JPH06334406A - Dielectric filter - Google Patents

Abstract

PURPOSE:To obtain the dielectric filter with an excellent separation characteristic at a low frequency region by adopting a structure of electrodes that coupling capacitance between the electrodes is connected in parallel with a coupling capacitance between each electrode and an inner conductor so as to increase the attenuation of lower frequencies. CONSTITUTION:A 1st electrode 7 of a 1st dielectric body 1 acts like an input electrode (or output electrode) and a 1st electrode 9 of a 2nd dielectric body 2 acts like an output electrode (or input electrode). A coupling capacitance 7a is formed between the 1st electrode 7 and an inner conductor 6, and a coupling capacitance 8a is formed between the 2nd electrode 8 and the inner conductor 6. Moreover, a coupling the capacitor 7b is produced between the 1st and 2nd electrodes 7, 8 and the coupling capacitance 7b is connected in parallel with the coupling capacitors 7, 8 connected in series. A coupling capacitance 9a is produced between the 1st electrode 9 and the inner conductor 6. The 1st and 2nd electrodes 9,10 of the 2nd dielectric body 2 is parted and the 2nd electrode 10 and the inner conductor 6 are connected so as not to form any coupling capacitance. Then a filter characteristic A in an equivalent circuit is obtained. The filter characteristic A is characterized in that a large attenuation is obtained at a low frequency 1A in comparison with a characteristic B and then the dielectric filter with excellent separation characteristic at a low frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter.

[0002]

2. Description of the Related Art For example, in a dielectric filter disclosed in Japanese Patent Laid-Open No. 4-103203, a plurality of resonator holes are provided in a dielectric block, electromagnetic fields are coupled between the resonator holes, and the resonator surface is further connected to the outer surface. A band filter is constructed by providing output electrodes.

[0003]

In the above-mentioned conventional dielectric filter, since the input and output electrodes are provided on the outer surface of the dielectric block, surface mounting can be performed, which is evaluated. .

The present invention makes it possible to obtain a large attenuation characteristic particularly in the low frequency region by modifying the electrode structure in this surface mounting structure.

[0005]

In order to achieve this object, the present invention includes columnar first and second dielectrics having through holes or bottomed holes, and the first and second dielectrics are provided. An outer conductor is provided on the outer surface of the second dielectric, an inner conductor is provided in the through hole or the hole, and the outer surface of each of the first and second dielectrics is separated from the outer conductor. First and second electrodes are provided, and the first and second electrodes of the first dielectric are capacitively coupled to the inner conductor, respectively, and the first and second electrodes are also capacitively coupled to each other to form the second dielectric. The first electrode of the body is capacitively coupled to the inner conductor, the second electrode is connected to the inner conductor, and the second electrode of the second dielectric is connected to the second electrode of the first dielectric. It was done.

[0006]

With the above configuration, the first electrode of the first dielectric and the first electrode of the second dielectric serve as input and output electrodes, and the first and second electrodes of the first dielectric are also provided. Since the coupling capacitance between them is connected in parallel to the coupling capacitance formed between the first and second electrodes of the first dielectric and the inner conductor, a large amount of attenuation is obtained on the low frequency side, and A dielectric filter having excellent isolation characteristics on the band side can be obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numerals 1 and 2 denote prismatic first and second dielectrics made of, for example, a barium titanate-based dielectric, and through holes 3 and 4 are formed in the central portions thereof.

Outer conductors 5 are provided on all five surfaces of the first and second dielectric bodies 1 and 2 except the open end surfaces 1a and 2a, and the through holes 3 are formed in the open end surfaces 1a and 2a. , 4
The outer conductor 5a connected to the inner conductor 6 is provided only at the opening edge.

Furthermore, a part of the outer conductor 5 on the upper surface and the right side surface of the first dielectric 1 is removed, and the first and second electrodes 7 and 8 are provided there, and the second electrode 8 is provided from the upper surface to the right side surface.

On the other hand, a part of the outer conductor 5 on the upper surface and the left side surface of the second dielectric 2 is removed, and the first and second electrodes 9, 1 are placed there.
0 is provided, and the second electrode 10 is provided from the upper surface to the left side surface.

The outer conductor 5 and the inner conductor 6 are connected at the respective short-circuited end faces of the first and second dielectric bodies 1 and 2.

The first and second dielectrics 1 and 2 are
Is integrated by, for example, soldering with its right and left side surfaces in contact with each other as shown in FIG. 1, whereby the second electrodes 8 and 10 of the first and second dielectric bodies 1 and 2 are connected. It will be.

