JPS6290001A - Comb-line filter - Google Patents

Abstract

PURPOSE:To easily change the capacitance of a capacitor by inserting a dielectric to all holes of a dielectric block from th open end face side, inserting a metallic pin to said dielectric and connecting the metallic pin to an earth electrode. CONSTITUTION:The dielectrics 6... are inserted to all the holes 2 of the dielectric block 1 from the open end side and the metallic pins 7... are inserted into the dielectrics 6.... The upper end of the metallic pins 7... are inserted to a metallic case 8 connected to an outer conductor 4 of the dielectric block 1 being the earth electrodes and fixed by solder or a conductive adhesives. Then a comb-line filter shown in equivalent circuit is formed. In this case, since the inserted end of the metallic pin is supported by the dielectric inserted in the dielectric block hole, the end is not a free end and the capacitance of the capacitor is made stable. Then the capacitance of the capacitor is easily changed by changing the inserting quantity of the metallic pin.

Description

[Detailed Description of the Invention] The present invention is characterized by a plurality of dielectrics formed by an inner conductor formed in the hole, an outer conductor formed on the outer circumferential surface, and a dielectric material present between the side conductors. The present invention relates to a combline filter using dielectric blocks constituting body coaxial resonators, and particularly to improvements in the coupling structure between the dielectric coaxial resonators.

Conventional ■ Kogyoku As shown in the outline in Fig. 3, the conventional combline filter has a dielectric material C filled around center conductors b erected at predetermined intervals from the bottom of a metal case a. A movable metal body d provided on the top plate of the case a is positioned on the open end side of the center conductor b.

According to this configuration, a dielectric coaxial resonator is formed by the center conductor b, the case a covering the outer periphery, and the dielectric C, and a capacitor is formed between the center conductor b and the metal d. Therefore, when the above configuration is expressed as an electric circuit, it becomes as shown in FIG. 4. In the figure, Xl.

X2... is a dielectric coaxial resonator, and C... is a capacitor formed between the center conductor and the whole air body d.

By the way, according to high frequency theory, the circuit shown in FIG. 4 is equivalent to a circuit in which dielectric coaxial resonators x1, x2, . . . are coupled to a coupling element as shown in FIG. Therefore,
The configuration shown in FIG. 3 forms a filter circuit as represented by the circuit in FIG.

In the combline filter having the above configuration, the capacitance of the capacitor formed between the center conductor and the metal body d has a large influence on the filter characteristics. Therefore, it is necessary that the capacity is stable, but in the above configuration, the metal body d (usually using screws) is supported at one point on the top plate of case a. Since it is a free end, it is prone to wobbling and has the disadvantage that the capacitance of the capacitor formed between it and the center conductor b becomes unstable.

Conventionally, as a means to eliminate such drawbacks, as shown in FIG. 6, an electrode is metallized on the entire outer surface of the dielectric block g except for the open end circumference f of the center conductor e... There are some that form a capacitor between the open end of ... and the electrodes around it.

According to this configuration, since the capacitor can be formed between the electrode formed on the outer surface of the dielectric block g and the open end of the center conductor e, the capacitance of the capacitor is stabilized. However, on the other hand, since the capacitance of a capacitor is determined by the electrode pattern, there is a drawback that the configuration and adjustment of the electrode pattern requires a high degree of skill.

Therefore, it is an object of the present invention to provide a combline filter with a novel configuration that is free from such drawbacks and difficulties.

Steps to Solve the Problems In order to achieve the above object, the combline filter of the present invention inserts dielectric material from the open end side into all holes of the dielectric block in which inner conductors are formed, and The feature is that a metal pin is inserted into the dielectric and this metal pin is connected to a ground electrode.

According to the above configuration, a capacitor is formed between the inner conductor and the metal pin connected to the ground electrode, so that the filter circuit shown in the figure is constructed. In this case, the insertion end side of the metal pin is supported by the dielectric inserted into the dielectric block hole, so it does not become a free end unlike the conventional one, so the capacitance of the capacitor is stable, and the metal pin By changing the insertion amount of the capacitor, the capacitance of the capacitor can be easily changed.

Figure 1 shows a front cross-sectional view of a combline filter as an embodiment of the present invention, in which 1 is a dielectric block made of, for example, titanium oxide type ceramic, and through holes 2 are formed at appropriate intervals.
... has been destroyed. An inner conductor 3 made of a metal film or the like is formed on the inner surface of the number hole 2 . An outer conductor 4 made of a metal film or the like is formed on the four outer sides of the dielectric block 1, and is connected to the inner conductor 3 by a shorting electrode 5 formed on the bottom surface of the dielectric block. On the other hand, the upper surface of the dielectric block is an open end surface on which no metal film, electrode, etc. are formed.

Dielectrics 6 are inserted into all the holes 2 of the dielectric block 1 from the open end side, and metal pins 7 are inserted into the dielectrics 6. Metal pin 7...
- The upper end side of the dielectric block 1 is inserted into a metal case 8 which is in contact with the outer conductor 4 of the dielectric block 1, which is a ground electrode, and is fixed with solder or conductive adhesive.

As described in the section on operation, this configuration forms the combline filter of the equivalent circuit shown in FIG.

It is preferable that the dielectric 6 be somewhat soft so as not to damage the inner conductor 3 during insertion. or,
In order to support the tip side of the metal bottle 7 with the dielectric 6 without wobbling, it is preferable to insert the dielectric 6 into the hole 2 in a normal size state.

If the metal pin 7 is a conductive rod,
The material does not matter. However, it is desirable to use metal screws so that the capacitance with the inner conductor 3 can be finely adjusted.

Incidentally, the dielectric body 6 may be provided in a state where it is buried in the hole 2 as shown in FIG. Further, the metal pin 7 is connected to the dielectric material 6
It is also possible to insert it into the hole 2 by passing it through.

Since the combline filter according to the present invention is constructed as described above, it has the following effects.

■Since a predetermined capacitor is formed between the metal bottle and the inner conductor, there is no need to form a complicated electrode pattern, and capacitance adjustment is as simple as changing the insertion amount of the metal pin. It can be done with

■Since the tip of the fully bent bottle is held by a dielectric, there is very little wobbling of the metal bottle, which stabilizes the capacitance of the capacitor formed between it and the inner conductor.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of a combline filter as an embodiment of the present invention, FIG. 2 is a diagram showing another embodiment of the present invention, and FIGS. 3 and 6 are respectively conventional combline filters. FIG. 4 is an electric circuit diagram of the combline filter of FIG. 3, and FIG. 5 is a circuit diagram equivalent to FIG. 4. 1... Dielectric block, 2... Hole, 3... Inner conductor 6... Dielectric, 7... Metal pin Patent applicant Murata Manufacturing Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] For all holes in the dielectric block with inner conductors formed,
A combline filter characterized in that a dielectric is inserted from the open end surface side, a metal pin is inserted into the dielectric, and the metal pin is connected to a ground electrode.