JPH08250903A - Dielectric filter - Google Patents

Abstract

PURPOSE: To make the dimensions of each resonator in a direction of their arrangement side by side small and to realize an excellent attenuation characteristic for frequencies outside the operating frequency band. CONSTITUTION: An inner conductor 9 is formed in an air gap 8 of a 1st column of a dielectric block 1 to form a band-pass filter section and an inner conductor 4 is formed in an air gap 2 of a 2nd column of the dielectric block 1 to form plural stages of resonators and the plural resonators and a resonator in the band-pass filter section are coupled at each stage. Since the plural resonators and the band-pass filter section are coupled at each stage acting like a band- block filter as a whole, a transmission line conductor required for a conventional filter is not needed. Furthermore, the gain at other frequency bands than the blocked frequency band except the operating frequency band is attenuated by the characteristic of the band-pass filter section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter which uses a blocked dielectric and acts as a band elimination filter.

[0002]

2. Description of the Related Art FIG. 17 shows the structure of a conventional dielectric filter in which a plurality of stages of resonators are provided in a dielectric block and used as a band elimination filter. In FIG. 17, a dielectric block 1 has a rectangular parallelepiped shape, three through holes 2 are formed inside, and an outer conductor 3 is formed at a predetermined position on the outer surface. An inner conductor 4 is formed on the inner surface of the through hole 2. In addition, the outer conductor 3 is not formed on a part of the surface of the dielectric block 1 on the right side in the drawing, but the outer conductor 3 is not formed, and the coupling conductor 5 extending from the inner conductor 4 and the coupling conductor 5 are capacitively coupled. Three coupling conductors 6 are formed, and a transmission line conductor 7 is provided between the coupling conductors 6.
Is formed. Outer conductors 3 are formed on the other five surfaces of the dielectric block 1 except the right front surface in the figure. FIG.
The equivalent circuit of the dielectric filter shown in FIG. 7 is as shown in FIG. Here, Z _T is a resonator formed in the dielectric block, and C _T is a trap capacitance formed between the coupling conductors 5-6 shown in FIG.

In this way, a band-stop type dielectric filter is constructed by coupling adjacent resonators with a phase difference of π / 2 (rad) using the transmission line conductor. The characteristics of the dielectric filters shown in FIGS. 17 and 18 are as shown in FIG. Here, fo is the used frequency, and this dielectric filter blocks the low frequency side of fo.

[0004]

In the conventional dielectric filter having band-stop characteristics shown in FIG. 17, an integrated dielectric filter is constructed by using a dielectric block having a relatively simple structure. However, the portion of the transmission line conductor 7 for coupling the adjacent resonators with a phase difference of π / 2 (rad) becomes very long (this transmission line has a dielectric half on one side and another half half on the other side). Since it is a stripline using air as air, its electrical length is longer than the resonator length of the dielectric resonator.) Therefore, there is a problem that the dimension of the resonators in the array direction becomes large. Further, as shown in FIG. 19, the out-of-band attenuation characteristic is also bad, and in particular, the attenuation of 2fo and 3fo could not be expected. Therefore, there is a possibility that a spurious circuit in the subsequent stage of this dielectric filter may adversely affect the used frequency fo.

An object of the present invention is to make it possible to easily reduce the size of the resonators in the array direction without using the above-mentioned transmission line conductor for coupling adjacent resonators with a predetermined phase difference. Another object of the present invention is to provide such a dielectric filter.

Another object of the present invention is to provide a dielectric filter having a good attenuation characteristic outside the used band (for example, 2fo, 3fo).

[0007]

A dielectric filter according to the present invention is characterized in that the adjacent resonators are coupled with a phase difference of π / 2 (rad) without using a conductor for a transmission line. In the dielectric filter having a dielectric block in which a plurality of voids are formed, the outer conductor is formed at a predetermined location on the outer surface of the dielectric block, and the inner conductor is formed in the void as described in 1. First and second two rows of voids are formed, and a plurality of stages of dielectrics are formed by the inner conductor formed in each of the first rows of voids and the dielectric of the dielectric block and the outer conductor formed on the outer surface of the dielectric block. Forming a resonator, coupling adjacent resonators to each other to form a band-pass filter unit including a plurality of stages of resonators, and forming an inner conductor and a dielectric block dielectric Formed on the outer surface of the body block With a resonator of multiple stages by the outer conductor, comprising by bonding the resonator and the said band pass filter unit in each stage.

