JPH077306A - Dielectric filter and mounting method for the same - Google Patents

Abstract

PURPOSE:To provide the dielectric filter which can easily form an attenuation pole near a passing band concerning the frequency characteristics and can be miniaturized as well. CONSTITUTION:Dielectric resonantors 10a and 10b constituted by forming through holes 4 at dielectric blocks 2, forming inner conductors 6 on the internal faces of these through holes and forming outer conductors 8 on the external faces of these dielectric blocks 2 are arranged. A conductive shield member 30 is arranged while connecting one part to the outer conductors of the dielectric resonantors 10a and 10b so as to cover a block 12 for coupling, and the head part of this shield member 30 is grounded through a capacitor formed by a conductor film pattern 26 and a conductor film 28 formed on both the sides of a wiring board 20. An element 24a is an input wire, an element 24b is an output wire, and an element 29 is a through hole.

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 combining a plurality of coaxial dielectric resonators, and more particularly to a high frequency dielectric filter which can easily obtain excellent frequency characteristics with a simple structure. .

[0002]

PRIOR ART AND PROBLEM TO BE SOLVED BY THE INVENTION λ / 4
In a high frequency dielectric filter configured by using a plurality of coaxial dielectric resonators or λ / 2 coaxial dielectric resonators, conventionally, interstage coupling and input / output are performed by an appropriate means through an inner conductor of each resonator. By coupling, the outer conductor of each resonator was grounded via a metal case or the like.

In recent years, as the communication technology using the dielectric filter as described above has advanced, further improvement of the frequency characteristic of the filter has been required. To improve the characteristics, an attenuation pole is formed as close to the pass band as possible. As such an example, for example, JP-A-61-117
A resonator for forming an attenuation pole is attached as described in Japanese Patent No. 2402, or a feedback circuit is attached to a coupling portion.

However, since the dielectric filter described in the above publication uses an extra resonator, the size becomes large and the demand for miniaturization cannot be satisfied, and in the case where the feedback circuit is attached to the coupling section, the coupling section is attached. The structure is complicated, and the size must be increased to some extent in order to avoid the mutual interference of elements, so that the demand for miniaturization cannot be satisfied.

Therefore, an object of the present invention is to provide a dielectric filter which can easily form an attenuation pole near the pass band in frequency characteristics and can be miniaturized.

[0006]

According to the present invention, in order to achieve the above object, a through hole is formed in a dielectric block, an inner conductor is formed on the inner surface of the through hole, and an outer conductor is formed on the outer surface of the dielectric block. What is claimed is: 1. A dielectric filter comprising a plurality of dielectric resonators formed by forming conductors, the conductive shield being in partial contact with an outer conductor of the dielectric resonator and covering at least part of coupling means. A dielectric filter is provided, in which members are arranged, and the other part of the shield member is grounded via a reactance element.

Further, according to the present invention, a plurality of dielectric resonators each having a through hole formed in the dielectric block, an inner conductor formed on the inner surface of the through hole, and an outer conductor formed on the outer surface of the dielectric block are provided. When mounting an array of dielectric filters,
A conductive shield member is arranged so as to partially contact the outer conductor of the dielectric resonator and cover at least a part of the coupling means, and the other part of the shield member is grounded via a reactance element. A method for mounting a dielectric filter is provided.

In the present invention as described above, a capacitor, a coil, or a combination thereof can be used as the reactance element.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view showing a first embodiment of a dielectric filter according to the present invention, and FIG. 2 is a sectional view thereof.

In the figure, 2 is a rectangular parallelepiped dielectric block, and the block 2 is, for example, BaTiO ₃
Ceramic materials of the system can be used. A circular through hole 4 is formed in the block 2. A conductor film is attached to the inner surface of the through hole 4, and the inner conductor 6 is formed by the conductor film. Further, conductor films are attached to the outer surfaces of the four side portions along the through holes 4 of the dielectric block 2,
The outer conductor 8 is formed of the conductor film. Further, a conductor film is also attached to one outer surface of the block 2 where the through hole 4 is opened, whereby the inner conductor 6 and the outer conductor 8 are short-circuited. Thus, the λ / 4 coaxial dielectric resonator 10a
Are formed.

