JP2001185903A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily make a dielectric filter small-sized by increasing flexibility in the design of input/output coupling. SOLUTION: Conductor patterns for connecting a terminal electrode and a short circuit conductor after assembling formed on joined surfaces of two dielectric substrates. The conductor patterns extend in parallel at prescribed intervals with an internal conductor and inductive coupling among them is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter having a plurality of resonators integrally formed in a dielectric block, and more particularly to an input / output coupling structure.

[0002]

2. Description of the Related Art Various dielectric filters are used in the field of mobile communication equipment and the like. There is a strong demand for smaller, thinner, and lighter terminal devices, and coaxial TEM resonance-type dielectric filters include those that combine individual resonators and those that integrate multiple resonators in a dielectric block. More and more, they are used not only as filters but also as duplexers.

As the miniaturization advances, it becomes difficult to adjust the coupling between input / output structures and resonators. Therefore, it has been considered to join two dielectric substrates and form a conductor pattern for input / output coupling and a conductor pattern for adjusting capacitive coupling and inductive coupling between resonators on the joint surface. . As the input / output coupling, it is considered to form a conductor film that forms a capacitance between the inner conductor of the resonator and a conductor film that is directly coupled at an impedance matching point.

[0004]

As the frequency band used increases, the size of the resonator also decreases, so that the area of the bonding surface of the dielectric substrate also decreases, and the size and shape of the conductor film formed thereon become smaller. Is also limited. Therefore, even when a conductor pattern for an input / output coupling structure is formed, a sufficient capacity may not be obtained, or a position where the conductor pattern is formed may be too close to an end face, making practical formation impossible.

An object of the present invention is to provide an input / output coupling structure of a dielectric filter in which a forming position is not restricted and sufficient input / output coupling can be obtained.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem by utilizing inductive coupling, which mainly couples the input / output conductor and the resonator by a magnetic field.

That is, in a dielectric filter having a plurality of coaxial resonators in a dielectric block, a dielectric substrate having a plurality of parallel concave grooves and a flat dielectric substrate are joined to form a plurality of parallel through holes. An inner conductor formed on the surface of the through hole, an outer conductor formed on the surface and the end surface of the dielectric block parallel to the direction in which the through hole extends, and an end surface on which the through hole is opened. And a terminal electrode formed in contact with the junction surface of the dielectric substrate surrounded by the outer conductor and at least one of the junction surfaces of the dielectric substrate between the inner conductor at both ends and the terminal electrode. In addition, a conductor film extending parallel to the through hole and having one end connected to the short-circuit conductor and the other end connected to the terminal electrode is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A conductor pattern connected to a terminal electrode is formed so as to extend in parallel with an inner conductor toward a short-circuit end face, and the end is connected to the short-circuit conductor. In the dielectric resonator, the magnetic field on the short-circuit end face side is maximized, so that the inductive coupling between the inner conductor and the conductor pattern is increased.

[0009]

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

FIG. 1 is a perspective view showing an embodiment of the present invention.
Before assembly. A flat dielectric substrate 12 is joined to a dielectric substrate 11 having two parallel concave grooves 13, but a conductor pattern 14 is formed on the flat dielectric substrate 12, and both ends are different. Pulled out to the end face. One end is drawn out to a portion where an input / output terminal electrode is formed, and the other end is drawn out to a short-circuit end face. Usually, most of the conductor pattern 14 is parallel to the direction in which the concave groove 13 extends.

FIG. 2 shows a dielectric filter in which electrodes are formed by bonding the dielectric substrates shown in FIG. The two dielectric substrates are joined to form a dielectric block 10, and a parallel through hole 15 is formed by the concave groove 13 and the dielectric substrate 12. A conductor film is formed on the surface of the through hole 15 to be an inner conductor 16, and a conductor film is also formed on an unbonded surface of the dielectric substrate and an end surface of the through hole where the through hole is not opened to become an outer conductor 17. Although not shown in FIG. 2, a conductor film is also formed on one end face where the through hole 15 is opened, and serves as a short-circuit conductor connecting the inner conductor and the outer conductor.

One end of the conductor pattern 14 formed on the joint surface of the dielectric substrate is connected to the terminal electrode 19 formed on the end surface where the through hole does not open, and the other end is connected to the short-circuit conductor.
Most of the conductor pattern on the joint surface faces the inner conductor 16 on the short-circuit end face side. Thus, a comb line type dielectric filter is formed.

FIG. 3 is a perspective view showing another embodiment of the present invention before assembly. A flat dielectric substrate 32 is joined to a dielectric substrate 31 having two parallel concave grooves 33, and a conductive pattern 34 is formed on the flat dielectric substrate 12 and is bent. Both ends are drawn to different end faces. One end is drawn out to the portion where the input / output terminal electrode is formed, and the other end is drawn out to the short-circuit end face. In this example, the short-circuit end face side is set in the opposite direction. Usually, most of the conductor pattern 34 is parallel to the direction in which the concave groove 33 extends.

FIG. 4 shows a dielectric filter in which electrodes are formed by bonding the dielectric substrates shown in FIG. The dielectric block 30 is formed by joining the two dielectric substrates, and a parallel through hole 35 is formed by the concave groove 33 and the dielectric substrate 32. A conductor film is formed on the surface of the through-hole 35 to form the inner conductor 36, and a conductor film is formed on the surface of the dielectric substrate where the through-hole is not joined and the end surface where the through-hole does not open, to become the outer conductor 37. Conductive films are alternately formed on the opposite side of each of the through-holes 35 at one end face where the through-holes 35 are opened, and the short-circuit conductors 38 connect the inner and outer conductors.

One end of the conductor pattern 34 formed on the joint surface of the dielectric substrate is connected to the terminal electrode 39 formed on the end surface where the through hole does not open, and the other end is connected to the short-circuit conductor.
Most of the conductor pattern on the joint surface faces the inner conductor 36 on the short-circuit end face side. Here, since the short-circuit conductors 38 are alternately provided in the opposite direction, an interdigital dielectric filter is formed.

In the above description, an example of a two-element filter has been described. However, a filter or a duplexer having three or more elements can be similarly applied. The coupling state can be adjusted according to the shape and dimensions of the conductor pattern. Further, the conductor pattern formed on the joint surface may be drawn out to the open end face and connected to the terminal electrode.

[0017]

According to the present invention, since input / output coupling is obtained by using inductive coupling, the shape of the conductor pattern for obtaining the coupling is less restricted, and the design of the dielectric filter is reduced. The degree of freedom is increased.

In addition, a small, thin, lightweight, and inexpensive dielectric filter can be obtained.

[Brief description of the drawings]

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

FIG. 2 is an assembled perspective view showing an embodiment of the present invention.

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

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

[Explanation of symbols]

 10, 30: dielectric block 11, 12, 31, 32: dielectric substrate 13, 33: concave groove 14, 34: conductor pattern 15, 35: through hole 16, 36: inner conductor 17, 37: outer conductor 38: Short-circuit conductor 19, 39: Terminal electrode

Claims (2)

[Claims] In a dielectric filter having a plurality of coaxial resonators in a dielectric block, a dielectric substrate having a plurality of parallel concave grooves and a flat dielectric substrate are joined to form a plurality of parallel through holes. An inner conductor formed on the surface of the through hole, an outer conductor formed on the surface and the end surface of the dielectric block parallel to the direction in which the through hole extends, and an end surface on which the through hole is opened. And a terminal electrode formed in contact with the junction surface of the dielectric substrate surrounded by the outer conductor and at least one of the junction surfaces of the dielectric substrate between the inner conductor at both ends and the terminal electrode. A dielectric film extending parallel to the through hole and having one end connected to the short-circuit conductor and the other end connected to the terminal electrode. 2. A dielectric filter having a plurality of coaxial resonators in a dielectric block, wherein a dielectric substrate having a plurality of parallel concave grooves and a flat dielectric substrate are joined to form a plurality of parallel through holes. An inner conductor formed on the surface of the through hole, an outer conductor formed on the surface and the end surface of the dielectric block parallel to the direction in which the through hole extends, and A short-circuit conductor alternately formed on one end face, and a terminal electrode formed in contact with the joint surface of the dielectric substrate surrounded by the outer conductor, and a dielectric substrate between the inner conductor and the terminal electrode at both ends. A dielectric filter, characterized in that at least one of the joining surfaces has a conductor film extending parallel to the through hole and having one end connected to the short-circuit conductor and the other end connected to the terminal electrode.