JP3250378B2 - Dielectric filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The present invention relates to a dielectric filter used for a mobile communication device such as a mobile phone.

[0002]

2. Description of the Related Art The applicant of the present invention has proposed a dielectric filter in which an excitation hole is provided in a dielectric block and an external coupling is obtained by electromagnetic field coupling between the excitation hole and a resonator hole adjacent to the excitation hole (Japanese Patent Application Laid-Open No. H10-163,197). 6-134475, Japanese Patent Application No. 6-14667
3). As a dielectric filter provided with such excitation holes, for example, there is an antenna duplexer having a structure as shown in FIG. FIG. 3A is an external perspective view of the antenna duplexer viewed from the open end face side, with the bottom surface serving as a mounting surface shown above, and FIG. 3B is a plan view of the short-circuit end face. It is shown with its bottom surface facing down. In the following figure,
The dot-filled portion indicates a portion where the base of the dielectric block is visible (a portion where the conductor is not formed).

As shown in FIGS. 3A and 3B, this antenna duplexer penetrates a pair of opposed end surfaces 1a and 1b of a dielectric block 1 having a substantially rectangular parallelepiped shape, and includes seven resonators. Holes 2a to 2g are formed, and excitation holes 5a, 5b, 5c are formed between resonator holes 2a, 2b, resonator holes 2c, 2d, and resonator holes 2f, 2g, and resonator holes 2a to 2g are formed. ,
An inner conductor 3 is provided on the inner surface of each of the excitation holes 5a, 5b, 5c.
Is formed, and an outer conductor 4 is formed on substantially the entire outer surface of the dielectric block 1. The inner conductor 3 of each of the excitation holes 5a, 5b, 5c spans the short-circuit side end face 1b and one side face (bottom face).
And three input / output electrodes 7a,
7b and 7c are formed. That is, each excitation hole 5a,
The inner conductors 5b and 5c are electrically connected to the outer conductor 4 on the open end face 1a, and are separated from the outer conductor 4 on the short-circuited end face 1b.
The inner conductor 3 in each of the resonator holes 2a to 2e is separated from the outer conductor 4 by an inner conductor non-formed portion on the open end face 1a side, and is electrically connected to the outer conductor 4 on the short-circuit end face 1b.

This antenna duplexer has two resonator holes 2b, 2b.
c, a transmission filter (or reception filter) including two resonators corresponding to c, a reception filter (or transmission filter) including three resonators corresponding to resonator holes 2d, 2e, and 2f, and resonator holes on both sides. And two traps formed by the resonators corresponding to 2a and 2g.

In this configuration, the excitation hole 5a and the resonator holes 2a and 2b adjacent thereto, the excitation hole 5b and the resonator holes 2c and 2d adjacent thereto, and the excitation hole 5c and the resonator hole adjacent thereto are provided. 2f and 2g are respectively electromagnetically coupled, and external coupling is obtained by the electromagnetic field coupling. Excitation hole 5a,
Input / output electrodes 7a, 7 which are electrically connected to the inner conductors 3 of 5b, 5c
b and 7c are connected to an external circuit. Input / output electrode 7b
Is an antenna electrode that shares one input / output of the transmission filter and the reception filter.

In such a configuration in which external coupling is obtained by using such excitation holes, the coupling degree and phase of the external coupling are set by changing the positions, shapes, dimensions, etc. of the excitation holes.

[0007]

However, in a dielectric filter having an excitation hole for external coupling as described above, there is a limit in setting the external coupling depending on the shapes and positional relationships of the excitation hole and the resonator hole. , Their settings are less flexible,
When the distance between the excitation hole and the resonator hole is reduced, the external coupling becomes stronger. In order to obtain a desired external coupling, the distance between the excitation hole and the resonator hole cannot be reduced, and it has been difficult to reduce the size.

Further, the degree and phase of the external coupling are determined by the formation position, shape, etc. of the dielectric block (excitation hole and resonator hole). After the filter is formed, the external coupling cannot be adjusted. There was a problem that the defect rate was high.

When the resonator holes are provided on both sides of the excitation hole as described above, the two resonator holes sandwiching the excitation hole are directly coupled to each other and interfere with each other to make it difficult to adjust the filter characteristics.
It was difficult to obtain good characteristics.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the conventional dielectric filter, to increase the degree of freedom in setting the external coupling, and to adjust the external coupling. An object of the present invention is to provide an inexpensive, high-performance dielectric filter which can suppress unnecessary coupling between the filters and can therefore be reduced in size.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, a resonator hole is formed between a pair of opposed end faces of a dielectric block, and an inner surface of the resonator hole is formed. Forming an inner conductor, in a dielectric filter having an outer conductor formed on an outer surface of a dielectric block, next to the resonator hole corresponding to an input / output stage, providing an excitation hole having an inner conductor formed on the inner surface thereof, An external coupling adjustment hole having an inner conductor formed on an inner surface thereof is provided near the excitation hole.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, a part of the inner conductor of the excitation hole or the external coupling adjustment hole is cut off to adjust the external coupling and the phase. is there.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the conductive member is electrically connected to the inner conductor of the excitation hole over one end face of the dielectric block or over the end face and the side face. And an input / output electrode separated from the outer conductor is formed.

[0014]

According to the first aspect of the present invention, a desired external coupling can be set by changing the formation position, shape, and size of the external coupling adjusting hole. That is, by newly providing the external coupling adjustment hole, the degree of freedom in setting the external coupling can be increased. In the case where the resonator holes are provided on both sides of the excitation hole, the coupling between the two resonator holes sandwiching the excitation hole can be suppressed.

According to the second aspect of the present invention, the external coupling and the phase can be adjusted by removing a part of the inner conductor of the excitation hole or the external coupling adjusting hole.

According to the third aspect of the present invention, in addition to the above-mentioned operation, it is possible to connect to an external circuit by input / output electrodes which are conducted to the inner conductor of the excitation hole.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing embodiments thereof. In the figure, the same reference numerals are given to parts having the same or corresponding functions and the same functions as those of the conventional example.

FIG. 1 shows the structure of an antenna duplexer according to an embodiment of the present invention. FIG. 1A is an external perspective view of the duplexer as viewed from the open end face side, with the bottom surface serving as a mounting surface shown above, and FIG. 1B is a plan view of the short-circuit end face, and FIG. Is shown with its bottom face down.

As shown in FIGS. 1A and 1B, the antenna duplexer of this embodiment penetrates a pair of opposed end surfaces 1a and 1b of a dielectric block 1 having a substantially rectangular parallelepiped shape. Are formed, and the resonator holes 2a, 2g are formed.
b, between the resonator holes 2c, 2d and the resonator holes 2f, 2g, the excitation holes 5a, 5b, 5c and the external coupling adjustment holes 6a, 6
b, 6c are formed, each resonator hole 2a to 2g, each excitation hole 5a, 5b, 5c and each external coupling adjustment hole 6a, 6b, 6
An inner conductor 3 is formed on each of the inner surfaces of c, and an outer conductor 4 is formed on substantially the entire outer surface of the dielectric block 1.
That is, the antenna duplexer according to the present embodiment is obtained by newly providing the external coupling adjustment holes 6a, 6b, and 6c to the one shown in FIG. 3 described above. The configuration is the same as that described above, and the description thereof is omitted.

The external coupling adjusting holes 6a, 6b, 6c are provided in the vicinity of the excitation holes 5a, 5b, 5c.
a, 5b, and 5c are formed in parallel with each other, and the inner conductors 3 formed on the inner surfaces thereof have outer conductors 4 at the open end surface and the short-circuit end surface.
It is conducting. That is, the external coupling adjustment holes 6a, 6b,
Each inner conductor 3 in 6c functions as an earth conductor together with the outer conductor 4.

This antenna duplexer is configured such that each excitation hole and the adjacent resonator hole are electromagnetically coupled to each other, and this electromagnetic field coupling obtains external coupling of the input / output portion of the antenna duplexer. I have.

In this configuration, the self-capacity of the excitation hole can be increased or decreased by changing the formation position, shape, and inner size (size) of the external coupling adjustment hole provided near each excitation hole. , The external coupling can be changed, and a more appropriate external coupling can be set. That is, by newly providing the external coupling adjustment hole, the degree of freedom in setting the external coupling can be increased.

Here, the self-capacitance of the excitation hole is the capacitance generated between the inner conductor of the excitation hole and the ground conductor (the outer conductor and the inner conductor of the outer coupling adjustment hole). By providing the external coupling adjustment hole, the self-capacity of the excitation hole can be increased.By reducing the distance between the excitation hole and the external coupling adjustment hole, the self-capacity of the excitation hole can be increased and the external coupling can be weakened. Conversely, by increasing the distance between the excitation hole and the external coupling adjustment hole, the self-capacity of the excitation hole can be reduced and the external coupling can be strengthened.

As described above, by providing the external coupling adjustment hole, the external coupling can be weakened, so that the distance between the excitation hole and the resonator hole can be reduced, and the size can be reduced. That is, in the present embodiment, the resonator holes 2a, 2b
The distance (pitch) between the resonator holes 2c and 2d and between the resonator holes 2f and 2g can be further reduced.

Further, the coupling between the two resonator holes sandwiching the excitation hole and the external coupling adjusting hole can be suppressed by the external coupling adjusting hole. In this embodiment, the external coupling adjustment hole 6
By a, 6b and 6c, direct coupling between the resonator holes 2a and 2b, between the resonator holes 2c and 2d, and between the resonator holes 2f and 2g can be suppressed. That is, a trap formed by the resonator hole 2a, a filter formed by the resonator holes 2b and 2c, a filter formed by the resonator holes 2d, 2e and 2f, and a trap formed by the resonator hole 2g, respectively. Can be greatly reduced, so that the characteristics of each filter and trap can be easily adjusted, and good characteristics can be obtained.

Also, after the filter is formed, a part of the inner conductor in the excitation hole or the external coupling adjustment hole is scraped off by a router or the like, so that the self-capacity of the excitation hole is changed to adjust the external coupling and the phase. Therefore, the characteristics can be improved and the defect rate can be reduced. in this case,
A part of the dielectric may be removed together with the inner conductor.

In the above embodiment, one external coupling adjustment hole corresponding to one excitation hole has been described. However, the present invention is not limited to this, and a plurality of external coupling adjustment holes may be provided for one excitation hole. External coupling adjustment holes may be formed,
The shape of the external coupling adjustment hole may be an arbitrary shape, and may be a cross-sectional shape such as an ellipse, a rectangle, a triangle, and a rhombus.

In the above embodiment, two dielectric blocks are used for one dielectric block.
Although a dielectric filter (antenna duplexer) having a complicated configuration in which one filter and two traps are formed has been described, the present invention is not limited to this, and one filter is formed in the dielectric block 1 as shown in FIG. The present invention can also be applied to an object.

In the dielectric filter shown in FIG. 2, two resonator holes 2, 2 are provided in a dielectric block 1, and each resonator hole 2,
Excitation holes 5 and 5 and external coupling adjustment holes 6 and 6 are formed outside 2. Also in this dielectric filter, the degree of external coupling can be changed by changing the formation position, shape, and internal size of the external coupling adjustment hole, and a part of the internal conductor in the excitation hole and the external coupling adjustment hole can be changed. , The outer coupling and phase can be adjusted. Note that the number of resonator holes formed in the dielectric block may be one.

In each of the above embodiments, the external coupling adjustment holes are provided for all the excitation holes. However, the present invention is not limited to this. The external coupling adjustment holes are provided for at least one excitation hole. It may be provided.

In each of the above embodiments, the input / output electrode is formed on the short-side end face side. However, the present invention is not limited to this, and the input / output electrode may be formed on the open end face side. The shape and the like of the output electrode are not particularly limited. Alternatively, the input / output electrodes may not be formed, and may be connected to an external circuit using metal terminals or the like.

[0032]

As described above, according to the dielectric filter of the present invention, the external coupling adjusting hole is provided near the external coupling exciting hole, and the position of the external coupling adjusting hole,
By appropriately setting the shape and dimensions, desired external coupling and phase can be obtained, and the degree of freedom in setting external coupling and phase can be increased.

Further, since the external coupling can be weakened by providing the external coupling adjusting hole, the distance between the excitation hole and the resonator hole adjacent to the excitation hole can be reduced, and the size can be reduced.

Further, the coupling between the two resonator holes with the excitation hole interposed therebetween can be suppressed by the external coupling adjusting holes. Therefore, even when a plurality of filters are formed in one dielectric block, each filter can be used. Interference between them can be eliminated, adjustment of each filter characteristic can be easily performed, and good characteristics can be obtained.

After the filter is formed, the external coupling and the phase can be adjusted by removing a part of the inner conductor or the dielectric in the excitation hole or the external coupling adjusting hole, so that the characteristics can be improved and the defect rate can be improved. Can be greatly reduced, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1A is an external perspective view of an antenna duplexer according to an embodiment of the present invention, and FIG. 1B is a plan view of an end face on the short-circuit side of FIG.

FIG. 2 is an external perspective view of a dielectric filter according to another embodiment of the present invention.

3A is an external perspective view of a conventional antenna duplexer, and FIG. 3B is a plan view of the short-circuit side end face of FIG. 3A.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric block 2, 2a-2g Resonator hole 3 Inner conductor 4 Outer conductor 5, 5a-5c Excitation hole 6, 6a-6c External coupling adjustment hole 7, 7a-7c Input / output electrode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01P 1/205 H01P 1/213 H01P 5/08

Claims (3)

(57) [Claims] 1. A dielectric having a resonator hole formed between a pair of opposed end faces of a dielectric block, an inner conductor formed on an inner surface of the resonator hole, and an outer conductor formed on an outer surface of the dielectric block. In the body filter, an excitation hole having an inner conductor formed on the inner surface thereof is provided next to the resonator hole corresponding to the input / output stage, and an outer coupling adjustment hole having an inner conductor formed on the inner surface near the excitation hole. A dielectric filter comprising: 2. The dielectric filter according to claim 1, wherein a part of the inner conductor of the excitation hole or the external coupling adjustment hole is cut off to adjust the external coupling and the phase. 3. An input / output electrode formed on one end face of the dielectric block, or on the end face and the side face thereof, to conduct to an inner conductor of the excitation hole and to separate from an outer conductor. 3. The dielectric filter according to claim 1 or 2.