JPH0846402A - Dielectric filter and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to improve the formation accuracy of the non-conductor part near both open ends of the input / output terminal hole and the open end of the resonator hole on the open side and to stabilize the characteristics, and moreover, easily. In addition, the non-conductor portion can be formed at low cost. Arranged in the longitudinal direction of a rectangular parallelepiped dielectric block 10 are resonator holes 12a, ..., 12c, and input / output terminal holes 14a, 1 penetrating in parallel with the resonator holes at both ends in the vicinity of the resonator holes.
4b is provided. The outer conductor 16 is provided on most of the outer surface of the dielectric block, and the resonator inner conductor is formed on the inner surface of the resonator hole so that one opening end is the open side and the other opening end is the short-circuit side.
An input / output conductor separated from the outer conductor is formed over the entire inner surface of the input / output terminal hole. In the dielectric block, island-shaped projections 22 and 23 projecting in the axial direction of the hole are integrally formed in the vicinity of the open end of the resonator hole and in the vicinity of both open ends of the input / output terminal holes. It has a structure, and the entire tip surface is a non-conductive surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integral structure coaxial dielectric filter using a rectangular parallelepiped dielectric block,
More specifically, a dielectric filter in which an input / output terminal hole is formed at a position near the ends of the dielectric block near the resonator holes located at both ends and independent input / output conductors are formed on the inner surface of the dielectric filter, and the manufacturing thereof. It is about the method. This dielectric filter is useful for various wireless devices for microwaves.

[0002]

2. Description of the Related Art A plurality of resonator holes are arranged at a predetermined interval in a longitudinal direction of a rectangular parallelepiped dielectric block, and an in-resonator conductor is formed on an inner surface of the resonator hole. A coaxial type dielectric filter having an outer conductor formed on a predetermined outer surface is conventionally known. In that case, regarding the adjacent resonator holes, the short-circuit side (the side where the conductor inside the resonator is electrically connected to the outer conductor) and the open side are alternately provided, and the short-circuit side (or open side). There is a comb line type installed in the same direction.

Resin pins are generally used as the input / output terminal structures of these dielectric filters.
In order to meet the demand for miniaturization, I / O terminal holes are provided near the dielectric block ends near the resonator holes on both ends, and I / O conductors are provided over the entire length of the inner surface of the I / O terminal holes. Has been adopted.

Also, in order to be compatible with surface mounting, in the case of the comb line type as well, the entire open surface, which is one of the surfaces where the resonator holes of the dielectric block are open, is not a non-conductive surface. , A non-grounding type that does not deteriorate the attenuation characteristics even if there is no grounding metal by forming a non-conductor part in an annular shape only on the opening edge periphery on the open side of the resonator hole and covering the other outer surface with an outer conductor. It is also done.

[0005]

In order to make only the vicinity of the opening end on the open side of the resonator hole a non-conductive portion, after metallizing the entire surface of the dielectric block, only the necessary hole end is conical. There is a method of rotating and grinding a circular grindstone to peel off the conductor layer, and a method of applying a conductive paste by a printing method so as to remove only a necessary hole end portion into an annular shape and baking it.

However, although the peeling of the conductor layer by the rotating grindstone is simple, the precision of the peeling work is poor and the characteristics cannot be stabilized. That is, there are some cases where the characteristics are deteriorated due to variations in peeling dimension. On the other hand, in forming the outer conductor by the printing method, although the accuracy can be improved and the characteristics can be stabilized, the number of steps is increased and the manufacturing cost is increased.

The object of the present invention is to improve the formation accuracy and stabilize the characteristics of the non-conductor portion provided near the open end of the resonator hole and near both open ends of the input / output terminal hole. Moreover, it is an object of the present invention to provide a dielectric filter having a structure capable of easily and inexpensively forming a non-conductive portion, and to provide a method of manufacturing the same.

[0008]

According to the present invention, a plurality of resonator holes are arranged in the longitudinal direction of a substantially rectangular parallelepiped dielectric block, and the dielectric block end portions near the resonator holes located at both ends are close to each other. I / O terminal hole penetrating in parallel with the resonator hole is provided at the position, the outer conductor is provided on most of the outer surface of the dielectric block, and the resonator inner conductor is formed on the inner surface of each resonator hole. One open end is the open side, the other open end is the short-circuit side,
It is a dielectric filter in which an input / output conductor (which is electrically non-conductive) separated from the outer conductor is formed over the entire inner surface length of both input / output terminal holes. Here, the dielectric block is integrally formed with island-shaped protrusions protruding in the hole axis direction in the vicinity of the open end of each resonator hole and in the vicinity of both open ends of both input / output terminal holes. With the above structure, the entire tip surface of the protrusion is a non-conductive surface, and this is a feature of the present invention. The resonator holes located at the ends of the dielectric block and the protrusions provided at the open ends of the input / output terminal holes preferably have a common island structure. Further, it is preferable that the protrusions protruding in the same direction have the same protrusion height.

Such a dielectric filter can be easily manufactured by the following steps. First, a plurality of resonator holes are arranged in the longitudinal direction of a substantially rectangular parallelepiped dielectric block, and at the positions near the ends of the dielectric block near the resonator holes at both ends, the resonator holes are penetrated in parallel with the resonator holes. I / O terminal holes are provided, and island-shaped projections projecting in the hole axis direction are formed near the open ends of both input / output terminal holes and near one open end of each resonator hole. Is integrally molded using. next,
The entire surface of the dielectric block having the protrusion is metallized. Then, the conductor layer adhered to the entire tip surface of the protrusion is pressed against the rotating sand belt to be peeled off.

[0010]

The projection functions to define the non-conductor portion.
That is, when the dielectric block is molded, the projection is also molded at the same time, and the shape of the projection is determined by the press die, so there is almost no variation. Since the non-conductor portion is the entire tip surface of the protrusion, the shape accuracy of the non-conductor portion is improved and the characteristics are stabilized. One of the resonator holes forming the in-resonator conductor has an open side and the other has a short-circuit side to form a quarter-wave resonator, which produces a predetermined filter characteristic. Since most of the dielectric block is covered with the outer conductor, the electric wave leakage is reduced and the attenuation characteristic is improved. This type of dielectric filter does not require the use of a metal casing, and therefore can be made smaller. Since the input / output coupling capacitance is determined by the in-resonator conductors of the resonator holes at both ends and the input / output conductors of the input / output terminal holes, stable coupling can be obtained. The input / output terminal hole is provided so as to penetrate the dielectric block, the input / output conductor is formed over the entire length thereof, and the entire tip end surface of the protrusion is a non-conductive surface, so that the capacitance of the capacitor can be accurately set.

[0011]

FIG. 1 shows an embodiment of a dielectric filter according to the present invention, and A and B are perspective views of the same three-stage interdigital filter as viewed from the front and back. 2 is a sectional view thereof. As the dielectric filter, a substantially rectangular parallelepiped dielectric block 10 made of a sintered body of a high dielectric constant ceramic material for microwaves is used. Dielectric block 1
0 indicates three resonator holes 12a, 12b,
12c through which the resonator holes 12a located at both ends,
12c at a position near the end of the dielectric block near 12c and in parallel with the resonator holes 12a, ..., 12c.
This is a structure in which a and 14b are provided in a penetrating manner. Dielectric block 10
An outer conductor 16 is provided on most of the outer surface of each resonator hole 12
, 12c has an inner resonator conductor 18, and the inner surfaces of both the input / output terminal holes 14a, 14b have an input / output conductor 20.
Are formed respectively.

Here, each resonator hole 12a, ..., 12c
, One end is open side, the other end is short circuit side,
Short-circuit side and open side are alternately provided in adjacent resonator holes. That is, on the front side surface (upper surface in FIG. 2) of FIG. 1A, the resonator holes 12a and 12c at both ends are opened,
The center resonator hole 12b is the short-circuit side, and on the front side surface (lower surface in FIG. 2) of FIG.
a and 12c are the short-circuit side, and 12b is the open side. The short-circuit side is in a state where the resonator inner conductor 18 on the inner surface of the resonator holes 12a, ..., 12c and the outer conductor 16 on the outer surface of the dielectric block 10 are electrically connected, and the open side is the resonator. The inner conductor 18 and the outer conductor 16 are separated (not electrically connected). Also, the input / output terminal holes 14a,
14b, the input / output conductor 20 has the outer conductor 1 at both open ends.
It is in a state of being released from 6.

Here, the feature of the present invention is that the dielectric block 1 is used.
It has a shape of 0. That is, the dielectric block 10 does not have a perfect rectangular parallelepiped shape, but has a structure in which a protrusion is provided on the surface where the holes are opened. Each resonator hole 12a,
, 12c are integrally formed in the vicinity of the open end on the open side and in the vicinity of both open ends of both the input / output terminal holes 14a, 14b so as to project in the axial direction of the hole. Here, the resonator hole and the opening end of the input / output terminal hole located at the end of the dielectric block 10 are the common eyeglass-shaped protrusions 22 (shown in FIG. 1A), and the other parts are circular. Ring-shaped protrusion 23
As shown in FIG. 1B, a total of five protrusions are provided. The entire tip surfaces of the protrusions 22 and 23 are non-conductive surfaces (represented by fine dots), thereby realizing a state of being separated from the outer conductor 16.

As clearly shown in the sectional view of FIG. 2, the input / output terminal holes 14a and 14b are provided with the input / output conductor 20 over the entire length of the inner surface thereof. Resonator hole 12a,
.., 12c, since the conductor 18 in the resonator is slightly trimmed from the open side for fine adjustment of the resonance frequency as necessary, the open end on the open side is a tapered surface from which the conductor layer is peeled off. .

Returning to FIG. 1, both input / output terminal holes 14 are shown.
a and 14b have resonator holes 12a and 12a located at both ends.
The metal terminal 24 is inserted from the opening on the open side of c (that is, from the front surface of FIG. 1A) and connected to the input / output conductor 20 on the inner surface. The metal terminal 24 may be manufactured by punching a metal plate, and a part of the metal terminal 24 is inserted into the input / output terminal holes 14a and 14b and soldered to the input / output conductor 20.

In order to make the drawings easy to understand, the metallized (conductor layer) portions in each figure are shaded, and the conductor layer is not present and the dielectric substrate is exposed. It is indicated by adding.

Such a dielectric filter is manufactured by the process shown in FIG. First, the dielectric block 10 having a predetermined shape as shown in A is manufactured. To this end, powder press molding is performed using a mold and firing is performed as in the conventional case. The dielectric block 10 has a substantially rectangular parallelepiped shape, and has three resonator holes 12a, ..., 12c arranged in the longitudinal direction thereof, and positions near the ends of the dielectric block near the resonator holes at both ends. And the input / output terminal holes 14a, 1 penetrating in parallel with the resonator hole
4b is provided, and island-shaped projections 22 and 23 projecting in the axial direction of the hole are integrally formed near both open ends of both input / output terminal holes and near one open end of each resonator hole. The shape.

Next, as shown in B, the dielectric block 10 is entirely metallized. For example, the dielectric block may be dipped in a conductive paste and then baked. After that, as shown in C, the conductor layer attached to the entire tip surfaces of the protrusions 22 and 23 is peeled off. To do that,
The entire tip surfaces of the protrusions 22 and 23 may be pressed against the rotating sand belt. This allows the input / output terminal holes 14a,
The input / output conductor 20 is separated from the outer conductor 16 at both open ends of 14b to complete the input / output section. At the same time, resonator hole 1
.., 12c, one of the open ends of the resonator inner conductor 18 and the outer conductor 16 is disconnected to form an open side. At this stage, if necessary, the resonator hole is ground from the open side by a conical rotating grindstone to slightly shorten the total length of the conductor in the resonator to adjust it to a predetermined resonance frequency.
Finally, the metal terminal 24 is inserted into the input / output terminal holes 14a and 14b from the open end of the resonator hole in the vicinity thereof and soldered to the internal input / output conductor.

Since the conductor layer on the entire tip surface of the protrusion is peeled off by grinding or polishing, it is desirable that the protrusion heights of the protrusions 22 and 23 are the same at least on the same side. Since it is sufficient to prevent the surfaces other than the tip end surface of the protrusion from being ground, the protrusion height may be extremely small.

FIG. 4 shows another embodiment of the present invention,
It is an example of a three-stage combline type filter. Similar to FIG. 1, this FIG. 4 is also a perspective view of the same dielectric filter as seen from the front and rear opposite directions. Each resonator hole 32a, ..., 32
In c, all open sides are formed in the same direction. Here, the front surface of FIG. 4A is the open side, and projections 42 and 43 are formed around the open ends of the resonator holes 32a, ..., 32c. The surface on the opposite side (the surface on the front side of B) has no protrusion around the resonator hole. With respect to the input / output terminal holes 34a and 34b located at both ends, the protrusions 43 are provided near the openings at both ends. And each protrusion 4
The entire tip surfaces of the reference numerals 2, 43 are non-conductive surfaces, and the outer surface of the other dielectric block 30 is covered with the outer conductor 36. The metal terminals 44 are inserted into the input / output terminal holes 34a and 34b and soldered.

As a result, the resonator holes 32a, ...
The comb-line type filter has the open end located in the same direction of c as the open side. The input / output conductors on the inner surfaces of the input / output terminal holes 34a and 34b are separated from the outer conductor 36 at both ends and completely floated from the ground, and are capacitively coupled with the resonator inner conductors of the adjacent resonator holes. Will be formed.

FIG. 5 shows still another embodiment of the present invention.
Indicates a surface on the open side, and B indicates a cross section. This is the case of a two-stage filter provided with two resonator holes. Both resonator holes 52a and 52b have open sides formed in the same direction. Here, the surface shown in FIG. 5A (the upper surface of B) is the open side, and the protrusion 62 is formed around both resonator holes 52a and 52b. On the opposite surface (lower surface of B), no protrusion is provided around the resonator hole. With respect to the input / output terminal holes 54a and 54b located at both ends, protrusions 63 are provided near the openings at both ends. The outer conductor 56 is provided on the outer surface of the dielectric block 50 excluding the entire tip surfaces of the protrusions 62 and 63.
To provide.

The shape of the protrusion is not particularly limited.
When the projections are provided in the input / output terminal holes and the resonator holes adjacent to the input / output terminal holes, it is preferable to use a common eyeglass-type structure in consideration of the proximity of the two. The protrusion may be square,
It is preferable that the base edges of the protrusions are rounded to improve the metallization adhesion. The present invention can be applied to a dielectric filter having two or more stages.

[0024]

As described above, according to the present invention, projections are provided in the vicinity of both open ends of the input / output terminal hole and in the vicinity of the open end of the resonator hole, and the entire front end surface thereof is a non-conductive surface. With this configuration, the distance between the open ends of the input / output terminal holes and the resonator holes and the non-conductor portion provided between the outer conductor is constant, and variations in characteristics can be suppressed. That is, the shape of the protrusion can be controlled to be constant by a press die used for forming the dielectric block, and if the conductor layer on the entire tip surface of the protrusion is removed by a method such as grinding or polishing after metallizing the entire surface. Since it is good, the work is easy, the mass production is easy, the variation in the non-conductor portion is small, and the characteristics are stabilized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a dielectric filter according to the present invention.

FIG. 2 is a sectional view thereof.

FIG. 3 is an explanatory view showing an example of the manufacturing process.

FIG. 4 is a perspective view showing another embodiment of the dielectric filter according to the present invention.

FIG. 5 is an explanatory view showing still another embodiment of the dielectric filter according to the present invention.

[Explanation of symbols]

 10 Dielectric Blocks 12a, 12b, 12c Resonator Holes 14a, 14b Input / Output Terminal Holes 16 Outer Conductor 18 Resonator Inner Conductor 20 Input / Output Conductor 22,23 Projection 24 Metal Terminal

Claims (4)

[Claims] 1. A plurality of resonator holes are provided in the longitudinal direction of a dielectric block having a substantially rectangular parallelepiped shape, and resonator holes are provided at positions near the ends of the dielectric block near the resonator holes at both ends. An input / output terminal hole penetrating in parallel is provided, an outer conductor is provided on most of the outer surface of the dielectric block, an inner resonator resonator is formed on the inner surface of each resonator hole, and one open end is opened.
In the dielectric filter in which the other open end is the short-circuit side and the input / output conductors separated from the outer conductor are formed over the entire inner surface lengths of both the input / output terminal holes, the dielectric block is the open end of each resonator hole. The structure is such that an island-shaped protrusion projecting in the hole axial direction is integrally formed in the vicinity and in the vicinity of both open ends of both input / output terminal holes, and the entire tip surface of the protrusion is a non-conductive surface. A dielectric filter characterized by the above. 2. The dielectric filter according to claim 1, wherein the resonator hole located at the end of the dielectric block and the projection provided at the opening end of the input / output terminal hole have a common island structure. 3. The dielectric filter according to claim 1, wherein the protrusions formed in the same direction have the same height. 4. A plurality of resonator holes are arranged in the longitudinal direction of a substantially rectangular parallelepiped dielectric block, and a resonator hole is provided at a position near the ends of the dielectric block near the resonator holes at both ends. I / O terminal holes penetrating in parallel are provided, and island-shaped protrusions protruding in the hole axis direction are pressed near both open ends of both I / O terminal holes and near one open end of each resonator hole. It is characterized in that it is integrally molded using a mold, the dielectric block that has the protrusion is metallized over the entire surface, and then the conductor layer that adheres to the entire tip surface of the protrusion is pressed against the sand belt and peeled off. And method for manufacturing a dielectric filter.