JPH11177307A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the increase in loss of a pass band and to shift an attenuation pole by setting the area, form and position of an area where conductors are not provided on the second sides of first and second dielectric resonators in such a way that first and second dielectric resonators can be inductively connected. SOLUTION: Patterns of conductors 5, 5b, 7a and 7b on the confronting second sides 13a and 13b in first and second dielectric resonators 1 and 2 are deformed compared to conventional ones. Comparatively large exposed areas, namely, non-conductor areas 17a are provided for the second sides 13a and 13b of the dielectric resonators 1 and 2. In the non-conductor areas 17a, mutual intervals of capacitively connected conductors 4a and 4b in the resonators and the outer conductors 5a and 5b are constituted of parts W1 and parts having intervals W2 wider than them. Areas of th non-conductor area 17a are set to about 1/4 of the whole areas of the second sides 13a and 13b. Thus, induction- connection is formed between the inner conductors 4a and 4b of the first and second dielectric resonators 1 and 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter for use in a mobile communication device such as a portable telephone.

[0002]

2. Description of the Related Art It is known to form a dielectric filter by juxtaposing a plurality of TEM mode coaxial dielectric resonators and capacitively coupling each other. A conventional dielectric filter of this type is configured by juxtaposing TEM mode coaxial first and second dielectric resonators 1 and 2 as shown in FIG. The first and second dielectric resonators 1 and 2 include dielectrics 3a and 3b, inner conductors 4a and 4b, outer conductors 5a and 5b connected to the ground, short-circuit conductors 6a and 6b, and a resonator. It comprises capacitive coupling conductors 7a, 7b, input / output capacitive coupling conductors 8a, 8b also having a terminal function, and through holes 9a, 9b.

Each of the two dielectrics 3a and 3b has a rectangular parallelepiped shape, that is, a prismatic shape, and includes first end faces 10a and 10b, second end faces 11a and 11b, and first side faces 12a and 12b.
A second side surface 13a, 13b, a third side surface 14a,
14b and fourth side surfaces 15a and 15b. First
The inner conductors 4a and 4b of the second dielectric resonators 1 and 2 are provided in the through holes 9a and 9b, respectively. Outer conductor 5
a, 5b are first to fourth side surfaces 12a, 12b, 13a,
It is provided in most of 13b, 14a, 14b, 15a, 15b. The short-circuit conductors 6a and 6b are connected to the second end face 11
a, 11b. Resonator capacitive coupling conductor 7
a, 7b are provided on the first side surfaces 12a, 12b and the second side surfaces 13a, 13b on the first end surfaces 10a, 10b side, and face the inner conductors 4a, 4b. The input / output capacitive coupling conductors 8a, 8b have third side surfaces 14a, 14b and fourth side surfaces 15a, 15a on the first end surfaces 10a, 10b side.
15b, facing the inner conductors 4a, 4b.
The outer conductors 5a, 5b have portions 16a, 16b protruding in the direction of the first end faces 10a, 10b on the second and third side faces 13a, 13b, 14a, 14b.

Each conductor 4a, 4b, 5a, 5b, 6a, 6
Each of b, 7a, 7b, 8a, and 8b is formed of a conductive film formed by selectively applying a known conductive paste (silver paste) to the dielectrics 3a and 3b. A conductive paste is applied to the entire exposed surfaces of the dielectrics 3a and 3b and baked, or a metal is plated on the entire surfaces of the dielectrics 3a and 3b to form a conductive film and selectively removed. Each conductor 4a,
4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8
b can also be obtained.

[0005] The first and second dielectric resonators 1 and 2 have a second dielectric resonator.
Side surfaces 13a, 13b of the outer conductor 5a,
5b and between the capacitive coupling conductors 7a and 7b are electrically and mechanically coupled by a conductive joining material (not shown) such as solder.

FIG. 2 shows an equivalent circuit of the dielectric filter based on FIG. The capacitors C1 and C4 in FIG. 2 indicate the capacitance between the input / output capacitive coupling conductors 8a and 8b and the inner conductors 4a and 4b, and the capacitors C2 and C3 are the resonator capacitive coupling conductors 7.
a, 7b and the capacitance between the inner conductors 4a, 4b.
, Ca, Lb, and Cb equivalently represent the resonance portions of the first and second dielectric resonators 1 and 2, respectively. Also, terminals T1, T2
Corresponds to the input / output capacitive coupling conductors 8a and 8b.

The dielectric filter based on FIG. 1 has a frequency characteristic as shown by a characteristic line A in FIG. This characteristic line A
Is a center frequency f0, and an attenuation pole is generated at a frequency f1 on the lower frequency side.

[0008]

By the way, there is a case where it is desired to move the position of the attenuation pole from the frequency f1 to f2 in FIG. In such a case, the dielectric filter is configured to narrow the pass band width of the filter as shown by the characteristic line B in FIG.
Shift the attenuation pole. However, if you narrow the pass bandwidth,
The loss (loss) in the pass band increases. In order to obtain a plurality of types of dielectric filters having different frequency characteristics, it is necessary to change the shapes and sizes of the dielectrics 3a and 3b, which inevitably increases the cost.

An object of the present invention is to provide a dielectric filter capable of shifting an attenuation pole while suppressing an increase in loss in a pass band. It is another object of the present invention to obtain a plurality of types of dielectric filters having different frequency characteristics without changing the structure of the dielectric.

[0010]

In order to solve the above-mentioned problems and to achieve the above-mentioned object, the present invention provides at least a first and a second dielectric resonators juxtaposed, wherein the first and the second dielectric resonators are arranged side by side. Each of the resonators has first and second end faces and the first
And a quadrangular prism-shaped dielectric having first, second, third, and fourth side surfaces between the second end faces, and provided so as to extend from the first end face of the dielectric to the second end face. An inner conductor arranged in the through hole provided, an outer conductor provided on at least a part of the first and third side faces facing each other, and a first end face side of the second side face. And a resonator capacitive coupling conductor provided in a region, wherein the outer conductor and the resonator capacitive coupling conductor of the first and second dielectric resonators are mutually connected. The first and second dielectric resonators are juxtaposed such that the second side face of the first dielectric resonator faces the second side face of the second dielectric resonator. The conductor on the second side face of the first and second dielectric resonators is not provided Area of range, the shape and position first
And a dielectric filter set so that the second dielectric resonator can be inductively coupled. In order to obtain good effect of inductive coupling (M-coupling or magnetic-field coupling), the area of the region on which the conductor on the second side is not provided is set to 1% of the total area of the second side. /
It is desirable to make it 4 to 1/3. Further, a short-circuit conductor can be provided as described in claim 3. In addition, an input or output capacitive coupling conductor can be provided.

[0011]

According to the present invention, the first and second dielectric resonators which are juxtaposed to each other have regions where no conductors are provided on the second side surfaces, so that the first and second dielectric resonators have the first and second dielectric resonators. The second dielectric resonators are coupled by magnetic coupling, that is, mutual inductive coupling (M-coupling), in addition to capacitive coupling (C-coupling) by the resonator capacitive-coupling conductor, causing a shift in the attenuation pole. This makes it possible to shift the attenuation pole while suppressing an increase in the attenuation in the pass band. Further, when manufacturing the dielectric filter according to the present invention, it is possible to use a dielectric having the same shape as the dielectric of the dielectric filter according to the present invention, which does not allow inductive coupling, so that the dielectric having the same structure has frequency characteristics. A plurality of different types of dielectric filters can be obtained, and the cost can be reduced.

[0012]

Embodiments and Examples Next, examples and embodiments of the present invention will be described with reference to the drawings. However, in FIGS. 4 to 12 showing the first embodiment, and FIGS. 14 to 19 showing the second embodiment and the modified examples, the substantially same parts as those in FIGS. The description is omitted here.

[0013]

First Embodiment FIGS. 4 and 5 for explaining a dielectric filter according to a first embodiment are shown in FIGS.
The outer conductors 5a and 5b of the second side surfaces 13a and 13b of the dielectric resonators 1 and 2 and the capacitive coupling conductors 7a and 7b are coupled by a conductive bonding material (not shown).
8 to 11 show side surfaces that cannot be seen in FIG.

