JPS6243904A - Dielectric resonator - Google Patents

Abstract

PURPOSE:To obtain a dielectric resonator with less variance in products, low cost and stable characteristic by forming a recess to an outer face of a dielectric block near an open end face, forming an electrode opposed to an inner conductor to the recess and coupling the block to an external circuit through the electrode. CONSTITUTION:A short-circuit electrode 7 short-circuiting inner conductors 4, 5 and an outer conductor 6 is formed to a bottom face 1a of the dielectric block 1 and the upper face 1b is an open end face not formed with the short- circuit electrode. Then recesses 8, 9 are formed to the outer face of the dielectric block 1 near the open end face and electrodes 10, 11 opposed to the inner conductors 4, 5 are formed to the recesses 8, 9. Thus, the filter is coupled with an external circuit through the electrodes 10, 11. Thus, since the inner conductors 4, 5 and the external circuit are coupled by adopting a structure forming the electrode to the recesses 8, 9 provided to the dielectric block, the manufacture cost is low by using the dielectric ceramic as the dielectric block, the variance in the characteristic is less, stable thermal characteristic is obtained for the dielectric resonator with low height and small size.

Description

Detailed Description of the Invention 11 JIUW Mizuno The present invention relates to a dielectric resonator in which an outer conductor is formed on the outer surface of a dielectric block having at least one hole, and an inner conductor is formed on the inner surface of the hole. This invention relates to improvements in the coupling structure with external circuits in dielectric resonators.

The dielectric resonator described above is used, for example, as a bandpass filter in a transmission mixer circuit for a car telephone. Filters used in such applications are required to be small and have a high QO (no load Q), so dielectric resonators using TEM mode are widely used. Conventionally, the filter shown in FIG. 6 has been used. This filter is made by drilling two holes c in a dielectric block a, forming inner conductors d and e on the inner surface and an outer conductor f on the outer surface of the block, and connecting both conductors d, e, and f to the dielectric block. It is short-circuited by a short-circuit electrode formed on the bottom surface, and the inner conductors d and e, the outer conductor f, and the dielectric block a therebetween constitute a pair of resonant units. The resonant units are coupled to each other by forming the holes c into stepped holes.

A so-called resin bottle k, which has a structure in which a metal terminal j is inserted into a resin l, is inserted into the hole c, and the inner conductors d and a of the filter are capacitively coupled to an external circuit through this resin pin k, and the necessary external Q (=Qs) is secured. Here, the external Q is the filter load Q (=Q
I,) is an important factor in determining

In equation L, Qo is the unloaded Q of the filter.

By the way, if a resin bottle k is used to connect the filter to an external circuit as described above, the following problem arises.

That is, ■Since the resin pin is inserted into the hole c of the dielectric block, it is desirable that the resin i is somewhat soft, and also that the filter characteristic - εr is high and tan δ is small. . However, the number of resins that satisfy all of these requirements is extremely limited, which increases the material cost of the resin pins and, in turn, increases the manufacturing cost of the entire filter.

■Resin generally has poor thermal stability, so the bond between the inner conductors d and e of the filter and the metal terminal j becomes thermally unstable.
It is difficult to obtain a filter with stable characteristics. ■ When inserting the resin bottle k into the hole c in which the inner conductor is formed, a gap may be formed between the resin surface and the inner conductor depending on the shape of the resin i. For this reason, variations in the coupling quality between the filter and the external circuit, and furthermore, variations in filter characteristics from product to product are extremely large.

In view of the above problems, the present invention has been developed to reduce the variation between products.
The purpose of this invention is to provide a dielectric resonator that is inexpensive and has stable characteristics.

To further achieve the above object, the present invention provides a dielectric block having at least one hole, in which an outer conductor is formed on the outer surface of the block, and an inner conductor is formed on the inner surface of the hole. In the dielectric resonator,
For JY, a recess is formed in a part of the outer surface of the dielectric block near the open end surface, an electrode facing the inner conductor is formed in the recess, and the electrode is connected to an external circuit through this electrode. Since the electrode formed in the recess on the outer surface of the dielectric block faces the inner conductor, the opposing portion connects the filter to the external circuit in the same way as a conventional resin pin. However, unlike conventional resin bottles, resin is not required and the dielectric block itself acts as a substitute, so the above problems can be solved. The reason for this will be explained in detail in the following examples.

