JP2661005B2 - 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 structure of a dielectric filter, and more particularly to an electrode structure for obtaining capacitive coupling between resonators.

[0002]

2. Description of the Related Art Various dielectric filters are used in a high frequency range from the UHF band to the microwave band. Among them, a dielectric filter including a TEM resonator in which an inner conductor is formed in a portion having a through hole and an outer conductor is formed on an outer peripheral surface thereof is often used. There are a resonator configured by connecting individual resonators and a resonator integrated with a block.

In these dielectric filters, in order to adjust the pass band characteristics, capacitive coupling between resonators,
Regulates inductive binding. In order to strengthen the capacitive coupling, a capacitor is connected between the resonators, or a conductor pattern drawn from the inner conductor of the resonator to the open end face is formed so as to be opposed to obtain a capacitance.

In the field of dielectric filters, there is also a demand for miniaturization and thinning, and the size must be shortened because the wavelength becomes shorter as the frequency band rises.

[0005]

As described above, as the size and thickness are reduced, the structure for obtaining the capacitive coupling between the resonators is restricted, and a simple structure is necessary and sufficient. An electrode structure that can obtain a high capacitive coupling is required.

It is also desirable to avoid adding or connecting special components to obtain capacitive coupling between the resonators.

An object of the present invention is to provide a dielectric filter which solves such a problem and has sufficient capacitance coupling with a simple structure and a simple manufacturing process.

[0008]

According to the present invention, a conductor film connected to an inner conductor is arranged inside a dielectric block, and a capacitance between the inner conductors of the resonator is formed by the conductor film. This is to solve the above problem.

That is, in a dielectric filter in which a plurality of resonators are integrally formed by bonding two dielectric substrates, a first dielectric substrate having a plurality of linear grooves extending linearly is provided. An inner conductor is formed on the entire surface in the through hole of the dielectric block in which a plurality of through holes are formed by bonding a flat second dielectric substrate on the surface with the concave groove, and the first dielectric Outer conductors are formed on the respective surfaces of the substrate and the second dielectric substrate facing the bonding surface, and on both end surfaces parallel to the direction in which the concave groove extends, and a short-circuit conductor is formed on one of the open end surfaces of the through hole. A plurality of resonators are integrally formed in the dielectric block, and are connected to the inner conductor of one resonator and are closely opposed to the inner conductor of the adjacent resonator on the surface to be bonded of at least one dielectric substrate. Characterized by having a conductor film that forms a capacitor It is intended.

[0010] Capacitive coupling can also be strengthened by forming conductive films from adjacent resonators, and forming the conductive films facing each other on the surface to which the dielectric substrate is bonded. Further, the conductor film may be further drawn to the open end face of the dielectric block and connected to the conductor film formed close to the inner conductor at the open end face.

[0011]

Since the conductor film connected to the inner conductor is formed, a large capacitance can be obtained, and at the same time, the capacitance can be adjusted according to the size, shape or position.

Further, when the dielectric block is pulled out to the open end face, the capacitance can be easily adjusted by removing or adding the conductive film on the open end face.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a state before assembling a dielectric filter according to the present invention. Two parallel grooves
A flat plate-shaped second dielectric substrate 12 is bonded to the side of the first dielectric substrate 11 having the grooves 14 with the concave groove 14 using glass or the like. As a result, a dielectric block having two parallel through holes is formed. In the present invention, the conductor pattern 16 is formed in advance on the bonding surface of the dielectric substrate. The conductor pattern 16 is preferably formed so as to extend from the edge of the groove 14 in the direction of the adjacent groove, and to be a parallel conductor pattern on the dielectric substrate between the two grooves 14.

FIG. 2 shows a state after bonding and after forming a conductive film.
FIG. 3 is a perspective view showing a dielectric filter according to the present invention. FIG.
A dielectric substrate formed by bonding a dielectric substrate 21 corresponding to the dielectric substrate 11 of FIG. 1 and a dielectric substrate 22 corresponding to the dielectric substrate 12 of FIG. 1 has two through holes 25 formed therein. . An inner conductor is formed on a surface inside the through hole 25, and an outer conductor 27 is formed on an outer peripheral surface parallel to a direction in which the through hole 25 extends. Although not shown in the drawing, a short-circuit conductor is formed on one end face of the through-hole 25, and the 波長 wavelength TEM
A resonant dielectric filter is formed.

The conductor pattern 26 formed on the joint surface is connected to the inner conductor formed on the surface of the through hole 25. As a result, a capacitance is formed between the resonators by the conductor film 26 connected between the inner conductors formed by the conductor film formed in the through hole 25. Note that the terminal electrode 28 is formed not only on an end surface parallel to the direction in which the through hole 25 extends, but also on a surface adjacent thereto. This is to enable surface mounting on a printed wiring board. Of course, the terminal electrode 28 must be insulated from the outer conductor.

In the example of FIG. 1, the conductor pattern 16 is formed on the side of the dielectric substrate 11 having the concave groove. However, when actually manufacturing, as shown in FIG. It is easier to form on the surface. At this time, a conductor pattern 39 serving as an input / output coupling electrode may be formed together with the conductor film 36 for obtaining coupling between the resonators.

In the above example, the conductor patterns are respectively drawn from the two resonators. However, the conductor patterns may be drawn only from one of the two resonators and formed so as to face a position close to the inner conductor of the other resonator. .

As shown in FIG. 4, a conductor pattern for obtaining coupling between resonators may be connected to a conductor pattern 46 formed on the open end face. This structure can be realized by extracting and forming the conductor pattern formed before bonding on the edge and the end face of the concave groove. Usually, the open end face is polished to adjust the resonance frequency, and thus the conductor pattern 46 on the open end face is formed after the polishing. In this structure, the conductor pattern is also formed on the open end face,
The capacity between the inner conductors can be further increased. Also,
The capacitance can be adjusted depending on the size and position of the conductor pattern, or can be adjusted by grinding or adding.

FIG. 5 is an explanatory diagram of characteristics of the dielectric filter according to the present invention. A 1.6 mm thick board with a groove and a 0.9 mm thick flat board are bonded together.The center spacing of the grooves is 2.5 mm, the width is 1 mm, and the depth is 0.9 mm. This is an example of a dielectric filter with dimensions of 2.7 mm x 6.5 mm. The length of the groove depends on the resonance frequency, but is about 9.5m
When m, a filter having a center frequency of 1575.4 MHz and an insertion loss of about 2 dB was obtained, and the pass band characteristics were as shown in FIG. As shown in the figure, the attenuation characteristic on the lower side of the pass band is steep.

[0021]

According to the present invention, it is easy to obtain a dielectric filter having strong capacitive coupling between resonators, whereby the frequency band-pass characteristics can be adjusted.
Moreover, no special parts are required, and only the formation of the conductor pattern is sufficient, so that an inexpensive dielectric filter can be obtained.

In addition, when the conductor pattern is drawn out to the open end face, the capacitance can be easily adjusted,
Either reduction is possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment (before assembly) of the present invention.

FIG. 2 is a perspective view showing an embodiment (after assembly) of the present invention.

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

FIG. 4 is a perspective view showing another embodiment of the present invention.

FIG. 5 is an explanatory diagram of characteristics of a dielectric filter according to the present invention.

[Explanation of symbols]

 11, 21: (first) dielectric substrate 12, 22, 32: (second) dielectric substrate 16, 26, 36: conductor pattern 46: conductor pattern

Claims (3)

(57) [Claims] 1. A dielectric filter in which a plurality of resonators are integrally formed by bonding two dielectric substrates to each other, wherein the first dielectric substrate includes a plurality of parallel concave grooves extending linearly. An inner conductor is formed on the entire surface in the through hole of the dielectric block in which a plurality of through holes are formed by bonding a flat second dielectric substrate on the surface with the concave groove, and the first dielectric An outer conductor is formed on each surface of the substrate and the second dielectric substrate facing the bonding surface, and outer conductors are formed on both end surfaces parallel to the extending direction of the concave groove, and a short-circuit conductor is formed on one of the open end surfaces of the through hole. A plurality of resonators are integrally formed in the dielectric block,
At least one of the dielectric substrates is provided with a conductive film connected to the inner conductor of one resonator and formed in close proximity to the inner conductor of an adjacent resonator to form a capacitor. Dielectric filter. 2. A dielectric filter in which a plurality of resonators are integrally formed by bonding two dielectric substrates to each other, wherein the first dielectric substrate includes a plurality of parallel concave grooves extending linearly. An inner conductor is formed on the entire surface in the through hole of the dielectric block in which a plurality of through holes are formed by bonding a flat second dielectric substrate on the surface with the concave groove, and the first dielectric Outer conductors are formed on the respective surfaces of the substrate and the second dielectric substrate facing the bonding surface, and on both end surfaces parallel to the direction in which the concave groove extends, and a short-circuit conductor is formed on one of the open end surfaces of the through hole. A plurality of resonators are integrally formed in the dielectric block,
At least one of the dielectric substrates is provided with a conductive film connected to the inner conductors of two adjacent resonators on the surface to be bonded and forming a capacitance in close proximity to the surface of the dielectric substrate between the resonators. A dielectric filter characterized by the above-mentioned. 3. The dielectric filter according to claim 2, wherein the two conductive films formed on the surface to be bonded are connected to the two conductive films formed on the open end surfaces, respectively.