In the dielectric filter of the present invention, the resonator length of each resonator is set to approximately λ / 4 and the resonators forming the band pass filter section are capacitively coupled. As described above, one opening of each void in the first row is a short-circuited end, the other opening is an open end, and a coupling conductor for capacitively coupling adjacent resonators is provided in the open-end opening. , The plurality of resonators are capacitively coupled to form the band-pass filter section, and one opening of each of the air gaps in the second row is an open end and the other opening is a short-circuit end.

Further, in the dielectric filter of the present invention, the resonator length of each resonator is set to approximately λ / 4 and the resonators constituting the band pass filter section are comb-line coupled to each other.
As described in claim 3, one opening of each of the gaps in the first row serves as a short-circuited end, and a tip capacitance is formed between the other opening and the outer conductor with an outer conductor to form a plurality of resonators. To form a bandpass filter unit by combline coupling the
One opening of each void in the row is an open end, and the other opening is a short-circuit end.

Further, in the dielectric filter of the present invention, the resonator length of each resonator is set to approximately λ / 2, and the resonators constituting the band pass filter section are comb-line coupled to each other.
As set forth in claim 4, one opening of each of the gaps in the first row is an open end, and a tip capacitance is formed between the opening and the other opening and an outer conductor to form a plurality of resonators. To form a bandpass filter unit by combline coupling the
Both openings of each void in the row are open ends or shorted ends.

[0011]

In the dielectric filter of the present invention, a plurality of dielectric resonators formed by the inner conductor formed in the first row of voids and the dielectric of the dielectric block and the outer conductor formed on the outer surface of the dielectric block. Acts as a band-pass filter unit composed of a plurality of stages of resonators in which adjacent resonators are coupled to each other. The inner conductor formed in each void of the second row on the one hand and the dielectric of the dielectric block and the outer conductor formed on the outer surface of the dielectric block act as a plurality of resonators,
Moreover, the resonator and the band pass filter section are coupled in each stage. In the multiple stages of resonators that constitute the bandpass filter unit, adjacent resonators are coupled to each other with a phase difference of π / 2 (rad). Between multiple resonators due to the air gap
They are combined with a phase difference of / 2 (rad) and act as a band elimination filter.

In the dielectric filter according to the second aspect, the first
The inner conductors formed in the row and the second row act as a resonator having a resonator length of λ / 4 because one opening is an open end and the other opening is a short-circuited end. A coupling conductor is provided at the open end of the inner conductor formed in the void, and the adjacent resonators are capacitively coupled to form a bandpass filter section.

In the dielectric filter according to claim 3, the first
The inner conductors formed in the row and the second row act as a resonator having a resonator length of λ / 4 because one opening is an open end and the other opening is a short-circuited end. Since the tip capacitance is formed between the outer conductor and one opening of one of the voids or near the opening, the resonators are combline-coupled,
This constitutes a bandpass filter section.

In the dielectric filter according to the fourth aspect, the first
One of the openings of each air gap in the row is an open end, and the tip capacitance is formed between the other opening and the outer conductor in the vicinity of the opening, resulting in a resonator of λ / 2 length and resonance. The units are combline-coupled, and a bandpass filter unit is configured by this. Since both openings of each air gap in the second row are open ends or short-circuited ends, they also become resonators of λ / 2 length, respectively, and this resonator and the band pass filter section are coupled at each stage. In the multiple-stage resonators forming the bandpass filter unit, the distance between adjacent resonators is π / 2 (r
Since they are coupled with a phase difference of (ad), a plurality of resonators due to the air gaps in the second row are coupled with a phase difference of π / 2 (rad) through the resonator of the band pass filter unit, resulting in band rejection. Will act as a type filter.

[0015]

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

FIG. 1 is a perspective view of the outer appearance of the dielectric filter, and FIG. 1B is a view as seen obliquely from above and rearward of FIG.
In FIG. 1, the dielectric block 1 has a rectangular parallelepiped shape and has a total of six through holes 2 and 8 penetrating therethrough in the same axial direction. An outer conductor 3 is formed on a predetermined portion of the outer surface of the dielectric block 1, and inner conductors 4 and 9 are formed on the inner surfaces of the through holes 2 and 8. An outer conductor 3 which is continuous from the inner conductor 4 is formed on the right front surface in FIG. 1A, and this portion is used as a short-circuit end. As shown in FIG. 1B, the surface of the inner conductor 4 facing the short-circuited end is an open end. In addition, an outer conductor 3 continuous from the inner conductor 9 is formed on the right front surface of FIG. 1B, and this portion serves as a short-circuit end. A coupling conductor 10 continuous from the inner conductor 9 is formed on the surface (the surface of FIG. 1A) facing the short-circuited end. These coupling conductors 10 form a capacitance between adjacent coupling conductors. Further, the coupling conductor 10 is provided on the upper surface in the figure.
To form a continuous input / output conductor 11. When mounting this dielectric filter on a circuit board, the upper surface in FIG. 1 is surface-mounted with the upper surface facing the circuit board. that time,
The outer conductor 3 on the upper surface in FIG. 1 is electrically connected to a ground electrode or the like on the circuit board, and the input / output conductor 11 is used.
Are electrically connected to the conductor pattern on the circuit board.

FIG. 2 is an equivalent circuit diagram of the dielectric filter shown in FIG. Here, Z _P is a resonator of the band pass filter portion formed by the inner conductor 9 formed in the through hole 8 shown in FIG. 1, the dielectric of the dielectric block 1 and the outer conductor 3,
C _P is an electrostatic capacitance formed by the coupling conductor 10. Z _T is a resonator constituted by the inner conductor 4 formed on the inner surface of the through hole 2 shown in FIG. 1, the dielectric of the dielectric block 1 and the outer conductor 3, and Z _K is the resonator Z _T. It is the mutual impedance with the dielectric resonator Z _P that constitutes the band-pass filter unit. In this way, the resonator Z _T
Are coupled via the mutual impedance Z _K and the resonator Z _P of the band pass filter section.

FIG. 3 is a characteristic diagram of the dielectric filter shown in FIG. (A) shows the characteristics of only the band pass filter section, and (B) shows the overall characteristics. The characteristics of the entire dielectric filter are the characteristics of the band-pass filter section and the characteristics of the band-stop filter. In this way, the used bandwidth f
Passes o, attenuates the low-frequency side, and 2f
Higher frequencies such as o and 3fo are also attenuated due to the characteristics of the bandpass filter unit.

Next, the structure of the dielectric filter according to the second embodiment of the present invention is shown in FIG. Unlike the example shown in FIG. 1, in this case, the coupling block hole 12 is formed between the three through holes 2. The outer conductor 3 is formed on the inner surface of the coupling block hole 12.
A continuous conductor is provided. Therefore, the three resonators formed by the through holes 2 are hardly coupled.
As a result, the attenuation pole of the band elimination filter and the resonance frequency have a one-to-one correspondence, which facilitates the characteristic adjustment.

Next, the structure of the dielectric filter according to the third embodiment of the present invention will be described with reference to FIG. The external perspective view of the dielectric filter according to the third embodiment is the same as that shown in FIG. FIG. 5 shows the three through holes 8 shown in FIG.
FIG. 9 is a cross-sectional view of the center portion of the section cut along a plane corresponding to a plane passing through the axial direction. In this way, the through hole 8 has a step structure in which the inner diameter is small on the short-circuited end side and large on the open end side. With this configuration, the resonator impedance on the open end side becomes smaller than the resonator impedance on the short circuit end side, and the overall resonator length is shortened, so that the axial dimension of the through hole can be shortened.

Next, FIG. 6 shows the structure of a dielectric filter according to the fourth embodiment. FIG. 6 is a front view seen from one opening surface of the through hole. The overall configuration is similar to the example shown in FIG. By thus making the cross-sectional shape of each through hole oval, the height dimension of the dielectric filter can be reduced.

Next, FIG. 7 shows the structure of the dielectric filter according to the fifth embodiment.

FIG. 7 is an external perspective view of the dielectric filter, and FIG. 7B is a view seen from diagonally above and rearward of FIG.
In FIG. 7, the dielectric block 1 has a rectangular parallelepiped shape and has a total of six through holes 2 and 8 penetrating therethrough in the same axial direction. An outer conductor 3 is formed on a predetermined portion of the outer surface of the dielectric block 1, and inner conductors 4 and 9 are formed on the inner surfaces of the through holes 2 and 8. 7A, a coupling conductor 5 continuous from the inner conductor 4 and a coupling conductor 10 continuous from the inner conductor 9 are formed on the right front surface. With this structure, capacitance is formed between the coupling conductor 5 and the coupling conductor 10 in each stage, and at the same time, capacitance is formed between the coupling conductors 10-10 adjacent to each other. Further, the input / output conductor 1 continuous from the coupling conductor 10 is provided on the upper surface in the figure.
1 is formed. Further, an outer conductor 3 continuous from the inner conductors 4 and 9 is formed on the right front surface of FIG. 7B, and this portion is used as a short-circuit end.

FIG. 8 is an equivalent circuit diagram of the dielectric filter shown in FIG. Here, Z _P is a resonator constituted by the inner conductor 9 formed in the through hole 8 shown in FIG. 7, the dielectric of the dielectric block 1 and the outer conductor 3, and C _P is the coupling conductor 1
0 is an electrostatic capacitance, C _T is a coupling conductor 5-1
It is the capacitance configured between zero. Z _T is a resonator constituted by the inner conductor 4 formed on the inner surface of the through hole 2 shown in FIG. 1, the dielectric of the dielectric block 1 and the outer conductor 3. Thus, the three resonators Z _T have three resonators Z _T
Through a bandpass filter unit consisting of _{P π} / 2 (ra
A dielectric filter that acts as a band stop filter by combining with the phase difference of d) is obtained. The characteristics of this filter are shown in Fig. 3.
It is almost the same as that shown in FIG.

Next, FIG. 9 shows the structure of a dielectric filter according to the sixth embodiment of the present invention.

FIG. 9 is an external perspective view of the dielectric filter, and FIG. 9B is a view seen from diagonally above and rearward of FIG.
In FIG. 9, the dielectric block 1 has a rectangular parallelepiped shape, and has a total of six through holes 2 and 8 penetrating therethrough in the same axial direction. An outer conductor 3 is formed on a predetermined portion of the outer surface of the dielectric block 1, and inner conductors 4 and 9 are formed on the inner surfaces of the through holes 2 and 8. An outer conductor 3 continuous from the inner conductor 4 is formed on the right front surface in FIG. 9A, and this portion is used as a short-circuit end. As shown in FIG. 9B, the surface of the inner conductor 4 facing the short-circuited end is an open end. Further, a coupling conductor 10 continuous from the inner conductor 9 is formed on the surface on the right front side of FIG. 9 (A). An outer conductor 3 continuous from the inner conductor 9 is formed on the surface facing this surface, and this portion is used as a short-circuit end. Further, the coupling conductor 10 is provided on the upper surface in the figure.
To form a continuous input / output conductor 11. With this structure, a tip capacitance is generated between the coupling conductor 10 continuous from the inner conductor 9 in the through hole 8 and the outer conductor 3, and the three resonators are comb-line coupled by the tip capacitance.

FIG. 10 is an equivalent circuit diagram of the dielectric filter shown in FIG. Here, Z _P is a resonator constituted by the inner conductor 9 formed in the through hole 8 shown in FIG. 9, the dielectric of the dielectric block 1 and the outer conductor 3. Z _T is shown in FIG.
Is a resonator constituted by the inner conductor 4 formed on the inner surface of the through hole 2 shown in FIG. 2, the dielectric of the dielectric block 1 and the outer conductor 3, and Z _K is a dielectric resonator constituting a bandpass filter section. It is the mutual impedance between Z _P and the dielectric resonator Z _T. In this way, the resonator Z _T is coupled via the mutual impedance Z _K and the resonator Z _P of the bandpass filter section. In this way, the three resonators Z _T pass through the band-pass filter unit composed of the three resonators Z _P to π / 2.
A dielectric filter that functions as a band elimination filter is obtained by coupling with a phase difference of (rad).

Next, FIG. 11 shows the structure of the dielectric filter according to the seventh embodiment.

FIG. 11 is an external perspective view of the dielectric filter, and FIG. 11B is a view as seen obliquely from above and rearward of FIG.
In FIG. 11, the dielectric block 1 has a rectangular parallelepiped shape,
A total of six through holes 2 and 8 are formed in the inside so as to penetrate in the same axial direction. An outer conductor 3 is formed on a predetermined portion of the outer surface of the dielectric block 1, and inner conductors 4 and 9 are formed on the inner surfaces of the through holes 2 and 8. 11A, a coupling conductor 5 continuous from the inner conductor 4 and a coupling conductor 10 continuous from the inner conductor 9 are formed on the right front surface. With this structure, a capacitance is formed between the coupling conductor 5 and the coupling conductor 10 in each stage. Further, an input / output conductor 11 continuous from the coupling conductor 10 is formed on the upper surface in the drawing. Further, an outer conductor 3 continuous from the inner conductors 4 and 9 is formed on the right front surface of FIG. 11B, and this portion is used as a short-circuit end.

