JPH04302503A - Method of adjusting frequency characteristic of dielectric resonator - Google Patents

Abstract

PURPOSE:To easily adjust the frequency characteristics of a dielectric resonator. CONSTITUTION:A dielectric block 1 has 1st-4th through holes 5-8 so as to obtain two resonators. Internal conductor films 11 are formed on the wall surfaces of the 1st-4th through holes 5-8. A 1st connecting conductor film 13 for connecting the internal conductor film 11 in the 1st through hole 5 to the internal conductor film 11 in the 2nd through hole 6 is provided on the 2nd end surface 3 of the dielectric block 1 and a 2nd connecting conductor film 14 for connecting the internal conductor film 11 in the 3rd through hole 7 to the internal conductor film 11 in the 4th through hole 8 is provided. The internal conductor films 11 in the 2nd and 4th through holes 6 and 8 are connected to an external conductor film 12 by a short-circuit conductor film on the 1st end surface. Further, the internal conductor films 11 in the 1st and 3rd through holes 5 and 7 are connected to a 1st and a 2nd input/output terminal. One or both of the 1st and 2nd connecting conductor films 13 and 14 are ground to adjust the resonance frequency.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to frequency characteristic adjustment of dielectric resonators or dielectric filters used in cordless telephones, mobile telephones, car telephones, etc.

0002

[Prior Art] A conventional typical quarter-wavelength dielectric filter has a plurality of resonance holes penetrating from one end face to the other end face of a prismatic dielectric block. A coupling hole is provided between each other, an inner conductor film is provided in the resonance hole, an outer conductor film is provided on the side surface of the dielectric block, and an inner conductor film and an outer conductor film are provided on one end surface of the dielectric block. It is constructed by providing an end face conductor film for connecting (shorting).

0003

By the way, the length of the resonant hole is determined to correspond to the resonant wavelength. Therefore, when the resonant wavelength is long because the resonant frequency is low, the length of the resonant hole inevitably becomes long, making it difficult to make the device smaller or thinner. In order to solve this kind of problem, the applicant of the present invention has prototyped a resonator having a configuration in which a dielectric block is provided with a plurality of resonance holes and inner conductive films of these holes are connected in series.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for easily adjusting the frequency characteristics of a dielectric resonator which has been miniaturized or whose resonance frequency has been lowered as described above.

[0005]

Means for Solving the Problems The present invention for achieving the above object has first and second end surfaces facing each other and a side surface between them, and a a dielectric block having first and second resonance through holes formed to penetrate through the second end surface; an inner conductor provided in the first and second through holes, respectively; an outer conductor provided on the side surface of the dielectric block;
The inner conductor of the first through hole and the second
a connecting conductor film that connects the inner conductor of the second through hole to the outer conductor at the first end surface; The present invention relates to a method for adjusting frequency characteristics of a dielectric resonator, characterized in that the frequency characteristics of the body resonator are adjusted by scraping off the connecting conductor film.

Furthermore, when forming a plurality of resonators in one dielectric block by providing the third and fourth through holes, the frequency characteristics can be adjusted by scraping off the connecting conductor film.

[0007]

[Operation] By providing a plurality of through holes according to the present invention and connecting the inner conductors in series, an equivalently long through hole can be obtained, and a dielectric resonator or dielectric filter with a low resonance frequency can be obtained. Can be done. Furthermore, when the resonant frequency is made the same as the conventional one, the length (thickness) from the first end surface to the second end surface of the dielectric block can be reduced. When the connecting conductor film is scraped, a capacitance change occurs and the resonant frequency changes.

[0008]

Embodiment Next, a dielectric filter and a method for adjusting its frequency characteristics according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6. A prismatic dielectric block 1 made of dielectric ceramic for constructing a dielectric filter has a first end surface 2, a second end surface 3, and four side surfaces 4a, 4b, 4c, and 4d, and further includes: It has first, second, third, and fourth resonance holes 5, 6, 7, and 8 penetrating from the first end surface 2 to the second end surface 3, and further has first and second coupling holes. It has 9 and 10.

[0009] First, second and third arranged parallel to each other.
Inner conductor films 11 are provided on the walls of the fourth resonance holes 5, 6, 7, and 8, respectively. An outer conductor film 12 is provided on the four side surfaces 4a to 4d. On the second end surface 3,
As shown in FIG. 3, a first connecting conductive film 13 connects the inner conductive films 11 of the first and second resonance holes 5 and 6 in series with each other.
A second connection conductor film 14 is provided which connects the inner conductor films 11 of the third and fourth resonance holes 7 and 8 in series. As shown in FIG.
A short-circuit conductor film 15 is provided for connecting the resonance holes 6 and 8 to the outer conductor film 12, respectively. In addition, in order to adjust the frequency characteristics by changing the strength of the coupling, a second coupling hole 10 is provided.
A conductor film 16 is provided on the wall surface of the cell and is connected to the short circuit conductor film 15 .

When connecting the dielectric filter to the transmission line, as shown in FIG.
Then, the second terminals 17 and 18 are inserted and connected to the respective inner conductor films 11, and the outer conductor film 12 is connected to the ground conductor. Note that the first and second terminals 17 and 18 are connected in series to a signal transmission path via a coupling capacitor.

FIG. 7 shows an equivalent circuit of a dielectric filter. A first resonator consisting of a capacitor C1 and an inductance L1 is based on the first and second resonance holes 5, 6, and a second resonator consisting of a capacitor C2 and an inductance L2 is based on the third and fourth resonators. is based on the resonance holes 7 and 8, and the coupling impedance Z is based on the coupling holes 9 and 1.
It is based on 0.

According to this embodiment, the first and second resonance holes 5 and 6 and the third and fourth resonance holes 7 and 8 are connected in series, so that the length is twice the length of one resonance hole. A similar effect occurs when a resonance hole with a length of . Therefore, when the resonance frequency is the same as the conventional one, the length of each of the resonant holes 5 to 8 can be reduced to approximately 1/2 of that of the conventional one. Moreover, when the lengths of the resonance holes 5 to 8 are made the same as in the conventional case, the resonance frequency can be lowered.

By the way, it is difficult to form a dielectric filter so that a target frequency can be obtained without adjustment. Therefore, the dielectric filter is formed so as to obtain a resonant frequency slightly higher than the target resonant frequency. After that, one or both of the connecting conductor films 13 and 14 shown in FIG. 3 are scraped off. This allows the first and second
The coupling capacitance between the connecting conductor films 13 and 14, that is, the first
The coupling capacitance of the second resonator is reduced, the resonant frequency is lowered, and the target resonant frequency is obtained. Therefore, frequency adjustment can be achieved very easily.

[0014]

[Modifications] The present invention is not limited to the above-described embodiments, but can be modified, for example, as follows.

As shown in FIG. 8, a single resonator structure can be obtained by omitting the second resonator from the dielectric filters of FIGS. 1 to 6. That is, a resonator can be formed in which the dielectric block 1 is provided with the first and second resonance holes 5 and 6, and these inner conductor films 11 are connected in series. The sectional view taken along the line DD in FIG. 8 is the same as that in FIG. 4. In addition, in FIG. 8 and FIGS. 9 and 10, which will be described later, the same parts as those in FIGS. In this case as well, by cutting the connection conductor film 13, the capacitance between this and the outer conductor film 12 changes, and the frequency characteristics change.

As shown in FIG. 9, the short circuit conductor film 15 is
The resonant frequency may be adjusted by extending between the third resonant holes 5 and 7. Further, as shown in FIG. 10, the resonance frequency can be adjusted by extending the outer conductor film 12 over the first end surface 2. Moreover, in the end surface 3 shown in FIG. 3, the inner conductor film 11 can be extended on the end surface 3 so as to surround the resonance holes 5 to 8 in a ring shape.

The conductor film 16 can be provided only in a portion of one or both of the coupling holes 9 and 10. Further, a configuration in which the conductive film 16 is not provided in the coupling hole 10 can be adopted. Note that in order to adjust the resonance frequency and frequency characteristics, the conductive film 16 of the coupling hole 10 can be scraped off.

[0018] The coupling holes 9, 10 can be omitted. In this case, the first resonators of the first and second resonance holes 5 and 6 and the second resonators of the third and fourth resonance holes 7 and 8 can be used independently. Further, the first and third resonance holes 5 and 7 are capacitively coupled with each other by a capacitor, and can be used as a two-stage filter.

Instead of providing the coupling holes 9 and 10, the side surface 4a
, 4b can be provided with a groove in the center thereof.

More resonance holes can be formed in the dielectric block 1 to provide a dielectric filter with three or more stages.

A part of the input/output coupling capacitor can be inserted into the resonance holes 5 and 7 and connected to the inner conductor film 11.

[0022]

As is clear from the above, according to the present invention, it is possible to easily adjust the frequency characteristics of a dielectric resonator that is downsized or whose resonance frequency is lowered.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a dielectric filter of an example.

FIG. 2 is a plan view of the dielectric filter of FIG. 1.

FIG. 3 is a bottom view of the dielectric filter of FIG. 1;

FIG. 4 is a sectional view taken along line AA in FIG. 2;

FIG. 5 is a sectional view taken along line BB in FIG. 2;

FIG. 6 is a sectional view taken along line CC in FIG. 2;

7 is an equivalent circuit diagram of the dielectric filter of FIG. 1. FIG.

FIG. 8 is a plan view showing a modified dielectric resonator.

FIG. 9 is a plan view showing a modified dielectric filter.

FIG. 10 is a plan view showing another modified example of a dielectric filter.

[Explanation of symbols]

1 Dielectric block 5 First resonance hole 6 Second resonance hole 7 Third resonance hole 8 Fourth resonance hole 11 Inner conductor film 12 Outer conductor film 13 First connection conductor film 14 Second connection conductor film 15 Short circuit conductor film

Claims (2)

[Claims] 1. First and second end surfaces having first and second end surfaces facing each other and a side surface therebetween, the first and second end surfaces being formed to penetrate from the first end surface to the second end surface. Second
a dielectric block having a resonance through hole, an inner conductor provided in each of the first and second through holes, an outer conductor provided on the side surface of the dielectric block; a connecting conductor film that connects the inner conductor of the first through hole and the inner conductor of the second through hole at the end face of the second through hole;
In the dielectric resonator, the dielectric resonator includes a short-circuit conductive film connecting the inner conductor of the second through hole to the outer conductor on the first end surface, and the frequency characteristics are improved by scraping off the connecting conductor film. A method for adjusting frequency characteristics of a dielectric resonator, characterized by adjusting the frequency characteristics of a dielectric resonator. 2. First and second end surfaces having first and second end surfaces facing each other and a side surface therebetween, and formed to penetrate from the first end surface to the second end surface. a dielectric block having a second through hole and third and fourth through holes arranged substantially parallel thereto; Connecting the provided inner conductor, the outer conductor provided on the side surface, and the inner conductor of the first through hole and the inner conductor of the second through hole at the second end surface. a first connection conductor film, a second connection conductor film that connects the inner conductor of the third through hole and the inner conductor of the fourth through hole at the second end surface; A dielectric resonator comprising: a short-circuit conductor film that connects inner conductors of the second and fourth through holes to the outer conductor, respectively, on a first end surface; A method for adjusting frequency characteristics of a dielectric resonator, characterized in that the frequency characteristics are adjusted by scraping off one or both of the second connecting conductor film.