JPH06125202A - Dielectric filter and its pass band width control method - Google Patents

Abstract

PURPOSE:To reduce the bonding strength between the resonators by providing a conductor in parallel to the extending directions of the hollow grooves and grounding both ends of the conductor pattern to a short circuit conductor. CONSTITUTION:A 1st dielectric substrate 11 contains two parallel hollow grooves 14, and a 2nd flat substrate 12 is adhered onto the grooved side of substrate 11 by means of the glass, etc. Thus a dielectric block having two parallel through holes is obtained. A conductor pattern is previously formed on the adhering surface of the substrate 12 so that the pattern extends up to the counter face of the substrate 11 between both grooves 14 and in the same direction as the groove 14 and then connected to a short circuit conductor after adhesion. Thus the bonding strength between the resonators can be reduced down to a desired level. Thus it is possible to easily secure a prescribed pass band width and also to obtain a compact dielectric filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an interdigital dielectric filter, and more particularly to an electrode structure for adjusting the coupling between the 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 is often used which is a combination of a TEM resonator having a through hole, an inner conductor formed in the through hole, and an outer conductor formed on the outer peripheral surface. There are a resonator configured by connecting individual resonators and an integrated resonator.

Among these dielectric filters, particularly in the one-piece dielectric filter, it is necessary to adjust the capacitive coupling and the inductive coupling between the resonators. Usually, in order to weaken the coupling, a coupling adjusting hole is formed between the resonators, or a conductor is interposed between the resonators.

In the field of dielectric filters, there is a demand for miniaturization and thinning, and the wavelength must be shortened as the frequency band rises, so that the dimensions must be shortened. Therefore,
In the Japanese Patent Application No. 4-186099 filed previously, the present inventor bonded two dielectric substrates to form an inner conductor with a conductor film formed in a groove in one of the dielectric substrates. A structure for obtaining a resonator is proposed.

[0005]

When it is necessary to adjust the pass bandwidth in the dielectric filter, the coupling between the resonators must be adjusted. Normally, a structure that weakens the coupling is adopted, but if the distance between the resonators is increased, it becomes a major obstacle to miniaturization. Further, forming a hole for adjusting coupling between the resonators causes the same problem as the processing problem.

The present invention solves the above problems and provides a dielectric filter which can weaken the adjustment of the coupling between the resonators with a simple structure and manufacturing process.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above problems by providing a conductor pattern between the inner conductors of the resonator which is grounded across the resonators and by adjusting the width of the conductor pattern. To do.

That is, a flat second dielectric substrate is adhered on the grooved surface of a first dielectric substrate having a plurality of parallel concave grooves extending linearly, and the second dielectric substrate is adhered to the inside of the concave groove and the second dielectric substrate. The inner conductor is formed on the surface of the dielectric substrate facing the groove, and the outer conductor is formed on the unbonded surface of the first and second dielectric substrates and the end surface parallel to the extending direction of the groove. In the dielectric filter having a plurality of resonators, a short-circuit conductor is formed on one of the exposed end surfaces of one concave groove, and a short-circuit conductor is formed on the exposed end surface on the opposite side of the adjacent concave groove.
It is characterized in that a conductor pattern parallel to the extending direction of the groove is provided on the adhesive surface of at least one of the dielectric substrates between the grooves, and both ends of the conductor pattern are connected to the short-circuit conductor.

Further, a flat second dielectric substrate is adhered onto the concave surface of the first dielectric substrate having a plurality of parallel concave grooves extending linearly, and the second dielectric substrate is bonded to the inside of the concave groove and the second dielectric substrate. The inner conductor is formed on the surface of the dielectric substrate facing the groove, and the outer conductor is formed on the unbonded surface of the first and second dielectric substrates and the end surface parallel to the extending direction of the groove. The short-circuit conductor is formed on one of the exposed end faces of one groove, and the short-circuit conductor is formed on the exposed end face on the opposite side of the adjacent groove. In the adjusting method, a conductor pattern, which is parallel to the extending direction of the groove and whose both ends are connected to the short-circuit conductor, is formed on at least one of the bonding surfaces of the dielectric substrate between the grooves, and the width of the conductor pattern is changed. Adjust the coupling between the resonators to adjust the passband width Those having features Rukoto.

[0010]

[Function] Since a conductor pattern is formed in advance between two dielectric substrates and the conductor pattern is located between the resonators and both ends are connected to the short-circuit conductor, the coupling between the resonators is effectively weakened. It is possible to control the coupling state by adjusting the width.

[0011]

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

FIG. 1 is a perspective view showing a state before assembly of a dielectric filter according to the present invention. Two parallel grooves
A flat second dielectric substrate (12) is adhered to the side of the first dielectric substrate (11) having the concave groove (14) with glass or the like. This forms a block of dielectric with two parallel through holes. In the present invention, the conductor pattern 16 is previously formed on the bonding surface of the dielectric substrate 12. The conductor pattern 16 is formed between the concave grooves 14 so as to extend in the same direction as the grooves and reach the opposite surface of the dielectric substrate 11, and is formed so as to be connected to the short-circuit conductor after bonding. Although not shown, input / output conductor patterns may be formed at the same time.

FIG. 2 shows that after the bonding and the formation of the 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 formed by adhering the dielectric substrate 21 and the dielectric substrate 22. An inner conductor is formed on the surface of the through hole 25, and the through hole
An outer conductor 27 is formed on the outer peripheral surface parallel to the extending direction of 25. A short-circuit conductor 28 is formed on one of the end faces of the exposed portion of the through hole 25a on the right side of the figure, and a quarter-wave TEM resonance dielectric filter is constructed. A conductor film is not formed around the same end face side where the adjacent through holes 25b are opened, but the open end face is formed. As a result, an interdigital dielectric filter is constructed.

The conductor pattern (16) formed on the joint surface shown in FIG. 1 is connected to the short-circuit electrode 28 at the end surface of the dielectric substrate, and is also connected to the short-circuit conductor at the opposite end surface (not shown). Therefore, the conductor pattern (16) is grounded. In order to capacitively connect the inner conductor of the resonator and the terminal electrode 29 to obtain an input / output coupling capacity, an input / output coupling electrode is formed on the bonding surface of the dielectric substrate, and the terminal electrode is bonded after bonding. Need to connect with 29.

The terminal electrode 29 is formed not only on the end surface parallel to the extending direction of the through hole 25 but also on the surface adjacent to the end surface. This is to enable surface mounting on the printed wiring board. Of course, the terminal electrode 29 must be insulated from the outer conductor. At the time of manufacturing, it may be formed by covering this portion with a resist, applying a metal paste, and baking. Further, by applying plating, electrical and mechanical characteristics can be improved.

In the above example, a two-element interdigital dielectric filter is shown, but a block of three or more elements can also be used. Further, the conductor pattern may be formed on a flat dielectric substrate instead of the dielectric substrate having the groove. By forming such a conductor pattern across the resonators, the coupling between the resonators can be weakened. FIG. 3 is an explanatory diagram showing the relationship between the width of the conductor pattern and the pass band width. The solid line 31 shows the characteristics when the width is narrow and the broken line 32 shows the characteristics when the width is wide. It is shown that as the width of the conductor pattern between the resonators is widened, the coupling between the resonators is weakened and the pass band width is narrowed.

[0017]

According to the present invention, it is possible to reduce the coupling between the resonators to a desired amount, which makes it easy to obtain a predetermined pass band width, and further, to reduce the size of the dielectric filter. It will be easy to obtain. Since no special parts are required and only the formation of the conductor pattern is required, an inexpensive dielectric filter can be obtained.

As a result, the same dielectric substrate can be used to manufacture different dielectric filters depending on the characteristics, which is very advantageous in terms of manufacturing.

[Brief description of 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 an explanatory diagram of pass band characteristics.

[Explanation of symbols]

 11, 21: (First) dielectric substrate 12, 22: (Second) dielectric substrate 16: Conductor pattern 28: Short-circuit electrode

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[Procedure amendment]

[Submission date] September 30, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Detailed explanation of the invention

[Correction method] Change

[Correction content]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interdigital dielectric filter structure and, more particularly, to an electrode structure for adjusting the coupling between the 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 is often used which is a combination of a TEM resonator having a through hole, an inner conductor formed in the through hole, and an outer conductor formed on the outer peripheral surface. There are a resonator configured by connecting individual resonators and an integrated resonator.

