JPH077305A - Dielectric filter and mounting method thereof - Google Patents

Abstract

(57) [Summary] [Object] To provide a dielectric filter that can easily form an attenuation pole near a pass band in frequency characteristics and can be downsized. A dielectric resonator 10a, 10b is formed by forming a through hole 4 in a dielectric block 2, forming an inner conductor 6 on the inner surface of the through hole, and forming an outer conductor 8 on the outer surface of the dielectric block 2.
In the dielectric filter, the outer conductors 8 of the dielectric resonators 10a and 10b are grounded via capacitors formed by conductor film patterns 14 and 18 formed on both surfaces of the substrate 12, respectively. The inter-stage coupling capacitance between the resonators 10a and 10b is obtained between the conductor film patterns 16a and 16b on the surface of the substrate 12, and the conductor film patterns 16a and 1b.
6c has an input coupling capacitance, and the conductor film patterns 16b and 16d have an output coupling capacitance.

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, there is provided a dielectric filter having a plurality of dielectric resonators arranged, wherein the dielectric resonators include a reactance element. A dielectric filter is provided, which is characterized in that it is grounded.

Further, according to the present invention, in mounting a dielectric filter having a plurality of dielectric resonators arranged, the dielectric resonator is grounded via a reactance element. A method for implementing a 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. As the dielectric resonator, a through hole is formed in a dielectric block, an inner conductor is formed on an inner surface of the through hole, and an outer conductor is formed on an outer surface of the dielectric block. Grounding can be performed through 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.

In FIG. 1, reference numeral 2 is a rectangular parallelepiped dielectric block, and the block 2 is, for example, BaTiO 3.
_Three types of ceramic materials can be used. A circular through hole 4 is formed in the block 2. The through hole 4
A conductor film is attached to the inner surface of the, and the inner conductor 6 is formed by the conductor film. Further, a conductor film is attached to the outer surface of the four side portions along the through hole 4 of the dielectric block 2, and the outer conductor 8 is formed by the conductor film. Also,
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 1
0a is 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.

In FIG. 1, reference numeral 12 is a dielectric substrate,
A conductor film pattern 14 and conductor film patterns 16a, 16b, 16c and 16d are formed on the surface of the substrate 12. A back view of the substrate 12 is shown in FIG. Board 1
A conductor film pattern 18 is formed on the back surface of 2 in correspondence with the conductor film pattern 14 on the front surface. The conductor film patterns 16c and 16d extend through the side surface of the substrate 12 to the back surface.

As shown in FIG. 1, the resonator 10a,
10b is mounted on the conductor film pattern 14, and the outer conductors 8 of these resonators are connected to the conductor film pattern 14. In addition, the inner conductor 6 of the resonators 10a and 10b is formed by the conductor wires 20a and 20b, respectively.
a, 16b. Thus, the conductor film patterns 16a and 16b form an inter-stage coupling capacitance, the conductor film patterns 16a and 16c form an input coupling capacitance, and the conductor film patterns 16b and 16d form an output coupling capacitance. There is. The conductor film pattern 16c is connected to the input circuit, and the conductor film pattern 16d is connected to the output circuit. On the other hand, the conductor film pattern 14 on the front surface of the substrate and the conductor film pattern 18 on the back surface of the substrate form a capacitance,
The conductor film pattern 18 is grounded.

FIG. 3 is an equivalent circuit diagram of the above dielectric filter. In FIG. 3, C ₁ is the input coupling capacitance, C ₂ is the interstage coupling capacitance, and C ₃ is the output coupling capacitance. C _C is the conductor film pattern 1
This is the capacitance of the ground path formed between No. 4 and No. 18.

FIG. 4 is an equivalent circuit diagram of a second embodiment of the dielectric filter according to the present invention. In this figure, members having the same functions as those in FIGS. 1 to 3 are designated by the same reference numerals. In this embodiment, an inductance L _C is used instead of the capacitance C _C of the ground path in the embodiments of FIGS.
Is used. Such an inductance is
It can be obtained by forming a conductor film coil pattern on the surface 2.

FIG. 5 is a perspective view showing a third embodiment of the dielectric filter according to the present invention, and FIG. 6 is a sectional view taken along line XX thereof. In these figures, members having the same functions as those in FIGS. 1 to 4 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 this figure, members having the same functions as those in FIGS. 1 to 4 are designated by the same reference numerals. Integrated resonators 10a, 10
Both sides of b are sandwiched by metal cases 24 with dielectric plates 22a and 22b interposed therebetween. Therefore, a capacitance is formed between the resonator outer conductor and the metal case 24. still,
The dielectric plates 22a and 22b may be those in which a conductor film is entirely formed on one side or both sides.

As shown in FIG. 6, the synthetic resin pin 2
6 is inserted into the through hole 4, and a conductive pin 28 is attached so as to penetrate the resin pin 26. The conductive pin 28 includes an insertion portion 28 a into the resin pin 26 and a terminal portion 28.
b and. Thus, an input / output coupling capacitance is formed between the conductive pin 28 and the inner conductor 6. In each of the resonators 10a and 10b, the inner conductor 6 on the inner surface of the through hole 4 extends to the outer surface of the dielectric block 2 to form an extending portion 7, and between the extending portions 7 Inter-stage coupling capacitance is formed.

In this embodiment, the conductive pin 28b of the resonator 10a is connected to the input circuit, and the conductive pin 28b of the resonator 10b is connected to the output circuit. On the other hand, the metal case 24
Is grounded.

FIG. 7 is a perspective view showing a fourth embodiment of the dielectric filter according to the present invention. In this figure, members having the same functions as those in FIGS. 1 to 6 are designated by the same reference numerals.

In this embodiment, the resonators 10a and 10b similar to those of the embodiment shown in FIG. 5 are used. However, the dielectric block 2 includes conductive film patterns 17a, 17a for input and output.
b is formed, and an input / output coupling capacitance is formed between these and the inner conductor extending portion 7. Reference numeral 32 denotes a wiring board, and a conductor film pattern 34 and conductor film patterns 36a and 36b are formed on the surface of the board 32.
A conductor film pattern 38 corresponding to the conductor film pattern 34 on the surface is formed on the back surface of the. The outer conductor 8 is connected to the conductor film pattern 34, and further the conductor film patterns 36a, 36
b in the input / output conductor film patterns 17a and 17b, respectively.
The resonators 10a and 10b are attached by connecting b. The conductor film patterns 36a and 36b are wirings for input and output, a capacitance is formed between the conductor film patterns 34 and 38, and the conductor film pattern 38 is grounded.

FIG. 8 is a perspective view showing a fifth embodiment of the dielectric filter according to the present invention. In this figure, members having the same functions as those in FIGS. 1 to 7 are designated by the same reference numerals.

In the present embodiment, the dielectric block 2 is used to provide interstage coupling and input / output coupling of the resonators 10a and 10b.
A coupling block 42 made of a dielectric material similar to the above is used. Then, the conductive rods 44a and 44b are inserted into the through holes of the respective resonators, and the tips of the rods are inserted into the through holes with the conductive film formed in the coupling block 42,
Conductor film patterns 36a, 36b for inputting and outputting the side surface portion of the coupling block 42 adjacent to the through hole with the conductor film.
Is connected to. That is, the inter-stage coupling capacitance is formed between the conductive rods 44a and 44b via the coupling block 42, and the input / output coupling capacitances are respectively generated between the conductive rods 44a and 44b and the conductor film patterns 36a and 36b. Has been formed.

FIG. 9 is a perspective view showing a sixth embodiment of the dielectric filter according to the present invention. In this figure, members having the same functions as those in FIGS. 1 to 8 are designated by the same reference numerals.

This embodiment is the same as the embodiment of FIG. 7 except for the structure of the ground path. In this embodiment, the wiring board 3
2, a conductor film coil pattern 35 that is connected to the conductor film pattern 34 is formed. The coil pattern is grounded. This embodiment corresponds to FIG. 4 described above.

10 to 12 are graphs showing examples of frequency characteristics of some of the above embodiments. FIG. 10 shows the embodiment of FIG. 1 described above, and attenuation poles are formed near both sides of the pass band. 11A shows the embodiment of FIG. 7 described above, and attenuation poles are formed near both sides of the pass band. 11B shows the case where the resonator outer conductor is directly grounded in the embodiment of FIG. 7 (reference example outside the present invention), and the attenuation pole is formed only near one side of the pass band. 12A shows the embodiment of FIG. 8 described above, in which attenuation poles are formed near both sides of the pass band. FIG. 12B shows the case where the resonator outer conductor is directly grounded in the embodiment of FIG. 8 (reference example outside the present invention), and no attenuation pole is formed near the pass band.

[0028]

As described above, according to the present invention, the attenuation pole can be easily formed near the pass band in the frequency characteristic with a simple structure in which the dielectric resonator is grounded via the reactance element. Moreover, the size can be reduced.

[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 back view of the substrate of the dielectric filter of FIG.

FIG. 3 is an equivalent circuit diagram of a dielectric filter according to the present invention.

FIG. 4 is an equivalent circuit diagram of a dielectric filter according to the present invention.

FIG. 5 is a perspective view showing a third embodiment of the dielectric filter according to the present invention.

6 is a sectional view taken along line XX of FIG.

FIG. 7 is a perspective view showing a fourth embodiment of the dielectric filter according to the present invention.

FIG. 8 is a perspective view showing a fifth embodiment of the dielectric filter according to the present invention.

FIG. 9 is a perspective view showing a sixth embodiment of the dielectric filter according to the present invention.

FIG. 10 is a graph showing frequency characteristics of the dielectric filter according to the present invention.

FIG. 11 is a graph showing frequency characteristics of the dielectric filter according to the present invention.

FIG. 12 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 Extension Part 8 Outer Conductor 10a, 10b Dielectric Resonator 12 Dielectric Substrate 14, 16a to 16d, 18 Conductive Film Pattern 20a, 20b Conductive Wire 22a, 22b Dielectric Plate 24 Metal Case 26 Resin pin 28 Conductive pin 32 Wiring board 34, 35, 36a, 36b, 38 Conductor film pattern 42 Dielectric block for coupling 44a, 44b Conductive rod

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shotaro Hayashi 5 1978, Kozugushi, Ube City, Yamaguchi Prefecture, Ube Kosan Co., Ltd.

Claims (4)

[Claims] 1. A dielectric filter in which a plurality of dielectric resonators are arranged, wherein the dielectric resonator is grounded via a reactance element. 2. The reactance, wherein the dielectric resonator has a through hole formed in a dielectric block, an inner conductor is formed on an inner surface of the through hole, and an outer conductor is formed on an outer surface of the dielectric block. The dielectric filter according to claim 1, wherein grounding through an element is performed by the outer conductor. 3. A method of mounting a dielectric filter, wherein, when mounting a dielectric filter having a plurality of dielectric resonators arranged, the dielectric resonator is grounded via a reactance element. 4. The dielectric resonator, wherein a through hole is formed in a dielectric block, an inner conductor is formed on an inner surface of the through hole, and an outer conductor is formed on an outer surface of the dielectric block, the reactance is used. The method of mounting a dielectric filter according to claim 3, wherein grounding through an element is performed by the outer conductor.