In this embodiment, a dielectric resonator 10b equivalent to the above dielectric resonator 10a is arranged in parallel with the dielectric resonator 10a to form a two-stage dielectric filter. Reference numeral 10a is a resonator at the input end, and 10b is a resonator at the output end.

Reference numeral 12 is a coupling block made of a dielectric material similar to the dielectric block 2. This block 12
The resonators 10a and 10b are arranged so as to face the open surface of the dielectric block (that is, the surface of the outer surface on which the through hole 4 is opened, on which the conductor film is not formed). And
Two through holes are formed corresponding to the through holes of the resonators 10a and 10b, and a conductor film is attached to the inner surface of the through holes, whereby the coupling electrodes 14a and 14b (shown in the figure). Is not formed). A conductor film is attached to two of the four corner end faces of the coupling block 12, whereby the input electrodes 16a and 16b are formed corresponding to the coupling electrodes 14a and 14b, respectively. 1
Reference numeral 8 denotes a conductive rod, which extends across the through hole 4 of the block 2 of the resonator 10a and the through hole of one of the coupling blocks 12, whereby the conductor 6 in the resonator and the coupling electrode 14a. And are connected. A similar conductive rod extends in the through hole of the block of the resonator 10b and in the other through hole of the coupling block 12, whereby the conductor in the resonator and the coupling electrode 14 are provided.
b is connected. Thus, the connecting block 18
Through, an inter-stage coupling capacitance is formed between the two conductive rods 18, and an input coupling capacitance is formed between one conductive rod and the input electrode 16a, and the other conductive rod and the output electrode 16b are formed. An output coupling capacitance is formed between them.

In the figure, reference numeral 20 is a wiring substrate, and a conductor film pattern 22, conductor film patterns 24a (input wiring), 24b (output wiring) and a conductor film pattern 26 are formed on the surface of the substrate 20. A conductor film 28 is formed on the back surface of the substrate 20. Incidentally, 29 is a through hole, and a conductor film is also formed on the inner surface of the through hole.
The through hole 29 connects the conductor film pattern 22 and the conductor film 28. The conductor film 28 is grounded.

In the resonators 10a and 10b and the coupling block 12, the resonator outer conductor 8 is connected to the conductor film pattern 22, and the coupling block input electrode 16a is input wiring 24a.
Is mounted on the wiring board 20 so that the output electrode 16b is connected to the output wiring 24b.

In the figure, 30 is a conductive shield member. A part of the shield member 30 is connected to the in-resonator conductor 8 and the other part (tip part) is connected to the conductor film pattern 26, and the part between them covers the coupling block 12. Are arranged. This allows
A capacitance is formed between the conductor film pattern 26 and the conductor film 28 and the coupling portion is shielded. Therefore, by appropriately setting the size of the capacitance of this ground path and the size and shape of the shield member 30, the filter It is possible to improve the characteristics by forming an attenuation pole in the vicinity of the pass band in the frequency characteristics of.

FIG. 3 is a partially cutaway perspective view showing a second embodiment of the dielectric filter according to the present invention, and FIG. 4 is a sectional view thereof. In these figures, members having the same functions as those in FIGS. 1 and 2 are designated by the same reference numerals.

In this embodiment, the outer conductor 8 is formed in common in one dielectric block and two dielectric resonators are integrally formed. In addition, each resonator 10
In a and 10b, the inner conductor 6 on the inner surface of the through hole 4 extends to the open surface of the dielectric block 2 to form the extension portion 7, and the conductor film pattern 9a corresponding to each extension portion 7 is formed.
(Input electrode), 9b (output electrode: not shown in the figure)
Is formed, an interstage coupling capacitance is formed between these two extending portions 7, and an input coupling capacitance is formed between the inner conductor extending portion 7 of the input end resonator 10a and the input electrode 9a. Similarly, an output coupling capacitance is formed between the inner conductor extending portion of the output end resonator 10b and the output electrode 9b. The input electrode 9a is connected to the input wiring 24a, and the output electrode 9b is connected to the output wiring 24b.

Also in this embodiment, the same effect as that of the first embodiment can be obtained. As shown, in this embodiment, the shape of the shield member 30 and the size of the conductor film pattern 26 are different from those in the first embodiment.

5 and 6 are perspective views showing modification examples of the shape of the shield member 30. As shown in FIG. Shield member 30 of FIG.
Is a flap portion 31a so that the resonator is sandwiched from both sides.
Is different from that of the second embodiment in that the tip portion 31b for connecting with the conductor film pattern is bent outward. The shield member 30 of FIG. 6 is different from that of FIG. 5 in that the tip portion for connection with the conductor film pattern is divided into two.

In the above embodiments, the tip of the shield member is grounded via the capacitance, but an inductance may be interposed instead of the capacitance. Such inductance can be obtained by forming a conductor film coil pattern on the wiring board 20.

FIG. 7A is a graph showing the frequency characteristic of the filter of the first embodiment, in which attenuation poles are formed near both sides of the pass band. FIG. 7B shows a case where the tip of the shield member is directly grounded in the first embodiment (reference example outside the present invention), and no attenuation pole is formed near the pass band. 8A is a graph showing the frequency characteristic of the filter of the second embodiment, in which attenuation poles are formed near both sides of the pass band. Figure 8
B of the case where the tip of the shield member is directly grounded in the second embodiment (reference example outside the present invention),
An attenuation pole is formed only near one side of the pass band.

[0023]

As described above, according to the present invention, the conductive shield member is arranged so as to partially contact the outer conductor of the dielectric resonator and cover at least part of the coupling means, and the shield is provided. With a simple configuration in which the other part of the member is grounded via a reactance element, an attenuation pole can be easily formed near the pass band in frequency characteristics, and size reduction is possible.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a first embodiment of a dielectric filter according to the present invention.

FIG. 2 is a cross-sectional view of FIG.

FIG. 3 is a partially cutaway perspective view showing a second embodiment of the dielectric filter according to the present invention.

4 is a cross-sectional view of FIG.

FIG. 5 is a perspective view showing a modification of the shape of the shield member.

FIG. 6 is a perspective view showing a modified example of the shape of the shield member.

FIG. 7 is a graph showing frequency characteristics of the dielectric filter according to the present invention.

FIG. 8 is a graph showing frequency characteristics of the dielectric filter according to the present invention.

[Explanation of symbols]

 2 Dielectric Block 4 Through Hole 6 Inner Conductor 7 Extending Part 8 Outer Conductor 9a Input Electrodes 10a, 10b Dielectric Resonator 12 Coupling Dielectric Block 14a Coupling Electrode 16a Input Electrode 16b Output Electrode 18 Conductive Rod 20 Wiring Board 22 conductor film pattern 24a input wiring 24b output wiring 26 conductor film pattern 28 conductor film 29 through hole 30 conductive shield member

Claims (2)

[Claims] 1. A dielectric body in which a plurality of dielectric resonators, each having a through hole formed in a dielectric block, an inner conductor formed on an inner surface of the through hole, and an outer conductor formed on an outer surface of the dielectric block, are arranged. In the filter, a conductive shield member is arranged so as to partially contact the outer conductor of the dielectric resonator and cover at least a part of the coupling means, and the other part of the shield member has a reactance element interposed therebetween. The dielectric filter is characterized in that it is grounded. 2. A dielectric body comprising a plurality of dielectric resonators, each having a through hole formed in the dielectric block, an inner conductor formed on the inner surface of the through hole, and an outer conductor formed on the outer surface of the dielectric block. When mounting the filter, a conductive shield member is arranged so as to contact a part of the outer conductor of the dielectric resonator and cover at least a part of the coupling means, and the other part of the shield member is connected via a reactance element. A method for mounting a dielectric filter, which is characterized by grounding.