JP2661004B2 - 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 its input / output coupling capacitance.

[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 an integrated resonator.

In these dielectric filters, input and output coupling capacitances must be formed between the input and output stages and the inner conductor of the resonator. The coupling capacitance can be changed by connecting a capacitor or inserting a metal rod coated with a dielectric into a through-hole forming an inner conductor, or by using a dielectric substrate in the vicinity of the inner conductor. Various methods have been considered, such as inserting a metal rod into the outer conductor, or forming a metal film on the outer conductor via an insulating portion.

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 input / output coupling capacitance is also restricted. An electrode structure that can obtain a capacity is required.

Further, when a terminal electrode is formed on the open end surface side to increase the coupling capacitance, solder is added to the electrode at the time of mounting on a board, so that the coupling capacitance increases and the frequency characteristics change. Would.

It is desirable to avoid adding or connecting special components to obtain input / output coupling capacitance.

An object of the present invention is to solve the above-mentioned problems and to provide a dielectric filter having an input / output coupling electrode capable of obtaining a sufficient capacitance with a simple structure and a simple manufacturing process.

[0009]

According to the present invention, a conductor film is arranged in a dielectric block close to an inner conductor, and the conductor film is connected to a terminal electrode, and the terminal electrode is separated from an open end face. The above-mentioned problem is solved by interposing an outer conductor in between.

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. A flat second dielectric substrate is adhered on the surface having the concave groove to form a plurality of through-holes to form a dielectric block, and an inner conductor is formed on the entire surface in the through-hole. An outer conductor is formed on each surface of the dielectric substrate and the second dielectric substrate facing the bonding surface, and on both end surfaces parallel to the extending direction of the concave groove, and a short-circuit conductor is formed on one of the end surfaces where the through holes are opened. Is formed, a plurality of resonators are integrally formed in the dielectric block, and the direction of the inner conductor of the input / output resonator is set on the bonding surface of at least one of the dielectric substrates from the end surface parallel to the extending direction of the concave groove. , Facing the inner conductors, and extending the groove. In both end surfaces parallel to the direction, is surrounded by an outer conductor, the outer conductor in which characterized in that comprises a conductive layer which is connected to a terminal electrode formed is isolated.

Further, the conductor film may be further drawn out to the open end face and connected to a conductor film formed close to the inner conductor on the open end face.

[0012]

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

Further, since the terminal electrode is formed apart from the open end face, even if solder is added at the time of mounting on the board, the capacitance between the terminal and the inner conductor does not change, and the frequency characteristic does not change.

[0014]

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 end face parallel to the extending direction of the concave groove 14 to the vicinity of the concave groove, and to be close to the concave groove, to be a conductor pattern extending in parallel to the extending direction of the concave groove.

FIG. 2 shows the state after bonding and after forming a conductor film.
FIG. 3 is a perspective view showing a dielectric filter according to the present invention. It has a structure in which two through holes 25 are formed in a dielectric block in which a dielectric substrate 21 and a dielectric substrate 22 are bonded. An inner conductor is formed on the surface inside the through hole 25,
An outer conductor 27 is formed on the outer peripheral surface parallel to the direction in which the 25 extends. Although not shown in the figure, a short-circuit conductor is formed on one exposed end face of the through hole 25, and a quarter-wave TEM resonance dielectric filter is formed.

The conductor pattern (16) formed on the joint surface shown in FIG. 1 is connected to the terminal electrode 28 at the end face of the dielectric substrate, and has a capacitance between the conductor and the inner conductor formed by the conductor film formed in the through hole 25. Is formed. This capacitance is the input / output coupling capacitance of the dielectric filter. Further, 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. At the time of manufacture, a metal paste may be applied by covering this portion with a resist, and then baked. Further, electrical and mechanical characteristics can be improved by plating.

In the present invention, the terminal electrode 28 is
The terminal is formed so as to be separated from the open end face where the open end faces, and the outer conductor 27 is formed between the open end face and the terminal electrode. Of course, the terminal electrode 28 must be insulated from the outer conductor 27.

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 manufacture on the surface.

FIG. 4 is a perspective view showing another embodiment of the present invention. This example is basically the same as the example shown in FIG. 2, except that the conductor pattern formed inside the dielectric substrate is connected to the terminal electrode 48 and the conductor pattern 49 formed on the open end face. Are also connected. This can be realized by extracting and forming the conductor pattern formed before bonding on the two end surfaces. Usually, since the open end face is polished for adjusting the resonance frequency, the conductor pattern 49 is formed after the polishing.

In the above example, since the conductor pattern is also formed on the open end face, the capacitance between the conductor and the inner conductor can be further increased. Also, the dimensions of this conductor pattern,
The capacity can be adjusted depending on the position, and can be adjusted by grinding or adding.

[0022]

According to the present invention, it is easy to obtain a dielectric filter having a sufficient input / output coupling capacitance. 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.

Further, since the terminal electrode is formed at a position separated from the open end face, the capacitance between the terminal electrode and the inner conductor of the resonator does not change during soldering. Stabilization becomes easy.

In addition, when the conductor pattern is drawn out from the open end face, the adjustment of the coupling capacitance is easy, and it is possible to increase or decrease the coupling capacity.

[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.

[Explanation of symbols]

 11, 21: (first) dielectric substrate 12, 22: (second) dielectric substrate 14: concave groove 25: through hole 16: conductive film 28, 48: terminal electrode

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,
On the adhesive surface of at least one of the dielectric substrates, an end face parallel to the extending direction of the concave groove extends in the direction of the inner conductor of the input / output resonator, faces the inner conductor, and is parallel to the extending direction of the concave groove. A dielectric filter, comprising: a conductor film surrounded by outer conductors at both end faces and connected to a terminal electrode formed insulated from the outer conductor. 2. The dielectric filter according to claim 1, wherein the conductive film is formed on a flat dielectric substrate. 3. 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 linear 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,
On the bonding surface of at least one of the dielectric substrates, an end face parallel to the extending direction of the concave groove extends in the direction of the inner conductor of the input / output resonator and faces the inner conductor, and the tip thereof faces the inner conductor. A conductive film connected to a terminal electrode formed on the open end face and surrounded by an outer conductor at both end faces parallel to the extending direction of the concave groove and insulated from the outer conductor. A dielectric filter comprising: