JPH0352004Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dielectric filter with an integral structure used in high frequency bands such as microwaves, and more specifically, to This relates to a dielectric filter in which ground plates located above and on both sides are connected by a strip-shaped conductor.

[Future technology] Multi-stage resonator filters using dielectric ceramics such as barium titanate have low loss, so-called high Q, and have a high dielectric constant, so they can be miniaturized. Widely used in the microwave band.

As a conventional technique regarding a dielectric filter, a plurality of resonator holes and coupler holes are provided alternately at predetermined intervals in the longitudinal direction of a rectangular parallelepiped dielectric block. An integrated multi-stage structure in which the surface and the inner surface of the resonator hole are metallized is known. In this case, one of the surfaces on which the resonator holes are open, the top surface which is not metallized, becomes an open surface, and the other bottom surface, which is metallized, becomes a short-circuit surface.

In such a filter, each resonator hole corresponds to an individual resonant element, and the resonator holes are connected by a connector hole located between the resonator holes to develop desired filter characteristics. .

[Problems to be solved by the invention] However, in the conventional multi-stage dielectric filter,
There are problems such as not necessarily exhibiting sufficiently satisfactory attenuation characteristics, and large spurious waves appearing in the harmonic region.

An object of the present invention is to provide a dielectric filter that improves the filter characteristics of the prior art as described above, has significantly improved attenuation characteristics, and reduces spurious.

[Means for Solving the Problems] The present invention, which can achieve the above-mentioned objects, consists of providing a plurality of resonator holes and coupler holes alternately in the longitudinal direction of a rectangular parallelepiped-shaped dielectric block. , wherein one of the surfaces of the dielectric block where the resonator hole is open is an open surface, and a metallized layer is formed on the other outer surface and the inner surface of the resonator hole, wherein both side surfaces of the dielectric block This is a dielectric filter in which a ground plate is provided on the side of the dielectric block, and the ground plates on both sides are connected by a strip-shaped conductor so as to cover the connector hole portion of the open face of the dielectric block while being separated from the open face. .

Such a ground plate and a band-shaped conductor can be manufactured extremely easily and inexpensively by, for example, punching and forming a thin metal plate and bending the metal plate.

[Function] When connecting the ground plates on both sides with a strip-shaped conductor so as to cover the connector hole part of the open surface of the dielectric block while keeping it spaced apart from the open surface, the detailed reason is still not fully elucidated. Not that there is, but
The amount of attenuation at frequencies outside the band becomes extremely large, and it is possible to provide extremely good characteristics with almost no spurious.

This has been confirmed through experiments.

[Embodiment] FIG. 1 is an exploded perspective view showing an embodiment of a dielectric filter according to the present invention, and is an example of a five-stage configuration. Figure 2 is a sectional view after assembly.
FIG. 3 is a sectional view showing the state in which each is housed in a housing.

The dielectric filter has five 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 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 further formed on both side surfaces, both end surfaces, the bottom surface of the dielectric block 10, and the inner surface of each resonator hole 12. Therefore, in this case, the upper surface of the dielectric block 10 becomes an open surface. Coupling capacitors 18 are mounted and fixed on the open ends of the coupler holes located at both ends of the dielectric block 10, thereby connecting to an external circuit.

In the drawings, portions where the dielectric base is exposed as is without metallization are shown with small dots. Although the metallized layer 16 is depicted as having a considerable thickness for ease of understanding, it is actually extremely thin and is formed by baking silver paste or the like.

Now, as is clear from Figures 1 and 2,
The present invention is significantly different from the prior art in that ground plates 20 are attached to both sides of the dielectric block 10, and the portions of each connector hole 14 on the open surface of the dielectric block 10 are separated from the open surface. A band-shaped conductor 22 connects between the ground plates 20 on both sides so as to cover the ground plate 20 in a state (without coming into close contact with the open surface).
The point is that we have established this.

