JP2661007B2 - Dielectric filter and pass band adjustment method thereof - 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 an interdigital dielectric filter, and more particularly to an electrode structure for adjusting the coupling between resonators.

[0002]

2. Description of the Related Art Various dielectric filters are used in a high frequency range such as a UHF band to a 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.

[0003] Among these dielectric filters, particularly in an integrated dielectric filter, it is necessary to adjust the capacitive coupling and the inductive coupling between the resonators. Usually, in order to weaken the coupling, holes for adjusting the coupling are formed between the resonators, or a conductor is interposed between the resonators.

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. Therefore,
The inventor of the present invention has previously filed Japanese Patent Application No. 4-186099, in which two dielectric substrates are attached to each other to form an inner conductor with a conductor film formed in one of the grooves, thereby forming a plurality of conductors. A structure to obtain the resonator was proposed.

[0005]

When it is necessary to adjust the pass bandwidth in a dielectric filter, the coupling between the resonators must be adjusted. Usually, a structure for weakening the coupling is adopted. However, if the spacing between the resonators is increased, it becomes a major obstacle to miniaturization. Forming a hole for coupling adjustment between resonators also causes a similar problem as well as a processing problem.

An object of the present invention is to solve the above problems and to provide a dielectric filter capable of weakening the adjustment of the coupling between resonators with a simple structure and a simple manufacturing process.

[0007]

The present invention solves the above-mentioned problems by providing a conductor pattern grounded across the resonators between the inner conductors of the resonator and adjusting the width of the conductor pattern. Is what you do.

That is, in a dielectric filter in which a plurality of resonators are integrally formed by bonding two dielectric substrates, a concave groove of the first dielectric substrate having a plurality of linearly extending grooves. A flat dielectric substrate having a plurality of through holes is formed by bonding a flat second dielectric substrate on a surface having a through hole, an inner conductor is formed on the surface in the through hole, and the first dielectric substrate and An outer conductor is formed on each of the surfaces facing the bonding surface of the second dielectric substrate and on both end surfaces parallel to the direction in which the concave groove extends, and a short-circuit conductor is formed on the open end surface of one through hole, and is adjacent to the outer surface. In the through-hole, a short-circuit conductor is formed on the end face that opens on the opposite side, and a conductor pattern parallel to the extending direction of the through-hole is provided on the bonding surface of at least one dielectric substrate between the through-holes, and both ends of the conductor pattern are provided. Characterized by being connected to a short-circuit conductor It is intended.

In a method for adjusting the pass bandwidth of a dielectric filter in which a plurality of resonators are integrally formed by bonding two dielectric substrates, a first method including a plurality of linearly extending grooves is provided. A dielectric block having a plurality of through-holes formed by bonding a flat plate of a second dielectric substrate on the surface of the dielectric substrate having the concave grooves is formed, and an inner conductor is formed on the surface in the through-hole, Outer conductors are formed on the respective surfaces of the first dielectric 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 short-circuited to the open end surface of one through hole. A conductor is formed, and a short-circuit conductor is formed on an end face of the adjacent through hole that opens on the opposite side, and a short-circuit conductor is formed on the bonding surface of at least one of the dielectric substrates between the through holes in parallel with the direction in which the through hole extends and at both ends. To form a conductor pattern connected to Those having features to adjust a coupling between the resonators by changing the width of the emission.

[0010]

[Function] 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, so that the coupling between the resonators can be weakened. And the coupling state can be controlled 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 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 on the bonding surface of the dielectric substrate 12 in advance. The conductor pattern 16 is formed between the concave grooves 14 so as to extend in the same direction as the groove and reaches 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 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. 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. 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 resonant dielectric filter is formed. A conductor film is not formed around the same end face side where the adjacent through-hole 25b is opened, and is an open end face. Thus, an interdigital dielectric filter is formed.

The conductor pattern (16) formed on the joint surface shown in FIG. 1 is connected to the short-circuit electrode 28 at the end face of the dielectric substrate, and is connected to the short-circuit conductor at the opposite end face (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 capacitance, an input / output coupling electrode is formed on the bonding surface of the dielectric substrate, and the terminal electrode Need to connect with 29.

The terminal electrode 29 is formed not only on the end face parallel to the extending direction of the through hole 25 but also on the surface adjacent thereto. This is to enable surface mounting on a printed wiring board. Of course, the terminal electrode 29 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 above example, a two-element interdigital dielectric filter has been described, but a block having three or more elements can be used. In addition, the conductor pattern may be formed on a flat dielectric substrate instead of the dielectric substrate having the concave groove. By forming such a conductor pattern crossing between 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. This shows that as the width of the conductor pattern between the resonators is increased, the coupling between the resonators is weakened and the pass bandwidth is reduced.

[0017]

According to the present invention, the coupling between the resonators can be reduced to a desired amount, whereby it is easy to obtain a predetermined pass bandwidth, and a small-sized dielectric filter can be obtained. It is 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 according to characteristics, which is very advantageous in terms of manufacturing.

[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 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

Claims (2)

(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 has a plurality of linearly extending grooves. A flat dielectric substrate having a plurality of through holes is formed by bonding a flat second dielectric substrate on a surface having a through hole, an inner conductor is formed on the surface in the through hole, and the first dielectric substrate and An outer conductor is formed on each of the surfaces facing the bonding surface of the second dielectric substrate and on both end surfaces parallel to the direction in which the concave groove extends, and a short-circuit conductor is formed on the open end surface of one through hole, and is adjacent to the outer surface. In the through-hole, a short-circuit conductor is formed on the end face that opens on the opposite side, and a conductor pattern parallel to the extending direction of the through-hole is provided on the bonding surface of at least one dielectric substrate between the through-holes, and both ends of the conductor pattern are provided. A dielectric filter connected to a short-circuit conductor. Ruta. 2. A method for adjusting the pass bandwidth of a dielectric filter in which a plurality of resonators are integrally formed by bonding two dielectric substrates to each other, the first method including a plurality of linearly extending grooves. A dielectric block having a plurality of through-holes formed by bonding a flat second dielectric substrate on the surface of the dielectric substrate having the concave grooves is formed, and an inner conductor is formed on the surface in the through-hole, Outer conductors are formed on the respective surfaces of the first dielectric 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 short-circuited to the open end surface of one through hole. A conductor is formed, and a short-circuit conductor is formed on an end face of the adjacent through hole that opens on the opposite side, and a short-circuit conductor is formed on the bonding surface of at least one of the dielectric substrates between the through holes in parallel with the direction in which the through hole extends and at both ends. To form a conductor pattern connected to A method for adjusting a pass bandwidth of a dielectric filter, comprising adjusting coupling between resonators by changing a width.