JPS63306702A - Dielectric filter - Google Patents

Abstract

PURPOSE:To obtain a dielectric filter with simplified input/output structure while the specific band is widened by setting up an input/output terminal to the end of the dielectric filter and connecting a capacitor mounted to the open end of the resonator hole by a lead wire. CONSTITUTION:The input/output terminal 32 is inserted and stood up in the input/output hole 30 formed to both ends of a dielectric block 10, a capacitor 34 is placed and fixed to the open end of the resonator hole placed at both ends and the terminal 32 and the capacitor 34 are connected by a lead wire 36. A metallic fixture 38 of a shape like a rivet is fixed to an open end of the resonator hole placed at both ends and the capacitor 34 is placed thereupon and soldered. The connection with an external circuit is implemented via the terminal 32. Since the capacitor 34 serves mainly to the coupling, a wide specific band is to be provided. For example, it is possible to take the band width of + or -26MHz, for example. Since the input/output terminal is directly stood up to the dielectric block, it is not required for a case or a special glass termi nal, the structure is remarkably simplified and the assembling is facilitated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a dielectric filter with an integral structure used in high frequency bands such as microwaves, and more specifically, to an input/output filter installed upright at both ends of a dielectric block. An object of the present invention is to provide a dielectric filter having a wide relative bandwidth and a simple input/output structure by connecting a terminal and a capacitor attached to a resonator hole at both ends with a lead wire.

[Prior Art] Multi-stage resonator filters using dielectric ceramics such as barium titanate are conventionally known, and have characteristics such as low loss and high Q (and high dielectric constant, so they can be made compact). It is widely used in micro-liquid mobile radio devices such as car phones.

As a conventional technique regarding dielectric fusulta, for example, the third
As shown in the figure, P ? has a rectangular parallelepiped shape? J body diblock 1
A plurality of resonator holes 12 and coupler holes 14 are provided alternately at predetermined intervals in the longitudinal direction, and a metallized layer 16 is provided on the outer surface of the dielectric block IO except the upper surface and the inner surface of the resonator hole 12. There is a built-in multi-stage structure. In this case, one of the surfaces on which the resonator holes 12 are open and which is not metallized (the upper surface) becomes an open surface.

In such a dielectric filter, each resonator hole 12 corresponds to a single resonant element, and the desired degree of coupling is adjusted by the coupler hole 14 located between the resonator holes to obtain the desired degree of coupling. A filter characteristic occurs.

Connection between the dielectric filter and external circuitry is made through input/output terminals. As an example of this input/output terminal structure, as shown in FIG. 3, there is a structure in which input/output holes are provided at both ends of a dielectric block 10 and input/output pin terminals 18 are inserted.

As another example, as shown in FIG. 4, coupling capacitors 20 are connected to the open ends of the resonator holes 12 located at both ends of the dielectric block IO! 3! There is a configuration in which the device is fixed in place and connected through it.

[Problems to be Solved by the Invention] A conventional dielectric filter having an input/output structure as shown in FIG. 3 has a fractional bandwidth of about 30 to 40 MHz. In order to widen this fractional band, the distance between the input/output pin terminal 18 and the resonator hole 12 closest to it must be made very narrow.

With powder compaction technology, which is common when manufacturing dielectric materials, it is extremely difficult to narrow the gap between them.In other words, the powder does not flow smoothly into the area during compaction, and the density locally increases. This is because it becomes insufficient and the crank easily enters during firing.

On the other hand, the capacitor-coupled structure shown in Figure 4 can widen the specific band, but the glass terminal (
In other words, it is necessary to use a terminal (having a pin 24 penetrated through the center of the glass insulator 22) and attach it to the case 26 to hold it, making the structure complicated, increasing the size, and increasing the cost. disadvantages arise.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above, to have a wide band ratio, to simplify the structure of the input/output coupling part, and to prevent defects from occurring during molding and firing of the dielectric. The object of the present invention is to provide a dielectric filter.

[Means for Solving the Problems] The present invention provides a plurality of resonator holes in the longitudinal direction of a dielectric block having a substantially rectangular parallelepiped shape, and one surface of the dielectric block where the resonator holes are open. This is based on a dielectric filter with an integral structure in which the surface is open and a conductor layer is formed on the other outer surface and the inner surface of the resonator hole.

In order to achieve the above object, in the present invention, input/output holes are formed at both ends of a dielectric filter, input/output terminals are inserted and erected, and open ends of the resonator holes located at both ends are formed. A configuration is adopted in which a capacitor is mounted and fixed on the capacitor, and the input/output terminal and the capacitor are connected with a lead wire.

[Operation] The dielectric filter and the external circuit are coupled through the input/output terminal and the capacitor. This coupling is mainly done by capacitors, so the distance between the input/output hole and the resonator hole adjacent to it is wide (but it has a wide fractional bandwidth), and the coupling between the input/output terminal and the first-stage resonant element is This can be done by adjusting the insertion depth of the output terminal, etc.

Although the present invention uses a capacitor for coupling, the input/output terminal installed on a dielectric block is used for the input/output structure of the signal to the capacitor, which eliminates the need for a case or glass terminal, resulting in a simple structure. This results in excellent assembly workability.

[Example] FIG. 1 is a perspective view showing an example of a dielectric filter according to the present invention, and FIG. 2 is a partial sectional view thereof.

The dielectric filter has three resonator holes 12 formed at intervals in the longitudinal direction of a rectangular parallelepiped dielectric block 10 made of a sintered body of a high permittivity ceramic material such as barium titanate. Coupler hole 1 between resonator hole 12
4, input/output holes 30 are provided at both ends of the dielectric block 10, and metallized I! 11
It forms a structure in which 6 is formed. Therefore, in this case, the upper surface of the dielectric block 10 becomes an open surface.

In order to make the drawing more clear, parts where the dielectric base is exposed without being metallized are shown with small dots. The metallized layer 16 formed here is a thin conductor layer formed by baking silver paste, for example.

Now, as is clear from FIGS. 1 and 2, the feature of the present invention is that the input/output terminals 32 are inserted and erected into the input/output holes 30 formed at both ends of the dielectric block IO.
In addition, capacitors 34 are installed at the open ends of the resonator holes located at both ends.
is placed and fixed, and the input/output terminal 32 and the capacitor 34
It is at the point where the lead wire 36 connects the two.

In this embodiment, rivet-shaped metal fittings 38 are fixed to the open ends of the resonator holes located at both ends, and the capacitor 34 is placed on top of the metal fittings 38 and soldered.

Connection with an external circuit is made via the input/output terminal 32 mentioned above. In addition, since the capacitor 34 is mainly in charge of the coupling, it is possible to have a wide fractional bandwidth as in the case of conventional capacitor coupling.
It is possible to have a bandwidth of about z.

Although a preferred embodiment of the present invention has been described in detail above, the present invention is not limited to only such a configuration.
Although the above embodiment is a case of a three-stage configuration in which three resonator holes are formed, it can also be applied to a dielectric filter having two stages or four stages or more. Further, although a coupler hole is provided between each resonator hole, it can also be applied to a configuration in which the coupler hole is eliminated by forming a specific conductor pattern on the open surface.

[Effects of the Invention] As described above, the present invention is configured such that the input/output terminals are provided upright at the ends of the dielectric filter, and are connected to the capacitors attached to the open ends of the resonator holes using lead wires. Therefore, it is basically capacitor coupled, and even if the distance between the input/output terminal and the resonator hole is widened, a dielectric filter with wide band ratio characteristics can be manufactured.

Since the distance between the input/output hole and the resonator hole may be widened as described above, the difficulty of powder molding can be solved, and the occurrence of cracks can be prevented, making molding and firing easier.

In addition, since the input/output terminals of the present invention are installed directly on the dielectric block, there is no need for a case or special glass terminals like in the conventional capacitor coupling method, which greatly simplifies the structure and allows assembly. It also becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a dielectric filter according to the present invention, FIG. 2 is a partial sectional view thereof, FIG. 3 is a perspective view showing a conventional coupling structure using input/output pin terminals, and FIG. 4 1 is a partial cross-sectional view showing a conventional coupling structure using a capacitor. 10... Dielectric block, 12... Resonator hole, 14
... Connector hole, 16... Metallized layer, 30...
Input/output hole, 32...Input/output terminal, 34...Capacitor, 36...Lead wire. Representative Shigeru Minoru Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A plurality of resonator holes are provided in the longitudinal direction of a dielectric block having a substantially rectangular parallelepiped shape, and one of the surfaces of the dielectric block where the resonator holes are open is an open surface, and the other outer surface and the resonator are connected. In a dielectric filter having an integral structure in which a conductive layer is formed on the inner surface of the hole, input/output holes are formed at both ends of the dielectric filter, and input/output terminals are provided upright, and resonator holes located at both ends are provided. Place and fix the capacitor on the open end of
A dielectric filter characterized in that the input/output terminal and a capacitor are connected by a lead wire.