JPH05167310A - Dielectric filter and resonator - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To obtain an input / output electrode with a small coupling capacitance that is compatible with high frequencies while having an area required for soldering and the like. [Structure] Dielectric filter 10 or outer conductor 1 of resonator
The outer conductor 1 faces the inner conductor 12 on the side surface where the outer conductor 3 is formed.
3 forms an insulated conductor film. This conductor film is surrounded by the outer conductor 13 and is formed at a distance from the open end face. The capacitance increases when the conductor film is closer to the open end face, and the capacitance decreases when the conductor film is farther away. It can be formed at a position where a desired capacity can be obtained. Also, this electrode 1
4 can be directly connected to the pattern on the printed circuit board.

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 a resonator, and more particularly to a dielectric filter and a dielectric resonator having an input / output coupling structure.

[0002]

2. Description of the Related Art Various dielectric filters are used for mobile communication filters, duplexers and the like. Generally, a plurality of quarter-wavelength dielectric resonators are used to couple them and form an input / output coupling capacitance to form a filter. Further, there is also one using a dielectric block in which a plurality of resonators are integrated.

In order to obtain the input / output coupling capacitance, a chip capacitor is connected to the inner conductor of the resonator at the input / output end, or the inner conductor is connected to another dielectric substrate on which a capacitor electrode is formed. There is. Further, a structure in which a conductor coated with a dielectric is inserted into a through hole in which an inner conductor is formed to obtain a coupling capacitance is also considered.

However, the above-mentioned input / output coupling structure increases the number of parts and becomes an obstacle in terms of downsizing. Therefore, a structure in which an electrode is formed on the side surface of the dielectric resonator to obtain a coupling capacitance with the inner conductor is considered. Figure 4
Is an example of such a dielectric filter. In the dielectric filter 40, a plurality of through holes are formed in a rectangular parallelepiped dielectric block 41, and inner conductors 42 are formed on the surfaces of the through holes.
An outer conductor 43 is formed on the outer peripheral surface. A part of the outer conductor 43 is removed, and another conductor film 44 is formed on the open end face side of the dielectric block 41.

The conductor film 44 is connected to the input / output end and faces the inner conductor 42 via a dielectric to obtain an input / output coupling capacitance. Also, the inner conductor 42 and the outer conductor of the two through holes
The resonator units composed of 43 are coupled to obtain a desired filter characteristic. That is, as shown in FIG. 5, the two resonators 50a and 50b are connected to the input and output ends via capacitors, and capacitive and inductive coupling is generated between them.

[0006]

In the dielectric filter, as the frequency becomes higher, the input / output coupling capacitance becomes smaller. If the area of the electrode formed on the side surface of the dielectric is too large, an unnecessarily large capacitance will be formed.

However, when the area of the electrode is reduced, the solderability at the time of surface mounting on a printed circuit board or the like is deteriorated, and the reliability of the dielectric filter often used under severe conditions is also problematic. Occurs.

Further, in a normal dielectric filter, the open end face is polished to adjust the frequency, and the electrode for the coupling capacitance is also scraped at that time, so that the capacitance value changes greatly.

An object of the present invention is to obtain a dielectric filter and a resonator having faceable input / output electrodes having a sufficient area in terms of reliability. Moreover, it is intended to obtain an input / output electrode that is not affected by the frequency adjustment.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above problems by forming input / output coupling electrodes at a distance from the open end face.

That is, a plurality of through holes are provided in a rectangular parallelepiped dielectric block, inner conductors are formed in the through holes, outer conductors are formed on side surfaces parallel to the through holes, and the through holes are exposed. A short-circuit conductor is formed on one of the surfaces
The other surface of the dielectric filter is an open end surface from which the dielectric is exposed.On the side surface facing the inner conductor formed in the through hole at the input / output end, the other surface is surrounded by the outer conductor and insulated from the outer conductor. It is characterized by having an input / output coupling electrode.

Further, in a dielectric filter of the type in which individual resonators are combined, similar input / output coupling electrodes are provided on the resonators at both ends. The resonator alone can be realized by forming two electrodes.

[0013]

In the quarter-wavelength TEM resonance mode, the electric field becomes maximum at the open end face and becomes smaller toward the short-circuited end face. If the input / output coupling electrode is formed in this portion where the electric field strength is small, it is possible to suppress the capacitance to a small value even in a large area. Further, it is possible to adjust the capacitance value depending on the position of formation.

[0014]

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. The dielectric filter 10 is formed by integrally forming a plurality of resonators into blocks, and the dielectric block 11 has a plurality of through holes formed in parallel with each other and an inner conductor formed on the surface thereof. Four outer conductors 13 are formed on the side surface parallel to the extending direction of the through hole in which the inner conductor 12 is formed. Although not shown in the figure, a conductor film is formed on one of the exposed surfaces of the through holes to form a short-circuit conductor that short-circuits the inner conductor 12 and the outer conductor 13. No conductor film is formed on the other surface, and the surface is an open end surface.

In the dielectric filter 10 according to the present invention, the input / output coupling electrode 14 is formed on the side surface on which the outer conductor 13 is formed, but at a distance from the open end surface. The input / output coupling electrode 14 is insulated from the outer conductor 13, and a dielectric film is exposed without a conductor film formed between them. Also,
An outer conductor 13 is provided between the input / output coupling electrode 14 and the open end surface.
Is intervening.

In this example, the input / output coupling electrodes 14 are formed so as to extend over two side surfaces, and the upper surface of the drawing, that is, the surface on which the two electrodes are formed is mounted facing the printed circuit board. , Soldering can be performed at that portion. It is also possible to confirm the soldering state on the surface not facing the substrate. It is also possible to form such an input / output coupling electrode 14 so as to straddle the side surface and the lower surface of the drawing together and connect only one of them to the wiring. This also eliminates directional problems.

FIG. 2 is a perspective view showing an example of a dielectric filter having a structure in which individual resonators are combined. The dielectric filter is a combination of two resonators 20a and 20b. Through holes are formed in the dielectrics 21a and 21b, respectively.
Inner conductors 22a and 22b are formed on the surface thereof. Four outer conductors 23a and 23b are formed on the side surfaces parallel to the extending direction of the through holes in which the inner conductors 22a and 22b are formed. Although not shown in the figure, a conductor film is formed on one of the exposed surfaces of the through holes to form a short-circuit conductor that short-circuits the inner conductor 22 and the outer conductor 23. No conductor film is formed on the other surface, and the surface is an open end surface.

In the dielectric filter 20 according to the present invention, the input / output coupling electrodes 24a, 24b are formed on the side surfaces on which the outer conductors 23a, 23b are formed, but at intervals from the open end surface. The input / output coupling electrodes 24a and 24b are the outer conductor 23.
It is insulated from a and 23b, and a dielectric film is exposed without forming a conductor film between them. The outer conductors 23a, 23b are provided between the input / output coupling electrodes 24a, 24b and the open end surface.
Is intervening.

FIG. 3 shows an example of a quarter wavelength resonator, in which input / output coupling electrodes 34a and 34b surrounded by an outer conductor 33 are formed on the side surface of a dielectric resonator 30. Is. Similarly, the input / output coupling electrodes 34 a and 34 b are arranged at a distance from the open end face and are surrounded by the outer conductor 33.

Input / output coupling electrodes can be similarly formed in a half-wavelength resonator in which short-circuit conductors are formed on both exposed surfaces of a through hole and a filter in which the resonator is coupled.

[0022]

According to the present invention, it is possible to obtain a desired capacitance value even if the size of the electrode is constant. That is, the capacitance value can be selected by adjusting the position where the electrode is formed. Therefore, it is possible to form an electrode having a small capacitance while having an area sufficient for soldering.

The coupling capacitance does not change even by polishing the open end face for adjusting the resonance frequency, and the capacitance as designed can be obtained.

Furthermore, since soldering at or near the open end face is not required at the time of mounting, an unnecessary capacitance is not formed and a dielectric filter having a small influence on the frequency characteristic can be obtained.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing another embodiment of the present invention.

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

FIG. 4 is a perspective view showing a conventional example.

FIG. 5 is an explanatory diagram of an equivalent circuit of a dielectric filter.

[Explanation of symbols]

 12, 22, 32: Inner conductors 13, 23, 33: Outer conductors 14, 24, 34: Input / output coupling electrodes

Claims (5)

[Claims] 1. A rectangular parallelepiped dielectric block is provided with a plurality of through holes, an inner conductor is formed in the through holes, an outer conductor is formed on a side surface parallel to the through holes, and the through holes are exposed. A short-circuit conductor is formed on one of the surfaces, and the other surface is a dielectric filter having an open end surface from which the dielectric is exposed.In the side surface facing the inner conductor formed in the through hole at the input / output end, A dielectric filter comprising an input / output coupling electrode surrounded by an outer conductor and insulated from the outer conductor. 2. A rectangular parallelepiped dielectric body is provided with a through hole, an inner conductor is formed in the through hole, an outer conductor is formed on a side surface parallel to the through hole, and one of the surfaces on which the through hole is exposed. A dielectric filter formed by coupling a plurality of dielectric resonators, each of which has a short-circuit conductor and whose other surface is an open end surface from which a dielectric is exposed, is connected to another resonator of the input / output end dielectric resonator. A dielectric filter comprising an input / output coupling electrode surrounded by an outer conductor and insulated from the outer conductor on a side surface which does not come into contact with the outer conductor. 3. A rectangular parallelepiped dielectric body is provided with a through hole, an inner conductor is formed in the through hole, an outer conductor is formed on a side surface parallel to the through hole, and one of the surfaces on which the through hole is exposed is formed. In a dielectric resonator in which a short-circuit conductor is formed and the other surface is an open end surface where the dielectric is exposed, the input coupling is surrounded by the outer conductor and insulated from the outer conductor on the side surface where the outer conductor is formed. A dielectric resonator comprising an electrode for output and an electrode for output coupling. 4. A rectangular parallelepiped dielectric body is provided with a through hole, an inner conductor is formed in the through hole, an outer conductor is formed on a side surface parallel to the through hole, and a short-circuit conductor is formed on a surface where the through hole is exposed. In the dielectric resonator having the outer conductor formed thereon, an input coupling electrode and an output coupling electrode surrounded by the outer conductor and insulated from the outer conductor are provided on a side surface where the outer conductor is formed. Body resonator. 5. A rectangular parallelepiped dielectric body is provided with a through hole, an inner conductor is formed in the through hole, an outer conductor is formed on a side surface parallel to the through hole, and a short-circuit conductor is formed on a surface where the through hole is exposed. In a dielectric filter formed by coupling a plurality of dielectric resonators formed with, is surrounded by an outer conductor and insulated from the outer conductor on the side surface of the dielectric resonator at the input / output end that does not contact other resonators. A dielectric filter comprising the above-mentioned input / output coupling electrode.