole is provided at the bottom surface center of the first resonator; and / or the first resonator is provided with a through hole penetrating the top surface and the bottom surface, and the through hole is located on the perpendicular bisector corresponding to the connection line of the pair of first tuning blind holes. Thereby, the present invention can reduce or increase the frequency of the loaded TE101 mode with little influence on the frequency of the loaded TE102 mode, can greatly improve the low-frequency suppression performance, and has a simple structure and is easy to implement, further improving the design flexibility and adaptability of the dielectric filter.

Description

Technical Field

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

[0002] A filter is an indispensable frequency selection device in wireless communication. Dielectric filters with ceramics as the carrier have a wider and wider application prospect due to their compact volume and excellent performance.

[0003] Chinese Patent CN201980001851.9 discloses a ceramic dielectric filter. The capacitive coupling method of the ceramic dielectric filter is realized by loading the TE102 mode using a double-blind hole structure. The capacitive coupling structure is simple and easy to implement by this method. However, since the resonator operating in the TE102 mode still has the TE101 mode and the resonant frequency of the TE101 mode is lower than that of the TE102 mode, parasitic harmonics will be generated at the low frequency of the passband of this ceramic dielectric filter, thus affecting the suppression performance of the filter at low frequencies. Especially when the ceramic dielectric filter has at least two resonators operating in the TE102 mode, the TE101 modes of these resonators will generate at least two parasitic harmonics at the low frequency of the passband. When their frequencies are close, the harmonics will be superimposed on each other, seriously affecting the suppression performance at low frequencies. Although the resonant frequency interval between the two modes can be adjusted to a certain extent by adjusting the distance between the double-blind holes of the resonator, the change in the distance not only affects the frequencies of the two modes simultaneously, but also changes the adjacent coupling amount. Therefore, there are great limitations in design, and the adjustment amount of the harmonic frequency is also very limited.

[0004] In summary, it is obvious that the prior art has inconveniences and defects in actual use, so it is necessary to be improved. Summary of the Invention

[0005] Aiming at the above defects, the purpose of the present invention is to provide a dielectric filter, which can greatly improve the low-frequency suppression performance and has a simple structure and is easy to implement.

[0006] To achieve the above purpose, the present invention provides a dielectric filter, including at least one first resonator operating in the TE102 mode and at least one second resonator operating in the TE101 mode;

[0007] The top surface and the bottom surface of the first resonator respectively include a symmetric top surface center and a bottom surface center;

[0008] A pair of first tuning blind holes are symmetrically arranged on the top surface of the first resonator with respect to the top surface center;

[0009] A bottom blind hole is provided at the bottom surface center of the bottom surface of the first resonator; and / or

[0010] The first resonator is provided with a through hole penetrating the top surface and the bottom surface, and the through hole is located on the perpendicular bisector corresponding to the connection line of the pair of first tuning blind holes.

[0011] For the dielectric filter according to the present invention, the dielectric filter includes one such first resonator and at least two such second resonators, and the bottom surface of the first resonator is provided with the bottom blind hole at the center of the bottom surface.

[0012] For the dielectric filter according to the present invention, the dielectric filter includes two such first resonators and at least two such second resonators. The bottom surface of one of the first resonators is provided with the bottom blind hole at the center of the bottom surface, and the other first resonator is provided with the through hole penetrating its top surface and bottom surface, and the through hole is located on the perpendicular bisector corresponding to the connection line of the pair of first tuning blind holes.

[0013] For the dielectric filter according to the present invention, the dielectric filter includes two such first resonators and at least two such second resonators. One of the first resonators is provided with the through hole penetrating its top surface and bottom surface, and the through hole is located on the perpendicular bisector corresponding to the connection line of the pair of first tuning blind holes.

[0014] For the dielectric filter according to the present invention, when the depth of the bottom blind hole of the first resonator increases, the resonant frequency of the loaded TE101 mode decreases, and the interval from the resonant frequency of the loaded TE102 mode increases; and / or

[0015] When the distance between the through hole of the first resonator and the center of the top surface or the center of the bottom surface decreases, the resonant frequency of the loaded TE101 mode increases, and the interval from the resonant frequency of the loaded TE102 mode decreases.

[0016] For the dielectric filter according to the present invention, the center of the top surface of the first resonator is the planar center or the predetermined center of the top surface of the first resonator;

[0017] The center of the bottom surface of the first resonator is the planar center or the predetermined center of the bottom surface of the first resonator.

[0018] For the dielectric filter according to the present invention, the top surface and the bottom surface of the second resonator respectively include a symmetric top surface center and a bottom surface center;

[0019] The top surface of the second resonator is provided with a second tuning blind hole at the center of the top surface, and the depth of the first tuning blind hole is greater than the depth of the second tuning blind hole.

[0020] For the dielectric filter according to the present invention, the first resonator adjusts the diameter, depth, and / or spacing of the first tuning blind hole so that the resonance frequency of the loaded TE102 mode is near the predetermined filter passband frequency; and / or

[0021] The second resonator adjusts the diameter, depth, and / or spacing of the second tuning blind hole so that the resonance frequency of the loaded TE101 mode is near the predetermined filter passband frequency.

[0022] For the dielectric filter according to the present invention, the center of the top surface of the second resonator is the planar center or the predetermined center of the top surface of the second resonator;

[0023] The center of the bottom surface of the second resonator is the planar center or the predetermined center of the bottom surface of the second resonator.

[0024] For the dielectric filter according to the present invention, the dielectric filter includes at least two of the second resonators, and one of the two second resonators has an input port blind hole and an output port blind hole at the center of the bottom surface respectively. The input port blind hole is used for inputting signals, and the output port blind hole is used for outputting signals.

[0025] For the dielectric filter according to the present invention, isolation rings made of non-metallic materials are respectively provided around the input port blind hole and the output port blind hole.

[0026] For the dielectric filter according to the present invention, the dielectric filter includes a ceramic dielectric block body, and at least one isolation through groove and / or isolation through hole is provided on the ceramic dielectric block body. The isolation through groove and / or the isolation through hole divide the ceramic dielectric block body into at least one of the first resonators and at least one of the second resonators; the first resonator and the second resonator are coupled through the dielectric connection section of the ceramic dielectric block body.

[0027] For the dielectric filter according to the present invention, the surfaces of the first resonator and the second resonator are coated with an electroplated layer made of a metallic material.

[0028] The dielectric filter of the present invention includes a first resonator operating in the TE102 mode and a second resonator operating in the TE101 mode. By utilizing the difference in the electromagnetic field distributions of the two resonance modes of loaded TE101 and loaded TE102, a bottom blind hole and / or a through hole are added to the first resonator, which can reduce or increase the frequency of the loaded TE101 mode with less influence on the frequency of the loaded TE102 mode, thereby achieving flexible adjustment of low-frequency parasitic harmonics. Preferably, when a bottom blind hole is provided at the center of the bottom surface of the first resonator, as the depth of the bottom blind hole increases, the resonance frequency of the loaded TE101 mode decreases, and the resonance frequency interval from the loaded TE102 mode increases, so that the low-frequency parasitic harmonics are far away from the working passband; when a through hole penetrating the top and bottom surfaces is provided in the first resonator and the through hole is located on the perpendicular bisector corresponding to the connection line of a pair of first tuning blind holes, as the distance between the through hole and the center decreases, the resonance frequency of the loaded TE101 mode increases, and the resonance frequency interval from the loaded TE102 mode decreases, thereby effectively improving the low-frequency harmonics of the dielectric filter using capacitive coupling in the TE102 mode, especially avoiding the situation where the low-frequency harmonic frequencies of at least two parasitic TE101 modes are close to each other and the mutual superposition leads to the exacerbation of low-frequency suppression. Thereby, the present invention can greatly improve the low-frequency suppression performance of the dielectric filter, and has a simple structure and is easy to implement, further enhancing the design flexibility and adaptability. Description of the Drawings

[0029] Figure 1 is a schematic structural diagram of the first resonator provided with a bottom blind hole according to the first embodiment of the present invention;

[0030] Figure 2 is a schematic diagram of the electric field distribution of the first resonator loaded with the TE101 mode according to the first embodiment of the present invention;

[0031] Figure 3 is a schematic diagram of the electric field distribution of the first resonator loaded with the TE102 mode according to the first embodiment of the present invention;

[0032] Figure 4 is a relationship diagram between the resonance frequencies of the first resonator loaded with the TE101 mode and the TE102 mode and the depth of the blind hole according to the first embodiment of the present invention;

[0033] Figure 5 is a relationship diagram between the quality factor Q of the first resonator loaded with the TE101 mode and the TE102 mode and the depth of the blind hole according to the first embodiment of the present invention;

[0034] Figure 6 is a schematic structural diagram of the first resonator provided with a through hole according to the second embodiment of the present invention;

[0035] Figure 7 It is a relationship diagram between the resonance frequency of the first resonator loaded with TE101 mode and TE102 mode and the blind hole depth provided by the second embodiment of the present invention;

[0036] Figure 8 It is a relationship diagram between the quality factor Q of the first resonator loaded with TE101 mode and TE102 mode and the blind hole depth provided by the second embodiment of the present invention;

[0037] Figure 9 It is a schematic diagram of the front and back structures of the dielectric filter provided by the third embodiment of the present invention;

[0038] Figure 10 It is a comparison diagram of the frequency response curves of the dielectric filter provided by the third embodiment of the present invention;

[0039] Figure 11 It is a schematic diagram of the front and back structures of the dielectric filter provided by the fourth embodiment of the present invention;

[0040] Figure 12 It is a comparison diagram of the frequency response curves of the dielectric filter provided by the fourth embodiment of the present invention.

[0041] Reference numerals:

[0042] Dielectric filter 100; First resonator 10; Second resonator 20;

[0043] First tuning blind hole 11; Bottom blind hole 12; Through hole 13;

[0044] Second tuning blind hole 21; Input port blind hole 22; Output port blind hole 22;

[0045] Isolation ring 30; Ceramic dielectric block body 40; Isolation through slot 41;

[0046] Isolation through hole 42. Detailed implementation manners

[0047] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to 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 used to limit the present invention.

[0048] It should be noted that references to "one embodiment", "embodiment", "exemplary embodiment", etc. in this specification mean that the described embodiment may include specific features, structures, or characteristics, but not every embodiment must include these specific features, structures, or characteristics. In addition, such expressions do not refer to the same embodiment. Further, when combining specific features, structures, or characteristics with an embodiment, it has been shown that combining such features, structures, or characteristics with other embodiments is within the knowledge of those skilled in the art, whether or not explicitly described.

[0049] In addition, in the specification and subsequent claims, certain terms are used to refer to specific components or parts. Those of ordinary skill in the art should understand that manufacturers may use different nouns or terms to refer to the same component or part. This specification and subsequent claims do not use the difference in name as a way to distinguish components or parts, but use the difference in function of components or parts as the criterion for distinction. The terms "comprising" and "including" mentioned throughout the specification and subsequent claims are open-ended terms and should be interpreted as "including but not limited to". In addition, the term "connected" herein includes any direct and indirect electrical connection means. Indirect electrical connection means include connection through other devices.

[0050] Figures 1 to 12 The structure of the dielectric filter of the present invention is shown. The dielectric filter 100 preferably uses ceramics as a carrier and includes at least one first resonator 10 operating in the TE102 mode and at least one second resonator 20 operating in the TE101 mode. The capacitive coupling of the dielectric filter 100 is achieved by loading the first resonator 10 in the TE102 mode. The present invention utilizes the difference in the electromagnetic field distributions of the two resonance modes of TE101 and TE102 loading, and adds a bottom blind hole 12 and / or a through hole 13 in the first resonator 10 operating in the TE102 mode to achieve flexible adjustment of low-frequency parasitic harmonics.

[0051] Such as Figure 1 and Figure 6As shown, the top surface and the bottom surface of the first resonator 10 respectively include a symmetric top surface center and a bottom surface center. Preferably, the top surface center of the first resonator 10 is the planar center or a predetermined center of the top surface of the first resonator 10, etc. The predetermined center refers to a center set in advance, and this predetermined center can be any point on the top surface. The bottom surface center of the first resonator 10 is the planar center or a predetermined center of the bottom surface of the first resonator 10, etc. The predetermined center refers to a center set in advance, and this predetermined center can be any point on the bottom surface. A pair of first tuning blind holes 11 are symmetrically arranged on the top surface of the first resonator 10 with respect to the top surface center. Since the resonance frequency of loading the TE101 mode is lower than that of loading the TE102 mode, when the first resonator 10 is integrated in the dielectric filter 100, loading the TE101 mode will generate parasitic harmonics at the low frequency of the passband.

[0052] As Figure 1 shown in the first embodiment, a bottom blind hole 12 is provided at the bottom surface center of the first resonator 10. From Figure 2 and Figure 3 the schematic diagrams of the electric field distributions, it can be found that there are significant differences in the electromagnetic field distributions of loading the TE101 mode and loading the TE102 mode near the bottom blind hole 12. Under the condition of loading the TE101 mode, the electric field at the bottom of the bottom blind hole 12 is stronger, and the direction is perpendicular to the bottom surface of the bottom blind hole 12; while under the condition of loading the TE102 mode, the electric field at the bottom of the bottom blind hole 12 is very weak, and the direction is parallel to the bottom surface of the bottom blind hole 12. It can be seen that the newly added bottom blind hole 12 has a greater influence on the resonance frequency of loading the TE101 mode, while having basically no influence on the resonance frequency of loading the TE102 mode.

[0053] Preferably, when the depth of the bottom blind hole 12 of the first resonator 10 increases, the resonance frequency of loading the TE101 mode decreases, and the interval from the resonance frequency of loading the TE102 mode increases. As Figure 4 shown, as the depth of the bottom blind hole 12 increases, the resonance frequency of loading the TE101 mode drops by nearly 500 MHz, while the resonance frequency of loading the TE102 mode only drops by about 10 MHz. In this embodiment, the height of the first resonator 10 is 6 mm, and when the depth of the bottom blind hole 12 is equal to 3 mm, it is half of the overall height of the first resonator 10. Of course, the height of the first resonator 10 can be set according to actual needs and is not restricted by any limitations. As Figure 5 shown, the addition of the bottom blind hole 12 has a small influence on the quality factor Q value of the resonator, indicating that the introduction of the bottom blind hole 12 basically does not affect the passband performance such as the insertion loss of the dielectric filter 100.

[0054] Preferably, the cross-sectional shape of the bottom blind hole 12 introduced by the first resonator 10 includes, but is not limited to, shapes such as circular and square. Optionally, in this embodiment, the cross-sectional shape of the bottom blind hole 12 is set to be circular to improve the processing convenience of the bottom blind hole 12 and facilitate ensuring the processing accuracy of the bottom blind hole 12.

[0055] Preferably, by adjusting the diameter, depth, and / or spacing of a pair of first tuning blind holes 11 of the first resonator 10, the resonant frequency of the loaded TE102 mode can be made near the predetermined required filter passband frequency. The first tuning blind hole 11 is used to generate capacitive loading so that the first resonator 10 operates in the TE102 mode. The first tuning blind hole 11 is a blind hole. On the one hand, it can leave a tuning margin. On the other hand, by changing the diameter, depth, and / or spacing of the first tuning blind hole 11, the resonant frequency of the first tuning blind hole 11 can be adjusted. The cross-sectional shape of the first tuning blind hole 11 includes, but is not limited to, shapes such as circular and square. Optionally, in this embodiment, the cross-sectional shape of the first tuning blind hole 11 is set to be circular to improve the processing convenience of the first tuning blind hole 11 and facilitate ensuring the processing accuracy of the first tuning blind hole 11.

[0056] Preferably, the surface of the first resonator 10 is coated with an electroplated layer made of a metal material. In this embodiment, the electroplated layer is made of copper or silver with a relatively high conductivity, which can further reduce the insertion loss of the dielectric filter 100 and thus improve the performance of the dielectric filter 100.

[0057] Aiming at the design limitation of the capacitive coupling of the TE102 mode in the existing dielectric filter, in the first embodiment of the present invention, the structure of the first resonator 10 operating in the TE102 mode of the dielectric filter 100 is optimized. It is proposed to add a bottom blind hole 12 to the first resonator 10 to adjust its TE101 mode frequency. Due to the difference in the electromagnetic field distributions of the two resonant modes of loaded TE101 and loaded TE102, setting the bottom blind hole 12 in the first resonator 10 can reduce the resonant frequency of the TE101 mode with less influence on the frequency of the loaded TE102 mode, making the interval between the resonant frequency of the loaded TE101 mode and the frequency of the loaded TE102 mode larger, so that the low-frequency parasitic harmonics are far away from the working passband, realizing the adjustment of the low-frequency parasitic harmonic frequency of the dielectric filter 100, improving the suppression performance of the dielectric filter 100 at low frequencies, and having a simple structure and being easy to implement.

[0058] As Figure 6 In the second embodiment shown, the first resonator 10 is provided with a through hole 13 penetrating the top surface and the bottom surface, and the through hole 13 is located on the perpendicular bisector corresponding to the connection line between a pair of first tuning blind holes 11. Figure 6 And Figure 1The difference of the first resonator 10 shown is that the bottom blind hole 12 provided at the bottom center is replaced by a through hole 13 provided on the perpendicular bisector of the connection line of the pair of first tuning blind holes 11. Due to the difference in the electromagnetic field distribution of the two modes of loaded TE101 and loaded TE102 on this perpendicular bisector, the newly added through hole 13 has a greater impact on the resonant frequency of the loaded TE101 mode, while having basically no impact on the resonant frequency of the loaded TE102 mode. Specifically, the introduction of the through hole 13 can increase the tuning frequency of the loaded TE101 mode, while having a relatively small impact on the increase of the tuning frequency of the loaded TE102 mode.

[0059] Preferably, the distance between the through hole 13 introduced in the first resonator 10 and the center of the top surface or the center of the bottom surface is reduced, the resonant frequency of the loaded TE101 mode increases, and the interval from the resonant frequency of the loaded TE102 mode decreases. As Figure 7 shown, as the through hole 13 translates on the perpendicular bisector corresponding to the connection line of the pair of first tuning blind holes 11, when the distance between the through hole 13 and the center (i.e., the center of the top surface or the center of the bottom surface) decreases, the interval between the resonant frequency of the TE101 mode and the resonant frequency of the TE102 mode continuously shrinks. However, different from the aforementioned addition of the bottom blind hole 12, as Figure 8 shown, as the distance between the through hole 13 and the center decreases, the quality factor Q of the two modes will also decrease to a certain extent. Therefore, it can be known that the method of introducing the through hole 13 is generally used to move the low-frequency parasitic harmonics to a specific frequency band in the high-frequency direction, or to avoid the superposition of multiple low-frequency harmonics. In practical applications, the distance between the through hole 13 and the center is increased as much as possible to avoid its impact on the quality factor Q of the first resonator 10.

[0060] Preferably, the cross-sectional shape of the through hole 13 introduced in the first resonator 10 includes but is not limited to shapes such as circular and square. Optionally, in this embodiment, the cross-sectional shape of the through hole 13 is set to be circular to improve the processing convenience of the through hole 13 and facilitate the guarantee of the processing accuracy of the through hole 13.

[0061] In view of the design limitations of the capacitive coupling of the TE102 mode in existing dielectric filters, in the second embodiment of the present invention, the structure of the first resonator 10 operating in the TE102 mode of the dielectric filter 100 is optimized. It is proposed to add a through hole 13 to the first resonator 10 to adjust its TE101 mode frequency. Due to the difference in the electromagnetic field distributions of the two resonant modes of loading TE101 and loading TE102, setting the through hole 13 in the first resonator 10 can increase the resonant frequency of the TE101 mode with less influence on the frequency of the loading TE102 mode. Thus, the low-frequency harmonics of the dielectric filter 100 using capacitive coupling of the TE102 mode can be effectively improved. Especially for the case where the low-frequency harmonic frequencies with at least two parasitic TE101 modes are close to each other and are superimposed, resulting in aggravated deterioration of low-frequency suppression, and the structure is simple and easy to implement.

[0062] Preferably, the dielectric filter 100 includes a ceramic dielectric block body 40. At least one isolation groove 41 and / or isolation through hole 42 are provided on the ceramic dielectric block body 40. The isolation groove 41 and / or isolation through hole 42 divide the ceramic dielectric block body 40 into at least one first resonator 10 and at least one second resonator 20. The coupling between the first resonator 10 and the second resonator 20 is achieved through the dielectric connection section of the ceramic dielectric block body 40. The ceramic dielectric block body 40 of the present invention preferably has a rectangular block structure. Of course, in other embodiments, other arbitrary shapes can also be adopted according to needs.

[0063] Preferably, the dielectric filter 100 includes one first resonator 10 and at least two second resonators 20. A bottom blind hole 12 is provided at the center of the bottom surface of the first resonator 10.

[0064] As Figure 9 shown in the third embodiment, the dielectric filter 100 is a sixth-order dielectric filter, and the designed passband frequency band is 3.4 - 3.6 GHz. Figure 9 The dielectric filter 100 in the middle includes a ceramic dielectric block body 40. The ceramic dielectric block body 40 is divided into six resonators by a plurality of isolation grooves 41 and one isolation through hole 42. Among them, five are second resonators 20 operating in the loaded TE101 mode, and another is a first resonator 10 operating in the loaded TE102 mode. Among them, the first resonator 10 is capacitively coupled to at least one second resonator 20 and inductively coupled to at least one second resonator 20. Any second resonator 20 is inductively coupled to at least one of the remaining second resonators 20. A pair of first tuning blind holes 11 are symmetrically provided about the center of the top surface of the first resonator 10. A bottom blind hole 12 is provided at the center of the bottom surface of the first resonator 10. By adjusting the depth of the bottom blind hole 12, the frequency of the first resonator 10 in the loaded TE101 mode can be reduced, so that the low-frequency parasitic harmonics are far away from the working passband.

[0065] Preferably, the top surface and the bottom surface of the second resonator 20 respectively include a symmetric top surface center and a bottom surface center. The top surface center of the second resonator 20 is the planar center or a predetermined center of the top surface of the second resonator 20, etc. The predetermined center refers to a center set in advance, and this predetermined center can be any point on the top surface. The bottom surface center of the second resonator 20 is the planar center or a predetermined center of the bottom surface of the second resonator 20, etc. The predetermined center refers to a center set in advance, and this predetermined center can be any point on the bottom surface. Each top surface of the second resonators 20 is provided with a second tuning blind hole 21 at the top surface center. The depth of the first tuning blind hole 11 is greater than the depth of the second tuning blind hole 21, so that the first resonator 10 operates in the loaded TE102 mode, thereby generating capacitive coupling with adjacent resonators.

[0066] Preferably, the second resonator 20 adjusts the resonant frequency of the loaded TE101 mode to be near a predetermined filter passband frequency by adjusting the diameter, depth, and / or spacing of the second tuning blind hole 21. That is, each second resonator 20 adjusts the loading amount of each second resonator 20 by adjusting the depth of its own second tuning blind hole 21, thereby realizing the adjustment of its own frequency. The second tuning blind hole 21 is used to generate capacitive loading, so that the second resonator 20 operates in the TE101 mode. The second tuning blind hole 21 is provided as a blind hole. On the one hand, a tuning margin can be left. On the other hand, the resonant frequency of the second tuning blind hole 21 can be adjusted by changing the diameter, depth, and / or spacing of the second tuning blind hole 21. Further, the cross-sectional shape of the second tuning blind hole 21 includes but is not limited to shapes such as circular and square. Optionally, in this embodiment, the cross-sectional shape of the second tuning blind hole 21 is set to be circular to improve the processing convenience of the second tuning blind hole 21 and facilitate ensuring the processing accuracy of the second tuning blind hole 21.

[0067] Preferably, the coupling between the first resonator 10 and the second resonator 20 is realized through the dielectric connection section of the ceramic dielectric block body 40. That is, after one first resonator 10 and five second resonators 20 are divided by the isolation through slot 41 and the isolation through hole 42, the coupling between the first resonator 10 and each second resonator 20 is formed through the remaining dielectric connection section on the ceramic dielectric block body 40.

[0068] Preferably, the dielectric filter 100 includes at least two second resonators 20. One input port blind hole 22 and one output port blind hole 22 are respectively provided at the bottom surface center of the two second resonators 20. The input port blind hole 22 is used for inputting signals, and the output port blind hole 22 is used for outputting signals. Preferably, isolation rings 30 made of non-metallic materials are respectively provided around the input port blind hole 22 and the output port blind hole 22 to separate the input port blind hole 22 and the output port blind hole 22 from other surface coatings.

[0069] Preferably, the surfaces of the ceramic dielectric block body 40 except for the isolation ring 30 are coated with an electroplated layer made of a metal material. In this embodiment, the electroplated layer is made of copper or silver with a relatively high conductivity, which can further reduce the insertion loss of the dielectric filter 100 and thus improve the performance of the dielectric filter 100.

[0070] Figure 10 FIG. is a comparison diagram of the frequency response curves of the dielectric filter provided by the third embodiment of the present invention before and after introducing the bottom blind hole. As can be seen from the figure, before and after adding the bottom blind hole 12 to the bottom of the first resonator 10 operating in the TE102 mode, the frequency response curve of the dielectric filter 100 near the working passband basically remains unchanged, while the low-frequency parasitic harmonic changes from the original 2.95 GHz to 2.78 GHz. Not only is the distance from the working passband farther, but the amplitude of the harmonic is also reduced by about 10 dB, which greatly improves the suppression performance in the low-frequency band.

[0071] Preferably, the dielectric filter 100 includes two first resonators 10 and at least two second resonators 20. A bottom blind hole 12 is provided at the center of the bottom surface of one of the first resonators 10, and a through hole 13 penetrating its top and bottom surfaces is provided in the other first resonator 10, and the through hole 13 is located on the perpendicular bisector corresponding to the connection line of a pair of first tuning blind holes 11.

[0072] As Figure 11 shown in the fourth embodiment, the dielectric filter 100 is an eighth-order dielectric filter, and the designed passband frequency band is 2.515 - 2.675 GHz. Except for the differences in the operating frequency and the order, the biggest difference between this fourth embodiment and the third embodiment is that it includes two first resonators 10 operating in the TE102 mode, which are respectively located in the cross-coupling structures of two quadrupoles to generate two transmission zeros on both sides of the working passband of the dielectric filter 100. Therefore, there are two parasitic harmonics brought by the respective TE101 modes at the low frequency of the passband.

[0073] Specifically, Figure 11The medium filter 100 includes a ceramic medium block body 40, which is divided into eight resonators by a plurality of isolation through slots 41 and a plurality of isolation through holes 42. Among them, six are second resonators 20 operating in the loaded TE101 mode, and the other two are first resonators 10 operating in the loaded TE102 mode. A pair of first tuning blind holes 11 are symmetrically arranged on the top surface of the two first resonators 10 with respect to the center of the top surface. Among them, any one of the first resonators 10 is capacitively coupled to at least one second resonator 20 and inductively coupled to at least one second resonator 20. Any one of the second resonators 20 is inductively coupled to at least one of the remaining second resonators 20. In this embodiment, a bottom blind hole 12 is provided at the center of the bottom surface of the first resonator 10 in the lower left corner, and the frequency of the first resonator 10 operating in the loaded TE101 mode is reduced by adjusting the depth of the bottom blind hole 12, so that the low-frequency parasitic harmonics are far away from the working passband. A through hole 13 penetrating the top surface and the bottom surface is provided in the first resonator 10 in the upper right corner, and the through hole 13 is located on the perpendicular bisector corresponding to the connection line of a pair of first tuning blind holes 11 thereof. The introduction of the through hole 13 can increase the tuning frequency of the first resonator 10 in the upper right corner operating in the loaded TE101 mode, thereby solving the problem that the two parasitic harmonics generated by the two first resonators 10 are superposed on each other, seriously affecting the low-frequency suppression performance.

[0074] Figure 12 FIG. 4 is a comparison diagram of the frequency response curves before and after the introduction of the bottom blind hole and the through hole for the medium filter provided by the fourth embodiment of the present invention. In the original design, the bottom blind hole 12 and the through hole 13 of the present invention are not introduced. Since the frequencies of the two parasitic harmonics are close, they are superposed on each other to a large extent, and the suppression performance in the frequency band of 2.05-2.1 GHz is relatively large. According to the method of the present invention, a bottom blind hole 12 is added at the center of the bottom surface of the first resonator 10 in the lower left corner to reduce the frequency of the first resonator 10 operating in the loaded TE101 mode, so that the frequency of the lowest-frequency parasitic harmonic is further reduced by about 100 MHz; at the same time, a through hole 13 is introduced on the perpendicular bisector corresponding to the connection line of a pair of first tuning blind holes 11 in the resonator 10 in the lower right corner to increase the frequency of the first resonator 10 operating in the loaded TE101 mode, so that the frequency of the other parasitic harmonic is increased by about 40 MHz, the distance between the two parasitic harmonics is increased, the superposition effect is weakened, and the overall harmonic amplitude is reduced by nearly 20 dB, thereby effectively improving the low-frequency suppression performance.

[0075] In the fourth embodiment of the present invention, by utilizing the difference in the electromagnetic field distributions of the two resonant modes of loaded TE101 and loaded TE102, the two first resonators 10 are respectively provided with a bottom blind hole 12 and a through hole 13, which can lower or raise the frequency of the loaded TE101 mode with little influence on the frequency of the loaded TE102 mode. When a bottom blind hole 12 is added to the center of the bottom of one of the first resonators 10, as the depth of the bottom blind hole 12 increases, the frequency of the loaded TE101 mode becomes lower, and the frequency interval from the loaded TE102 mode increases; while when a through hole 13 is introduced on the perpendicular bisector corresponding to the connection line of a pair of first tuning blind holes 11 in the other first resonator 10, as the distance between the through hole 13 and the center decreases, the frequency of the loaded TE101 mode increases, and the frequency interval from the loaded TE102 mode decreases. Thus, the adjustment of the low-frequency parasitic harmonic frequency of the filter is realized, and the situation that the low-frequency harmonic frequencies of the two parasitic TE101 modes are close to each other and the mutual superposition leads to the exacerbation of low-frequency suppression is solved. With the structure of the present invention, the harmonic frequencies can be separated, the low-frequency suppression performance is greatly improved, the structure is simple and easy to implement, thereby enhancing the design flexibility and adaptability.

[0076] In the fifth embodiment of the present invention, the dielectric filter 100 includes two first resonators 10 and at least two second resonators 20. One of the first resonators 10 is provided with a through hole 13 penetrating its top surface and bottom surface, and the through hole 13 is located on the perpendicular bisector corresponding to the connection line of a pair of first tuning blind holes 11. In the fifth embodiment of the present invention, the structure of the first resonator 10 operating in the TE102 mode of the dielectric filter 100 is optimized. It is proposed to add a through hole 13 to the first resonator 10 to adjust its TE101 mode frequency. Due to the difference in the electromagnetic field distributions of the two resonant modes of loaded TE101 and loaded TE102, setting the through hole 13 in the first resonator 10 can raise the resonant frequency of the TE101 mode with little influence on the frequency of the loaded TE102 mode, and can solve the situation that the low-frequency harmonic frequencies of at least two parasitic TE101 modes are close to each other and the mutual superposition leads to the exacerbation of low-frequency suppression, thereby realizing the suppression of low-frequency parasitic harmonics.

[0077] Preferably, each of the first resonators 10 and each of the second resonators 20 in the dielectric filter 100 of the present invention are integrally formed. Based on the above settings, on the one hand, the production convenience of the dielectric filter 100 can be improved to a certain extent, that is, the production efficiency of the dielectric filter 100 is improved, which is conducive to its mass production; on the other hand, the processing errors between each of the first resonators 10 and each of the second resonators 20 can be reduced, thereby ensuring the position accuracy between each of the first resonators 10 and each of the second resonators 20, which is conducive to accurately controlling the coupling amount between each of the first resonators 10 and each of the second resonators 20, that is, conducive to ensuring the manufacturing accuracy of the dielectric filter 100.