ACTUAL EXAMPLE FIG. 1 shows a two-stage bandpass filter as an example of the dielectric resonator of the present invention, and FIG. 2 shows its cross-sectional view. In the figure, 1 is a rectangular parallelepiped dielectric block made of titanium oxide dielectric ceramic, and has two stepped holes 2.
．． 3 is bored, and an inner conductor 4.5 is formed on the inner surface of the hole. An outer conductor 6 is formed on, for example, four sides of the outer periphery of the dielectric block 1, and a pair of resonant units are constituted by the outer conductor 6, the inner conductor 4.5, and the dielectric block 1 sandwiched therebetween. In this embodiment, the coupling between the resonant units is realized by a configuration called a stepped impedance type in which the holes 2.3 are stepped. However, in addition to this, the bottom surface 1, a of the dielectric block 1 can also be coupled by a structure in which a coupling hole is formed between both resonance units, or a structure in which a coupling electrode is formed on the open end surface to be electrically connected to the inner conductor. Inner conductor 4゜5
The short-circuiting electrode 7 that short-circuits the outer conductor 6 and the outer conductor 6 is formed as a short-circuiting end surface, and the -L surface 1b is an open end surface on which no short-circuiting electrode is formed. A recess 8°9 is formed on the outer surface of the dielectric block 1 near this open end surface, and the recess 8,
Electrodes 10 and 11 facing the inner conductors 4 and 5 are formed at 9 . The filter is therefore coupled to an external circuit through said electrodes 1o, tl. In the figure, reference numerals 12 and 13 indicate input/output terminals connected to an external circuit, which are firmly attached to the electrodes 10 and 11 by brazing or the like.

Since the electrode 10.11 is formed near the open end face, the coupling between the inner conductor 4.5 and the external circuit is capacitive.

In this case, since the electrodes 10.11 are formed on the four parts 8.9, the distance between them and the inner conductor 4.5 is narrow, so that the required amount of coupling can be achieved without increasing the area of the electrodes 10.11. Obtainable. Further, since the area of the electrodes 10, 11 is small, the area of the outer conductor 6 is not sacrificed much, and therefore, deterioration of QO can be prevented. As a result, a small filter with high Qo and a predetermined amount of coupling can be obtained. Further, since the electrode 10.11 is formed on the dielectric block 1 itself and is connected to the inner conductor 4.5 through the block 1, there is no gap between the electrode 10.11 and the inner conductor like a conventional resin pin. Therefore, there is little variation in the coupling ports.

When the dielectric block 1 is made of dielectric ceramic, the recesses 8 and 9 can be formed at the same time as the dielectric block 1 is manufactured. In this case, since the dielectric ceramic is thermally stable due to its characteristics, a stable external Q can be ensured, and 6r is high (tan
A bonded structure with a small δ can be easily realized. The amount of depression of the recess 8.9 may be set to an appropriate amount depending on the amount of coupling between the filter and the external circuit.

Further, the shape, size, and position of the recess 8.9 are not limited to the example shown in FIG. 4.
As shown in FIG. 5, it can be formed in an appropriate shape and size at an appropriate position.

In addition, as the dielectric block 1, the number of holes is 21 (not limited to 1i1, but 3 or more) as in the embodiment,
Alternatively, only one may be formed.

Further, in the embodiment, the holes 2.3 formed in the dielectric block 1 are 'M communicating holes, but they may be holes with only one side open.

Invention pI Director As explained above, according to the present invention, the inner conductor and the external circuit are connected by a structure in which electrodes are formed on the four parts provided on the dielectric block without using resin pins, so that the inner conductor and the external circuit are connected to each other. The use of dielectric ceramic has the advantageous effects that it is possible to obtain a dielectric resonator that is low in manufacturing cost, has little variation in characteristics, is thermally stable, and is low in bulk and compact.

In addition, the input/output terminals for connecting to external circuits using the electrodes can be attached very firmly by brazing, etc., so the mechanical strength is higher than the conventional structure using resin pins. It is possible to obtain a dielectric resonator with excellent performance such as being expensive and easy to handle.

[Brief explanation of the drawing]

FIG. 1 is an overall perspective view showing one embodiment of the dielectric resonator of the present invention, FIG. 2 is a sectional view of WIS 1, and FIGS. 3 to 5 are views showing other embodiments of the present invention, respectively. , FIG. 6 is a diagram showing a filter using a conventional dielectric resonator. 1... Dielectric block, 2.3... Hole 4.5...
Inner conductor, 6... Outer conductor, 8, 9... Recessed portion 10.11
... Electrode patent applicant Murata Manufacturing Co., Ltd. Figure 1 Figure 2 Figure Ia Figure 3 Figure 5 Figure 7 and Figure 6 (A)

Claims (1)

[Scope of Claims] In a dielectric resonator in which an outer conductor is formed on the outer surface of a dielectric block having at least one hole, and an inner conductor is formed on the inner surface of the hole, the outer surface of the dielectric block has an open end surface. A dielectric resonator characterized in that a recess is formed in a part of the recess, an electrode facing the inner conductor is formed in the recess, and the resonator is coupled to an external circuit through the electrode.