The ground plate 20 and the strip-shaped conductor 22 can be easily manufactured integrally by punching and bending a thin metal plate. In other words, it is punched out leaving two rectangular parts corresponding to the side shape of the dielectric block 10 and a band-shaped part that connects them, and the connecting part between the rectangular parts and the band-shaped part is formed at an almost right angle. All you have to do is bend it. Of course, the ground plate and the strip conductor may be manufactured separately and connected by soldering, welding, or the like. The ground plate 20 and the dielectric block 10 are fixed with a conductive adhesive or the like.

Such a dielectric filter may be further housed in a metal housing 24 as shown in FIG. The ground plate 20 and the metal casing 24 are also fixed with a conductive adhesive or the like so as to be electrically conductive. In particular, as shown in FIG. 4, if a large number of U-shaped notches 26 are provided in the grounding plate 20, and the tongue portions 28 formed thereby are bent slightly outward, the structure shown in FIG. As shown, when inserted into the housing 24, the tongue portion 28 comes into contact with the inner wall surface of the housing 24 due to its spring properties, thereby establishing a reliable electrical connection with the housing 24 without using a conductive adhesive. Mechanical fixation can also be performed.

Now, FIG. 5 is a comparative explanatory diagram of the characteristic curves of the dielectric filter according to the present invention and the dielectric filter of the conventional structure. In the figure, the characteristic curve shown by a solid line is the measurement result for the product of the present invention, and the characteristic curve shown by the broken line is the measurement result for the conventional product. As is clear from FIG. 5, in the product of the present invention, the attenuation is extremely large in the out-of-band frequencies, and the spurious in the harmonic region twice the resonance frequency fo is extremely small. From these measurement results, it is clear that the present invention can exhibit far more favorable filter characteristics than the prior art.

The metallized layer 16 formed on the outer surface of the dielectric block 10 and the inner surface of the resonator hole 12 may be formed by applying a conventionally known technique, such as applying a silver paste and baking it. Furthermore, the shape of the strip-shaped conductor that connects both ground plates can be arbitrary, and the hole opened on the top surface of the dielectric block can be shaped not only squarely as in this example but also roundly, hexagonally, etc. The shape of the conductor may be as follows.

The structure of the input/output coupling section is also arbitrary. In the above embodiment, the input/output coupling capacitors are mounted on the open sides of the resonator holes located at both ends of the dielectric block and connected to the external circuit, but the input/output coupling capacitors are placed at both ends of the dielectric block. Alternatively, a hole may be formed and a coupling pin inserted thereinto be coupled to an external circuit. Of course, the number of stages of the dielectric filter, ie, the number of resonator holes formed in the dielectric block, is also arbitrary.

[Effects of the invention] As described above, the present invention provides ground plates on both sides of the dielectric block, and also provides earth plates on both sides so as to cover the connector hole portion of the open surface of the dielectric block while being spaced from the open surface. Since a band-shaped conductor is provided to connect the ground plates on the surface, the amount of attenuation at out-of-band frequencies is extremely large, spurious noise can be kept low, and extremely good filter characteristics can be achieved. It is possible to have a certain effect.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the dielectric filter according to the present invention, FIG. 2 is a sectional view after assembly, FIG. 3 is a sectional view showing the dielectric filter housed in a housing, and FIG. The figure is a partial perspective view showing another embodiment of the ground plate, and FIG. 5 is a comparative explanatory diagram showing the difference in filter characteristics between the present invention and the prior art. 10...Dielectric block, 12...Resonator hole,
14... Connector hole, 16... Metallized layer, 18
...Coupling capacitor, 20... Earth plate, 22
...band-shaped conductor, 24...casing.

Claims (1)

[Scope of utility model registration request] A plurality of resonator holes and coupler holes are provided alternately in the longitudinal direction of a rectangular parallelepiped dielectric block, and one of the surfaces of the dielectric block where the resonator holes are open is an open surface, and the other surface is open. In a dielectric filter having an integrated structure in which a metallized layer is formed on the surface and the inner surface of the resonator hole, a ground plate is provided on both end surfaces of the dielectric block, and a portion of the coupler hole on the open surface of the dielectric block is provided. A dielectric filter characterized in that a band-shaped conductor is provided to connect between ground plates on both sides so as to cover the open surface while being separated from the open surface.