As a result, the electrical equivalent circuit of the dielectric filter shown in FIG. 1 is as shown in FIG.

That is, the first electrode 7 of the first dielectric 1 serves as an input electrode (or output electrode), and the first electrode 9 of the second dielectric 2 serves as an output electrode (or input electrode).

Reference numeral 7a in FIG. 6 indicates the first electrode 7 and the inner conductor 6.
The coupling capacitance formed between the second electrodes 8 and the inner conductor 6 is indicated by 8a. Reference numeral 7b is a coupling capacitance formed between the first and second electrodes 7 and 8, and the coupling capacitance 7b is connected in parallel to the coupling capacitances 7a and 8a connected in series.

Next, 9a is a coupling capacitor formed between the first electrode 9 and the inner conductor 6. FIG. 4 shows an equivalent circuit of the first dielectric 1 alone, and FIG. 5 shows an equivalent circuit of the second dielectric 2 alone. As a result of connecting the second electrodes 8 and 10 to each other, FIG. The equivalent circuit shown in is formed.

Further, as can be seen from FIG. 5, the first and second electrodes 9 and 10 of the second dielectric 2 are separated from each other so that no coupling capacitance is formed. The conductors 6 are also connected so that no coupling capacitance is formed. The equivalent circuit shown in FIG. 6 results in the filter characteristic A shown in FIG. 7. The characteristic of this filter characteristic A is that it is on the low frequency side 1 as compared with that shown in B.
This means that a large amount of attenuation can be obtained at A, and a dielectric filter having excellent isolation characteristics on the low frequency side can be obtained.

The reason why a large amount of attenuation is obtained on the low-frequency side 1A is that the coupling capacitance 7b is connected in parallel to the coupling amounts 7a and 8a connected in series as described above.

[0019]

As described above, the present invention is provided with the columnar first and second dielectrics having the through holes or the bottomed holes, and the outer conductors are provided on the outer surfaces of the first and second dielectrics. And an inner conductor is provided in the through hole or the hole, and
First and second electrodes are provided on the outer surface of the second dielectric in a state of being separated from the outer conductor, respectively, and the first and second electrodes of the first dielectric are respectively capacitively coupled with the inner conductor. At the same time, the first and second electrodes are capacitively coupled to each other, and the first electrode of the second dielectric is capacitively coupled to the inner conductor.
Is connected to the inner conductor, and the second electrode of the second dielectric is connected to the second electrode of the first dielectric.

With the above structure, the first electrode of the first dielectric material and the first electrode of the second dielectric material serve as input / output electrodes, and the first and first electrodes of the first dielectric material are used. Since the coupling capacitance between the two electrodes is connected in parallel to the coupling capacitance formed between the first and second electrodes of the first dielectric and the inner conductor,
A large amount of attenuation is obtained on the low frequency side, and a dielectric filter having excellent isolation characteristics on the low frequency side is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing the first dielectric.

FIG. 3 is a perspective view showing the second dielectric.

FIG. 4 is an equivalent circuit diagram of the first dielectric.

FIG. 5 is an equivalent circuit diagram of the second dielectric.

6 is an equivalent circuit diagram of FIG.

FIG. 7 is a filter characteristic diagram of FIG.

[Explanation of symbols]

 1 First Dielectric 2 Second Dielectric 3 Through Hole 4 Through Hole 5 Outer Conductor 6 Inner Conductor 7 First Electrode 8 Second Electrode 9 First Electrode 10 Second Electrode

Front page continuation (72) Hideyuki Miyake 55-12, Tamabe, Otsumi, Tanabe-cho, Tsuzuki-gun, Kyoto Pref. Matsuda Nitto Electric Co., Ltd.

Claims (1)

[Claims] 1. A columnar first and second dielectric body having a through hole or a bottomed hole, wherein an outer conductor is provided on an outer surface of the first and second dielectric bodies, and a through hole, Alternatively, an inner conductor is provided in the hole, and first and second electrodes are provided on the outer surfaces of the first and second dielectrics separately from the outer conductor, respectively. The first and second electrodes are capacitively coupled to the inner conductor, respectively, and the first and second electrodes are also capacitively coupled to each other so that the first electrode of the second dielectric is capacitively coupled to the inner conductor. A dielectric filter in which the second electrode is connected to the inner conductor, and the second electrode of the second dielectric and the second electrode of the first dielectric are connected.