A dielectric filter

Abstract

The dielectric filter provided by the present invention comprises a rectangular ceramic dielectric block, a resonant hole arranged on the dielectric block, a conductive layer covering the surface of the dielectric block and a shielding shell formed by two vertical bends of a metal plate, wherein the shielding shell comprises a first vertical plate, a horizontal plate and a second vertical plate connected in sequence, wherein the first vertical plate is welded and connected to the rear surface of the dielectric block, the horizontal plate is located above the dielectric block and parallel to the upper surface of the dielectric block, and the lower end of the second vertical plate is welded and connected to the upper surface of the dielectric block. By providing a stress release groove on the shielding shell, the stress release groove is extended upward from the lower end surface of the second vertical plate, passes through the right-angle connection between the second vertical plate and the horizontal plate and extends to the horizontal plate, so that the stress release groove passes through the second vertical plate and the horizontal plate, which can eliminate the stress between the shielding shell and the dielectric block during thermal expansion and contraction, avoid damage to the conductive layer and the dielectric block, and can also fine-tune the performance of some finished products, which is convenient to operate and saves time and effort.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a dielectric filter. Background Art

[0002] Dielectric filter is designed and manufactured by utilizing the characteristics of dielectric ceramic materials such as low loss, high dielectric constant, small frequency temperature coefficient and thermal expansion coefficient, and ability to withstand high power. It is composed of several long resonators connected in series or in parallel in a ladder-shaped circuit.

[0003] Most of the existing dielectric filters include a ceramic dielectric block, a resonant hole opened on the dielectric block, a conductive layer covering the surface of the dielectric block and the inner wall surface of the resonant hole, and a metal shielding shell connected to the dielectric block. The shielding shell is usually fixed by welding the conductive layer on the surface of the dielectric block. In order to facilitate welding and positioning, there is also a method of opening a shallow groove on the dielectric block to match the shielding shell. When the dielectric filter is subjected to a temperature shock test or a temperature cycle test, due to a certain difference in the thermal expansion coefficient of the dielectric block and the thermal expansion coefficient of the shielding shell, the dimensional changes of the shielding shell and the dielectric block are not the same during thermal expansion and contraction, and the difference in dimensional change along the long side is most obvious, which can easily tear the conductive layer from the dielectric block or crack the dielectric block. Even if no obvious damage occurs, stress will be formed at the connection between the shielding shell and the dielectric block. Over time, the stress can easily lead to poor contact between the shielding shell and the dielectric block and the conductive layer, affecting the performance of the dielectric filter.

[0004] During the processing and forming of existing ceramic dielectric blocks and the coating of the conductive layer, due to slight collapse and deformation and slight burring of the conductive layer, the performance of some finished products is outside the allowable range, but not much beyond it. Although the performance of these finished products can be adjusted by grinding the dielectric blocks and the conductive layer, the degree of grinding must be precisely controlled to avoid deformation and cracking of the dielectric blocks, which is inconvenient, time-consuming and labor-intensive to operate. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a dielectric filter which can eliminate the stress between the shielding shell and the dielectric block, avoid damage to the conductive layer and the dielectric block, and can conveniently adjust the performance.

[0006] To achieve the above object, the technical solution adopted by the present invention is that a dielectric filter comprises: a dielectric block, a resonant hole, a conductive layer and a shielding shell, wherein the dielectric block is a rectangular parallelepiped ceramic dielectric block, the resonant hole is arranged on the dielectric block, the conductive layer covers the surface of the dielectric block, the shielding shell is formed by two vertical bends of a metal plate, the directions of the two vertical bends are the same, so that the cross section of the shielding shell is in the shape of a vertical bend hook, the shielding shell comprises a first vertical plate, a horizontal plate and a second vertical plate connected in sequence, the first vertical plate is welded to the rear surface of the dielectric block, the horizontal plate is located above the dielectric block and parallel to the upper surface of the dielectric block, and the second The lower end of the vertical plate is welded to the upper surface of the dielectric block, and a stress release groove is provided on the shielding shell. The stress release groove is used to eliminate the stress between the shielding shell and the dielectric block during thermal expansion and contraction to avoid damage to the conductive layer and the dielectric block, and is also used to fine-tune the performance of the dielectric filter. The stress release groove extends upward from the lower end surface of the second vertical plate, passes through the right-angle connection between the second vertical plate and the horizontal plate and extends to the horizontal plate. The stress release groove on the second vertical plate passes through the second vertical plate in the front-to-back direction, and the stress release groove on the horizontal plate passes through the horizontal plate in the up-down direction.

[0007] Preferably, there are multiple stress relief grooves.

[0008] Further preferably, a plurality of the stress release grooves are arranged in parallel and at intervals.

[0009] Further preferably, the spacings between adjacent stress release grooves are equal.

[0010] Further preferably, the number of the stress release grooves is positively correlated with a low-frequency side suppression index of the dielectric filter, and negatively correlated with a high-frequency side suppression index of the dielectric filter.

[0011] Preferably, the width of the stress release groove is in the range of 0.3-0.6 mm.

[0012] Further preferably, the width of the stress release groove is positively correlated with a low-frequency side suppression index of the dielectric filter, and negatively correlated with a high-frequency side suppression index of the dielectric filter.

[0013] Further preferably, the stress relief groove located on the second vertical plate is perpendicular to the horizontal plate.

[0014] Further preferably, the stress relief groove on the horizontal plate is perpendicular to the second vertical plate.

[0015] Further preferably, the length of the stress release groove on the horizontal plate is less than or equal to one half of the width of the horizontal plate in the front-to-back direction.

[0016] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0017] The dielectric filter provided by the present invention comprises a rectangular ceramic dielectric block, a resonant hole arranged on the dielectric block, a conductive layer covering the surface of the dielectric block and a shielding shell formed by two vertical bends of a metal plate, wherein the shielding shell comprises a first vertical plate, a horizontal plate and a second vertical plate connected in sequence, wherein the first vertical plate is welded and connected to the rear surface of the dielectric block, the horizontal plate is located above the dielectric block and parallel to the upper surface of the dielectric block, and the lower end of the second vertical plate is welded and connected to the upper surface of the dielectric block. By providing a stress release groove on the shielding shell, the stress release groove is extended upward from the lower end surface of the second vertical plate, passes through the right-angle connection between the second vertical plate and the horizontal plate and extends to the horizontal plate, so that the stress release groove passes through the second vertical plate and the horizontal plate, and the stress release groove can be used to eliminate the stress between the shielding shell and the dielectric block during thermal expansion and contraction to avoid damage to the conductive layer and the dielectric block, and the stress release groove can be used to fine-tune the performance of some finished products, which is convenient to operate and saves time and effort. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a three-dimensional schematic diagram of a preferred embodiment of the dielectric filter in the present invention.

[0020] Figure 2 yes Figure 1 Schematic top view of .

[0021] Figure 3 yes Figure 1 Schematic diagram of the main view.

[0022] Figure 4 yes Figure 1 Schematic diagram of the left side.

[0023] Figure 5 This is the electrical performance diagram of the dielectric filter without stress relief grooves.

[0024] Figure 6 yes Figure 1 Electrical performance diagram of the dielectric filter shown.

[0025] Among them: 10. dielectric block; 20. resonant hole; 30. conductive layer; 40. shielding shell; 41. first vertical plate; 42. horizontal plate; 43. second vertical plate; 44. stress release groove. DETAILED DESCRIPTION

[0026] The following will describe the technical solutions in the embodiments of the present invention in detail in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, the terms “first”, “second” and “third” are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0028] The front-to-back direction described in the present invention refers to Figure 2 The up-down direction in the present invention refers to the left-right direction. Figure 2 The left and right directions in the present invention refer to the up and down directions described in the present invention. Figure 3 The up and down directions in .

[0029] like Figure 1-4 As shown, the dielectric filter provided by the present invention comprises: a dielectric block 10, a resonant hole 20, a conductive layer 30 and a shielding shell 40, the dielectric block 10 is a rectangular parallelepiped ceramic dielectric block, the resonant hole 20 is arranged on the dielectric block 10, the conductive layer 30 covers the surface of the dielectric block 10 and the inner wall surface of the resonant hole 20, the shielding shell 40 is formed by two vertical bends of a metal plate (brass or nickel silver), the two vertical bends are in the same direction, so that the cross section of the shielding shell 40 is in the shape of a vertical bend hook, the shielding shell 40 comprises a first vertical plate 41, a horizontal plate 42 and a second vertical plate 43 connected in sequence, the first vertical plate 41 is welded and connected to the conductive layer 30 on the rear surface of the dielectric block 10, the horizontal plate 42 is located above the dielectric block 10 and parallel to the dielectric block 10 The upper surface of the second vertical plate 43, the lower end of the second vertical plate 43 is welded to the conductive layer 30 on the upper surface of the dielectric block 10, and a stress release groove 44 is opened on the shielding shell 40. The stress release groove 44 is used to eliminate the stress between the shielding shell 40 and the dielectric block 10 during thermal expansion and contraction, avoid peeling and tearing of the conductive layer 30, and cracking and damage of the dielectric block 10, and is also used to fine-tune the performance of the dielectric filter. The stress release groove 44 extends upward from the lower end surface of the second vertical plate 43, passes through the right-angle connection between the second vertical plate 43 and the horizontal plate 42 and extends to the horizontal plate 42. The stress release groove 44 on the second vertical plate 43 passes through the second vertical plate 43 in the front-to-back direction, and the stress release groove 44 on the horizontal plate 42 passes through the horizontal plate in the up-down direction.

[0030] The advantage of this arrangement is that the stress relief groove can be used to eliminate the stress between the shielding shell and the dielectric block during thermal expansion and contraction, thereby avoiding damage to the conductive layer and the dielectric block; the stress relief groove can also be used to fine-tune the performance of some finished products, which is easy to operate and saves time and effort.

[0031] In this embodiment, there are three stress release grooves 44. The above performance is specifically the suppression index of the low-frequency side and the suppression index of the high-frequency side of the dielectric filter. The low-frequency side suppression index is within the range of 3450-3550MHz (inclusive), and the high-frequency side suppression index is within the range of 3700-3800MHz (inclusive). Specifically, Figure 5-6 As shown, the number of stress release grooves 44 is positively correlated with the low-frequency side suppression index of the dielectric filter and negatively correlated with the high-frequency side suppression index of the dielectric filter.

[0032] In this embodiment, the three stress release grooves 44 are arranged in parallel and at intervals, and the spacing between adjacent stress release grooves 44 is equal. The advantage of such an arrangement is that the correlation between the number of stress release grooves 44 and the performance of the dielectric filter is more orderly and controllable, which facilitates fine-tuning of the performance of the dielectric filter.

[0033] The width of the stress release groove 44 has a great influence on the stress elimination and fine-tuning performance. If the width is too small, the effect of eliminating the stress between the shielding shell 40 and the dielectric block 10 during thermal expansion and contraction is limited. When the temperature changes too much, there is still a risk of damage to the conductive layer and the dielectric block. If the width is too large, the shielding effect of the dielectric filter will be reduced. Preferably, the width of the stress release groove 44 ranges from 0.3 to 0.6 mm. Within this range, the width of the stress release groove 44 is positively correlated with the low-frequency side suppression index of the dielectric filter and negatively correlated with the high-frequency side suppression index of the dielectric filter. In this embodiment, the width is 0.5 mm.

[0034] In order to improve the efficiency of the stress release groove 44 in eliminating stress, in this embodiment, the stress release groove 44 located on the second vertical plate 43 is perpendicular to the horizontal plate 42, and the stress release groove 44 located on the horizontal plate 42 is perpendicular to the second vertical plate 43. In order to avoid affecting the strength of the shielding shell, the length of the stress release groove 44 on the horizontal plate 42 is less than half of the width of the horizontal plate 42 in the front-to-back direction.

[0035] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0036] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A dielectric filter, comprising: A dielectric block, a resonance hole, a conductive layer and a shielding shell, wherein the dielectric block is a rectangular parallelepiped ceramic dielectric block, the resonance hole is arranged on the dielectric block, the conductive layer covers the surface of the dielectric block, the shielding shell is formed by two vertical bends of a metal plate, the shielding shell comprises a first vertical plate, a horizontal plate and a second vertical plate connected in sequence, the first vertical plate is welded and connected to the rear surface of the dielectric block, the horizontal plate is located above the dielectric block and parallel to the upper surface of the dielectric block, and the lower end of the second vertical plate is welded and connected to the upper surface of the dielectric block, characterized in that: A stress release groove is provided on the shielding shell, and the width range of the stress release groove is 0.3-0.6mm; the stress release groove extends upward from the lower end surface of the second vertical plate, passes through the right-angle connection between the second vertical plate and the horizontal plate and extends to the horizontal plate, the stress release groove on the second vertical plate passes through the second vertical plate in the front-to-back direction and is perpendicular to the horizontal plate, and the stress release groove on the horizontal plate passes through the horizontal plate in the up-down direction and is perpendicular to the second vertical plate.

2. The dielectric filter according to claim 1, characterized in that: There are multiple stress release grooves.

3. The dielectric filter according to claim 2, characterized in that: A plurality of stress release grooves are arranged in parallel and at intervals.

4. The dielectric filter according to claim 3, characterized in that: The spacings between adjacent stress release grooves are equal.

5. The dielectric filter according to claim 2, characterized in that: The number of the stress release grooves is positively correlated with a low-frequency side suppression index of the dielectric filter, and negatively correlated with a high-frequency side suppression index of the dielectric filter.

6. The dielectric filter according to claim 1, characterized in that: The width of the stress release groove is positively correlated with the low-frequency side suppression index of the dielectric filter, and negatively correlated with the high-frequency side suppression index of the dielectric filter.

7. The dielectric filter according to any one of claims 1 to 6, characterized in that: The length of the stress release groove on the horizontal plate is less than or equal to one half of the width of the horizontal plate in the front-to-back direction.

Images