In the dielectric filter of the first embodiment, the patterns of the conductors 5a, 5b, 7a, 7b on the second side surfaces 13a, 13b of the first and second dielectric resonators 1, 2 facing each other are different. Except for being modified, the configuration is the same as that of FIG. That is, as is clear from FIGS. 7 and 10, the second side surfaces 13a and 13b of the dielectric resonators 1 and 2 of the first embodiment.
Have relatively large exposed surfaces, that is, non-conductive regions 17a, 17
b is provided. The non-conductive regions 17a and 17b are composed of a portion where the mutual interval between the resonator capacitive coupling conductors 4a and 4b and the outer conductors 5a and 5b is W1 and a portion having a wider interval W2 than this. The areas of the non-conductive regions 17a and 17b are set to be about 1/4 of the total area of the first side surfaces 13a and 13b. As a result, the first and second
Inductive coupling (M coupling) occurs between the inner conductors 4a and 4b of the dielectric resonators 1 and 2 of FIG.

FIG. 12 shows an equivalent circuit of the dielectric filter shown in FIGS. A first dielectric resonator 1 indicated by Ca and La and a second dielectric resonator 2 indicated by Cb and Lb are capacitively coupled by capacitors C2 and C3, and indicated by M. Magnetic or inductive coupling.

FIG. 13 shows the characteristic line 31 of the dielectric filter of this embodiment shown in FIGS. 4 to 7 and the characteristic line 32 of the dielectric filter of the comparative example. A characteristic line 32 of the comparative example shown by a dotted line shows the characteristic of the conventional dielectric filter shown in FIG. 1, that is, the characteristic line A of FIG. 3, and has an attenuation pole at the frequency f1. The attenuation pole of the dielectric filter of this embodiment has a frequency f1
It occurs at f2 closer to the center frequency f0 than at f2. In the dielectric filter of this embodiment, the loss (attenuation) in the pass band including the center frequency f0 despite the shift of the attenuation pole.
Has hardly occurred. Therefore, according to the present embodiment,
The attenuation pole can be shifted while suppressing an increase in loss in the pass band. Also, the dielectric 3a shown in FIGS.
Since the shape of 3b is the same as the shape of the dielectrics 3a and 3b of FIG. 1, a large number of dielectrics 3a and 3b are prepared to provide two types of dielectric filters of characteristic lines 31 and 32 of FIG. And cost can be reduced.

[0017]

Second Embodiment A three-stage dielectric filter according to a second embodiment shown in FIGS. 14 and 15 is composed of first and second dielectric resonators 1 and 2 having the same configuration as that of the first embodiment. The third dielectric resonator 30 is arranged between them. Third dielectric resonator 3
0 has a dielectric 3c, an inner conductor 4c, an outer conductor 5c, a short-circuit conductor 6c, two resonator capacitive coupling conductors 7c and 7d, and a through hole 9c formed from one end face 10c to the other end face 11c. Further, it has a protruding portion 16c of the outer conductor 5c. The first and third dielectric resonators 1 and 30 are mutually coupled by outer conductors 5a and 5c and resonator capacitive coupling conductors 7a and 7c, and the second and third dielectric resonators 2 and 30 are outer conductors. 5b, 5c and the resonator capacitive coupling conductors 7b, 7d. These connections are made with a conductive bonding material. Note that the first dielectric resonator 30 has the first
The surfaces facing the second and first dielectric resonators 1 and 2 are formed in the same pattern as the facing surfaces of the first and second dielectric resonators 1 and 2, that is, the second side surfaces 13a and 13b. . Therefore, M coupling (magnetic field or inductive coupling) occurs between the first and third dielectric resonators 1 and 30, and between the second and third dielectric resonators 2 and 30. Therefore, the same operation and effect as in the first embodiment can be obtained in the second embodiment.

[0018]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) The pattern of the non-conductive region 17a on the second side surface 13a can be variously modified as shown in FIGS. 16, 17, 18, and 19. In the dielectric resonator 1 of FIG.
The width W1 extending from the open end of the dielectric resonator 1 to the short-circuit end in addition to the region of the width W1 for separating the resonator capacitive coupling conductor layer 7a from the outer conductor 5a by the non-conductive region 17a Has a band-shaped region. In the dielectric resonator 1 of FIG. 17, the non-conductive region 17a on the second side surface 13a
Has an area of width W1 for separating the resonator capacitive coupling conductor layer 7a from the outer conductor 5a, and an area of width W2 extending downward from above the second side surface 13a. . In the dielectric resonator 1 of FIG. 18, the non-conductive region 17a on the second side surface 13a has a width W1 for separating the resonator capacitive coupling conductor layer 7a from the outer conductor 5a, and also has a short-circuit end side. The second side surface 13a has a region extending downward from above. In the dielectric resonator 1 of FIG. 19, the non-conductive region 17a on the second side surface 13a has a width W1 for separating the resonator capacitive coupling conductor layer 7a from the outer conductor 5a. 1 has a width W extending from the top to the bottom of the second side surface 13a substantially at the center between the open end and the short-circuit end.
2 band-shaped regions. The conductor pattern on the second side surface 13b of the second dielectric resonator 2 is also shown in FIGS.
Is formed so as to correspond to. In addition, Examples and FIGS.
In the nineteenth modification, the ratio of the non-conductive regions 17a and 17b to the area of the second side surfaces 13a and 13b is set to 1/5 to
It is desirable to make it 4/5, preferably 1/4 to 1/3. 16 to 19, it is possible to obtain dielectric filters having different frequency characteristics without changing the shape of the dielectric 3a, and it is possible to easily reduce the cost and improve the characteristics of the dielectric filter. it can. (2) The input / output terminal members can be connected to the inner conductors 4a, 4b without the input / output capacitive coupling conductors 8a, 8b. (3) The short-wave conductors 6a and 6b can be omitted to provide a half-wave type.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a conventional dielectric filter.

FIG. 2 is an equivalent circuit diagram of the dielectric filter of FIG.

FIG. 3 is a frequency characteristic diagram of a conventional dielectric filter.

FIG. 4 is a front view showing the dielectric filter according to the first embodiment of the present invention.

FIG. 5 is a plan view of the dielectric filter of FIG.

FIG. 6 is a sectional view taken along line AA of FIG. 4;

FIG. 7 is an exploded perspective view of the dielectric filter of FIG.

8 is a left side view of the first dielectric resonator of FIG.

FIG. 9 is a bottom view of the first dielectric resonator of FIG. 4;

FIG. 10 is a left side view of the second dielectric resonator shown in FIG. 4;

11 is a bottom view of the second dielectric resonator shown in FIG.

FIG. 12 is an equivalent circuit diagram of the dielectric filter of FIG.

FIG. 13 is a plan view showing a dielectric filter according to a second embodiment.

FIG. 14 is a front view of the dielectric filter of FIG.

FIG. 15 is a side view of a dielectric resonator according to a modification.

FIG. 16 is a side view of a dielectric resonator according to another modification.

FIG. 17 is a side view of a dielectric resonator of still another modification.

FIG. 18 is a side view of a dielectric resonator of still another modification.

FIG. 19 is a side view of a dielectric resonator of still another modification.

[Explanation of symbols]

 1, 2 First and second dielectric resonators 7a, 7b Resonator capacitive coupling conductors 8a, 8b Input / output capacitive coupling conductors 17a, 17b Non-conductive region

Claims (4)

[Claims] At least first and second dielectric resonators are juxtaposed, wherein each of the first and second dielectric resonators has first and second end faces and the first and second dielectric resonators. A quadrangular prism-shaped dielectric having first, second, third, and fourth side surfaces between end faces, and a through hole provided from the first end face of the dielectric to the second end face An inner conductor arranged in the
An outer conductor provided on at least a part of the first and third side faces facing each other; and a resonator capacitive coupling conductor provided on a region of the second side face on the first end face side. A dielectric filter in which the outer conductor and the resonator capacitive coupling conductor of the first and second dielectric resonators are respectively connected to each other, wherein the second dielectric resonator has a second dielectric resonator. The first and second dielectric resonators are juxtaposed such that a side surface of the first dielectric resonator faces the second side surface of the second dielectric resonator. The area, shape, and position of the region on the second side where no conductor is provided are set so that the first and second dielectric resonators can be inductively coupled. Body filter. 2. The area of the first and second dielectric resonators on which the conductor on the second side face is not provided is 、 to ３ of the total area of the second side face. The dielectric filter according to claim 1, wherein 3. A short-circuit conductor for connecting the inner conductor and the outer conductor is provided on the second end face of each of the first and second dielectric resonators. The dielectric filter according to claim 1 or 2, wherein: 4. An input or output capacitive coupling conductor is provided in a region on the first end face side of the fourth side face of the first and second dielectric resonators, respectively. The dielectric filter according to claim 1, 2 or 3, wherein: