JPH07226604A - Dielectric filter - Google Patents

Abstract

PURPOSE:To easily adjust capacitance connected to respective dielectric coaxial resonators, to simplify the structure of a dielectric filter and to facilitate mounting. CONSTITUTION:This dielectric filter 1 is constituted of a filter block 2 for which the plural dielectric coaxial resonators are integrally formed and a capacitance substrate 3 attached to the open end face 201A of the filter block 2. An electrode to be connected to the internal conductors of second and forth dielectric coaxial resonators composed by forming the electrodes in through holes 203 and 205 are formed on the mounting surface of the capacitance substrate 3 and the electrodes 303 and 304 constituting the capacitance connected to the electrodes by the through holes 303A and 304A are formed on the opposite surface of the mounting surface. When the capacitance substrate 3 is attached, the capacitance constituted of the electrodes 303 and 304 is provided between the internal conductors of the second and forth dielectric coaxial resonators is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter formed by coupling a plurality of dielectric coaxial resonators to each other, and more particularly to the structure of a dielectric filter composed of an integrally molded filter.

[0002]

2. Description of the Related Art FIG. 13 is an exploded perspective view of a conventional dielectric filter. The dielectric filter 10 shown in the figure is a dielectric filter in which five dielectric coaxial resonators are integrally molded, and has the same equivalent circuit as the equivalent circuit of the dielectric filter according to the present invention shown in FIG. is doing.

The dielectric filter 10 is composed of a filter block 11, coupling pins 12A to 12D, and a capacitor substrate 13 forming a capacitor C3 for providing a pole on the filter characteristic.

The filter block 11 has a columnar dielectric body 111 having a length of λg / 4 (λg; a guide wavelength) having a rectangular cross section in which five through holes 112A to 112E extending in the axial direction are formed in parallel. The electrode 11 made of copper or the like is provided on the outer peripheral surface excluding the one end surface 111A and the inner peripheral surfaces of the through holes 112A to 112E.
3 (indicated by stippling in the figure).

Further, coupling pins 12A to 12D are fitted and mounted in the four through holes 112A to 112E except for the central through hole 112C via fitting members 121A to 121D made of resin.

The capacitor substrate 13 is made of a dielectric substrate having the same rectangular shape as the open end surface of the dielectric 111, and holes 131A-1 are provided at positions facing the coupling pins 12A-12D.
31D is drilled. In addition, the holes 13 on the substrate surface
Electrodes 131A to 1 are formed at the formation positions of 1A to 131D, respectively.
31D is formed, and the electrodes 132B and 132C are arranged to face each other to form the capacitor C3.

The capacitive substrate 13 has a coupling pin 12A.
To 12D are holes 131A to 131 of the capacitance substrate 13, respectively.
It is fitted in D and is connected and connected to the electrodes 132A to 132D by soldering or the like.

FIG. 14 is a perspective view of a main part of another embodiment of the conventional dielectric filter, and FIG. 15 is a vertical sectional view of the dielectric filter.

The dielectric filter 15 shown in FIG. 14 is a dielectric filter in which three dielectric coaxial resonators are integrally molded, and has the same equivalent circuit as the equivalent circuit of the dielectric filter according to the present invention shown in FIG. It has a circuit.

The dielectric filter 15 includes coupling pins 12A to 12A.
12D and a filter block 16 configured similarly to the filter block 11 described above.

Each through hole 162A of the filter block 16
As shown in FIG. 15, a gap 163 is provided in a part of the inner conductor formed by forming the electrode 113 on the inner peripheral surface of each of the to 162C, and the capacitance Cs1 in FIG. Cs2 and Cs3 are configured.

[0012]

In the above-mentioned conventional dielectric filter, a coupling pin is fitted and mounted in each opening of the open end surface of the filter block, and is connected to an external circuit through the coupling pin. Since it has many components, its structure is complicated and it is difficult to mount it on a printed circuit board.

In particular, the polarized dielectric filter 10 requires a capacitance substrate 13 for forming a capacitance for polarization, the number of components is increased, and the structure is more complicated.

Further, a capacitor Cs is provided in parallel with the dielectric coaxial resonator.
In the dielectric coaxial resonator 15 provided with 1, Cs2, Cs3, the capacitors Cs1, Cs2, Cs are provided by providing the inner conductor with the gap 163.
3 is configured, it is difficult to set a large capacity and adjust the capacity.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a dielectric filter having a simple structure, in which the capacitance can be easily adjusted and mounted.

[0016]

In order to solve the above-mentioned problems, the present invention provides electrodes on the outer peripheral surface excluding one end surface of a columnar dielectric having a plurality of axially extending holes and on the inner peripheral surface of the holes. An outer conductor and an inner conductor of a plurality of dielectric coaxial resonators formed respectively, and a filter block integrally formed with the plurality of dielectric coaxial resonators mutually coupled, and an electrode. At least one capacitor is formed, and the capacitor substrate is attached to one end face of the dielectric so as to provide the capacitor between predetermined dielectric coaxial resonators of the filter block (claim 1).

In the capacitor substrate, the capacitor may be formed on the intermediate layer of the multilayer substrate, and an electrode for grounding may be formed on the entire outer surface (claim 2).

Further, according to the present invention, electrodes are formed on the outer peripheral surface except the one end surface of the columnar dielectric having a plurality of holes extending in the axial direction and the inner peripheral surface of the hole, and the outer periphery of the plurality of dielectric coaxial resonators is formed. A filter block in which a conductor and an inner conductor are respectively configured, and a filter in which the plurality of dielectric coaxial resonators are coupled to each other is integrally configured, and a predetermined dielectric coaxial resonator of the filter block on one surface. An electrode connected to the inner conductor of the filter block is formed, and a ground electrode connected to the ground of the filter block is formed on the other surface, and a capacitance is provided between the predetermined dielectric coaxial resonator of the filter block and the ground. Therefore, it is provided with a capacitance substrate attached to one end surface of the filter block (claim 3).

[0019]

According to the first aspect of the present invention, the dielectric filter is constructed by attaching the capacitance substrate to the end surface of the filter block where the electrodes are not formed. When the capacitance substrate is attached, the inner conductor of the predetermined dielectric coaxial resonator of the filter block is connected to the electrode forming the capacitance formed on the capacitance substrate, and the capacitance is provided between the predetermined dielectric coaxial resonators. A dielectric filter is constructed. This creates a pole in the filter characteristics.

According to the second aspect of the present invention, when the capacitance substrate is attached to the filter block, the ground electrode of the capacitance substrate and the outer conductor (ground electrode) of the filter block are connected, and the intermediate layer of the capacitance substrate is connected. The capacitance formed in the above is shielded by the ground electrode. This prevents high frequency leakage from the capacitive substrate.

According to the third aspect of the present invention, when the capacitance substrate is attached, the inner conductor of each dielectric coaxial resonator of the filter block is connected to the electrode forming the capacitance formed on the capacitance substrate. The outer conductor (ground electrode) of the filter block is connected to the ground electrode formed on the capacitance substrate, thereby forming a dielectric filter in which the capacitance is provided between the inner conductor of each of the dielectric coaxial resonators and the ground. Let

[0022]

EXAMPLES A dielectric filter according to the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a first embodiment of the dielectric filter according to the present invention. For convenience of explanation,
The bottom surface (mounting surface) is drawn up. Further, FIG. 2 is an equivalent circuit of the same dielectric filter.

The dielectric filter 1 is one of five terminal short circuits.
/ 4 wavelength dielectric coaxial resonators θ1 to θ5 (see FIG. 7) are coupled to each other in a five-stage filter, and a capacitor C3 is provided between the dielectric coaxial resonator θ2 and the dielectric coaxial resonator θ4. Thus, a pole on the filter characteristic is formed (see FIG. 2).

The dielectric filter 1 comprises a filter block 2 in which the dielectric coaxial resonators θ1 to θ5 and external coupling capacitors C1 and C2 for input and output are integrally formed, and the capacitor C3 for forming a pole. It is composed of the formed capacitive substrate 3.

The filter block 2 has a horizontally long rectangular cross-sectional shape and has five axially extending through holes 202 to 20.
Electrodes 4 of required copper, silver, platinum, gold or the like are formed on the outer peripheral surface of the dielectric 201 made of ceramics in the shape of a rectangular parallelepiped in which 6 are formed in parallel and the inner peripheral surfaces of the through holes 202 to 206 (in the figure,
It is shown by stippling. ) Is formed.

The dielectric coaxial resonators θ1 to θ are formed by forming the electrode 4 on the entire inner peripheral surface of the through holes 202 to 206.
5 inner conductors are configured. One end surface 201A of the dielectric body 201 is an open end surface of the dielectric coaxial resonators θ1 to θ5, and the through holes 203 and 2 of the open end surface 201A.
As shown in FIG. 3, in the vicinity of 05, the connecting portions 301, 302 formed on the back surface 3B of the capacitance substrate 3 described later.
(Refer to FIG. 5), connecting portions 203A,
205A is formed by the electrode 4. Connection part 2
03A and 205A are connected to the electrodes 4 formed on the inner peripheral surfaces of the through holes 203 and 205, respectively.

Both side surfaces 201B, 20 of the dielectric body 201
Strip-shaped terminal electrodes 207 and 208 are formed by the electrode 4 at positions 1C and the bottom surface (mounting surface) 201D near the open end surface 201A. The terminal electrode 20
Reference numerals 7 and 208 are formed so as to extend from the side surfaces 201B and 201C to the bottom surface 201D.

Both side surfaces 201B and 201C, bottom surface 2
01D and the upper surface 201E, the ground electrode 209 is formed so as to surround the terminal electrodes 207 and 208 by the electrode 4 described above.
To form a common outer conductor of the dielectric coaxial resonators θ1 to θ5.

Then, the dielectric coaxial resonators θ1 to θ5
The inner conductor and the outer conductor are short-circuited at their ends by an electrode 4 formed on the entire end face facing the open end face 201A.

In this embodiment, since the axial dimensions of all the dielectric coaxial resonators θ1 to θ5 are the same, the axial dimension of the filter block 2 is constant in the width direction. The axial dimensions of the body coaxial resonators θ1 to θ5 may be different from each other. Each dielectric coaxial resonator θ1
When the axial dimensions of .about..theta.5 are different, the filter block 2 has a shape in which the end surface is uneven in the width direction according to the axial dimensions of the dielectric coaxial resonators .theta.1 to .theta.5.

In the dielectric filter 1, after the electrodes 4 are formed on the entire surface of the dielectric 201, the unnecessary portions of the electrodes 4 are peeled off or the portions to be peeled off are masked in advance so that the electrodes 4 are formed only on the necessary portions. Formed and manufactured.

The electrode 4 is formed on the dielectric 201 by using a thick film manufacturing technique, a thin film manufacturing technique, a plating process, or the like. For example, in the thick film manufacturing technique, a conductive paste such as copper, silver and platinum is applied to the entire surface of the dielectric 201 and then heated at a predetermined high temperature to burn the conductive paste to form the electrode 4. It Then, after this, the open end surface 201A
And the electrode 4 in the insulating region around the terminal electrodes 207 and 208
Then, the dielectric filter 1 is manufactured.

FIG. 4 is a front view of the capacitance substrate 3, and FIG.
FIG. 4 is a rear view of the same capacity substrate 3. The capacitor substrate 3 is a horizontally long rectangular substrate made of a dielectric material such as glass epoxy resin or alumina having the same shape as the open end surface 201A of the dielectric material 201. As shown in FIG. 5, the capacitor substrate 3 has connection portions 301 and 302 formed by electrodes 4 at positions facing the connection portions 203A and 205A provided on the open end surface 201A of the dielectric 201 on the back surface 3B. There is.

On the other hand, the strip-shaped electrode 30 is formed substantially at the center of the surface 3A.
A capacitor C3 is formed by alternately arranging 3,304. One electrode 303 of the capacitor C3 is a through hole 303A.
The other electrode 304 of the capacitor C3 is connected to the connecting portion 302 via the through hole 304A.

Further, the strip electrodes 303, 30 constituting the capacitor C3 are formed on the entire surface 3A and the four side surfaces of the capacitor substrate 3.
A ground electrode 305 is formed so as to surround 4. The electrodes of the capacitance substrate 3 are also formed by the same method as in the above filter block.

Then, as shown in FIG. 1, in the capacitive substrate 3, the back surface 3B is opposed to the open end surface 201A of the dielectric 201, and the connecting portions 301 and 302 are connected to the connecting portions 203A and 205A of the dielectric 201, respectively. At the same time, the ground electrode 305 is connected to the ground electrode 209 of the dielectric 201 and attached to the filter block 2.

The connection between the connection portion 301 and the connection portion 203A and the connection between the connection portion 302 and the connection portion 205A are performed by soldering or a conductive adhesive. In addition, the connection between the ground electrode 305 and the ground electrode 209 is performed by the open end surface 201 of the dielectric 2.
A connecting portion 210 connected to the ground electrode 209 on the periphery of A
(Indicated by phantom lines in FIG. 3), a connecting portion 306 (indicated by phantom lines in FIG. 5) connected to the ground electrode 305 is formed on the periphery of the back surface 3B of the capacitor substrate 3, and the connecting portion 3 is formed.
06 and the connecting portion 209 are connected by soldering or a conductive adhesive.

With the above structure, the dielectric coaxial resonators θ1 to θ1
θ5 is magnetically coupled to each other by the magnetic field component of the electromagnetic field generated in the dielectric 201, and the dielectric coaxial resonators θ1 to θ1
A filter in which θ5 is coupled is integrally configured.

By mounting the capacitance substrate 3 on the filter block 2, the inner conductor of the dielectric coaxial resonator θ3 is connected to the connecting portion 203A and the connecting portion 30 as shown in FIG.
1 and the one electrode 303 of the capacitor C3 via the through hole 303A, and the inner conductor of the dielectric coaxial resonator θ5 is the connecting portion 205A, the connecting portion 302, and the through hole 304.
A capacitor C3 for forming a pole is provided between the dielectric coaxial resonator θ3 and the dielectric coaxial resonator θ5 by being connected to the other electrode 304 of the capacitor C3 via A.

FIG. 7 is a sectional view of the essential parts of a second embodiment of the dielectric filter according to the present invention. In the second embodiment, the capacitor substrate is formed of a multi-layer substrate to prevent high frequency leakage from the capacitor substrate.

In the dielectric filter 1'shown in FIG. 7, a capacitive substrate 3'made of a two-layer substrate is attached to the open end surface 201A of the filter block 2. Substrate intermediate layer 307
The capacitor C3 is formed on the upper surface, and the ground electrode 305 is formed on the entire surface 3A and the four side surfaces.

In the second embodiment, the capacitor C3 has the ground electrode 305.
Since it is completely surrounded by, there is an advantage that the leakage of high frequency from the capacitor substrate 3'is small and the filter characteristics are stable.

FIG. 8 is an exploded perspective view of a third embodiment of the dielectric filter according to the present invention. For convenience of explanation, the bottom surface (mounting surface) is drawn upward. In addition, FIG.
FIG. 4 is an equivalent circuit diagram of the same dielectric filter.

The dielectric filter 5 has one of three terminal short circuits.
This is a filter of a three-stage configuration in which quarter wavelength dielectric coaxial resonators θ1 to θ3 are coupled to each other (see FIG. 9). The dielectric filter 5 is configured such that the capacitors Cs1, Cs2, and Cs3 are formed in parallel with the dielectric coaxial resonators θ1 to θ3, respectively, and the axial dimension L is shortened.

The dielectric filter 5 includes a filter block 6 in which the dielectric coaxial resonators θ1 to θ3 and external coupling capacitors C1 and C2 for input and output are integrally formed, and the capacitor C described above.
The capacitor substrate 7 is formed with s1, Cs2 and Cs3.

The filter block 6 uses the same method as that of the filter block 2 to form each of the dielectric coaxial resonators θ1 to θ.
3 inner conductor and outer conductor 605 and terminal electrodes 606,
607 is formed. Further, connecting portions 602A, 603A, 604A are provided at the positions where the through holes 601, 602, 603 are formed on the open end surface 601A of the dielectric 601 respectively. The connection parts 602A, 603A, 604A are
A rectangular electrode 4 having a predetermined area is formed and provided.

The connecting portions 602A, 603A, 6
04A is connected to the ground electrode 704, which will be described later, and has the capacitance Cs.
1, Cs2 and Cs3 are configured, the shape thereof is not limited to the above-mentioned rectangular shape, and may be a circle, an ellipse or the like, and any other shape can be adopted.

The capacitive substrate 7 has the connection portion 60 on the back surface 7B.
2A, 603A, 604A, the connecting portion 70 of the same shape as the connecting portion 602A, 603A, 604A.
1, 702, 703 are provided, and the ground electrode 704 is formed on the entire surface 7A and the four side surfaces. The connection part 7
01, 702, and 703 are capacitively coupled to the ground electrode 704 through the substrate, respectively, and the capacitance Cs is caused by these capacitances.
1, Cs2, Cs3 are configured.

Incidentally, the filter block 6 and the capacitor substrate 3
The electrodes 4 are formed in the same manner as in the filter block 2 and the capacitor substrate 3 of the first embodiment.

As shown in FIG. 8, the capacitance substrate 7 has a back surface 7
B is opposed to the open end surface 601A of the dielectric 601 and the connection portions 701, 702, 703 are connected to the connection portions 602A, 603A, 604A of the dielectric 601 respectively, and the ground electrode 704 is connected to the ground electrode (outside of the dielectric 601). (Conductor) 605 and attached to the filter block 6.

The connection between the connecting portion 701 and the connecting portion 602A, between the connecting portion 702 and the connecting portion 603A, and between the connecting portion 703 and the connecting portion 604A is performed by soldering or a conductive adhesive. Further, the connection between the ground electrode 704 and the ground electrode 605 is similar to that of the first embodiment, and the open end surface 601 of the dielectric 6 is connected.
A connecting portion 607 connected to the ground electrode 605 on the periphery of A
(Indicated by an imaginary line in FIG. 11), a connection portion 705 (indicated by an imaginary line in FIG. 10) connected to the ground electrode 704 is formed along the periphery of the back surface 7B of the capacitor substrate 7, and the connection portion 705 is formed. And the connection portion 607 are connected by soldering or a conductive adhesive.

With the above structure, the capacitance substrate 7 is attached to the filter block 6, so that the inner conductors of the dielectric coaxial resonators θ1 to θ3 are coupled to the capacitance C as shown in FIG.
s1, Cs2, Cs3 one of the connection portions 701-7
03, and the ground electrode 704 is connected to the ground electrode 605, whereby the capacitors Cs1, Cs2, and Cs3 are connected between the inner conductors of the dielectric coaxial resonators θ1 to θ3 and the ground.

As described above, by the filter block formed by integrally molding a plurality of dielectric coaxial resonators and the capacitance substrate that constitutes the capacitance provided between the dielectric coaxial resonators or between the dielectric coaxial resonators and the ground. Since the dielectric filter is configured, the structure is simplified, and the dielectric filter can be made smaller, lighter and more compact. Moreover, since the number of parts is small, the number of assembling steps and the assembling time are reduced, which contributes to cost reduction.

Furthermore, since the terminal electrode is formed on the outer peripheral surface of the filter block so that the outer shape is a box shape without a protruding member and the entire outer peripheral surface is covered with the ground electrode,
The quality of the dielectric filter in terms of mechanical characteristics such as shape, structure, strength, etc. and electrical characteristics is stable, mounting on a printed circuit board is facilitated, and product reliability is improved.

Since a desired capacitance can be easily obtained by adjusting the thickness of the capacitance substrate, the shape of the electrodes formed on the capacitance substrate, the dielectric constant of the capacitance substrate, etc., the dielectric filter can be easily designed. It is also possible to eliminate the above-mentioned capacity adjustment.

In the above embodiments, the dielectric filter having a three-stage or five-stage structure has been described, but the present invention is not limited to this, and can be applied to a dielectric filter having an arbitrary number of stages. Further, in the above-described embodiment, the case where only the capacitor for polarizing is formed as the capacitor substrate and the case where only the capacitor for axial dimension adjustment is formed are described.
Both capacitors may be formed on the capacitor substrate.

For example, in FIG. 5, the capacitances Cs1 and Cs between the ground electrode 305 and the positions corresponding to the inner conductors of the first, third and fifth dielectric coaxial resonators θ1, θ3 and θ5.
3 and Cs5 to form the connecting portion, the first, third and fifth dielectric coaxial resonators θ1 and θ of the dielectric filter 1 are formed.
The capacitors Cs1, Cs3 and Cs5 may be connected in parallel to 3 and θ5, respectively.

[0058]

As described above, according to the present invention,
A filter block, in which a filter formed by coupling a plurality of dielectric coaxial resonators to each other is integrally configured, and at least one capacitor is configured by an electrode, and the capacitor is provided with a predetermined dielectric coaxial resonator of the filter block. Since the dielectric filter is constituted by the capacitance substrate attached to one end face of the dielectric so as to be provided between them, the structure of the dielectric filter having polar characteristics becomes simple.

Further, since the number of parts is small, it is easy to assemble, the number of assembling steps and the assembling time can be shortened, and the cost can be reduced. In particular, by appropriately adjusting the capacitance formed on the capacitance substrate to eliminate the adjustment of the characteristics of the dielectric filter, it is possible to significantly reduce the assembly time. Furthermore, since the shape of the dielectric filter becomes compact, mechanical,
The stability of electrical characteristics is improved, and mounting on a printed circuit board is facilitated.

Further, according to the present invention, since the capacitance substrate is formed of a multi-layer substrate and the circuit (capacitance) formed on the capacitance substrate is shielded by the ground electrode, high frequency leakage from the capacitance substrate is reduced. As a result, the filter characteristics are improved and stabilized.

Further, according to the present invention, a filter block integrally formed with a filter in which a plurality of dielectric coaxial resonators are coupled to each other, and a predetermined dielectric coaxial resonance of the filter block on one surface are provided. And a grounded electrode connected to the ground of the filter block on the other surface of the capacitor substrate, and a predetermined dielectric coaxial resonator of the filter block and ground. Since the dielectric substrate is configured by attaching the capacitance substrate to one end surface of the filter block to provide a capacitance therebetween, the structure of the dielectric filter in which the capacitance is connected in parallel to the dielectric coaxial resonator is simplified, It has the same effects as the above.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a first embodiment of a dielectric filter according to the present invention.

FIG. 2 is an equivalent circuit diagram of a first embodiment of a dielectric filter according to the present invention.

FIG. 3 is a front view of a filter block of the dielectric filter according to the first embodiment.

FIG. 4 is a front view of a capacitive substrate of the dielectric filter according to the first embodiment.

FIG. 5 is a rear view of the capacitive substrate of the dielectric filter according to the first embodiment.

FIG. 6 is a sectional view of a first embodiment of a dielectric filter according to the present invention.

FIG. 7 is a cross-sectional view of an essential part of a second embodiment of the dielectric filter according to the present invention.

FIG. 8 is an exploded perspective view of a third embodiment of the dielectric filter according to the present invention.

FIG. 9 is an equivalent circuit diagram of a third embodiment of the dielectric filter according to the present invention.

FIG. 10 is a front view of a filter block of a dielectric filter according to a third embodiment.

FIG. 11 is a front view of a capacitive substrate of a dielectric filter according to a third embodiment.

FIG. 12 is a sectional view of a third embodiment of the dielectric filter according to the present invention.

FIG. 13 is an exploded perspective view of a conventional dielectric filter.

FIG. 14 is a perspective view of another embodiment of the conventional dielectric filter.

FIG. 15 is a vertical cross-sectional view of another embodiment of the conventional dielectric filter.

[Explanation of symbols]

1,1 ', 5 Dielectric filter 2,6 Filter block 201,601 Dielectric 202-206,602-604 Through hole 203A, 205A, 210,602A-604A, 6
07 connection portion 207, 208, 606, 607 terminal electrode 209, 605 ground electrode 3, 7 capacitance substrate 301, 302, 306, 701, 702, 703, 7
05 connection part 303,304 strip electrode 303A, 304A through hole 305,704 ground electrode 4 electrode

Claims (3)

[Claims] 1. An outer conductor and an inner conductor of a plurality of dielectric coaxial resonators, wherein electrodes are formed on an outer peripheral surface of a columnar dielectric body having a plurality of axially extending holes except one end surface and an inner peripheral surface of the hole. And a filter block integrally formed with a filter in which the plurality of dielectric coaxial resonators are coupled to each other, and at least one capacitor is configured by an electrode. A dielectric substrate comprising: a capacitance substrate attached to one end face of the dielectric to be provided between predetermined dielectric coaxial resonators. 2. The dielectric filter according to claim 1, wherein the capacitance substrate is a multilayer substrate, the capacitance is formed in an intermediate layer, and an electrode for grounding is formed on the entire outer surface. A dielectric filter characterized by the above. 3. An outer conductor and an inner conductor of a plurality of dielectric coaxial resonators, wherein electrodes are formed on an outer peripheral surface of a columnar dielectric material having a plurality of axially extending holes except one end surface and an inner peripheral surface of the hole. And a filter block integrally formed with a filter in which the plurality of dielectric coaxial resonators are coupled to each other, and an inner conductor of a predetermined dielectric coaxial resonator of the filter block on one surface An electrode to be connected is formed, and a ground electrode connected to the ground of the filter block is formed on the other surface of the filter block so as to provide a capacitance between a predetermined dielectric coaxial resonator of the filter block and the ground. And a capacitance substrate attached to one end face of the dielectric filter.