JPH06164205A - Dielectric filter - Google Patents

Abstract

PURPOSE:To control the resonance frequency to secure the coincidence with a prescribed level by adding an inducing part capable of varying the inductive impedance in the increasing direction to a dielectric resonator. CONSTITUTION:A slender ground part 7 formed at the fringe of an open surface 2 is connected to a conductor covering each side face. The connection parts 8-11 extended from the end part of the conductor which covers the inner wall surfaces of the through holes 3-6 construct a dielectric resonator together with these holes 3-6. Meanwhile the connection parts 12-14 which secure the capacitive connection among those ajacent through holes 3 and 4, 4 and 5 and 5 and 6 consist of the pairs of electrodes set opposite to each other with each prescribed space and connected to those adjacent connection parts 8 and 9, 9 and 10 and 10 and 11 respectively. The induction parts 15-22 consist of plural inductive impedances which are connected in parallel to each other contain plural slender electrodes which are connected to the parts 8-11 at one of both ends of each electrode and also connected to a ground part 7 at the other end respectively in a comb shape. Then these impedances are controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter using a dielectric resonator.

[0002]

2. Description of the Related Art FIG. 2 is a perspective view showing an example of a conventional dielectric filter, which is disclosed in Japanese Patent Application Laid-Open No. 61-80901.

In this dielectric filter, a dielectric resonator 4 is provided by providing a plurality of cylindrical center conductors on a dielectric having an integral structure.
3 to 48 are formed, and the distance between the dielectric resonators is set to a value at which the degree of coupling required to realize the filter is obtained, and it operates as follows.

That is, the electric signal applied to the input terminal 41 is converted into an electromagnetic field by the dielectric resonator 43 at the input stage, and the dielectric resonance is performed via the coupling portion 49 set between the adjacent dielectric resonators 44. It is transmitted to the vessel 44. Dielectric resonator 4
The electromagnetic field reaching 4 is transmitted to the adjacent dielectric resonator 45 via the coupling section 50 set between the dielectric resonator 45 and the electromagnetic field. While sequentially repeating such operations, the electromagnetic field reaches the dielectric resonator 48 at the output stage, is converted into an electric signal, and is output from the output end 42.

Here, the resonance frequencies of the dielectric resonators 43 to 48 are determined by the height of the dielectric resonator and the patterns 54 to 59 provided on the end faces extending from the cylindrical central conductor, and this adjustment is performed. It can be performed by a mechanical construction method or an optical construction method.

Coupling portions 49 to 53 are portions between a pattern provided on the end face extending from a cylindrical central conductor provided on the integral dielectric and a pattern from a similar central conductor adjacent thereto. , The degree of coupling is determined by the distance between the central conductors and the shape of the pattern.

Such a dielectric filter can be realized as a high frequency filter only by processing a cylindrical central conductor on an integrally structured dielectric, and the manufacturing method is very easy. The distance between the center conductors, which has the largest characteristic variation in the configuration, does not vary during assembly, and the assembly is advantageous because the dielectric body is integrated so that the attachment is easy.

[0008]

However, in the dielectric filter having the above-described structure, the height of the dielectric resonator and the shape of the pattern (electrode) extending from the central conductor of the dielectric resonator and provided on the end face are formed. , The resonance frequency of the dielectric resonator is set by adjusting the initial resonance frequency before adjustment of the dielectric resonator to be lower than the specified resonance frequency, and deleting the pattern by mechanical method or optical method during adjustment. Was adjusted to match the specified resonance frequency, the pattern was deleted unnecessarily during adjustment, and when the resonance frequency of the dielectric resonator became higher than the specified resonance frequency, the resonance was no longer present. It is difficult to lower the frequency, and there is a problem that a dielectric filter having predetermined characteristics cannot be obtained.

The present invention has been made to solve the above-mentioned problems, and a pattern that can increase and decrease the resonance frequency of a dielectric resonator is provided by cutting off a part of the pattern. An object of the present invention is to provide a dielectric filter capable of surely matching the resonance frequency with a specified resonance frequency.

[0010]

To achieve the above object, the first invention is a dielectric filter in which a plurality of through holes forming a resonator are arranged in parallel in a dielectric block. A thin film electrode having a characteristic impedance is connected in parallel.

A second aspect of the present invention is a dielectric filter comprising a dielectric block and a plurality of through-holes forming a resonator arranged side by side, wherein the through-hole has a thin film electrode having inductive impedance and a capacitive element. A thin film electrode having impedance is connected in parallel.

[0012]

The present invention adjusts the inductive impedance or capacitive impedance of a thin film electrode connected in parallel to the through hole by trimming or the like to adjust the resonant frequency of the resonator. It is what makes me.

[0013]

1 is a plan view showing a dielectric filter according to a first embodiment of the present invention, FIG. 3 is a partial perspective view, and FIG. 4 is a front view.

In FIGS. 1, 3 and 4, reference numeral 1 denotes a dielectric block made of a rectangular parallelepiped dielectric. Each surface except the upper surface (open surface 2) is covered with a thin film conductor formed by plating or the like. It is being appreciated. Reference numerals 3 to 6 are through-holes forming a dielectric resonator having one end short-circuited and the other end open, and a hole penetrating from the open surface 2 to the bottom surface of the dielectric block 1 is provided, and the inner wall surface of this hole is plated. And the like, and the lower end of the conductor is electrically connected to the conductor covering the bottom surface (hereinafter simply referred to as connection).

Various patterns are formed on the open surface 2 of the dielectric block 1. Reference numeral 7 denotes an elongated ground portion formed on the edge of the open surface 2 and connected to a conductor covering each side surface. Reference numerals 8 to 11 denote connecting portions extending from the end portions of the conductors covering the inner wall surfaces of the through holes 3 to 6 and formed around the end portions, and together with the through holes 3 to 6, the dielectric resonator. I am configuring. Reference numerals 12 to 14 denote coupling portions for capacitively coupling the through holes 3 and 4, 4, 5, 5 and 6 adjacent to each other, which are connected to the adjacent connecting portions 8 and 9, 9, 9 and 10, 10 and 11, respectively. A pair of electrodes are opposed to each other at regular intervals. Reference numerals 15 to 22 are inductive portions composed of a plurality (4 in this embodiment) of inductive impedances connected in parallel with each other, one end of which is connected to the connecting portions 8 to 11 and the other end of which is connected to the ground portion 7. A plurality of elongated electrodes are arranged in parallel in a comb shape. Note that the earth portion 7 may be omitted and the other end of each electrode may be directly connected to the conductor covering the side surface.

FIG. 5 is an equivalent circuit of the dielectric filter having the above structure. Here, L ₁ and C ₁ , L ₂ and C ₂ , L ₃
And C ₃ , L ₄ and C ₄ are through holes 3 to 6 and connecting portion 8 respectively.
Represents the equivalent inductance and equivalent capacitance of the resonant circuit of each dielectric resonator, and C _{5 to} C ₇ represent the capacitive impedances existing between the through holes 3, 4, 4, 5, 5 and 6, respectively. Where L _{5 to} L ₁₂ represent inductive impedances of the inductive portions 15 to 22.

By the way, in order to obtain a dielectric filter having a predetermined characteristic, it is necessary to make the resonance frequency of each dielectric resonator match the predetermined resonance frequency. However, in practice, there is a certain limit to the processing accuracy in manufacturing, and there are variations in the characteristics of the materials used, so it is difficult to achieve a predetermined resonance frequency without adjustment. Therefore, in this embodiment, the through holes 3 to 6, the connecting portions 8 to 11, the guiding portion 1
The shapes and dimensions of the through holes 3 to 6 are set so that the resonance frequency of the resonance circuit composed of 5 to 22 is higher than a predetermined resonance frequency, and the inductive impedance of the induction parts 15 to 22 is adjusted after the manufacture, The resonance frequency of the resonance circuit is lowered to obtain a predetermined resonance frequency.

For example, the inductive impedance L ₅ of the inductive portion 15 shown in FIG. 1 is composed of four inductive impedances L _{51 to} L ₅₄ as shown in FIG. 6, and the inductive impedance L ₆ of the inductive portion 16 is 4 inductive impedances L ₆₁
~ L ₆₄ , these inductive impedances L ₅₁ ~ L
₅₄ , L _{61 to} L ₆₄ are all L of the resonance circuit (L ₁ , C ₁ ).
Connected in parallel to ₁ . Therefore, if a part of the inductive impedances L _{51 to} L ₅₄ and L _{61 to} L ₆₄ is removed, the inductive impedance obtained by combining them becomes large and the resonance frequency is lowered. Thereby, the resonance frequency can be lowered to the predetermined resonance frequency.

However, since the resonance frequency changes stepwise in the above adjusting method, there is a possibility that the resonance frequency may exceed the predetermined resonance frequency and become lower than that depending on the step width. In this case, the outer edge of the connecting portion 8 is partially deleted.
As a result, the length of the dielectric resonator is shortened, L ₁ and C ₁ shown in FIG. 5 are decreased, and the resonance frequency of the resonance circuit changes to the higher side. The same applies to other resonance circuits.