Among these dielectric filters, particularly in the one-piece dielectric filter, it is necessary to adjust the capacitive coupling and the inductive coupling between the resonators. Usually, in order to weaken the coupling, a coupling adjusting hole is formed between the resonators, or a conductor is interposed between the resonators.

In the field of dielectric filters, there is a demand for miniaturization and thinning, and the wavelength must be shortened as the frequency band rises, so that the dimensions must be shortened. Therefore,
In the Japanese Patent Application No. 4-186099 filed previously, the present inventor bonded two dielectric substrates to form an inner conductor with a conductor film formed in a groove in one of the dielectric substrates. A structure for obtaining a resonator is proposed.

[0005]

When it is necessary to adjust the pass bandwidth in the dielectric filter, the coupling between the resonators must be adjusted. Normally, a structure that weakens the coupling is adopted, but if the distance between the resonators is increased, it becomes a major obstacle to miniaturization. Further, forming a hole for adjusting coupling between the resonators causes the same problem as the processing problem.

The present invention solves the above problems and provides a dielectric filter which can weaken the adjustment of the coupling between the resonators with a simple structure and manufacturing process.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above problems by providing a conductor pattern between the inner conductors of the resonator which is grounded across the resonators and by adjusting the width of the conductor pattern. To do.

That is, a flat second dielectric substrate is adhered on the grooved surface of a first dielectric substrate having a plurality of parallel concave grooves extending linearly, and the second dielectric substrate is adhered to the inside of the concave groove and the second dielectric substrate. The inner conductor is formed on the surface of the dielectric substrate facing the groove, and the outer conductor is formed on the unbonded surface of the first and second dielectric substrates and the end surface parallel to the extending direction of the groove. In the dielectric filter having a plurality of resonators, a short-circuit conductor is formed on one of the exposed end surfaces of one concave groove, and a short-circuit conductor is formed on the exposed end surface on the opposite side of the adjacent concave groove.
It is characterized in that a conductor pattern parallel to the extending direction of the groove is provided on the adhesive surface of at least one of the dielectric substrates between the grooves, and both ends of the conductor pattern are connected to the short-circuit conductor.

Further, a flat second dielectric substrate is adhered onto the concave surface of the first dielectric substrate having a plurality of parallel concave grooves extending linearly, and the second dielectric substrate is bonded to the inside of the concave groove and the second dielectric substrate. The inner conductor is formed on the surface of the dielectric substrate facing the groove, and the outer conductor is formed on the unbonded surface of the first and second dielectric substrates and the end surface parallel to the extending direction of the groove. The short-circuit conductor is formed on one of the exposed end faces of one groove, and the short-circuit conductor is formed on the exposed end face on the opposite side of the adjacent groove. In the adjusting method, a conductor pattern, which is parallel to the extending direction of the groove and whose both ends are connected to the short-circuit conductor, is formed on at least one of the bonding surfaces of the dielectric substrate between the grooves, and the width of the conductor pattern is changed. Adjust the coupling between the resonators to adjust the passband width Those having features Rukoto.

[0010]

[Function] Since a conductor pattern is formed in advance between two dielectric substrates and this conductor pattern is positioned between the resonators and both ends are connected to the short-circuit conductor, the coupling between the resonators can be weakened. Further, it becomes possible to control the coupling state by adjusting the width.

[0011]

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

FIG. 1 is a perspective view showing a state before assembly of a dielectric filter according to the present invention. Two parallel grooves
A flat second dielectric substrate (12) is adhered to the side of the first dielectric substrate (11) having the concave groove (14) with glass or the like. This forms a block of dielectric with two parallel through holes. In the present invention, the conductor pattern 16 is previously formed on the bonding surface of the dielectric substrate 12. The conductor pattern 16 is formed between the recessed grooves 14 so as to extend in the same direction as the grooves and reach the opposing surface of the dielectric substrate 11, and is formed so as to be connected to the short-circuit conductor after bonding. Although not shown, input / output conductor patterns may be formed at the same time.

FIG. 2 shows that after the bonding and the formation of the 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 formed by adhering the dielectric substrate 21 and the dielectric substrate 22. An inner conductor is formed on the surface of the through hole 25, and the through hole
An outer conductor 27 is formed on the outer peripheral surface parallel to the extending direction of 25. A short-circuit conductor 28 is formed on one of the end faces of the exposed portion of the through hole 25a on the right side of the figure, and a quarter-wave TEM resonance dielectric filter is constructed. A conductor film is not formed around the same end face side where the adjacent through holes 25b are opened, but the open end face is formed. As a result, an interdigital dielectric filter is constructed.

The conductor pattern (16) formed on the joint surface shown in FIG. 1 is connected to the short-circuit electrode 28 at the end surface of the dielectric substrate, and is also connected to the short-circuit conductor at the opposite end surface (not shown). Therefore, the conductor pattern (16) is grounded. In order to capacitively connect the inner conductor of the resonator and the terminal electrode 29 to obtain an input / output coupling capacity, an input / output coupling electrode is formed on the bonding surface of the dielectric substrate, and the terminal electrode is bonded after bonding. Need to connect with 29.

The terminal electrode 29 is formed not only on the end surface parallel to the extending direction of the through hole 25 but also on the surface adjacent to the end surface. This is to enable surface mounting on the printed wiring board. Of course, the terminal electrode 29 must be insulated from the outer conductor. At the time of manufacturing, it may be formed by covering this portion with a resist, applying a metal paste, and baking. Further, by applying plating, electrical and mechanical characteristics can be improved.

In the above example, a two-element interdigital dielectric filter is shown, but a block of three or more elements can also be used. Further, the conductor pattern may be formed on a flat dielectric substrate instead of the dielectric substrate having the groove. By forming such a conductor pattern across the resonators, the coupling between the resonators can be weakened. FIG. 3 is an explanatory diagram showing the relationship between the width of the conductor pattern and the pass band width. The solid line 31 shows the characteristics when the width is narrow and the broken line 32 shows the characteristics when the width is wide. It is shown that as the width of the conductor pattern between the resonators is widened, the coupling between the resonators is weakened and the pass band width is narrowed.

[0017]

According to the present invention, it is possible to reduce the coupling between the resonators to a desired amount, which makes it easy to obtain a predetermined pass band width, and further, to reduce the size of the dielectric filter. It will be easy to obtain. Since no special parts are required and only the formation of the conductor pattern is required, an inexpensive dielectric filter can be obtained.

As a result, the same dielectric substrate can be used for manufacturing different dielectric filters depending on the characteristics, which is very advantageous in terms of manufacturing.

Claims (2)

[Claims] 1. A flat second dielectric substrate is adhered onto the grooved surface of a first dielectric substrate having a plurality of parallel grooves extending linearly, and a flat second dielectric substrate is adhered to the inside of the groove and the second dielectric substrate. The inner conductor is formed on the surface of the dielectric substrate facing the groove, and the outer conductor is formed on the unbonded surface of the first and second dielectric substrates and the end surface parallel to the extending direction of the groove. In a dielectric filter having a plurality of resonators, a short-circuit conductor is formed on one of the exposed end surfaces of one concave groove, and a short-circuit conductor is formed on the exposed end surface on the opposite side of the adjacent concave groove. A dielectric filter having a conductor pattern parallel to the extending direction of the groove on the adhesive surface of at least one of the dielectric substrates between which the both ends of the conductor pattern are connected to the short-circuit conductor. 2. A flat second dielectric substrate is adhered onto the grooved surface of a first dielectric substrate having a plurality of parallel grooves extending linearly, and a flat second dielectric substrate is adhered to the inside of the groove and the second dielectric substrate. The inner conductor is formed on the surface of the dielectric substrate facing the groove, and the outer conductor is formed on the unbonded surface of the first and second dielectric substrates and the end surface parallel to the extending direction of the groove. The short-circuit conductor is formed on one of the exposed end faces of one groove, and the short-circuit conductor is formed on the exposed end face on the opposite side of the adjacent groove. In the adjusting method, a conductor pattern, which is parallel to the extending direction of the groove and whose both ends are connected to the short-circuit conductor, is formed on at least one of the bonding surfaces of the dielectric substrate between the grooves, and the width of the conductor pattern is changed. Adjust the coupling between the resonators to adjust the passband width. A method of adjusting a pass band width of a dielectric filter, characterized by: