JPH10242720A - Dielectric resonator and dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the leakage of an electromagnetic field and the deterioration of no-load resonance sharpness Qo by forming an electrode of a plane part as a thin film multilayer electrode where both thin film electrode and dielectric layers are alternately laminated and the peripheral part of every thin film electrode layer is short-circuited and then forming a hole on a face almost vertical to the plane part of a dielectric plate or post. SOLUTION: A thin film multilayer electrode 2 is formed at a plane part by laminating alternately both thin film electrode and dielectric layers and short-circuiting the peripheral part of every thin film electrode layer. When the resonance frequency of a dielectric resonator of such a constitution is controlled, a hole 6 is formed on a face vertical to the upper and lower plane parts of a dielectric plate 1. The change of the resonance frequency is increased when the depth of the hole 6 is controlled at a position near the center of the plate 1, and the resonance frequency is finely controlled when the depth of the hole 6 is controlled at a position excluding the center of the plate 1. Thus, it's possible to decide the size of the hole 6 in order to secure the prescribed resonance frequency even in a design step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric resonator and a dielectric filter mainly used in a microwave band or a millimeter wave band.

[0002]

2. Description of the Related Art Conventionally, for example, a TM mode dielectric resonator having electrodes formed on the surface of a dielectric plate or a dielectric column has been used as a dielectric resonator in a microwave band which handles relatively high power. I have. This TM mode dielectric resonator is small and can obtain a high no-load Q (Qo).
For example, it is used as a filter for communication equipment in a base station of a cellular system for mobile communication.

[0003] When a filter or the like is formed using a TM mode dielectric resonator having electrodes formed on the surface of such a dielectric plate or a dielectric pillar, it is similar to the case where another type of dielectric resonator is used. Even if the relative permittivity and the dimensions of the dielectric plate or the dielectric column are simply designed, it is difficult to obtain the resonance frequency as designed due to the variation of the material constant and the influence of the molding accuracy. Therefore, fine adjustment of the resonance frequency is usually required. Also,
Even if variations in the material constants and dimensions of the dielectric plate or the dielectric column can be sufficiently suppressed, if dielectric resonators having different resonance frequencies are to be obtained using the same mold, depending on the characteristics, The electrode pattern on the surface will be different.

Therefore, as a method of adjusting or setting the resonance frequency of such a TM mode dielectric resonator, for example, as shown in FIG. 20, a method of partially removing a flat electrode perpendicular to an electric field component is used. Can be considered. That is, FIG. 20A is a perspective view showing a state before the electrode portion is deleted. By forming electrodes on the outer surface (six surfaces) of the dielectric plate, as shown by arrows in FIG. Acts as a TM mode dielectric resonator having an electric field component in a direction perpendicular to the plane portion of the flat portion. However, as shown in FIG. If the forming part 7 is provided, the resonance frequency can be changed by perturbing the electric field.

[0005]

However, in such a TM mode dielectric resonator, if an electrode-free portion is provided on a surface perpendicular to the electric field component, the electric field energy is concentrated on that portion. Electromagnetic field leakage is likely to occur, and a portion of the actual current flowing through the electrode where the current density is high will be deleted. Therefore, the current density in the vicinity will increase, the overall conductor loss will increase, and Qo will deteriorate. Will be.

Further, the applicant of the present application has proposed a method of increasing the Qo by avoiding an increase in current density due to a skin effect at a boundary portion between a dielectric portion and an electrode film, in order to increase the Qo by replacing an electrode having a surface perpendicular to an electric field component with a thin film electrode layer. A thin-film multilayer electrode formed by alternately laminating a thin-film dielectric layer and a thin-film dielectric layer is filed in Japanese Patent Application No. 08-331316. In a dielectric resonator provided with such a thin-film multilayer electrode, FIG. If the electrodes are partially deleted as shown in FIG. 20, there is a possibility that the thin film electrode layers may be short-circuited between the layers, which hinders a low-loss operation due to a reduction in current density.

An object of the present invention is to solve the above-described problem of electromagnetic field leakage, and to provide a dielectric resonator with less Qo degradation and a dielectric filter using the same.

[0008]

According to the present invention, there is provided a dielectric plate or a dielectric column having two substantially parallel polygonal or circular flat portions and a surface substantially perpendicular to the two flat portions. An electrode is formed on the surface, and in a dielectric resonator that resonates in one or more modes having an electric field component in a direction perpendicular to the plane portion, an electromagnetic field leak is suppressed, an increase in current density is suppressed, and In order to set the resonance frequency while avoiding the problem of interlayer short-circuiting when a thin-film multilayer electrode is formed, as described in claim 1, the electrodes in the plane portion are alternately formed by a thin-film electrode layer and a thin-film dielectric layer. And a thin-film multilayer electrode formed by short-circuiting the peripheral portion of each thin-film electrode layer, and a hole is formed in a plane substantially perpendicular to the plane portion of the dielectric plate or the dielectric pillar. This hole partially replaces the dielectric plate or the dielectric pillar with a substance (air) having a low relative dielectric constant, so that the effective capacitance of the resonator in the predetermined resonance mode is reduced, and the resonance frequency is reduced. Changes in the upward direction. Thereby, the resonance frequency of the predetermined resonance mode is determined. Alternatively, the resonance frequency of the coupling mode changes in the rising direction, and the degree of coupling between two predetermined resonance modes is determined.

Further, the dielectric resonator according to the present invention is provided in claim 2 of the present invention.
As described in the above, a partial electrode non-forming portion is provided on a surface substantially perpendicular to the plane portion of the dielectric plate or the dielectric column to provide a resonance frequency of a predetermined resonance mode or a degree of coupling between two predetermined resonance modes. Is determined. By providing the non-electrode-formed portion in this manner, the area of the current path is reduced, the effective inductance of the resonator is increased, and the resonance frequency is changed in a decreasing direction. Thereby, the resonance frequency of the predetermined resonance mode is determined. Alternatively, the resonance frequency of the coupling mode changes in a decreasing direction, and the degree of coupling between two predetermined resonance modes is determined.

According to the dielectric resonator according to the first and second aspects, the aperture of the electrode is formed on the plane parallel to the electric field component, so that the electromagnetic field leakage is reduced. In addition, since a portion having no electrode is provided in a region where the current density is originally small, deterioration of Qo is reduced. Also, two parallel
Since the electrodes of the two flat portions are thin-film multilayer electrodes, an increase in the current density due to the skin effect at the boundary portion between the dielectric portion and the electrode film is avoided and Qo is increased. Since the hole or the non-electrode-formed portion does not affect the Qo improving effect by using the thin-film multilayer electrode.

Further, the present invention is a dielectric filter in which a plurality of dielectric resonators according to claim 1 or 2 are stacked with their respective plane portions facing each other, and the dielectric resonators are coupled. 4. The method according to claim 3, wherein the dielectric material is used to suppress electromagnetic field leakage, suppress an increase in current density, and determine filter characteristics while avoiding the problem of interlayer short-circuit when a thin-film multilayer electrode is formed. A hole is formed in a surface of the plate or the dielectric column substantially perpendicular to the plane portion of the dielectric resonator to determine the filter characteristic, or as described in claim 4, the dielectric plate or the dielectric column The filter characteristics are set by providing a partial electrode non-forming portion on a surface substantially perpendicular to the plane portion of the dielectric resonator. Thus, by providing a hole in a plane parallel to the electric field component of the dielectric resonator or providing an electrode non-forming portion, it is possible to prevent electromagnetic field leakage and decrease in Qo due to the dielectric resonator. Thus, a dielectric filter having low electromagnetic field leakage and low insertion loss can be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a dielectric resonator according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1A is an external perspective view, FIG. 1B is a view showing an electromagnetic field distribution, and FIG. 1C is a view showing a current distribution flowing through an electrode portion. 2A, reference numeral 2 denotes a thin-film multilayer electrode formed on the upper and lower surfaces of a dielectric plate having a hexahedral shape in the drawing.
Is a single-layer electrode formed on the remaining four surfaces.

In (B), the solid arrows in the dielectric resonator indicate the direction and intensity of the electric field in the main part, and the broken arrows indicate the magnetic field distribution. As described above, the electric field is distributed in the thickness direction of the dielectric resonator 10, and the magnetic field is distributed in a plane direction perpendicular to the electric field. The x-axis and the y-axis are set in the plane direction of the magnetic field,
Taking the z-axis in a direction perpendicular to each of these, this dielectric resonator can be expressed as a TM110 mode. Since an electromagnetic field distribution is generated in this manner, as shown in FIG. 3C, a current flows through the thin film multilayer electrode 2 on the upper surface in a direction spreading from the center to four directions or in a direction gathering from the four directions to the center. 5 flows in the vertical direction in the figure.

FIG. 2 is a sectional view of the dielectric resonator shown in FIG. 1 and a partially enlarged view thereof. In the figure, 3a, 3
b, 3c and 3d are thin film electrode layers, 4a, 4b and 4 respectively.
c is a thin film dielectric layer, and the thin film multilayer electrode 2 is formed by alternately laminating the two. This thin film multilayer electrode is formed by repeating a process of forming a thin film electrode layer by sputtering Cu, for example, and forming a thin film dielectric layer by sputtering a material having a low dielectric constant from the dielectric plate 1 a predetermined number of times. . The single-layer electrode on the side is C
It is formed by u plating. By providing the electrode on this side surface after the formation of the thin-film multilayer electrode, the peripheral portion of the thin-film multilayer electrode is short-circuited.

FIG. 3 is a diagram showing a state of a current flowing through each thin-film electrode layer shown in FIG. As shown in FIG. 3B, each of the thin film dielectric layers 4a, 4b, and 4c constitutes an extremely thin dielectric resonator together with the thin film electrode layers above and below the thin film dielectric layers. By making the resonance frequency substantially equal to the resonance frequency of the dielectric resonator according to 1, the directions (phases) of the currents flowing through the thin film electrode layers on the upper and lower surfaces become uniform. As a result, as shown in (A), the current ia of the dielectric resonator flows through the thin film electrode layer 3a, and the current ib of the resonator formed by the thin film dielectric layer 4a flows through the thin film electrode layers 3a and 3b. Similarly, the current ic of the dielectric resonator by the thin film dielectric layer 4b flows through the thin film electrode layers 3b and 3c,
The current id of the dielectric resonator by the dielectric layer 4c flows through the thin film electrode layers 3c and 3d. Therefore, the thin film electrode layer 3a
Is ia-ib, the combined current flowing in the thin-film electrode layer 3b is ib-ic, and the combined current flowing in the thin-film electrode layer 3c is ic-id. The white arrows in the figure schematically represent the direction and magnitude of these combined currents.
In this way, the current concentration on the surface of the dielectric plate 1 is reduced, and the current is dispersed to the surface layer.

As the dielectric plate, for example, a dielectric ceramic having a relative dielectric constant of about 40 is used, and as each thin film electrode layer, a dielectric having a relative dielectric constant lower than 40 is used. Can be made substantially equal to the resonance frequency of the dielectric resonator by the dielectric plate 1. Also, each thin film electrode layer does not completely shield the electromagnetic field of the dielectric resonator due to the dielectric plate or the dielectric pillar, and the dielectric resonator formed by each thin film electrode layer and the thin film dielectric layer does not The thickness of each thin-film electrode layer is set to be equal to or smaller than the skin depth at the resonance frequency so as to be coupled to the dielectric resonator formed by the body pillar.

When adjusting the resonance frequency of the dielectric resonator having such a structure, holes 6 are formed in a plane perpendicular to the upper and lower plane portions of the dielectric plate as shown in FIG. (A) of FIG.
Is a perspective view, and (B) is a horizontal sectional view. In this example, after the electrodes are formed on each surface of the dielectric plate 1, the holes 6 are formed with a diamond bar (rotary grindstone). Therefore, no electrodes exist on the inner surfaces of the holes 6. The inside of the hole 6 is air,
Since the dielectric constant is lower than that of the dielectric plate 1, the effective capacitance of the resonator is reduced as compared with before the hole 6 is provided. Here, the effective capacitance of the resonator is Co, and the effective inductance is L.
If o, the resonance frequency fo = 1 / {(2π} (LoC
o) Since it is expressed as｝, forming the hole 6 increases the resonance frequency from before the hole 6 is formed.

FIG. 5 shows the dielectric resonator shown in FIG. 4, in which the relative permittivity εr of the dielectric plate 1 is 37, and a = b = 1.
4 [mm], c = 4 [mm], d = 2 [mm],
It is a result obtained by FEM simulation of the resonance frequency when h is changed and the change amount of the resonance frequency with respect to the change amount of h. Here, the resonance frequency is fo, the variation thereof is dfo, and the variation of fo with respect to the variation of h is df.
These numerical results are shown as o / dh.

H [mm] fo [MHz] dfo [MHz] dfo / dh [MHz / mm] 0.0 2489.3 0.5 2489.4 0.1 0.2 1.0 2490.1 0.7 1.4 1.5 2491.8 1.7 3.4 2.0 2495.0 3.2 6.4 2.5 2500.0 5.0 10.0 3.0 2507.1 7.1 14.2 3.5 2516.4 9.3 18.6 4.0 2527.9 11.5 23.0 4.5 2541.9 14.0 28.0 5.0 2558.2 16.3 32.6 5.5 2576.9 18.7 37.4 6.0 2597.6 20.7 41.4 6.5 2620.3 22.7 45.4 7.0 2644.7 24.4 48.8 7.5 2670.3 25.6 51.2 8.0 2696.5 26.2 52.4 8.5 2722.7 26.2 52.4 9.0 2747.9 25.2 50.4 9.5 47.0 10.0 2792.4 21.0 42.0 10.5 2810.0 17.6 35.2 11.0 2824.2 14.2 28.4 11.5 2834.8 10.6 21.2 12.0 2841.9 7.1 14.2 12.5 2846.4 4.5 9.0 13.0 2848.6 2.2 4.4 13.5 2849.4 0.8 1.6 The resonance frequency at the point of time when only
[MHz], and the resonance frequency when h = 13.5 [mm] was 2849.4 [MHz]. Also, h =
In the case of 8.0 to 8.5 [mm], the variation of the resonance frequency with respect to the variation of h became the maximum, and was 52.4 [MHz / mm]. As described above, the resonance frequency can be largely changed by adjusting the depth of the hole 6 near the center of the dielectric plate. Conversely, the depth of the hole 6 is adjusted while avoiding the center of the dielectric plate. Thereby, the resonance frequency can be finely adjusted. In the above description, the holes 6 are formed after the electrodes are formed on the outer surface of the dielectric plate. However, the holes 6 are formed integrally when the dielectric plate is formed. The resonance frequency may be set according to the depth. That is, instead of finely adjusting the resonance frequency, the dimensions of the hole 6 may be designed so as to obtain a predetermined resonance frequency from the design stage.

Next, the structure of a dielectric resonator according to a second embodiment of the present invention will be described with reference to FIGS.

In the first embodiment, an example in which holes are formed in the dielectric plate to set the resonance frequency has been described. In the second embodiment, as shown in FIG. The electrode non-forming portion 7 is provided on the side surface to set the resonance frequency.
FIG. 6B schematically shows a distribution of a current flowing through the electrode on the side surface on which the electrode non-formed portion 7 is provided. As described above, the area through which the current flows is reduced, and the effective inductance of the resonator is increased. Therefore, the resonance frequency is reduced as compared with the case where the electrode non-formed portion 7 is not provided.

FIG. 7 shows the dimensions of each part shown in FIG.
Let the relative permittivity εr of the dielectric plate 1 be 37, and a = b = 14
[Mm], c = 4 [mm], and the width u2 of the electrode non-formed portion 7 in the height direction is 4 [mm], and the resonance frequency when the width u1 of the electrode non-formed portion 7 in the horizontal direction is changed is It is a result obtained by FEM simulation. Here, the resonance frequency is fo, the amount of change is dfo, and f is the amount of change of u1.
These numerical results are shown with the amount of change of o being dfo / du1.

U1 [mm] fo [MHz] dfo [MHz] dfo / du1 [MHz / mm] 0.0 2489.3 0.5 2488.8 1.0 2486.6 -2.2 -4.4 1.5 2480.2 -6.4 -12.8 2.0 2473.3 -6.9 -13.8 2.5 2460.7 -12.6- 25.2 3.0 2446.6 -14.1 -28.2 As described above, u1 = 0, that is, the resonance frequency before forming the electrode non-formed portion 7 is 2489.3 [MHz], and u1 =
When it is 3.0 [mm], the resonance frequency is 2446.6.
[MHz]. Further, as u1 is increased, the amount of change in the resonance frequency with respect to the amount of change in u1 is increased. As described above, the resonance frequency can be adjusted in a lowering direction by the width of the electrode non-formed portion 7. Also, as the width of the electrode non-formed portion 7 is increased, the resonance frequency can be largely changed. The resonance frequency can be finely adjusted by increasing the width of the non-formed portion 7 in a minute range.

The electrode non-forming portion 7 shown in FIG.
As in the case of the embodiment, the electrode formed in advance can be provided by deleting it using a diamond bar or the like. However, in reality, it is extremely difficult to delete only the electrode. A part of the body plate will be cut. Therefore, in order to lower the resonance frequency, the cutting depth is made as shallow as possible and the range of the non-electrode portion is increased. In order to raise the resonance frequency, the cutting amount (hole depth) of the dielectric plate is reduced. You just need to increase it.

Next, the structure of a dielectric resonator according to a third embodiment will be described with reference to FIGS.

FIG. 8 is a perspective view and a horizontal sectional view of the dielectric resonator. In (A), reference numeral 2 denotes a thin-film multilayer electrode formed on the upper and lower surfaces in the figure of a dielectric plate having a hexahedral shape, and reference numeral 5 denotes a single-layer electrode formed on the remaining four surfaces. This dielectric resonator is a TM dual mode dielectric resonator using the TM210 mode and the TM120 mode as described later, and has a (TM210 + TM120) mode and a (TM2
10-TM120) mode.
In order to couple the 210 mode and the TM120 mode, the dielectric plate has a shape in which one corner is removed, and a hole 6 is provided in the corner.

FIG. 9 is a diagram showing the state of the electromagnetic field distribution of the two modes and the coupling mode between the two modes. (A), (B) is a figure regarding TM120 mode and TM210 mode, and the arrow of a broken line shows a magnetic field distribution.
These two modes have a reduced mode relationship. (C) and (D) in the same figure are each used as a coupling mode (T
(M210 + TM120) mode and (TM210-TM1)
20] It is a figure regarding a mode, and the arrow of a broken line shows a magnetic field distribution. By forming the dielectric plate with the corners removed as shown in FIG.
(M120) mode resonance frequency is increased, and (TM21)
Since the resonance frequency of the (0 + TM120) mode does not change much, the degeneracy of the TM120 mode and the TM210 mode is resolved, and coupling occurs between the TM120 mode and the TM210 mode.

FIG. 10 shows a state in which the relative permittivity εr of the dielectric plate 1 is 37 in FIG. 8B, and a = b = 22 and c = 4.
[Mm] and the resonance frequency when the depth h of the hole 6 is changed, assuming that the inner diameter d of the hole 6 is 2 [mm], by FEM simulation. Here, (TM210-
The resonance frequency of the (TM120) mode is f1, and (TM210)
+ TM120) The resonance frequency of the mode is f2, the variation of f1 is df1, and the variation of f1 with respect to the variation of h is df1.
These numerical results are shown as / dh.

H [mm] f1 [MHz] f2 [MHz] df1 [MHz] df1 / dh [MHz / mm] 0.0 2520.9 2504.8 0.5 2520.9 2504.8 0.0 0.0 1.0 2521.2 2504.8 0.3 0.6 1.5 2521.9 2504.8 1.0 1.4 2.0 2523.2 2504.8 2.3 2.6 2.5 2525.2 2504.8 4.3 4.0 3.0 2528.2 2504.8 7.3 6.0 3.5 2532.0 2504.8 11.1 7.6 4.0 2536.9 2504.8 16.0 9.8 4.5 2542.9 2504.8 22.0 12.0 5.0 2549.7 2504.9 28.8 13.6 5.5 2557.5 2505.0 36.6 15.6 6.0 2566.0 2505.0 45.1 17.0 6.5 2575.1 2505.0 54.2 18.2 7.0 2584.5 2505.1 63.6 18.8 As described above, by increasing the depth of the corner hole 6, the resonance frequency of one resonance mode can be adjusted in the upward direction. Further, as the depth h of the hole 6 is increased to reach the center of the dielectric plate, the amount of change in the resonance frequency with respect to the amount of change in h increases. Note that the difference between the resonance frequencies f1 and f2 at the stage where h = 0, that is, when the electrode at the position where the hole 6 is to be formed is deleted, is due to the shape obtained by removing one corner of the dielectric plate.

Here, the coupling degree k between the TM120 mode and the TM210 mode is represented by k = 2 (f1−f2) / (f1 + f2) or k = (f1−f2) / √ (f1 · f2). By providing a difference between f1 and f2, the TM120 mode and the TM210 mode can be coupled, and the degree of coupling can be increased as the hole 6 is deepened and the difference between f1 and f2 is increased.

FIGS. 11 and 12 show the structure of a dielectric resonator according to the fourth embodiment. The difference from the third embodiment is that the resonance frequency is not adjusted by holes, but is adjusted. As shown in FIG. 11, the resonance frequency of one resonance mode of the coupling modes is adjusted by providing the electrode non-formed portion 7 at the corner of the dielectric plate. FIG. 12 shows a state where the relative dielectric constant εr of the dielectric plate 1 is 37 in FIG.
22 [mm], c = 4 [mm], and the width u2 in the height direction of the electrode non-formed portion 7 is 4 [mm], and the resonance frequency when the horizontal width u1 of the electrode non-formed portion 7 is changed Is a result obtained by FEM simulation. Where (TM
The resonance frequency of the (210-TM120) mode is f1, (T
M210 + TM120) The resonance frequency of the mode is f2, f
These numerical results are shown assuming that the change amount of 1 is df1 and the change amount of f1 with respect to the change amount of u1 is df1 / du1.

H [mm] f1 [MHz] f2 [MHz] df1 [MHz] df1 / du1 [MHz / mm] 0.0 2520.9 2504.8 1.0 2519.9 2504.8 2.0 2514.8 2504.8 2.5 2510.0 2504.8 -4.8 -9.6 3.0 2504.6 2504.8 -5.4 -10.8 3.5 2498.1 2504.8 -6.5 -13.0 4.0 2490.8 2504.8 -7.3 -14.6 As described above, the resonance frequency of one of the coupling modes can be adjusted in the decreasing direction by the width of the corner electrode non-formed portion 7. Thus, by giving a difference between f1 and f2, the TM120 mode and the TM210 mode can be coupled, and the width of the electrode non-formed portion 7 is increased to increase the width of f1 and f2.
As the difference between the two increases, the degree of coupling can be increased.

Next, the structure of a dielectric filter according to a fifth embodiment will be described with reference to FIGS.

FIG. 13 is a perspective view and a partial sectional view of a dielectric filter constituted by combining four dielectric resonators. In (A), 11, 12, 13 and 14 are dielectric resonators basically similar to those shown in FIG. 1, respectively. A window consisting of a part is formed. Dielectric resonator 1
On the opposing surfaces of 2 and 13, a window made of an electrode non-formed portion indicated by W2 is formed. Further, a window made of an electrode-free portion indicated by W3 is formed on the surface facing the dielectric resonators 13 and 14. Further, coaxial connectors 15 and 16 are attached to the end faces of the dielectric resonators 11 and 14, respectively. Of these dielectric resonators, thin-film multilayer electrodes are formed on the upper surface in FIGS. 12 and 13 and the lower surface in the drawings of dielectric resonators 11 and 14, and ordinary single-layer electrodes are formed on the other surfaces. doing. When adjusting the characteristics of the dielectric filter, one or several holes 61, 62, 63, and 64 are formed on the side surfaces of the dielectric resonators 11, 12, 13, and 14, and the holes are formed. Adjust according to depth.

FIG. 13B is a cross-sectional view of a portion where the coaxial connector 15 is attached to the dielectric resonator 11, and a coupling loop 17 is formed by the center conductor of the coaxial connector 15.
This is inserted into a hole provided in the dielectric plate of the dielectric resonator 11. Similarly, for the coaxial connector 16, a coupling loop is formed by the center conductor, and this is connected to the dielectric resonator 1.
4 is inserted into a hole provided in the dielectric plate.

FIG. 14 shows the dielectric resonator 11 shown in FIG.
FIG. 13 is a cross-sectional view showing a coupling structure between the first and second embodiments. In the figure, (A) shows the electric field distribution in the even mode, and (B) shows the electric field distribution in the odd mode. Thus window W
If there is no part of the electrode, the capacitance component is reduced with respect to the odd mode, so that the odd mode resonance frequency fodd becomes higher than the even mode resonance frequency feven, and electric field coupling occurs between the dielectric resonators 11 and 12. .

FIG. 15 shows the dielectric resonator 12 shown in FIG.
FIG. 14 is a diagram showing a connection state between the and. (A) shows the odd-mode magnetic field distribution, and (B) shows the even-mode magnetic field distribution. As described above, if there is no electrode in the window W2, the inductance component increases, the resonance frequency in the even mode decreases, and the relationship of fodd> feven is established, and the dielectric resonators 12 and 13 are magnetically coupled. FIG.
The electric field coupling between the dielectric resonators 13 and 14 shown in FIG. Figure 13
The dielectric filter shown in (1) is coupled in the path of the coaxial connector 15 → the dielectric resonator 11 → 12 → 13 → 14 → the coaxial connector 16 and acts as a filter having a band-pass filter characteristic composed of four resonators. . This filter characteristic is determined by the resonance frequency of each of the dielectric resonators 11 to 14 and the degree of coupling between the resonators. In this configuration example, the degree of coupling is fixed and the depth of the holes 61 to 64 shown in FIG. The filter characteristics are determined by setting the resonance frequency of each resonator.

FIG. 16 is a perspective view of a dielectric filter according to the sixth embodiment. The difference from the dielectric filter shown in FIG. 13 is that instead of setting the resonance frequency of each resonator by forming a hole, a resonance frequency is adjusted by providing a non-electrode forming portion. That is, in FIG. 16, the resonance frequencies of the dielectric resonators 11, 12, 13, and 14 are adjusted according to the size of the electrode non-formed portions 71, 72, 73, and 74, thereby determining the filter characteristics.

Next, the structure of the dielectric filter according to the seventh embodiment will be described with reference to FIGS.

In FIG. 17, reference numerals 11 and 12 denote TMs, respectively.
This is a dual-mode dielectric resonator, in which thin-film multilayer electrodes are formed on the upper and lower surfaces in the figure of the dielectric plate, a single-layer electrode is formed on the peripheral surface, and a non-electrode is formed on the joint surface of the two dielectric resonators. A window W composed of a forming part is formed. Also, coaxial connectors 15, 16 each having a coupling loop inside are formed side by side on the same plane. When adjusting the characteristics of the dielectric filter, the corners of the dielectric resonators 11 and 12 are adjusted to 6
Forming one or both holes indicated by 1, 62,
Adjust according to the depth.

FIG. 18 shows the dielectric resonator 11 shown in FIG.
And FIG. 12 are diagrams illustrating resonance modes and coupling states, and broken arrows indicate magnetic field distributions. As shown in FIGS. 18A and 18B, the two dielectric resonators 11 and 12 have a degenerate TM120 mode and a TM2 mode.
Resonating in ten modes, respectively, the coupling loops of the coaxial connectors 15 and 16 shown in FIG.
In the TM120 mode. FIG. 18C is a diagram showing a coupling state between the dielectric resonators 11 and 12. Since there is no electrode in the window W, the TM210 modes are magnetically coupled to each other. By forming the shape of the dielectric plate by removing the corners, the combined mode of the TM210 mode and the TM120 mode (TM210 +
There is a difference between the resonance frequencies of the (TM120) mode and the (TM210-TM120) mode, and the degeneracy is resolved.
The coupling occurs between the two modes, the mode and the TM120 mode. Therefore, the dielectric filter shown in FIG. 17 is composed of the coaxial connector 15 → the TM120 mode of the dielectric resonator 11 → the TM210 mode of the dielectric resonator 11 → the TM210 mode of the dielectric resonator 12 → the TM12 mode of the dielectric resonator 12.
The mode is coupled in the order of 0 mode → coaxial connector 16 and acts as a band-pass filter composed of four stages of resonators. In this case, the degree of connection between the first and second stages depends on the depth of the hole 61.
The degree of connection between the third and fourth steps depends on the depth of the hole 62.
Adjust each.

FIG. 19 is a sectional view showing two structural examples of the dielectric resonator according to the eighth embodiment. In the above-described dielectric resonator and the dielectric filter using the same, a square-column-shaped dielectric plate having a square bottom surface is used. However, the dielectric plate may be formed as a dielectric column in the center of the dielectric plate and the cavity may be formed as a cavity. Good. That is, FIG. 19A shows that a rectangular cylindrical cavity 22 and a prismatic dielectric column 21 provided at the center thereof are integrally formed, and the dielectric plate 2 is formed in the opening of the cavity 22.
This is a TM110 mode dielectric resonator formed by providing electrodes 3 and 24 and forming electrodes on the outer surface. Also in this structure, a hole is provided in the dielectric plate 23 or 24, or an electrode non-forming portion is provided. Thereby, the resonance frequency can be adjusted. Also, FIG.
Cylindrical cavity 22 with bottom and cylindrical dielectric column 21
Are integrally formed to cover the dielectric plate 23 in the form of a disc on the opening surface of the cavity 22, and a dielectric resonator of the TM010 mode constituted by forming electrodes on the peripheral surface. The resonance frequency can be adjusted by providing a hole or an electrode-free portion on the side surface of the cavity 22.

[0044]

According to the first and second aspects of the present invention, since the opening of the electrode is formed on the plane parallel to the electric field component, the electromagnetic field leakage is reduced. In addition, since a thin film multilayer electrode can be formed on the entire surface of the plane portion perpendicular to the electric field component, an increase in current density due to a skin effect at a boundary portion between the dielectric portion and the electrode film is avoided and Qo is increased. . In addition, since the holes and the portions where the electrodes are not formed are originally provided only in the region where the current density is small, the deterioration of Qo due to the provision of the holes and the portions where the electrodes are not formed is small.

According to the third and fourth aspects of the present invention, by providing a hole in a surface parallel to the electric field component of the dielectric resonator or providing an electrode non-forming portion, the electromagnetic field leakage due to the dielectric resonator is provided. And a decrease in Qo can be prevented, and a dielectric filter with small electromagnetic field leakage and low insertion loss can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external appearance, an electromagnetic field distribution, and a current distribution of a dielectric resonator according to a first embodiment.

FIG. 2 is a sectional view and a partially enlarged sectional view of the dielectric resonator.

FIG. 3 is a diagram showing a current distribution in a thin-film multilayer electrode portion in the dielectric resonator.

FIG. 4 is a perspective view and a horizontal sectional view showing an example of forming a frequency adjusting hole.

FIG. 5 is a diagram showing a change in resonance frequency when the depth of a hole is changed.

FIG. 6 is a diagram illustrating a perspective view of a dielectric resonator according to a second embodiment and a diagram illustrating an example of a current distribution;

FIG. 7 is a diagram showing a change in resonance frequency when the width of an electrode-free portion in the dielectric resonator is changed.

FIG. 8 is a perspective view and a horizontal sectional view of a dielectric resonator according to a third embodiment.

FIG. 9 is a diagram showing an example of an electromagnetic field distribution in each mode of the dielectric resonator.

FIG. 10 is a diagram showing a change in resonance frequency when the depth of a hole in the dielectric resonator is changed.

FIG. 11 is a perspective view and a horizontal sectional view of a dielectric resonator according to a fourth embodiment.

FIG. 12 is a diagram showing a change in resonance frequency when the width of an electrode-free portion of the dielectric resonator is changed.

FIG. 13 is a perspective view and a partial cross-sectional view illustrating a configuration of a dielectric filter according to a fifth embodiment.

FIG. 14 is a diagram showing a coupling state between dielectric resonators in the vertical direction in the dielectric filter.

FIG. 15 is a diagram showing a coupling state between dielectric resonators in a horizontal direction in the dielectric filter.

FIG. 16 is a perspective view of a dielectric filter according to a sixth embodiment.

FIG. 17 is a perspective view of a dielectric filter according to a seventh embodiment.

FIG. 18 is a diagram showing an example of an electromagnetic field distribution of each mode in the dielectric filter.

FIG. 19 is a sectional view showing a structure of a dielectric resonator according to an eighth embodiment.

FIG. 20 is a perspective view showing an example of adjusting the resonance frequency of a dielectric resonator according to the related art.

[Explanation of symbols]

 1-dielectric plate 2-thin-film multilayer electrode 3-thin-film electrode layer 4-thin-film dielectric layer 5-single-layer electrode 6,61-64-hole 7,71-74-electrode non-formed portion 10,11-14-dielectric Body resonator 15, 16-Coaxial connector 17-Coupling loop 21-Dielectric column 22-Cavity 23, 24-Dielectric plate

Claims (4)

[Claims] 1. An electrode is formed on a surface of a dielectric plate or a dielectric column having two substantially parallel polygonal or circular flat portions and a surface substantially perpendicular to the two flat portions. In a dielectric resonator that resonates in one or more modes having an electric field component in a direction perpendicular to a plane portion, an electrode of the plane portion is formed by alternately stacking a thin film electrode layer and a thin film dielectric layer. A thin-film multilayer electrode is formed by short-circuiting the peripheral portion of each thin-film electrode layer, and a hole is formed in a surface substantially perpendicular to the plane portion of the dielectric plate or the dielectric column to form a resonance frequency of a predetermined resonance mode or a predetermined resonance frequency. A dielectric resonator having a degree of coupling between two resonance modes. 2. An electrode is formed on the surface of a dielectric plate or a dielectric pillar having two substantially parallel polygonal or circular plane parts and a plane substantially perpendicular to the two plane parts. In a dielectric resonator that resonates in one or more modes having an electric field component in a direction perpendicular to a plane portion, an electrode of the plane portion is formed by alternately stacking a thin film electrode layer and a thin film dielectric layer. A thin-film multilayer electrode is formed by short-circuiting the peripheral portion of each thin-film electrode layer, and a partial electrode non-forming portion is provided on a surface substantially perpendicular to the plane portion of the dielectric plate or the dielectric column to provide resonance in a predetermined resonance mode. A dielectric resonator having a frequency or a degree of coupling between two predetermined resonance modes. 3. The dielectric filter according to claim 1, wherein a plurality of the dielectric resonators according to claim 1 are stacked with their respective plane portions facing each other, and the dielectric resonators are coupled to each other. A dielectric filter, characterized in that a hole is formed in a surface of a body plate or a dielectric column substantially perpendicular to a plane portion of the dielectric resonator, and filter characteristics are determined. 4. A dielectric filter according to claim 1, wherein a plurality of the dielectric resonators according to claim 1 are stacked with their respective plane portions facing each other, and the dielectric resonators are coupled to each other. A dielectric filter, wherein a filter characteristic is determined by providing a partial electrode non-forming portion on a surface of the dielectric plate or the dielectric column substantially perpendicular to a plane portion of the dielectric resonator.