JP2715350B2 - Dielectric filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter, and more specifically, to a dielectric filter having a predetermined shape of a conductor in a resonator interposed between a plurality of stacked dielectric blocks. Regarding improvement.

[0002]

2. Description of the Related Art Dielectric filters are used for components of automobile telephones, portable telephones and various other mobile communication circuits. In such mobile communication, the frequency band used is changed from the VHF band to the UH
It is shifting to ultra-high frequency in the F band. Along with this, various shapes and configurations of dielectric filters have been developed.

[0003] Japanese Patent Application Laid-Open No. 57-204602 discloses an example of an object for providing a small, high-quality and inexpensive dielectric filter. That is, the dielectric filter disclosed in this publication has the structure shown in FIG.
As shown in the figure, a pair of rectangular flat plate-shaped dielectric blocks 1
A metal plate 2 of a predetermined shape is interposed between the two.
The metal plate 2 includes a conductor 2a in the resonator that resonates at a quarter wavelength or an integral multiple thereof, and a ground conductor 2b commonly connected to one side of the conductor 2a in the resonator.

[0004]

In the above-described conventional dielectric filter, a dielectric filter comprising a quarter-wave coaxial dielectric resonator or the like in which a predetermined portion of a cylindrical dielectric is covered with a conductor. Although they are smaller in size, higher in quality, and less expensive than those described above, they cannot sufficiently meet the demand for further downsizing of a device body such as a mobile phone on which such a dielectric filter is mounted. That is, in the above-described conventional dielectric filter, the length of the conductor 2a in the resonator constituting the metal plate 2 needs to be at least 1/4 wavelength long. The dimensions were limited, and further miniaturization was not possible. As a result, the mounting area (projection area) becomes large, which causes a problem in miniaturizing a device such as a mobile phone to be finally mounted.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has as its object to provide a small, inexpensive, and excellent dielectric filter having a length of a quarter wavelength or less. Is to provide.

[0006]

In order to achieve the above object, in a dielectric filter according to the present invention, a dielectric block main body formed by stacking a plurality of dielectric blocks is provided. A dielectric filter comprising: an intra-resonator conductor interposed in a gap formed between two adjacent dielectric blocks of a block; and a ground layer formed on substantially the entire outer periphery of the dielectric block. Is assumed. The conductor in the resonator is bent and continuously arranged in a plurality of different gaps, one end of the continuous conductor in the resonator is connected to the ground layer, and the other end is an open end. So that Further, the dielectric block sandwiched between the bent resonator inner conductors is configured to have a dielectric constant smaller than that of another dielectric block (claim 1).

[0007] Preferably, the intra-resonator conductor is bent inside the dielectric block, and between the bent series of bent intra-resonator conductors located in the gaps.
An earth portion connected to the earth layer is inserted and arranged (claim 2). Further, an auxiliary earthing portion may be provided outside the open end portion of the inner conductor of the resonator (claim 3).

[0008]

Since the conductor in the resonator is bent and located over different gaps, for example, a length corresponding to a quarter wavelength may be obtained by the total length of the series of bent conductors in the resonator. Therefore, the length of the dielectric filter is shorter than a quarter wavelength. In addition, since a ground portion is provided between the bent series of resonator inner conductors located in the plurality of gaps, upper and lower patterns forming the series of resonator inner conductors respectively face the ground portion. To do
There is no distribution capacitance between the patterns, and a desired size and shape can be achieved (miniaturization is achieved). If the dielectric constant of the dielectric block sandwiched between the bent resonator inner conductors is made smaller than the dielectric constant of the other dielectric blocks, the dielectric block is generated even when the thickness of the dielectric block having a small dielectric constant is reduced. The distribution capacity does not change. Therefore, the thickness can be reduced while suppressing the adverse effects caused by the distributed capacitance, and the size of the entire dielectric filter can be reduced. Further, according to the second aspect of the present invention, since a series of bent conductors in the resonator as well as the bent portions are present inside the dielectric block, the continuity of the characteristic impedance of the conductor in the resonator is maintained. Can be substantially maintained from the short-circuit end to the open end, whereby the Q of the resonator can be maintained high. Moreover,
There is no influence from the approaching members, and the radiation loss does not increase, so that the characteristics do not deteriorate. Further, desired characteristics can be obtained without a part of the conductor in the resonator being accidentally removed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an example of the structure of the basic configuration of the dielectric filter according to the present invention. As shown in the figure, first, three dielectric blocks 10a, 10b, 1 on a rectangular flat plate having substantially the same planar shape and substantially the same thickness.
0c are sequentially stacked to form the dielectric block main body 10. The input / output terminal patterns 12, 12 each having a substantially L-shape in a plane are formed at adjacent upper and middle gaps between the dielectric blocks 10a, 10b, that is, at predetermined positions on the upper surface of the middle dielectric block 10b. One ends 12a of the input / output terminal patterns 12, 12 reach the same side A of the dielectric block 10b, and the other ends 12a.
The b and 12b are formed so as to reach opposite sides B and C adjacent to the side A, respectively.

The input / output terminal patterns 12,
A strip-shaped first pattern 15, which constitutes a part of the in-resonator conductor pattern 14, is formed between the conductor patterns 12. The first pattern 15 has one end 15a located on one side A where the one end 12a of the input / output terminal pattern 12 is located,
The other end 15b is extended toward the opposite side D of one side A, and a predetermined distance is formed between the other end 15b and the opposite side D.

A second pattern 16 penetrating vertically through the central dielectric block 10b is formed so as to be continuous with the other end 15b of the first pattern 15. Further, the dielectric block 10b and the lower dielectric block 1
0c, that is, the dielectric block 1
On the lower surface of the first pattern 15, a third surface parallel to the lower end 16 a of the second pattern 16 and parallel to the first pattern 15 is formed.
A pattern 17 is formed. Then, the tip 17a of the third pattern 17 (the non-contact side with the second pattern 16)
Are located at a predetermined distance from one side A of the dielectric block 10b. That is, the third pattern 17 and the first pattern 15 are formed of strips having the same width, and the third pattern 17 is shorter by a predetermined length. Then, the first to third patterns 15
The conductor pattern 14 in the resonator which is bent at the positions 17 to 17 is formed, and the total of the lengths of the patterns 15 to 17 is
The wavelength is set to be approximately 1/4 wavelength.

Further, in the present embodiment, the ground layer 18 is formed by being surrounded by a conductor over substantially the entire periphery of the dielectric block main body 10 except for the periphery of the other ends 12b, 12b of the input / output terminal patterns 12, 12. . One end 12a of the input / output terminal pattern 12, 12 and one end 15a of the first pattern 15 constituting the resonator internal conductor 14 are connected to the ground layer 18, and grounded.

With this configuration, a dielectric filter having an equivalent circuit as shown in FIG. 1C is formed. In the dielectric filter of this embodiment, the conductor pattern 14 in the resonator is folded as described above. Therefore, the length in the direction in which the in-resonator conductor pattern 14 extends can be made shorter than the length of １ ／ wavelength, and the length of the dielectric filter can be shortened.

Here, an example of a method of manufacturing the dielectric filter having the above-described configuration will be described. For example, a conductor paste is applied to predetermined portions of the upper and lower surfaces of the dielectric block 10b by screen printing and then sintered at a low temperature. The first and third patterns 15 and 17 are formed by etching, etc., and a conductive paste is poured into a through hole formed at a predetermined position of the dielectric block 10b, or a metal plate is inserted and arranged. The second pattern 16 can be formed.

When each pattern is formed using a conductive paste, the conductive paste is screen-printed at a predetermined position on a dielectric ceramic green sheet that can be sintered at a low temperature, dried, superposed, and pressed. Thereafter, by performing simultaneous sintering, the dielectric filter can be manufactured by one sintering.

In addition, alignment and each pattern 15
As long as the connection between .about.
The first pattern 15 and the third pattern 17 may be formed on the lower surface of Oa or the upper surface of the lower dielectric block 10c.

FIG. 2 shows still another basic form. In this example, unlike the above, the conductor 14 ′ is formed by bending a plurality of times (three times in this example). Accordingly, a plurality of dielectric blocks 10b constituting an intermediate layer are provided.

With such a configuration, even if the wavelength becomes long, the manufactured dielectric filter can be suppressed within a predetermined size and shape, and if the wavelength is the same, a smaller dielectric filter can be used. Can be manufactured. In addition, other configurations and operational effects are described in FIG.
The detailed description is omitted because it is the same as that of the basic mode shown in FIG.

FIG. 3 shows a first embodiment of the dielectric filter according to the present invention. In the present example, based on the basic configuration shown in FIG.
The dielectric constant .epsilon.1 of the dielectric block 10b constituting the intermediate layer sandwiched between the upper and lower dielectric blocks 10b
a, 10c (consisting of a dielectric having a small dielectric constant). That is, the distribution capacitance generated between the first pattern 15 and the third pattern 17 is
Since it is proportional to the dielectric constant and inversely proportional to the distance between the two tubes, that is, the thickness t1 of the dielectric block 10b, ε1
Is reduced, the generated distributed capacitance does not change even if the thickness t1 is reduced. Therefore, the thickness t1 can be reduced while suppressing the adverse effect caused by the distributed capacitance, and the size of the entire dielectric filter can be reduced.

The other configuration and operation and effect are the same as those of the above-described examples, and thus detailed description is omitted. In addition, the structure using the dielectric blocks having different dielectric constants in this example can be applied to the basic embodiment shown in FIG. 2 as a matter of course.

FIG. 4 shows a third example of the dielectric filter according to the present invention.
Is shown. In the present example, the ground pattern 20 is inserted and arranged in the bent conductor 14 ″ in the resonator based on the first basic form shown in FIG. The dielectric block 10b constituting the layer is divided into upper and lower two layers, and a conductive paste is applied to a predetermined position between the blocks 10b 'and 10b' constituting the two layers, or a metal plate is inserted and arranged. A ground pattern 20 is formed, and the ground pattern 20 is composed of the first pattern 15 "and the third pattern 1 constituting the resonator internal conductor 14".
7 "and the three members 15", 1
7 ", 20 are arranged at a position where they coincide with each other in the vertical direction, one end 20a of which is connected to the earth layer 18" provided around the dielectric block 10, and the other end 20b of which forms the in-resonator conductor 14. The two patterns 16 "are located at positions separated by a predetermined distance.

By adopting such a configuration, an adverse effect due to the distributed capacitance generated between the first pattern 15 "and the third pattern 17" is suppressed.
7 "can be shortened. As a result, the thickness can be further reduced.

Further, in the above configuration, when first looking at the first pattern 15 "of the conductor 14" in the resonator, it is sandwiched from above and below by the earth layer 18 "and the earth pattern 20 located on the upper surface side. Similarly, the third pattern 17 "is sandwiched from above and below by the ground pattern 20 and the ground layer 18" located on the bottom surface side, so that the Q value of the dielectric filter can be improved. Because of this, the upper dielectric block 10a and both blocks 10
It is preferable that the thicknesses of b ', 10b' and the lower dielectric block 10c are equal (t3).

[0024] Since other configurations, functions and effects are the same as those of the above-described basic embodiments, detailed description will be omitted. Further, the structure in which the ground pattern is interposed in the present example can be applied to the above-described second basic mode shown in FIG. 2, and in such a case, it is necessary to insert and arrange the ground pattern between all the patterns. However, it can be formed at an appropriately selected place.

FIG. 5 shows a second embodiment of the dielectric filter according to the present invention. As shown in FIG.
This is based on the third basic mode described above. That is,
An earth pattern 20 is inserted and arranged at a predetermined position in the bent resonator inner conductor 14 ". In this embodiment, the dielectric constant ε3 of the two blocks 10b 'and 10b' constituting the intermediate layer is determined. The other upper or lower dielectric block 10
a, 10c are smaller than the permittivity ε4. As a result, the thickness of the blocks 10b 'and 10b' constituting the intermediate layer can be reduced as in the first embodiment, and the effect of the insertion of the ground pattern 20 can be synergistically reduced to make the device smaller (thinner). Can be done. Note that the other configuration, operation, and effect are the same as those of the above-described embodiments, and thus detailed description is omitted.

FIG. 6 shows a third embodiment according to the present invention. As shown in the drawing, in the present embodiment, unlike the above-described embodiments, the resonance composed of a plurality of resonators (three in this embodiment, but the number is arbitrary) is shown. A dielectric filter (an equivalent circuit is as shown in FIG. 3B) is formed by using the internal conductor 22. In addition,
In this example, the dielectric filter (conductor in the resonator) shown in the first embodiment is used as a base.
The configurations of any of the above-described embodiments can be applied, and they can be appropriately combined. That is, one of the plurality of resonators is formed by bending only once, and the other is formed by bending a plurality of times (the number of times of bending may be changed as necessary) as in the second basic mode. Or Then, the dielectric constant of the dielectric block constituting the intermediate layer sandwiched between the bent resonator inner conductors 22 is made smaller than the dielectric constants of the other dielectric blocks.

Further, in the present invention, as shown by the imaginary line in FIG. 5, the open end (third pattern 1
The auxiliary grounding portion 24 may be provided so as to be close to the outside of the 7 ″ end. With such a configuration, the auxiliary grounding portion 24 is generated between the auxiliary grounding portion 24 and the conductor 14 ″ in the resonator. The resonance frequency is lowered by the load capacitance.
Therefore, the length of the conductor in the resonator required to resonate at a desired frequency can be shortened, and the size of the dielectric filter can be further reduced. Note that the auxiliary grounding section 24 is not limited to the configuration shown in FIG. 5, that is, the second embodiment, and can be applied to all the above-described embodiments and modifications.

In each of the above-described embodiments, an example in which the conductor in the resonator is formed of a thin film or a thick film has been described. However, the present invention is not limited to this. Alternatively, it may be formed from various materials. Further, the input / output terminal patterns are merely examples, and it is needless to say that various configurations conventionally used can be used.

[0029]

As described above, in the dielectric filter according to the present invention, since the conductor in the resonator is bent and located over different gaps, for example, the length for １ ／ wavelength is:
Since it is only necessary to obtain the entire length of the series of bent conductors in the resonator, the distance in the length direction can be made shorter than １ ／ wavelength, and the size of the dielectric filter can be reduced. .

Further, it is only necessary to bend the conductor in the resonator, and a substantially flat dielectric block can be used. Therefore, even if the size is reduced, the manufacturing cost can be reduced. Can be planned. Since the dielectric constant of the dielectric block sandwiched between the bent conductors in the resonator is reduced, the Q of the resonator can be kept high, and as a result, the size can be reduced.

[Brief description of the drawings]

FIG. 1A is a perspective view showing a first basic mode of a dielectric filter according to the present invention. FIG. 3B is a cross-sectional view taken along line BB in FIG. (C) is an equivalent circuit diagram thereof.

FIG. 2 is a sectional view showing a second basic mode of the dielectric filter according to the present invention.

FIG. 3 is a sectional view showing a first embodiment of the dielectric filter according to the present invention.

FIG. 4 is a sectional view showing a third basic mode of the dielectric filter according to the present invention.

FIG. 5 is a sectional view showing a second embodiment of the dielectric filter according to the present invention.

FIG. 6A is a perspective view showing a third embodiment of the dielectric filter according to the present invention. FIG. 3B is a cross-sectional view taken along line BB in FIG.

FIG. 7 is a perspective view showing an example of a conventional dielectric filter.

[Explanation of symbols]

 10a, 10b, 10c Dielectric block 14, 14 ', 14 "Conductor in resonator 20 Earth pattern (earth part) 24 Auxiliary earth part

Claims (3)

(57) [Claims] 1. A dielectric block main body configured by stacking a plurality of dielectric blocks and being interposed in a gap formed between two adjacent dielectric blocks among the plurality of dielectric blocks. A dielectric filter comprising: a resonator inner conductor; and a ground layer formed on substantially the entire outer periphery of the dielectric block, wherein the resonator inner conductor is bent and continuous in a plurality of different gaps. One end of the continuous in-resonator conductor is connected to the ground layer, and the other end is arranged to be an open end, and the continuous inner conductor is sandwiched between the bent inner conductors. A dielectric filter, wherein the dielectric constant of a dielectric block is smaller than that of another dielectric block. 2. The resonator inner conductor is bent inside the dielectric block, and is connected to the ground layer between the bent series of bent resonators located in the plurality of gaps. The dielectric filter according to claim 1, wherein a grounded portion is inserted and arranged. 3. The dielectric filter according to claim 1, wherein an auxiliary earth portion is provided outside an open end portion of the conductor in the resonator.