JPH01220501A - Dielectric filter - Google Patents

Abstract

PURPOSE:To easily and inexpensively realize a dielectric filter with integrated structure having a higher harmonic suppression effect by providing at least one or more non-penetrating holes on which no metallization is applied in the periphery of a hole for resonance formed in a dielectric block. CONSTITUTION:The holes 21-23 for resonance formed in the dielectric block 11 vary line impedance partially by the non-penetrating holes 41-46 in the periphery of the holes, and enables a spurious resonance frequency to be shifted by odd times. The title filter is operated as a band-pass filter with three step structure by performing the desired inter-step coupling by holes 31 and 32 for coupling, and the input/output coupling with an external circuit by capacitance elements 51 and 52. Therefore, it is possible to realize an integrated dielectric filter having the higher harmonic suppression effect and manufactured easily without attaching a specific external circuit only by forming the non-penetrating hole in which no conductor film is applied in the periphery of the holes 21-23 for resonance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dielectric filter with an integrated structure used mainly in a high frequency region such as a microwave band.

BACKGROUND OF THE INVENTION In recent years, dielectric materials have been developed that have a high dielectric constant in a high frequency range, low loss, and good temperature characteristics, and dielectric filters using these materials have been actively developed. Particularly recently, a dielectric filter (for example, described in Japanese Patent Application Laid-Open No. 165401/1983) has been realized that has an integrated structure in which a dielectric block using the above-mentioned dielectric material has resonance holes, coupling holes, and a conductive film. , smaller size, and lower cost.

Below, a conventional dielectric filter with an integrated structure will be explained with reference to FIG. Here, as an example,
An example of a three-stage configuration of resonance holes will be described.

In FIG. 4, 11 is a rectangular parallelepiped dielectric block;
4 to 26 are resonance holes formed in parallel at predetermined intervals in the dielectric block 11, 31 and 32 are coupling holes formed between the resonance holes 24 to 26, and 64 are holes other than the top surface of the dielectric block 11. The outer conductor films 61 to 63 formed on the outer surface are inner conductor films formed on the inner peripheral surfaces of the resonance holes 24 to 26, respectively, and connected to the outer conductor film 64 at one end. With the above configuration, the resonance holes 24 to 26 operate as a quarter-wavelength resonance element with one end open and one end shorted, and the coupling holes 31 and 32 form a crotch connection between the resonance holes 24 to 26. Further, the resonance holes 24 and 26 are connected to an external circuit via, for example, a capacitive element (not shown).

In the above configuration, the conventional example operates as a three-stage band pass filter having three resonance holes 24 to 26.

Problems that the invention aims to solve However, the dielectric filter with the above configuration.

Because of the integrated structure, there is no need to arrange and assemble unit resonators individually, and at the same time, there is no need for a bonding board, making manufacturing easy and reducing costs. Because it uses a resonant element with a wavelength of 1/2, it creates a passband even for odd harmonics such as the 3rd and 5th harmonics, and can be used as an output filter for oscillators, class C amplifiers, etc. to suppress harmonics. It had a characteristic problem that it did not have the same characteristics.

The present invention solves the above-mentioned problems of the prior art, and aims to provide a dielectric filter that is easy to manufacture, has an integrated structure that can be manufactured at low cost, and has a harmonic suppression effect. It is something to do.

Means for Solving the Problems The present invention achieves the above object by forming a non-through hole without a conductive film around at least one resonance hole.

Operation The present invention partially changes the line impedance of the resonant hole that operates as a resonant element with the above configuration, shifts the spurious resonance frequency from an odd multiple of the fundamental resonance frequency, or partially changes the line impedance. By combining a resonator with a positive resonator and a resonator with a negative resonator, a filter with a suppressing effect on harmonics is realized by expanding the stopping range.

Moreover, the high frequency suppression effect of the above structure can be obtained by simply changing the internal structure of the conventional dielectric block without the need to add any special external circuit. Dielectric blocks are usually manufactured by molding them in a mold and then firing them, so to change the internal structure, you only need to slightly change the mold, and the manufacturing process for dielectric blocks is completely different from the conventional one. (Identical.

Therefore, the manufacturing advantages of the monolithic dielectric filter, which are easy to manufacture and can be manufactured at low cost, are not impaired.

As described above, it is possible to realize a dielectric filter having a harmonic suppression effect with an integrated structure that is easy to manufacture and can be manufactured at low cost.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a dielectric filter having an integrated structure according to a first embodiment of the present invention. This embodiment also has the same three-stage configuration as the conventional example. In FIG. 1, 11 is a rectangular parallelepiped dielectric block, 21 to 23 are resonance holes formed in parallel at predetermined intervals in the dielectric block 11, and 31.3
2 is a coupling hole formed between resonance holes 21 to 230, 41
-46 are non-through holes formed around the resonance holes 21-23, 64 are outer conductor films formed on the outer surface of the dielectric block 11 except for the top surface, and 61-63 are the resonance holes 21-2, respectively.
An inner conductor film 51 and 52 formed on the inner circumferential surface of 3 and connected to the outer conductor film 64 at one end is a capacitive element for connection to an external circuit.

The operation of the above configuration will be explained below. Resonance hole 21 formed in dielectric block 11
23 can partially change the line impedance by the non-through holes 41 to 46 formed around them, and can shift the spurious resonance frequency from an odd multiple. Connection hole 31. 32 to achieve the desired crotch connection, and the capacitor 51
．． 52 forms an input/output connection with an external circuit, and operates as a three-stage band pass filter.

As is clear from the above description, according to this embodiment, the line impedance of the resonant element is partially changed by forming non-through holes without a conductive film around the resonant holes 21 to 23. By shifting the spurious resonance frequency from an odd multiple, it becomes possible to realize a dielectric filter with an integrated structure that has a harmonic suppression effect and is easy to manufacture.

In this embodiment, a capacitive element is used for connection to an external circuit, but other known connection methods such as tap coupling may be used.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a perspective view of a dielectric filter in a second embodiment of the invention. This embodiment also has a three-stage configuration.

In Fig. 2, the difference from the configuration in Fig. 1 is that the resonance hole 2
The point is that the non-through holes 47 to 49 formed around the holes 1 to 23 are ring-shaped and cylindrical. Components with the same numbers as in FIG. 1 have the same functions as in FIG.

The operation of the above configuration will be explained below. By providing ring-shaped cylindrical non-through holes 47 to 49 around the resonance holes 21 to 23 of the rectangular dielectric block 11, the line of the resonant element can be formed similarly to the embodiment shown in FIG. By partially changing the impedance, it is possible to realize a resonator in which the spurious resonance frequency is shifted from an odd multiple. Combined with the desired degree of crotch coupling through the coupling holes 31 and 32 and the input/output coupling via the capacitive elements 51 and 52 for connection with external circuits, it operates as a band pass filter with an odd harmonic suppression effect. do.

According to the μ Josui Example, by providing ring-shaped cylindrical non-through holes 47 to 49 around the resonance hole, the line impedance of the resonance element is partially changed, and the spurious resonance frequency is increased by an odd number. A band pass filter having a harmonic suppressing effect can be realized by shifting the value from .

Next, a third embodiment of the present invention will be described.

FIG. 3 is a perspective view of a dielectric filter in a third embodiment of the present invention. This embodiment also has a three-stage configuration.

3 differs from FIG. 2 in that a ring-shaped cylindrical non-through hole 48 is provided only around the resonance hole 22 formed in the rectangular dielectric block 11. No ring-shaped cylindrical non-through holes are provided around the resonance holes 21 and 23.

The operation of the above configuration will be explained below. By providing a ring-shaped cylindrical non-through hole 48 only around the resonance hole 22 formed in the dielectric block 11,
Similar to the embodiment shown in Fig. 2, the line impedance of the resonant element is partially changed, and the fundamental resonant frequency is the same as that of the quarter wavelength resonator, but the spurious resonant frequency is shifted from an odd multiple. has been realized. On the other hand, no ring-shaped cylindrical non-through hole is provided around the resonance hole 21°230. That is, it is operated as a quarter wavelength resonator with -like line impedance. By combining a resonator in which the line impedance of the resonant element is partially changed and a negative resonator, the mutual spurious resonance frequencies cancel each other out, making it possible to create a band pass filter with a wide sparse range.

It can have harmonic suppression characteristics.

As described above, according to this embodiment, the ring-shaped cylindrical non-through holes 48 are provided only around some of the resonance holes formed in the dielectric block, and the line impedance is partially changed. - It combines various types of resonators. In this way, the fundamental frequencies of the resonators are the same, but the spurious resonance frequencies are different, so it is possible to realize a band pass filter with a wide sparse region where they cancel each other out. Therefore, a harmonic suppression effect can be obtained.

In this embodiment, an example is shown in which the input/output is a resonator whose impedance is partially changed, and the crotch is a resonator whose impedance is partially changed, but the combination is not limited to this.

Further, in FIG. 1, two non-through holes formed around the resonance hole are formed so as to sandwich the resonance hole in between. In FIGS. 2 and 3, a ring-shaped cylindrical shape is formed around the resonance hole.

This is not the case as long as the line impedance of the resonator is partially changed.

Effects of the Invention As described above, the present invention partially reduces the line impedance of the resonator by providing at least one non-through hole without metallization around the resonance hole formed in the dielectric block. A simple structure that has a harmonic suppression effect by changing the spurious resonance frequency by changing the spurious resonance frequency from an odd multiple, or by combining a resonator with a partially changed line impedance and a negative resonator to expand the stop band. It is possible to realize an integrated dielectric filter with a large effect.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a dielectric filter according to a first embodiment of the present invention, FIG. 2 is a perspective view of a dielectric filter according to a second embodiment of the present invention, and FIG. 3 is a perspective view of a dielectric filter according to a second embodiment of the present invention. A perspective view of a dielectric filter in an embodiment, and FIG. 4 is a perspective view of a conventional dielectric filter. 11... Dielectric block, 21-26... Resonance hole, 31, 32... Coupling hole, 41-49... Non-through hole, 51° 52... Capacitive element, 61-63 ...Inner conductor film, 64...Outer conductor film. Name of agent: Patent attorney Toshio Nakao (1st person)
Illustration 2nd figure vinegar figure 3

Claims (1)

[Claims] A rectangular parallelepiped dielectric block, a plurality of resonance holes formed in parallel at predetermined intervals in the dielectric block, a coupling hole formed between the resonance holes, and an axis of the resonance holes of the dielectric block. an outer conductor film metallized on the outer surface except one surface perpendicular to the resonant hole, and an inner conductor film metallized on the inner peripheral surface of the resonant hole and having one end connected to the outer conductor; What is claimed is: 1. A dielectric filter having an integrated structure, characterized in that a non-penetrating hole is formed around at least one portion of the filter without a conductive film.