JPH0290801A - Dielectric filter - Google Patents

Abstract

PURPOSE:To fetch inputs and outputs and to give them polarization by generating strips constituting a strip line or a coplanar line with a ground electrode film on the outer surface of a ceramic case and electromagnetically connecting them with dielectric poles in an inner part through the use of a part of the strip. CONSTITUTION:The ground electrode film 9 is generated on the whole surface of the ceramic case 1, and a part including the upper parts of the dielectric poles 2a, 2b, 2d and 2f are peeled.The strips 6-8 consisting of this metallic films are generated on the peeled parts 10-12, and they constitute the coplanar line with the ground electrode 9. One of the ends 6a and 7a of the strips 6 and 7 are used as the connection parts with an external circuit, and the other ends 6b and 7b are used as connecting electrodes which are electromagnetically connected with the dielectric poles 2a and 2f through the ceramic case 1. Thus, a difficult working is eliminated for a ceramic block input and output connectors can be fitted and they are given polarization.

Description

[Detailed description of the invention] Product] Yu! 1. The present invention provides a grounding conductor on substantially the entire inner or outer surface.
1 is formed in the cavity in the ceramic casing in which at least 1
The present invention relates to a dielectric filter having a structure in which dielectric pillars are provided.

Figure 4 shows a conventional TM mode dielectric filter equipped with six dielectric columns 2.... Each dielectric column 2・
... are arranged at predetermined intervals within the ceramic casing 1 whose internal cavity is partitioned by a partition plate 5. A ground electrode film serving as a cavity is formed on almost the entire surface of the outer or inner surface of the ceramic casing 1, and this ground electrode film and one dielectric column in the cavity equivalently cause one resonance. Configure the vessel.

Then, by disposing the dielectric columns 2 at predetermined intervals within the cavity, adjacent resonators are electromagnetically coupled to each other. Therefore, the illustrated dielectric filter constitutes a bandpass filter in which six resonators are coupled.

In order to connect this dielectric filter to an external circuit, a coaxial connector 3.4 connected to the external circuit by a cable (not shown) is attached to one side of the ceramic casing l. Since a loop antenna or the like is inserted from each connector 3.4 into the cavity within the ceramic casing l, the resonator of the input/output stage is coupled to an external circuit via the antenna.

Note that the housing 1 is made of ceramic because the dielectric pillars 2
This is to improve the temperature characteristics of the dielectric filter by making the coefficient of linear expansion as similar as possible.

By the way, with the dielectric filter in which ceramic is used for the housing 1, the problem is that it is extremely difficult to form holes in the housing 1 to attach the input/output connectors 3 and 4 because the ceramic is hard and brittle. There is.

Furthermore, in Japanese Patent Application No. 60-298149, etc., the present applicant proposed forming poles on both sides or near one side of the pass band (polarization) in order to obtain a desired pass band. Although polarization is desired for filters, there is a problem in that it is difficult to do so. In other words, in order to polarize, it is necessary to couple the resonators on both sides of at least one resonator with reactance elements.
In the above dielectric filter, all the dielectric columns are sealed inside the ceramic casing, so two dielectric columns can be connected using a reactance element without the need for difficult drilling in the ceramic casing. It cannot be done.

The present invention has been made in view of the above circumstances, and provides a dielectric filter having a structure that allows input/output connectors to be attached and polarized without requiring difficult processing on the ceramic block. The purpose is to provide

f7J° The present invention provides a TM mode dielectric filter in which at least one dielectric column is disposed in a cavity of a ceramic casing in which a ground electrode is formed on substantially the entire inner surface. A feature is that a strip forming a microstrip line together with the ground electrode on the inner surface is formed on the surface, and a part of this strip is electromagnetically coupled to a dielectric column via a ceramic casing.

Further, the present invention provides a TM mode dielectric filter in which at least one dielectric pillar is disposed in a cavity of a ceramic casing in which a ground electrode is formed on substantially the entire outer surface of the ceramic casing. The present invention is characterized in that a strip forming a coplanar line is formed together with the ground electrode, and a part of this strip is electromagnetically coupled to a dielectric column via a ceramic casing.

In the present invention, by forming a strip at a predetermined location on the outer surface of the ceramic casing, a microstrip line can be formed along with a ground electrode on the inner or outer surface of the ceramic casing. Or a coplanar line is constructed. A part of the strip of this microstrip line or coplanar line is electromagnetically coupled to the dielectric pillar via the ceramic casing. Therefore, by using the other part of the strip as an input/output extraction electrode, it is possible to connect to an external circuit without drilling holes in the ceramic casing. Further, another part of the strip can be used to electromagnetically couple with another dielectric pillar, and in that case polarization can be achieved.

An embodiment of the present invention will be described in detail below. FIG. 1 is a perspective view of the present invention applied to a dielectric bandpass filter. In the figure, reference numeral 1 denotes a ceramic casing formed, for example, into a rectangular hexahedron. Inside this housing 1, a partition plate 5 on which a shield electrode film is formed, which is also made of ceramic and has a length of about 2/3 of the length of the housing 1, is located at the center in the width direction. They are provided with one end in contact with each other. This partition plate 5 forms a U-shaped cavity. In this cavity, for example, six ceramic dielectric columns 2a, 2b, 2c, 2d, 2e, and 2f are provided at predetermined intervals.

On the outer surface of the ceramic casing 1, a ground electrode film 9 made of a conductive material such as Ag is formed substantially over the entire surface. This basic configuration is the same as that shown in FIG. 4, and therefore equivalently constitutes a bandpass filter in which six resonators are electromagnetically coupled by 5tin*.

Earth electrode film 9 on the outer surface of the upper surface of the ceramic housing 1
As shown in 10.11.12 in the figure, the dielectric columns 2a, 2
Parts including the upper portions of b, 2e, and 2f have been peeled off, and a strip 6.7.8 made of a thin metal film is formed in the peeled off portion 10.1112. This strip 6.7.8 together with the earth electrode membrane 9 constitutes a coplanar line.

Said strips 6 and 7 have one end 6a, ? a extends to the edge of the ceramic casing l, and the other ends 6b and 7b are located above the first and sixth dielectric columns 2a and 2f. One end 6a7a of the strip 6.7 is used as a connection part with an external circuit, and the other ends 6b and 7b are used as coupling electrodes that electromagnetically couple with the dielectric columns 2a and 2f via the ceramic casing 1. There is. The reason why the electrode areas at the other ends 6b and 7b are made large is to obtain the necessary coupling with the dielectric columns 2a and 2f.

Another strip 8 has one end 8a located above the second stage dielectric pillar 2b, and the other end 8b located above the fifth stage dielectric pillar 2b.
It is located above e. Therefore, the two dielectric columns 2b and 2f are electromagnetically coupled through both ends 8a and 8b of the strip 8. Since the electromagnetic coupling equivalently forms a reactance, the strip 8 achieves polarization of the bandpass filter.

FIG. 2 is an equivalent circuit diagram of the filter having the above configuration. In addition, R1,..., R6 in the figure represent the housing l and each dielectric pillar 2.
A resonator configured between a + ...2f is shown.

FIG. 3 is a perspective view showing another embodiment of the present invention, in which the present invention is applied to a band illumination filter. This filter has a ground electrode film 13 on almost the entire outer surface.
Inside the ceramic casing 1, there are three partition plates 5a, 5b, each having a shield electrode formed of a ceramic plate.
The cavity is partitioned into six cavities by 5c, and dielectric columns 2a, 2b, 2c, 2d, 2e, and 2f are provided in each cavity.

A dielectric column 2a is provided on the upper surface of the housing l from one end in the longitudinal direction.
, 2b, 2c, 2d, 2e, and 2f, and returns to one end again.A strip 14 made of a conductive material, for example, Ag, is formed in a U-shape. This strip 14 is connected to each dielectric column 2a, 2b.

A length of λ/4 (λ: pipe wavelength) is ensured between 2c, 2d, 2e, and 2f.

In the above embodiments, a ceramic casing with a ground electrode film formed on the outer surface is used, but the present invention is not limited to this, and a ceramic casing with a ground electrode film formed on the inner surface can also be used. In that case, the strip on the outer surface and the ground electrode film constitute a microstrip line.

In this case, it is necessary to peel off the ground electrode film existing on the opposing portion of the strip and the top surface of the dielectric column. This is to ensure the connection between the strip and the dielectric pillar.

As detailed above, according to the present invention, a strip that forms a strip line or a coplanar line together with the ground electrode film formed on the inner or outer surface of the ceramic casing is formed on the outer surface of the ceramic casing. However, a part of this strip is used to electromagnetically couple with the internal dielectric pillar, making it possible to take out the input/output and polarize it without the need for difficult drilling of holes in the ceramic casing. This has the excellent effect of making it possible.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of a dielectric filter according to the present invention, FIG. 2 is an equivalent circuit diagram thereof, FIG. 3 is a perspective view showing another embodiment of the present invention, and FIG. 4 is a conventional filter. FIG. 2 is a perspective view showing a dielectric filter of the configuration. 1... Housing, 2... Dielectric pillar, 6, 7, 8.14.
...Strip, 9.13...Earth electrode film. Patent applicant: Murata Manufacturing Co., Ltd.

Claims (2)

[Claims] (1) In a dielectric filter in which at least one dielectric pillar is arranged in a cavity of a ceramic casing in which a ground electrode is formed on substantially the entire inner surface, a ground electrode on the inner surface is provided on the outer surface of the ceramic casing. A dielectric filter comprising a strip forming a microstrip line together with an electrode, and a part of the strip being electromagnetically coupled to a dielectric column via a ceramic casing. (2) In a dielectric filter in which at least one dielectric column is disposed within a cavity of a ceramic casing in which a ground electrode is formed on substantially the entire outer surface of the ceramic casing, the earth electrode is provided on the outer surface of the ceramic casing along with the ground electrode. A dielectric filter characterized in that a strip forming a coplanar line is formed, and a part of the strip is electromagnetically coupled to a dielectric column via a ceramic casing.