The above-mentioned inductive impedance L ₅₁ to
The removal of L ₅₄ and L _{61 to} L ₆₄ is performed by scraping off an arbitrary portion (for example, the portion A shown in FIG. 1) of the corresponding elongated electrode with a certain width and interrupting its conduction. The method of shutting off is arbitrary, but it should be noted that when the width of scraping is narrow, a capacitance is formed in that portion, which causes the resonance frequency to be lowered on the contrary.

As described above, according to this embodiment, the resonance frequency can be increased or decreased by adjusting the inductive impedance of the inductive portions 15 to 22 and deleting the pattern of the connecting portions 8 to 11 if necessary. Therefore, it is possible to surely match the predetermined resonance frequency. Further, the adjustment of the inductive impedance is performed by scraping the pattern, and the scraping amount does not directly relate to the change amount of the resonance frequency, so that the work becomes easy.

FIG. 7 is a plan view showing a dielectric filter which is a second embodiment of the present invention.

The present embodiment has substantially the same construction as the first embodiment shown in FIG. 1, except that a capacitance portion is formed on the open surface 2. In FIG. 7, reference numerals 23 to 26 are the above-mentioned capacitance portions, one end of which is connected to the connection portions 3 to 6 and the other end of which forms electrodes 23-1 to 26-1 facing the ground portion 7 at regular intervals, It constitutes a capacitive impedance. In this embodiment, the guiding parts 16, 18, 20, 2 shown in FIG. 1 are used.
Although the capacitance portions 23 to 26 are formed at the two locations, the formation location is not limited to this embodiment, and the number of capacitance portions formed for each of the through holes 3 to 6 is arbitrary.

FIG. 8 is a diagram showing an equivalent circuit of this embodiment. This equivalent circuit has the same configuration as that of the equivalent circuit shown in FIG. 5 in which the inductive impedances L ₆ , L ₈ , L ₁₀ and L ₁₂ are replaced by the capacitive impedances C _{8 to} C ₁₁ of the capacitance sections 23 to 26.

Therefore, in this embodiment, for example, the through holes 3,
The resonance frequency of the resonance circuit (L ₁ , L ₅ , C ₁ , C ₈ ) including the connection portion 8, the induction portion 15, and the capacitance portion 23 is set to be higher than or equal to a predetermined resonance frequency or near the predetermined resonance frequency. The resonance frequency is made equal to a predetermined resonance frequency by adjusting the inductive impedance of 15 to lower the resonance frequency, or adjusting the capacitive impedance of the capacitor section 23 to increase the resonance frequency.

The inductive impedance of the inducing section 15 is the first
Adjustment is performed in the same manner as in the case of the above embodiment. In addition, the capacity unit 2
The capacitive impedance of 3 is adjusted by scraping off a part of the end of the electrode 23-1 or the part of the earth part 7 facing the end. In this case, the capacitive impedance tends to decrease, and therefore the resonance frequency changes to the higher direction.

FIG. 9 is a plan view showing a dielectric filter which is a third embodiment of the present invention.

In this embodiment, electrodes 27 to 35 as shown in FIG. 9 are formed on the open surface 2, and a dielectric filter having adjacent through holes inductively coupled to each other is provided with a guiding portion 1 for adjusting resonance frequency.
5 to 22 are provided, and can be adjusted to a predetermined resonance frequency in the same manner as in the first embodiment.

[0029]

As described above in detail, according to the present invention, the dielectric resonator is provided with an inductive portion capable of varying the inductive impedance in the increasing direction, or the inductive portion and the capacitive impedance are in the decreasing direction. Since the variable capacitance section is provided, the resonance frequency can be increased or decreased, and the resonance frequency can be surely matched with the predetermined resonance frequency.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing a conventional dielectric filter.

FIG. 3 is a partial perspective view showing the first embodiment of the present invention.

FIG. 4 is a front view showing the first embodiment of the present invention.

5 is an equivalent circuit diagram of the dielectric filter shown in FIG.

6 is a diagram showing a configuration of L ₅ and L ₆ shown in FIG.

FIG. 7 is a plan view showing a second embodiment of the present invention.

8 is an equivalent circuit diagram of the dielectric filter shown in FIG.

FIG. 9 is a plan view showing a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric block 3-6 Through hole 7 Ground part 8-11 Connection part 12-14 Coupling part 15-22 Induction part 23-26 Capacitance part 27-35 Electrode

Claims (2)

[Claims] 1. A dielectric filter comprising a dielectric block and a plurality of through holes forming a resonator arranged side by side, wherein thin film electrodes having inductive impedance are connected in parallel to the through holes. Dielectric filter. 2. A dielectric filter in which a plurality of through holes forming a resonator are arranged in parallel in a dielectric block, wherein the through holes have a thin film electrode having inductive impedance and a thin film electrode having capacitive impedance. A dielectric filter in which the electrodes of are connected in parallel.