FIG. 12 is an equivalent circuit diagram of the dielectric filter shown in FIG. Here, Z _P is a resonator constituted by the inner conductor 9 formed in the through hole 8 shown in FIG. 11, the dielectric of the dielectric block 1 and the outer conductor 3, and C _T is between the coupling conductors 5-10. Is the capacitance configured in. See also Z _T
Is a resonator constituted by the inner conductor 4 formed on the inner surface of the through hole 2 shown in FIG. 11, the dielectric of the dielectric block 1 and the outer conductor 3. Thus, the three resonators Z _T are 3
Π / through a bandpass filter consisting of two resonators Z _P
A dielectric filter that functions as a band elimination filter is obtained by coupling with a phase difference of 2 (rad).

FIG. 13 shows the structure of the dielectric filter according to the eighth embodiment.

FIG. 13 is an external perspective view of the dielectric filter, and FIG. 13B is a view seen from diagonally above and rearward of FIG.
In FIG. 13, the dielectric block 1 has a rectangular parallelepiped shape,
A total of six through holes 2 and 8 are formed in the inside so as to penetrate in the same axial direction. An outer conductor 3 is formed on a predetermined portion of the outer surface of the dielectric block 1, and inner conductors 4 and 9 are formed on the inner surfaces of the through holes 2 and 8. As shown in FIGS. 13A and 13B, both ends of the inner conductor 4 are short-circuited ends. Further, a coupling conductor 10 continuous from the inner conductor 9 is formed on the right front surface of FIG. 13A, and the surface facing this surface is an open end. Further, the coupling conductor 1 is provided on the upper surface in the figure.
An input / output conductor 11 continuous from 0 is formed. With this structure, a tip capacitance is generated between the coupling conductor 10 and the outer conductor 3, and the three resonators are comb-line coupled by the tip capacitance.

FIG. 14 is an equivalent circuit diagram of the dielectric filter shown in FIG. Here, Z _P is a resonator having a resonator length λ / 2 constituted by the inner conductor 9 formed in the through hole 8 shown in FIG. 13, the dielectric of the dielectric block 1 and the outer conductor 3, and Z _T is It is a resonator having an electric length λ / 2 configured by the inner conductor 4 formed on the inner surface of the through hole 2 shown in FIG. 13, the dielectric of the dielectric block 1 and the outer conductor 3. In this way, the three resonators Z _T are coupled with a phase difference of π / 2 (rad) via the band pass filter composed of the three resonators Z _P to obtain a dielectric filter that functions as a band elimination filter.

FIG. 15 shows the structure of the dielectric filter according to the ninth embodiment.

FIG. 15 is an external perspective view of the dielectric filter, and FIG. 15B is a view as seen obliquely from above and rearward of FIG.
In FIG. 15, the dielectric block 1 has a rectangular parallelepiped shape,
A total of six through holes 2 and 8 are formed in the inside so as to penetrate in the same axial direction. An outer conductor 3 is formed on a predetermined portion of the outer surface of the dielectric block 1, and inner conductors 4 and 9 are formed on the inner surfaces of the through holes 2 and 8. As shown in FIGS. 15A and 15B, both ends of the inner conductors 4 and 9 are open ends.
In addition, a coupling conductor 10 continuous from the inner conductor 9 is formed on the right front surface of FIG. Further, on the upper surface in the figure, an input / output conductor 11 continuous from the coupling conductor 10 is provided.
Is formed. With this structure, a tip capacitance is generated between the coupling conductor 10 and the outer conductor 3, and this tip capacitance causes 3
Two resonators are comb-line coupled.

FIG. 16 is an equivalent circuit diagram of the dielectric filter shown in FIG. Here, Z _P is a resonator having a resonator length λ / 2 constituted by the inner conductor 9 formed in the through hole 8 shown in FIG. 15, the dielectric of the dielectric block 1 and the outer conductor 3, and Z _T is It is a resonator having an electric length λ / 2, which is composed of an inner conductor 4 formed on the inner surface of the through hole 2 shown in FIG. 15, a dielectric of the dielectric block 1 and an outer conductor 3. In this way, the three resonators Z _T are coupled with a phase difference of π / 2 (rad) via the band pass filter composed of the three resonators Z _P to obtain a dielectric filter that functions as a band elimination filter.

In each of the embodiments, an example was shown in which a single dielectric block was provided with a void consisting of a through hole, but by laminating a plurality of grooved dielectric plates, a plurality of dielectric plates can be formed inside. You may comprise the dielectric block provided with a space | gap.

[0038]

According to the dielectric filter of the present invention, a plurality of resonators are configured together with a bandpass filter section composed of a plurality of stages of resonators in which adjacent resonators are coupled to each other, and these resonators and bandpass filters are formed. Since the filter section is coupled at each stage to act as a band-stop filter as a whole, the conventional transmission line conductor for coupling the adjacent resonators with a predetermined phase difference is unnecessary, The size of the resonators in the array direction is reduced. Further, the band other than the stop band except the used band is also attenuated by the characteristics of the band pass filter unit, so that the adverse effect due to the spurious of the circuit in the subsequent stage of this dielectric filter can be sufficiently suppressed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a dielectric filter according to a first embodiment.

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

FIG. 3 is a characteristic diagram of the dielectric filter according to the first embodiment.

FIG. 4 is a diagram showing a configuration of a dielectric filter according to a second embodiment.

FIG. 5 is a diagram showing a configuration of a dielectric filter according to a third embodiment.

FIG. 6 is a diagram showing a configuration of a dielectric filter according to a fourth embodiment.

FIG. 7 is a diagram showing a configuration of a dielectric filter according to a fifth example.

FIG. 8 is an equivalent circuit diagram of a dielectric filter according to a fifth embodiment.

FIG. 9 is a diagram showing a configuration of a dielectric filter according to a sixth embodiment.

FIG. 10 is an equivalent circuit diagram of a dielectric filter according to a sixth embodiment.

FIG. 11 is a diagram showing a configuration of a dielectric filter according to a seventh embodiment.

FIG. 12 is an equivalent circuit diagram of a dielectric filter according to a seventh embodiment.

FIG. 13 is a diagram showing a configuration of a dielectric filter according to an eighth embodiment.

FIG. 14 is an equivalent circuit diagram of a dielectric filter according to an eighth example.

FIG. 15 is a diagram showing a configuration of a dielectric filter according to a ninth embodiment.

FIG. 16 is an equivalent circuit diagram of a dielectric filter according to a ninth embodiment.

FIG. 17 is a diagram showing a configuration of a conventional dielectric filter.

18 is an equivalent circuit diagram of the dielectric filter shown in FIG.

19 is a characteristic diagram of the dielectric filter shown in FIG.

[Explanation of symbols]

 1-dielectric block 2-through hole (void) 3-outer conductor 4-inner conductor 5-coupling conductor 6-coupling conductor 7-transmission line conductor 8-through hole (void) 9-inner conductor 10-coupling Conductor 11-input / output conductor 12-coupling prevention hole

Claims (4)

[Claims] 1. A dielectric filter comprising a dielectric block having a plurality of voids formed therein, an outer conductor formed at a predetermined location on the outer surface of the dielectric block, and an inner conductor formed in the void. First and second two rows of voids are formed, and a plurality of stages of dielectrics are formed by the inner conductor formed in each of the first rows of voids and the dielectric of the dielectric block and the outer conductor formed on the outer surface of the dielectric block. Forming a resonator, coupling adjacent resonators to each other to form a band-pass filter unit including a plurality of stages of resonators, and forming an inner conductor and a dielectric block dielectric A dielectric filter in which a plurality of stages of resonators are constituted by an outer conductor formed on the outer surface of the body block, and the resonators and the bandpass filter section are coupled in respective stages. 2. A coupling conductor for capacitively coupling between adjacent resonators, wherein one opening of each of the gaps in the first row is a short-circuited end and the other opening is an open end. 2. The band-pass filter section is formed by capacitively coupling a plurality of stages of resonators provided in a section, one opening of each of the voids in the second row is an open end, and the other opening is a short-circuited end. The dielectric filter described. 3. A plurality of resonators are comblined by forming one end of each of the voids in the first row as a short-circuit end and forming a tip capacitance with the outer conductor at or near the other opening. 2. The dielectric filter according to claim 1, wherein the band pass filter portion is formed by combining the two portions, one opening portion of each of the voids in the second row is an open end, and the other opening portion is a short circuit end. 4. One or more openings of each gap in the first row are made open ends, and a tip capacitance is formed between the other openings or near the openings with an outer conductor to form a plurality of resonators in a combline. The dielectric filter according to claim 1, wherein the band-pass filter portion is configured by being coupled to each other, and both opening portions of each void in the second row are open ends or short-circuited ends.