JPH0680962B2 - Dielectric filter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dielectric filter having an integral structure used in a high frequency band such as a microwave, and more specifically, to a resonator hole located at an end of a dielectric block. The present invention relates to a dielectric filter in which a coupling plate attached to an open end and a terminal portion are connected to each other by a conductor plate, and an adjusting screw which is capable of advancing and retreating facing a dielectric plate for impedance adjustment is attached to a housing wall.

[Prior Art] A multistage resonator type filter using a dielectric ceramic such as barium titanate has a small loss and therefore a so-called high Q, and has a large permittivity, so that it can be miniaturized. It is widely used in mobile radio equipment for wave bands and satellite communication equipment.

As a conventional technique relating to a dielectric filter, a plurality of resonator holes and connector holes are alternately provided at predetermined intervals in the longitudinal direction of a substantially rectangular parallelepiped dielectric block, and the resonator holes of the dielectric block are provided. There is an integrated multi-stage structure in which a metallized layer (for example, a conductor layer baked with silver paste or the like) that is the inner surface of the resonator hole and the entire outer surface except one of the open surfaces is formed.

Here, one of the surfaces where the resonator holes are opened and where the metallized layer is not formed is called an open surface, and is usually housed in a metal housing with the open surface facing upward.

There are various methods for connection with an external circuit, but a typical one is a structure using a coupling capacitor. In the prior art, a structure is adopted in which a coupling capacitor is placed and fixed at the open ends of the resonator holes located at both ends of the dielectric block, and the input and output terminals attached to the housing are connected by lead wires.

In a dielectric filter having such a structure, each resonator hole corresponds to one resonance element, and the desired degree of filter characteristics can be obtained by providing an appropriate degree of coupling by means of the connector holes located between the resonator holes. Is causing.

[Problems to be Solved by the Invention] However, in the above-described conventional dielectric filter, since the coupling capacitor and the terminal portion are connected by the lead wire, the impedance is high due to the L component (inductance component). In addition, since there are variations in the length of the lead wire, the forming of the wiring, and the like, there is a drawback that adjusting the impedance with respect to the input signal is complicated and the characteristics tend to be unstable, and the adjustment takes time. In particular, if the lead wire becomes long, the impedance may become too high and adjustment may not be possible.

If a pipe cable is used instead of the lead wire, the impedance can be lowered, but this is expensive and not preferable.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, to provide a dielectric filter that can reduce impedance, can be easily adjusted in a short time, and have stable characteristics. It is in.

[Means for Solving the Problems] In the present invention that can achieve the above object, a plurality of resonator holes are arranged in the longitudinal direction of a dielectric block having a substantially rectangular parallelepiped shape, and the dielectric block is provided. Using one of the surfaces where the resonator hole is opened as an open surface, the outer surface other than the open surface and a metallized layer formed on the inner surface of the resonator hole are housed in a housing, and at the end portion. In a dielectric filter in which a coupling capacitor attached to an open end of a resonator hole located and a terminal portion are electrically connected, the coupling capacitor and the terminal portion are connected by a conductor plate, and the tip portion is This is a dielectric filter in which an adjusting screw is attached to the housing so as to be able to move back and forth so as to face the conductor plate.

Here, for example, a metal plate is preferably used as the conductor plate, and both surfaces thereof are preferably coated with an insulating film. The shape of the conductor plate may be appropriately changed depending on the position of the terminal portion and the like.

Although the number of adjusting screws may be one or plural, it is preferable that the tip end portion is provided with an insulating coating.

INDUSTRIAL APPLICABILITY The present invention is suitable for, for example, a transmission-side filter of a dielectric duplexer, and the conductor plate is attached to the input terminal side.

[Operation] When a conductor plate such as a metal plate is used for the connection between the coupling capacitor and the terminal portion, the impedance is close to the 50Ω system, which facilitates adjustment. Moreover, the distance (spacing) between the tip of the adjustment screw and the conductor plate can be changed by simply operating the adjustment screw that is attached to the housing so that it can be finely adjusted for impedance. Much easier than adjusting.

After the adjustment is completed, the adjustment screw may be fixed with an adhesive.

The conductor plate can be formed by punching, and unlike the lead wire, it is difficult to lose its shape when it is formed into a certain shape, so that stable characteristics can be obtained.

[Embodiment] FIG. 1 is a perspective view showing an embodiment of a dielectric filter according to the present invention without a housing. This embodiment is an example of a four-stage structure used as a transmission side filter of a dielectric demultiplexer.

The basic structure of the dielectric filter is the same as that of the above-mentioned conventional technique.

The dielectric filter has four resonator holes 12 formed at intervals in the longitudinal direction of a substantially rectangular parallelepiped-shaped dielectric block 10 made of a sintered body of a high dielectric constant ceramic material such as barium titanate. A connector hole 14 is provided between the child holes 12, and a metallized layer 16 is formed on all side surfaces and the bottom surface of the dielectric block 10 and on the inner surface of each resonator hole 12, and a metal housing (not shown) is formed. It is configured to be stored in. Here, the upper surface of the dielectric block 10 is an open surface and the lower surface is a short circuit surface.

Coupling capacitors 18 and 19 are mounted and fixed on the open ends of the resonator holes located at both ends of the dielectric block 10, and an input terminal 20 is attached to the housing. The coupling capacitor 18 and the input terminal 20 and the output terminal 21 are electrically connected.

The present invention is significantly different from the prior art in that the conductor plate 22 is used to connect the coupling capacitor 18 and the input terminal 20, and the adjustment screw 24 is attached to the housing so that the tip end faces it. It is a point.

In this embodiment, the conductor plate 22 is a thin metal plate having a width of 2 to 3 mm and a thickness of about 0.1 mm and coated with an insulating film on both sides. Both ends of the conductor plate 22 have a narrow width so that they are not easily peeled off when soldered to the coupling capacitor 18 and the input terminal 20. The adjusting screw 24 is made of metal and the tip 24
Insulation is applied to a.

In this way, when connecting the coupling capacitor 18 and the input terminal 20 with the conductor plate 22 like a metal plate, the impedance of 50 Ω is obtained.
It becomes closer to the system and adjustment becomes easier. In addition, the distance (spacing) between the metal adjustment screw 24 and the conductor plate 22 that is electrically connected to the housing changes and the impedance can be finely adjusted simply by operating the adjustment screw 24 that is attached to the housing so that it can move back and forth. The adjustment is much easier than the conventional configuration in which the lead wire is used for connection.

After the adjustment is completed, the adjusting screw 24 may be fixed to the housing with an adhesive.

The coupling capacitor 19 and the output terminal 21 are connected by a lead wire as in the conventional case.

2 and 3 show another embodiment of the present invention.
Since the basic structure is the same as that of the embodiment shown in FIG. 1, corresponding parts are designated by the same reference numerals and the description thereof is omitted.

This embodiment is an example in which the input terminal 20 is provided on the side surface of the metal housing 30. In such a case, the conductor plate 32 has an L-shaped thin plate structure, and each end is soldered to the coupling capacitor 18 and the input terminal 20.

Here, the legs of the rivet-shaped fittings 34 are inserted into the open ends of the resonator holes located at both ends of the dielectric block 10 for soldering connection with the metallized layer on the inner surface of the resonator holes. Capacitor 18 coupled to the head of 34
Are mounted and soldered in the same manner to connect.

In addition, in the accompanying drawings, in order to make the drawings easy to understand, the portions where the base material of the dielectric is exposed as it is without metallization are shown with fine dots. Although the metallized layer 16 is drawn to have a considerable thickness in these drawings, it is actually an extremely thin layer formed by baking silver paste as described above.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to such a configuration.
The shape of the conductor plate and the number of adjusting screws to be attached may be changed as appropriate. The above-mentioned embodiment is a case of a four-stage filter, but it can be applied to a two-stage or three-stage filter.
The present invention can also be applied to a multi-stage filter having stages or more. Further, in the above-mentioned embodiment, the connector holes are provided between the resonator holes, but it is also possible to generate desired filter characteristics by forming an appropriate conductor pattern on the open surface without providing the connector holes. Needless to say, the present invention can be applied to such a filter.

The combination structure of the conductor plate and the adjusting screw may be provided at any place where impedance adjustment is required. Therefore, not only one end of the dielectric block but also the input and output sides may have such a connection structure. The present invention can be applied to other than the filter on the transmission side of the dielectric duplexer.

EFFECTS OF THE INVENTION The present invention connects the coupling capacitor attached to the open end of the resonator hole located at the end portion of the dielectric block and the terminal portion with the conductor plate, and the tip portion is Since it is a dielectric filter with an adjusting screw that can move forward and backward with respect to the housing so as to face the conductor plate, the impedance is close to 50 Ω system and adjustment is easy, and it can be installed forward and backward in the housing. Since the impedance for the input signal can be finely adjusted simply by operating the adjustment screw that is provided, the adjustment is much easier than the connection using the conventional lead wire, and the forming is performed in a fixed shape. The characteristics are stable because it is easy, and there is an effect that the adjustment work time can be shortened and the yield can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a dielectric filter according to the present invention, excluding a housing, FIG. 2 is a partial longitudinal sectional view showing another embodiment of the present invention, and FIG. 3 is a partial plan view thereof. It is a figure. 10 ... Dielectric block, 12 ... Resonator hole, 14 ... Coupler hole, 16 ... Metallization layer, 18 ... Coupling capacitor, 20 ...
… Input terminal, 22 …… conductor plate, 24 …… adjustment screw.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-21033 (JP, A) JP-A-59-10001 (JP, A) JP-A-53-72549 (JP, A) Actual development Sho-61- 136601 (JP, U)

Claims (3)

[Claims] 1. A plurality of resonator holes are provided in a longitudinal direction of a dielectric block having a substantially rectangular parallelepiped shape, and one of the surfaces of the dielectric block in which the resonator holes are opened is defined as an open surface, and the resonator block is opened. Between the coupling capacitor attached to the open end of the resonator hole located at the end and the terminal part by housing the integrated structure in which a metallized layer is formed on the outer surface other than the surface and the inner surface of the resonator hole in the housing. In the dielectric filter electrically connected to, the coupling capacitor and the terminal portion are connected by a conductor plate, and an adjusting screw is attached to the housing so that the tip end faces the conductor plate. A dielectric filter characterized by the above. 2. The dielectric filter according to claim 1, wherein the conductor plate is a metal plate coated with an insulating film on both surfaces. 3. The dielectric filter according to claim 1 or 2, wherein the dielectric filter is a transmission side filter of the dielectric duplexer, and the terminal portion is an input terminal thereof.