JPWO2013129538A1 - Dielectric resonator - Google Patents

Abstract

A tuning rod for adjusting the resonance frequency is stably fixed to a predetermined position in the through hole for a long period of time. The dielectric block 2, the through hole 4 having openings on the main surfaces 2a and 2b of the dielectric block 2, the inner conductor 6 deposited on the inner peripheral surface of the through hole 4, and the side surface of the dielectric block 2 When the end portion 14a of the through hole 4 has the first surface 23 and the second surface 25 and is viewed in a cross section including the central axis C of the through hole 4, The first surface 23 is substantially perpendicular to the inner peripheral surface of the parallel portion 16, and the connection portion 27 between the first surface 23 and the second surface 25 is the connection portion between the second surface 25 and the main surface 2a. Compared with 29, the inner conductor 6 is thicker toward the central axis C at the portion where the inner conductor 6 is attached to the end portion 14a, and the inner peripheral surface 6α is attached to the parallel portion 16. The dielectric resonator 10 is characterized in that it is closer to the central axis C than the inner peripheral surface 6β of the inner conductor 6.

Description

  The present invention relates to a dielectric resonator used as a component constituting, for example, a bandpass filter.

  For example, in a communication system such as a cellular phone line network or a WiFi network, a small and lightweight portable terminal that can be carried by a person and a fixed base station communication device that communicates with each portable terminal are used. Many of the radio waves used in these many communication systems are transmitted from the mobile terminal and received by the base station communication device, and the base station reception frequency band is transmitted from the base station communication device to the mobile terminal. And the frequency band for transmitting the base station.

  In both the mobile terminal and the base station communication device, the radio waves are separated so that the transmission signal and the reception signal do not interfere with each other, and signal processing is performed on each radio wave. A band pass filter (hereinafter also simply referred to as a filter) is used for the separation of the radio waves. A filter used in a portable terminal is required to be light and small so that a person can easily carry the portable terminal. On the other hand, since a base station communication device needs to radiate high-power radio waves from an antenna in order to realize a wide communication area, a filter for a base station communication device has a high-power electric power amplified by a semiconductor device or the like. It is required that the loss be as low as possible so that the signal can be supplied to the antenna without waste.

  Patent Document 1 gives an example of a low-loss dielectric resonator used on the base station communication device side. 6A and 6B are diagrams showing a dielectric resonator 100 which is an embodiment of a conventional dielectric resonator. FIG. 6A is a schematic perspective view, and FIG. 6B is a diagram shown in FIG. 2 is an enlarged schematic cross-sectional view showing a part of a dielectric resonator 100. FIG. A dielectric resonator 100 shown in FIG. 6 includes a dielectric block 110 having a pair of main surfaces (main surfaces 110A and 110B) located on opposite sides, and a dielectric block having openings on the pair of main surfaces. A through hole 112 passing through the inner hole, an inner conductor 120 attached to the entire inner peripheral surface of the through hole 112, and an outer conductor 140 attached to the side surface of the dielectric block 110 so as to surround the inner conductor 120. Yes. The inner conductor 120 is continuously attached from the entire inner peripheral surface of the through hole 112 to a part of the main surface 110A. In the dielectric resonator 100 described in Patent Document 1, a coaxial resonator structure that resonates at a specific frequency is formed by the inner conductor 120 and the outer conductor 140 arranged so as to surround the periphery thereof. An electrical signal having a specific frequency can be selectively extracted via a signal extraction electrode (not shown) that is electromagnetically coupled to 120.

  By the way, the resonance frequency of this type of dielectric resonator changes in accordance with parameters relating to the material such as the relative permittivity (εr) of the dielectric material constituting the dielectric block, and the outer shape of the dielectric block 110. It also changes in accordance with the parameters relating to the shape, such as the size, the size and shape of the through hole 112, and the thickness variation of the inner conductor 120 inside the through hole 112. Various shapes of dielectric resonators are designed to resonate at a specific frequency.

  However, in an actual dielectric resonator, parameters related to these shapes are slightly deviated from design values due to environmental changes during manufacturing. Due to the deviation of the parameters relating to this shape, the resonance frequency of the dielectric resonator also deviates from the design value. In order to correct the deviation of the resonance frequency in such a dielectric resonator within a predetermined range, a resonance frequency adjustment operation so-called tuning operation has been conventionally performed for each of the manufactured dielectric resonators. Is doing.