[0078] In summary, the dielectric filter of the present invention includes a first resonator operating in the TE102 mode and a second resonator operating in the TE101 mode. By utilizing the difference in the electromagnetic field distributions of the two resonance modes of loaded TE101 and loaded TE102, a bottom blind hole and / or a through hole are added in the first resonator, which can reduce or increase the frequency of the loaded TE101 mode with little impact on the frequency of the loaded TE102 mode, thereby achieving flexible adjustment of low-frequency parasitic harmonics. Preferably, when a bottom blind hole is provided at the center of the bottom surface of the first resonator, as the depth of the bottom blind hole increases, the resonance frequency of the loaded TE101 mode decreases, and the resonance frequency interval from the loaded TE102 mode increases, so that the low-frequency parasitic harmonics are far away from the working passband; when a through hole penetrating the top surface and the bottom surface is provided in the first resonator and the through hole is located on the perpendicular bisector corresponding to the connection line of a pair of first tuning blind holes, as the distance between the through hole and the center decreases, the resonance frequency of the loaded TE101 mode increases, and the resonance frequency interval from the loaded TE102 mode decreases, thereby effectively improving the low-frequency harmonics of the dielectric filter using capacitive coupling in the TE102 mode. In particular, it can avoid the situation where the low-frequency harmonic frequencies of at least two parasitic TE101 modes are close to each other and the mutual superposition leads to the aggravation of low-frequency suppression deterioration. Thereby, the present invention can greatly improve the low-frequency suppression performance of the dielectric filter, and has a simple structure and is easy to implement, further enhancing the design flexibility and adaptability.

[0079] Of course, the present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the appended claims of the present invention.

Claims

1. A dielectric filter, characterized in that, Comprising at least one first resonator operating in the TE102 mode and at least one second resonator operating in the TE101 mode; The top surface and the bottom surface of the first resonator respectively include a symmetric top surface center and a bottom surface center; A pair of first tuning blind holes are symmetrically provided on the top surface of the first resonator with respect to the top surface center; The bottom surface of the first resonator is provided with a bottom blind hole at the bottom surface center; and / or The first resonator is provided with a through hole penetrating the top surface and the bottom surface, and the through hole is located on the perpendicular bisector corresponding to the connection line of the pair of first tuning blind holes; The dielectric filter includes two of the first resonators and at least two of the second resonators, wherein the bottom surface of one of the first resonators is provided with the bottom blind hole at the bottom surface center, and the other first resonator is provided with the through hole penetrating its top surface and bottom surface, and the through hole is located on the perpendicular bisector corresponding to the connection line of the pair of first tuning blind holes.

2. The dielectric filter according to claim 1, characterized in that, When the depth of the bottom blind hole of the first resonator increases, the resonant frequency of the loaded TE101 mode decreases, and the interval from the resonant frequency of the loaded TE102 mode increases; and / or When the distance between the through hole of the first resonator and the top surface center or the bottom surface center decreases, the resonant frequency of the loaded TE101 mode increases, and the interval from the resonant frequency of the loaded TE102 mode decreases.

3. The dielectric filter according to claim 1, characterized in that, The top surface center of the first resonator is the planar center or a predetermined center of the top surface of the first resonator; The bottom surface center of the first resonator is the planar center or a predetermined center of the bottom surface of the first resonator.

4. The dielectric filter according to claim 1, wherein The top surface and the bottom surface of the second resonator respectively include a symmetric top surface center and a bottom surface center; The top surface of the second resonator is provided with a second tuning blind hole at the top surface center, and the depth of the first tuning blind hole is greater than the depth of the second tuning blind hole.

5. The dielectric filter according to claim 4, wherein The first resonator adjusts the diameter, depth and / or spacing of the first tuning blind hole so that the resonant frequency of the loaded TE102 mode is near a predetermined filter passband frequency; and / or The second resonator adjusts the diameter, depth and / or spacing of the second tuning blind hole so that the resonant frequency of the loaded TE101 mode is near a predetermined filter passband frequency.

6. The dielectric filter according to claim 4, wherein The top surface center of the second resonator is the planar center or a predetermined center of the top surface of the second resonator; The bottom surface center of the second resonator is the planar center or a predetermined center of the bottom surface of the second resonator.

7. The dielectric filter according to claim 4, wherein The dielectric filter includes at least two of the second resonators, wherein the bottom surfaces of two of the second resonators respectively have an input port blind hole and an output port blind hole at the bottom surface center, the input port blind hole is used for inputting a signal, and the output port blind hole is used for outputting a signal.

8. The dielectric filter according to claim 7, wherein, Isolation rings made of non-metallic materials are respectively provided around the input port blind hole and the output port blind hole.

9. The dielectric filter according to claim 1, characterized in that, The dielectric filter includes a ceramic dielectric block body, and at least one isolation through slot and / or isolation through hole is / are provided on the ceramic dielectric block body, and the isolation through slot and / or the isolation through hole divides the ceramic dielectric block body into at least one of the first resonators and at least one of the second resonators; the first resonator and the second resonator are coupled through a dielectric connection section of the ceramic dielectric block body.

10. The dielectric filter according to claim 1, characterized in that, The surfaces of the first resonator and the second resonator are coated with an electroplated layer made of a metal material.

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