  This resonance frequency adjustment operation includes a method of cutting a part of the inner conductor 120 to change the size and shape of the inner conductor 120, a method using a so-called tuning rod, and the like. In the method of changing the size and shape of the inner conductor 120, for example, by using a hand grinder device, a rotating grinding wheel is brought into contact with a part of the inner conductor 120 to grind a part of the inner conductor 120. To remove.

  FIG. 7A is a schematic cross-sectional view showing a state in which the resonance frequency of the dielectric resonator 100 shown in FIG. The resonance frequency is adjusted using the tuning rod 200 by inserting the metal tuning rod 200 into the through hole 112. The metal tuning rod 200 has a screw shape as shown in FIG. Specifically, the tuning rod 200 is inserted so as to be screwed into the through hole 112 of the dielectric resonator 100, and the outer periphery of the tuning rod 200 is bitten into the inner conductor 120, and the tuning rod 200 is screwed to the through hole 112. . In the adjustment of the resonance frequency using the tuning rod 200, the resonance frequency can be adjusted by adjusting the amount of insertion of the tuning rod 200 into the through hole 112. After adjusting the resonance frequency using the tuning rod 200, the tuning rod 200 can be used as a dielectric resonator in a state where the tuning rod 200 is screwed into the through hole 112.

JP 2011-97209 A

  These tuning tasks have the following problems. For example, in a method in which a part of the inner conductor 120 is cut to change the size or shape of the inner conductor 120, a relatively large force due to machining using a hand grinder device or the like is applied to the inner conductor 120 or the dielectric block 110. For example, as shown in FIG. 6B, in the vicinity of the corner portion X corresponding to the peripheral portion of the opening 114 of the through hole 112, the force accompanying such machining tends to concentrate. For this reason, in the tuning method in which the size and shape of the inner conductor 120 are changed by removing a part of the inner conductor 120, the inner conductor 120 is easily peeled off from the dielectric block 110 in the vicinity of the corner portion X by this concentrated force. There was a problem. In addition, the thickness of the inner conductor 120 tends to be relatively thin in the vicinity of the corner portion X, and the inner conductor 120 itself in the vicinity of the corner portion X is likely to be damaged due to the concentration of force by machining. there were.

  In addition, in the resonance frequency adjustment method using the tuning rod 200, the tuning rod 200 is firmly screwed at the position adjusted during tuning in order to stably maintain the state after tuning (tuning state) for a long period of time. It is important to be. In order to screw the tuning rod 200 firmly, it is preferable that the difference between the outer diameter of the tuning rod 200 and the inner diameter of the through-hole 112 is small so that the outer periphery of the tuning rod 200 is firmly inserted into the inner conductor 120. However, when the difference between the outer diameter of the tuning rod 200 and the inner diameter of the through hole 112 is small, the conventional dielectric resonator 100 shown in FIG. 7A is a portion where stress from the tuning rod 200 tends to concentrate. A certain corner X may be damaged by the stress from the tuning rod 200. In this case, it is difficult to finely adjust the frequency because the shape of the dielectric block 110 is changed, and the force applied to the tuning rod 200 is loosened at the portion where the stress is concentrated. There is a problem that the adjustment state is easily maintained and the adjustment state cannot be maintained for a long time. In addition, as shown in FIG. 7B, means for reducing the concentration of stress from the tuning rod 200 by providing an inclined portion 130 in the vicinity of the opening 114 of the through hole 112 has been studied. As a result, the tuning rod 200 is not securely fixed in the through-hole 112, and the tuning rod 200 is likely to be displaced from the adjustment position, and the adjustment state cannot be maintained for a long time. The present invention has been devised to solve such problems in the prior art.

  The present invention relates to a dielectric block having a pair of main surfaces positioned on opposite sides, a pair of main surfaces having openings in the main surfaces and penetrating the dielectric block, and an inner periphery of the through holes. A dielectric resonator comprising an inner conductor deposited on the entire surface and an outer conductor deposited on a side surface of the dielectric block so as to surround the inner conductor, wherein the through-hole is formed in each of the openings. Including a pair of end portions and a parallel portion located between the pair of end portions, the inner peripheral surface of which is parallel to the central axis, and the inner diameter of the parallel portions is smaller than the inner diameter of each of the openings, Each of the pair of end portions includes a first surface continuous to the inner peripheral surface of the parallel portion, and a second surface continuous to the first surface and the main surface, and includes a cross section including the central axis. When viewed, the first surface is substantially perpendicular to the inner peripheral surface of the parallel portion, and the first surface The connecting portion between the surface and the second surface is closer to the central axis than the connecting portion between the second surface and the main surface, and the inner conductor is attached to each of the pair of end portions. The dielectric is characterized in that the thickness increases toward the central axis, and the inner peripheral surface is closer to the central axis than the inner peripheral surface of the inner conductor in a portion attached to the parallel portion. A resonator is provided.

  The present invention also provides a dielectric block having a pair of main surfaces located on opposite sides of each other, a through hole having an opening on each of the pair of main surfaces and penetrating the dielectric block, An inner conductor deposited on the entire peripheral surface, an outer conductor deposited on the side surface of the dielectric block so as to surround the inner conductor, and the through-hole from the opening of one of the main surfaces. A dielectric resonator comprising a threaded tuning rod inserted into a hole, wherein the through-hole is located between a pair of ends including the openings and a pair of the ends. A peripheral portion having a parallel portion parallel to the central axis, wherein an inner diameter of the parallel portion is smaller than an inner diameter of each of the openings, and the pair of end portions are respectively connected to the inner peripheral surface of the parallel portion. A surface, and a second surface continuous to the first surface and the main surface, When viewed in a cross-section including the central axis, the first surface is substantially perpendicular to the inner peripheral surface of the parallel portion, and the connecting portion between the first surface and the second surface is the The tuning rod has an outer periphery that bites into the inner conductor nearer to the central axis than at the connection between the second surface and the main surface and at least in the vicinity of the end portion on the one main surface side. And a dielectric resonator characterized by being screwed into the through hole.

  A pair of end portions of the through holes of the dielectric block each have a first surface continuous to the inner peripheral surface of the parallel portion of the through holes, and a second surface continuous to the first surface and the main surface of the dielectric block. An inner conductor attached to the inner surface of the through hole, the connecting portion between the first surface and the second surface being closer to the central axis of the through hole than the connecting portion between the second surface and the main surface. The thicknesses of the portions attached to the pair of end portions increase toward the central axis, and the inner peripheral surface is closer to the central axis than the inner peripheral surface of the inner conductor of the portion attached to the parallel portion. Therefore, when the tuning rod is screwed into the through-hole, the tuning rod can be screwed into the thick inner conductor near this end, so that the tuning rod can be placed in the through-hole for a long time. It can be stably fixed over. In addition, since the bonding area between the inner conductor and the dielectric block is relatively large near the end of the through hole, the bonding strength between the inner conductor and the dielectric block is relatively strong. Even when tuning is performed to change the size and shape of the conductor, the inner conductor easily peels from the dielectric block. In addition, since the thickness of the inner conductor in the vicinity of the end portion of the through hole is easy to concentrate stress due to the force applied from the outside, the inner conductor itself is hardly damaged.

(A) is a schematic perspective view which shows the example of one Embodiment of the dielectric resonator of this invention, (b) is a schematic sectional drawing. FIG. 2 is an enlarged cross-sectional view showing a part of the dielectric resonator shown in FIG. 1. FIG. 3 is a cross-sectional view further enlarging the vicinity of the end portion of the through hole of the dielectric resonator shown in FIGS. It is a schematic sectional drawing shown about an example of the state which is adjusting the resonant frequency which changes the magnitude | size and shape of an inner conductor about the dielectric resonator shown in FIGS. It is a schematic sectional drawing shown about an example of the state which is adjusting the resonant frequency using the tuning rod about the dielectric resonator shown to FIGS. It is a figure which shows one Embodiment of the conventional dielectric resonator, (a) is a schematic perspective view, (b) is a schematic sectional drawing which expands and shows a part of conventional dielectric resonator shown to (a). It is. (A) And (b) is a schematic sectional drawing which shows an example of the state which is adjusting the resonant frequency using a tuning rod about the conventional dielectric resonator shown in FIG.

  Hereinafter, an embodiment of a dielectric resonator according to the present invention will be described with reference to the drawings. FIG. 1A is a schematic perspective view of a dielectric resonator 10 which is an embodiment of the dielectric resonator of the present invention. FIG. 1B is a schematic sectional view of the dielectric resonator 10. FIG. 2 is an enlarged cross-sectional view showing a part of the dielectric resonator 10 shown in FIG. In FIG. 2, one of the plurality of through-holes 4 is representatively shown, but the through-holes 4 of the dielectric resonator 10 shown in FIG. 1 have the same structure as that shown in FIG. have. FIG. 3 is a cross-sectional view further enlarging the vicinity of the end portion 14a of the through hole 4. Although the reference numerals are omitted in the figure, the end portion 14b has the same configuration as the end portion 14a. FIGS. 1B, 2, and 3, and FIGS. 4 and 5 to be described later, are cross-sectional views taken along a plane including the central axis C of the through hole 4.

  The dielectric resonator 10 includes a dielectric block 2 having a pair of main surfaces 2a and 2b located on opposite sides, and openings 4a and 4b on the pair of main surfaces 2a and 2b, respectively. Dielectric body comprising a through hole 4 that penetrates, an inner conductor 6 that is attached to the entire inner peripheral surface of the through hole 4, and an outer conductor 8 that is attached to the side surface of the dielectric block 2 so as to surround the inner conductor 6. In the resonator 10, the through-hole 4 has an inner peripheral surface that is located between an end portion 14 a including an opening 4 a and an end portion 14 b including an opening 4 b and a pair of end portions 14 a and 14 b and is parallel to the central axis C. The parallel portion 16 has an inner diameter smaller than the inner diameters of the respective openings 4a and 4b, and the pair of end portions 14a and 14b are respectively connected to a first surface 23 ( FIG. 2 and FIG. 3) and the first surface 2 And the second surface 25 (see FIGS. 2 and 3) continuous with the main surface 2a, and the first surface 23 is formed on the inner peripheral surface of the parallel portion 16 when viewed in a cross section including the central axis C. The connecting portion 27 (see FIGS. 2 and 3) between the first surface 23 and the second surface 25 is substantially perpendicular to the connecting portion 29 (see FIGS. 2 and 2) between the second surface 25 and the main surface 2a. The inner conductor 6 is closer to the central axis C than the central axis C, and the inner conductor 6 is thicker toward the central axis C at the portions attached to the pair of end portions 14a and 14b. Is closer to the central axis C than the inner peripheral surface 6β of the inner conductor 6 at the portion deposited on the parallel portion 16. The first surface 23 being substantially perpendicular to the inner peripheral surface of the parallel portion 16 means that the angle α (see FIG. 3) formed by the first surface 23 and the parallel portion 16 is 70 ° to 110 °. Say.

  Hereinafter, the dielectric resonator 10 will be described in more detail. In the dielectric resonator 10 shown in FIG. 1, the dielectric block 2 includes a plurality of through holes 4, and the inner conductor 6 is attached to the entire inner peripheral surface of each through hole 4. The inner conductor 6 is continuously attached from the entire inner peripheral surface of the through hole 4 to a part of at least one main surface (main surface 2a in this embodiment) of the pair of main surfaces 2a and 2b. Yes.

  The outer conductor 8 is provided on the entire side surface of the dielectric block 2 so as to surround the periphery of the plurality of through holes 4 to which the inner conductor 6 is attached. In the present embodiment, the metal layer 7 is also provided on the entire other main surface 2 b of the dielectric block 2, and the metal layer 7 is connected to both the inner conductor 6 and the outer conductor 8. The inner conductor 6 and the outer conductor 8 are electrically connected via each other. When the dielectric resonator 10 is used, the metal layer 7 is used in a state of being in contact with an external ground conductor.

  In the dielectric resonator 10, the inner conductor 6 and the outer conductor 8 constitute a plurality of coaxial resonator structures that resonate at a specific frequency for each through-hole 4, and the plurality of coaxial resonator structures. Are arranged to be electromagnetically coupled to each other. In the dielectric resonator 10, for example, a so-called TEM mode type resonance structure is configured in each of the plurality of through holes 4. That is, when a microwave band high frequency is applied to the dielectric resonator 10, each of the plurality of through holes 4 constitutes a TEM mode type resonator and resonates. In the dielectric resonator 10, a plurality of coaxial resonator structures are arranged so as to be electromagnetically coupled to each other, so that a signal extraction electrode (not shown) that is electromagnetically coupled to the inner conductor 6 of the specific through-hole 4. )), An electrical signal having a specific frequency can be selectively extracted. For example, by setting the resonance frequency corresponding to each through-hole 4 to be different from about 2.139 GHz, 2.131 GHz, 2.130 GHz, and 2.139 GHz, respectively, and adjusting the coupling between the resonators, Can constitute a bandpass filter of approximately 2.1 to 2.2 GHz.

  The dielectric block 2 is made of, for example, ceramics such as alumina, and a material having a relative dielectric constant of, for example, about 5 to 70 may be appropriately selected according to a required frequency or the like. In the present embodiment, the height of the dielectric block 2 along the vertical direction in FIG. 1B is, for example, about 5 to 15 mm, and the inner diameter of the through hole 4 is, for example, about 2 to 10 mm. The inner conductor 6, the metal layer 7, and the outer conductor 8 may be mainly composed of a material having a small resistance value such as Ag, Cu, or Au.

  The end portion 14 a includes a first surface 23 continuous with the inner peripheral surface of the parallel portion 16, a second surface 25 continuous with the first surface 23 and the main surface 2 a, and the first surface 23 and the second surface 25. And a connection portion 29 between the second surface 25 and the main surface 2a. The width of the first surface 23 in the left-right direction in FIG. 3 is about 0.5 to 5 mm, and the height of the second surface 25 in the vertical direction in the drawing is about 0.5 to 5 mm.

  As shown in FIG. 3, the first surface 23 is perpendicular to the parallel portion 16, and the connection portion 27 between the first surface 23 and the second surface 25 is connected to the second surface 25 and the main surface 2a. It is closer to the central axis C than the connection part 29. Further, the inner conductor 6 is thicker toward the central axis C at the portion attached to the end portion 14a, and the inner peripheral surface 6α of the inner conductor 6 at the portion attached to the end portion 14a is a parallel portion. 16 is closer to the central axis C than the inner peripheral surface 6β of the portion of the inner conductor 6 that is attached to 16. In the present embodiment, the inner peripheral surface 6α of the inner conductor 6 in the portion corresponding to the end portion 14a is, for example, about 0.01 to 1 mm compared to the inner peripheral surface 6β of the inner conductor 6 in the portion corresponding to the parallel portion 16. It is close to the central axis C. Moreover, in this embodiment, the thickness of the part corresponding to the parallel part 16 of the inner conductor 6 is about 0.005-0.05 mm.

  4 and 5 show a state in which the resonant frequency adjustment work called so-called tuning work is performed on the dielectric resonator 10. For adjusting the resonance frequency, a method of adjusting the resonance frequency by cutting a part of the inner conductor 6 to change the size and shape of the inner conductor 6, or a method of adjusting the resonance frequency using a so-called tuning rod 50. There is.

  FIG. 4 is a schematic cross-sectional view for explaining an example of a method for adjusting the resonance frequency by changing the size and shape of the inner conductor 6. In the example shown in FIG. 4, a part of the inner conductor 6 is ground and removed by using a hand grinder device 62 that rotationally drives the rotating shaft 64 by a built-in motor. The resonance frequency changes according to the removal shape and removal amount of the inner conductor 6. Specifically, a part of the inner conductor 6 in which the rotating grindstone 60 is attached to one main surface 2a while the disc-shaped grindstone 60 is attached to the rotating shaft 64 of the hand grinder device 62 and the grindstone 60 is rotated. The portion of the inner conductor 6 where the grinding stone 60 is pressed is ground and removed. At this time, since the rotating grindstone 60 is pressed against the inner conductor 6, a relatively large force is applied to the inner conductor 6. When the inner conductor 6 is ground and removed while moving the grindstone 60 in the left-right direction in FIG.

  In the present embodiment, the end portion 14 a includes a first surface 23 that is continuous with the inner peripheral surface of the parallel portion 16, a second surface 25 that is continuous with the main surface 2 a, and the first surface 23 and the second surface 25. It has a connection portion 27 and a connection portion 29 between the second surface 25 and the main surface 2a. The first surface 23 is substantially perpendicular to the parallel portion 16, and the first surface 23 and the first surface 23 The connecting portion 27 with the second surface 25 is closer to the central axis C than the connecting portion 29 between the second surface 25 and the main surface 2a. In the present embodiment, since the end portion 14a has such a shape, the bonding area between the inner conductor 6 and the end portion 14a is relatively large. For this reason, even when a grinding force is concentrated on the portion of the inner conductor 6 attached to the end portion 14a, the bonding strength between the inner conductor 6 and the dielectric block 2 is relatively strong. The inner conductor 6 is difficult to peel off from the block 2.

  Further, since the inner conductor 6 has a relatively thick portion attached to the end portion 14a, the rigidity in the vicinity of the end portion 14a where stress tends to concentrate is high. For this reason, even when the force when cutting a part of the inner conductor 6 to change the size or shape of the inner conductor 6 is concentrated on the portion of the inner conductor 6 attached to the end 14a, the end 14a itself Is hard to break.

  FIG. 5 is a schematic cross-sectional view showing a state of adjusting the resonance frequency using the tuning rod 50. The tuning operation using the tuning rod 50 is performed by inserting a metal tuning rod 50 made of stainless steel or the like into the through hole 4. The tuning rod 50 of this embodiment uses a screw-like one as shown in FIG. Specifically, the tuning rod 50 is inserted into the through hole 4 of the dielectric resonator 10 so as to be screwed, the outer periphery of the tuning rod 50 is bitten into the inner conductor 6, and the tuning rod 50 is screwed to the through hole 4. . In the adjustment of the resonance frequency using the tuning rod 50, the resonance frequency can be adjusted by adjusting the amount of insertion of the tuning rod 50 into the through hole 4. After adjusting the resonance frequency using the tuning rod 50, the tuning rod 50 can be used as a dielectric resonator in a state where the tuning rod 50 is screwed into the through hole 4.

  In the present embodiment, the end portion 14 a includes a first surface 23 that is continuous with the inner peripheral surface of the parallel portion 16, a second surface 25 that is continuous with the main surface 2 a, and the first surface 23 and the second surface 25. It has a connection portion 27 and a connection portion 29 between the second surface 25 and the main surface 2a. The first surface 23 is substantially perpendicular to the parallel portion 16, and the first surface 23 and the first surface 23 The connecting portion 27 with the second surface 25 is closer to the central axis C than the connecting portion 29 between the second surface 25 and the main surface 2a. In the present embodiment, since the end portion 14a has such a shape, even when the tuning rod 50 is inserted from the opening 4a of the through hole 4, the dielectric block 2 and the tuning rod are located in the vicinity of the opening 4a. 50 is relatively far away. The portion of the inner conductor 6 attached to the end portion 14a is thicker toward the central axis C, and the inner peripheral surface 6α of the inner conductor 6 of the portion attached to the end portion 14a is parallel to the parallel portion 16. Compared to the inner peripheral surface 6β of the inner conductor 6 in the portion deposited on the inner conductor 6, it is closer to the central axis C. That is, in the vicinity of the opening 4a of the through hole 4, a layer of the inner conductor 6 made of a metal that is relatively easily deformed is provided with a relatively large thickness. The tuning rod 50 inserted from the opening 4a of the through hole 4 first comes into contact with the inner peripheral surface 6α of the inner conductor 6 in the portion attached to the end portion 14a.

  For this reason, when the tuning rod 50 is inserted from the opening 4a of the through-hole 4, the impact from the tuning rod 50 is reduced by the thick inner conductor 6 made of a metal that is relatively easily deformed. The impact force applied to 2 itself is suppressed, and the dielectric block 2 is hardly damaged.

  When the tuning rod 50 is inserted so as to be screwed, the outer peripheral surface of the tuning rod 50 bites into the thick inner conductor 6 of the portion attached to the end portion 14a and is attached to the end portion 14a. The thick inner conductor 6 and the tuning rod 50 are fastened relatively firmly. In the present embodiment, the tuning rod 50 can be screwed into the thick inner conductor 6 in the vicinity of the end portion 14a so as to bite into the thick inner conductor 6, so that the tuning rod 50 can be stabilized at a predetermined position in the through hole 4 for a long period of time. Can be fixed.

  After adjusting the resonance frequency using the tuning rod 50, the tuning rod 50 can be used as the dielectric resonator 10 in a state where the tuning rod 50 is screwed into the through hole 4. That is, as shown in FIG. 5, a dielectric block 2 having a pair of main surfaces 2a and 2b located on opposite sides, and a pair of main surfaces 2a and 2b having openings 4a and 4b, respectively. 2, a through hole 4 penetrating 2, an inner conductor 6 attached to the entire inner peripheral surface of the through hole 4, an outer conductor 8 attached to the side surface of the dielectric block 2 so as to surround the inner conductor 6, and a pair A dielectric resonator 10 comprising a screw-like tuning rod 50 inserted into an through hole 4 from an opening 4a provided on one main surface 2a of the main surface 2a and the main surface 2b, and a pair of ends Each of the portions 14a and 14b has a first surface 23 that continues to the inner peripheral surface of the parallel portion 16, and a second surface 25 that continues to the first surface 23 and the main surface 2a, and includes a central axis C. The first surface 23 is the inner periphery of the parallel portion 16 when viewed at The connecting portion 27 between the first surface 23 and the second surface 25 is closer to the central axis C than the connecting portion 26 between the second surface 25 and the main surface 2a, and at least one of them is In the vicinity of the end portion 14a on the main surface 2a side, the outer periphery of the tuning rod 50 bites into the inner conductor 6 so that the dielectric resonator 10 in which the tuning rod 50 is screwed to the through hole 4 is replaced with a bandpass filter. Can be used as In the present embodiment, the tuning rod 50 can be stably fixed at a predetermined position in the through hole 4 for a long period of time, so that the dielectric resonator in which the tuning bar 50 is inserted is stable for a long period of time. Characteristics can be maintained.

  Hereinafter, a method for manufacturing the dielectric resonator 10 will be described. First, a dielectric block 2 made of ceramic is prepared. As a material of the dielectric block 2, a material having a relative dielectric constant of about 5 to 70 can be selected according to a required frequency and size. The shape of the dielectric block 2 and the like may be set according to the required frequency. For example, when forming the dielectric block 2 made of alumina, first, a high-purity alumina powder is mixed and pulverized with water in a ball mill. The alumina powder preferably has a purity of 99% by mass or more and an average particle diameter of 0.3 to 1 μm. An organic binder is added to the resulting slurry and spray dried to produce granules. Next, the obtained granule is press-molded to obtain a generated shape having a shape corresponding to the dielectric block 2. Subsequently, the processed formed body is fired at a maximum temperature of 1400 to 1600 ° C. to produce a dielectric block 2 made of ceramics.

  Next, a paste containing conductive metal powder is prepared. The main component of the metal contained in the paste is desirably a low resistance value such as Ag, Cu, Au. The paste is composed of a metal powder, an organic binder, and an organic liquid. This paste is applied to portions corresponding to the inner conductor 6, the outer conductor 8 and the metal layer 7 in the dielectric resonator 10.

  The dielectric block 2 has a first surface 23 and a second surface 25 at each of the end portions 14 a and the end portions 14 b of the plurality of through holes 4. A thick paste may be applied to the end portion 14a and the end portion 14b having the first surface 23 and the second surface 25 so as to protrude toward the central axis of the through hole 4 by the action of surface tension. it can. In particular, when the viscosity of the paste is set to 10 to 500 Pa · s, a relatively large amount of paste can be applied. If the dielectric block 2 thus coated with paste is heat-treated at about 800 to 900 ° C. and then cooled, the dielectric in which the inner conductor 6, the outer conductor 8 and the metal layer 7 are formed on the surface of the dielectric block 2. The resonator 10 can be manufactured. In the manufacturing method of the present embodiment, since a relatively large amount of paste can be applied to the end portion 14a and the end portion 14b of the through hole 4, the sufficiently thick inner conductor 6 is attached to the end portion 14a and the end portion 14b. Can be made. According to such a manufacturing method, since the thickness of the inner conductor 6 in the vicinity of the end portion 14 of the through hole 4 where stress due to an impact applied from the outside is likely to be concentrated can be relatively easily increased, The inner conductor 6 itself is also difficult to break.

  As mentioned above, although the example of embodiment of the dielectric resonator of this invention was demonstrated, this invention is not limited to said each embodiment. The material of the dielectric block, the material of the inner conductor and the outer conductor, the signal extraction electrode structure, and the like are not particularly limited to the example of the embodiment of the present invention. In the above embodiment, a dielectric resonator having a plurality of through holes and used as a band pass filter has been described. However, a dielectric resonance having one through hole and resonating at one specific frequency is described. A plurality of through holes and input / output terminal structures may be provided in addition to the four in the example of the above embodiment. The dielectric resonator of the present invention can be used as a so-called duplexer or multiplexer. Of course, various improvements and modifications may be made without departing from the scope of the present invention.

2 Dielectric block 2a, 2b Main surface 4 Through hole 4A, 4B Opening 6 Inner conductor 6α, 6β Inner peripheral surface 7 Metal layer 8 Outer conductor 10 Dielectric resonator 14a, 14a End portion 16 Parallel portion 23 First surface 25 2nd surface 27, 29 Connection part 50 Tuning stick C Center axis

Claims (5)

A dielectric block having a pair of main surfaces located on opposite sides;
A through hole having an opening on each of the pair of main surfaces and penetrating the dielectric block;
An inner conductor deposited on the entire inner peripheral surface of the through hole;
A dielectric resonator comprising an outer conductor deposited on a side surface of the dielectric block so as to surround the inner conductor;
The through-hole includes a pair of end portions including the respective openings, and a parallel portion located between the pair of end portions and having an inner peripheral surface parallel to the central axis. Smaller than the inner diameter of the opening,
Each of the pair of end portions includes a first surface continuous to the inner peripheral surface of the parallel portion, and a second surface continuous to the first surface and the main surface, and includes a cross section including the central axis. When viewed, the first surface is substantially perpendicular to the inner peripheral surface of the parallel portion, and the connecting portion between the first surface and the second surface is the second surface and the main surface. Close to the central axis compared to the connection with the surface,
The inner conductor has a thickness that is thicker toward the central axis at a portion attached to each of the pair of end portions, and an inner peripheral surface of the inner conductor at a portion where the inner peripheral surface is attached to the parallel portion. A dielectric resonator characterized by being closer to the central axis than a plane.   2. The inner conductor is continuously attached from the entire inner peripheral surface of the through hole to a part of at least one of the main surfaces of the pair of main surfaces. Dielectric resonator.   A metal layer is also provided on the entire main surface of at least one of the pair of main surfaces, and the metal layer is connected to both the inner conductor and the outer conductor so that the metal layer is interposed therebetween. The dielectric resonator according to claim 1, wherein the inner conductor and the outer conductor are electrically connected.   2. The dielectric resonator according to claim 1, wherein the dielectric block includes a plurality of the through holes, and the inner conductor is attached to the entire inner peripheral surface of each of the through holes. A dielectric block having a pair of main surfaces located on opposite sides;
A through hole having an opening on each of the pair of main surfaces and penetrating the dielectric block;
An inner conductor deposited on the entire inner peripheral surface of the through hole;
An outer conductor deposited on the side surface of the dielectric block so as to surround the inner conductor;
A dielectric resonator comprising a screw-shaped tuning rod inserted into the through-hole from the opening of one main surface of the pair of main surfaces,
The through-hole includes a pair of end portions including the respective openings, and a parallel portion located between the pair of end portions and having an inner peripheral surface parallel to the central axis. Smaller than the inner diameter of the opening,
Each of the pair of end portions includes a first surface continuous to the inner peripheral surface of the parallel portion, and a second surface continuous to the first surface and the main surface, and includes a cross section including the central axis. When viewed, the first surface is substantially perpendicular to the inner peripheral surface of the parallel portion, and the connecting portion between the first surface and the second surface is the second surface and the main surface. Close to the central axis compared to the connection with the surface,
The dielectric resonator according to claim 1, wherein the tuning rod is screwed into the through hole by an outer periphery biting into the inner conductor at least in the vicinity of the end portion on the one main surface side.

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