JPH03293802A - Dielectric filter - Google Patents

Abstract

PURPOSE:To improve the mass productivity by providing an area free from a short-circuit conductor between resonator holes on one end face of a dielectric block. CONSTITUTION:A long and narrow area C free from a short-circuit conductor 10 is provided between both resonator holes 4 on a short-circuit end face B of a dielectric block 2. The shortcircuit conductor 10 is formed in a required pattern on the short-circuit end face B by screen printing or the short-circuit conductor 10 is etched after being formed on the short-circuit end face B throughout, thereby easily forming this area C free from the short-circuit conductor. The size and the form of this area C are changed to obtain various coupling coefficients with the same dielectric block B. Thus, the mass productivity is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dielectric filter having a structure in which a plurality of dielectric resonators are integrated, and more specifically, to a means for coupling between each of the resonators. Regarding the improvement of

[Conventional ° technology]

A conventional example of this type of dielectric filter is shown in FIG.

This dielectric filter includes a dielectric block 2 made of ceramic, for example, in which a plurality of (two in the illustrated example) resonator holes 4 are arranged in parallel, and an inner conductor 6 is provided on the inner peripheral surface of each resonator hole 4.
An outer conductor 8 is provided on the outer peripheral surface of the dielectric block 2, and a short-circuiting conductor 10 short-circuiting the outer conductor 8 and each inner conductor 6 is provided on the entire lower end surface (short-circuited end surface) B of the dielectric block 2 in the figure. are provided to integrally constitute two dielectric resonators (dielectric coaxial resonators) centered around each resonator hole 4.

Furthermore, a coupling hole 12 is provided in the dielectric block 2 between both the resonator holes 4 in order to obtain a coupling between both the resonators.

Note that the opposite side of the short-circuited end surface B is an open end surface A without a short-circuited conductor.

[Problem to be solved by the invention]

In the dielectric filter described above, the coupling coefficient between the two resonators is determined by the size of the coupling hole 12.

Therefore, conventionally, when making dielectric filters with different characteristics, each dielectric block 2 is required to have the coupling holes 12 necessary to obtain a coupling coefficient suitable for the characteristics.

Therefore, there is a problem that the number of types of dielectric blocks 2 increases, and many molds are required for molding them, resulting in poor mass production.

Therefore, the main object of the present invention is to provide a dielectric filter that can be mass-produced by improving the means for coupling between two resonators.

[Failure to solve the problem]

In order to achieve the above object, the dielectric filter of the present invention is characterized in that a region without the shorting conductor is provided between the resonators on the one end surface (that is, the shorting end surface) of the dielectric block.

[Effect]

By providing a region without a short-circuit conductor on the short-circuit end face as described above, adjacent resonators can be coupled together even without a coupling hole.

This is because without a coupling hole, the electromagnetic field distribution between the resonators would cancel each other out in the even mode and the odd mode, and there would be no coupling between the resonators. If a region without a short-circuit conductor is provided on the short-circuit end face, the magnetic field coupling between the resonators becomes weaker in the even mode due to its presence, and the electric field coupling becomes stronger as a whole. be.

The magnitude of the coupling at this time is determined by the size and shape of the region without shorted conductors.

〔Example〕

FIG. 1 is a perspective view showing a dielectric filter according to an embodiment of the present invention with its short-circuited end facing upward. Components equivalent to those of the conventional example shown in FIG. 6 are given the same reference numerals, and the differences from the conventional example will be mainly explained below.

In this embodiment, a coupling hole 12 is provided in the dielectric block 2.
Instead of providing a short circuit conductor 10, an elongated region C without a short circuit conductor 10 is provided between both valve vibrator holes 4 on the short circuit end surface B.

Such a region C without a short-circuit conductor can be obtained by, for example, screen printing the short-circuit conductor 10 in a desired pattern on the short-circuit end surface B, or by etching after forming the short-circuit conductor 10 on the entire surface of the short-circuit end surface B. can be easily formed by (the same applies to other embodiments)
.

If such a region C without a short-circuit conductor is provided, the two resonators can be coupled together even without a coupling hole due to the effect described above.

Moreover, by changing the size and shape of the region C without a short-circuit conductor, various sizes of coupling coefficients can be obtained. For example, the region C. having no shorting conductor may be square as in the embodiment of FIG. 2, or circular as in the embodiment of FIG. 3.

Therefore, since various coupling coefficients can be obtained with the same dielectric block 2, many molds are needed to mold the dielectric block 2 having coupling holes 12 of different sizes as in the past. This does not happen, and the mass productivity of the dielectric filter is improved.

Furthermore, as in the embodiment shown in FIG. 4 or FIG. It is possible to obtain a coupling coefficient of a different magnitude than when there is no short-circuit conductor, and it is also possible to obtain various coupling coefficients by changing the size and shape of the region C without a short-circuit conductor for the same dielectric block 2. This increases the degree of freedom in design.

In addition, if the coupling coefficient of the finished product deviates from the design value, for example, the short-circuit conductor 10 in contact with the area C without a short-circuit conductor or the dielectric block 2 exposed in the area C without a short-circuit conductor may be removed. Since the coupling coefficient can be easily fine-tuned by cutting, it is also easy to increase the accuracy of the coupling coefficient.

Incidentally, in the above, the case where there are two resonator holes 4 (that is, two resonators integrated) is illustrated, but the present invention is not limited thereto, and the case where there are three resonator holes 4 is illustrated. In that case, a region C without a short-circuit conductor is provided between each resonator hole 4, or a coupling hole 1 is provided instead.
Whether to include a portion where 2 is provided or to combine both may be determined depending on the required coupling coefficient and the like.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain coupling coefficients of various sizes with the same dielectric block by changing the size and shape of the region without a short-circuit conductor provided on the short-circuit end face of the dielectric block. This improves mass productivity.

Further, it is also possible to combine the provision of a region without a short-circuit conductor and the provision of a coupling hole, thereby increasing the degree of freedom in design.

In addition, the coupling coefficient can be easily fine-tuned by scraping the short-circuited conductor in contact with an area without a short-circuited conductor or the dielectric block exposed there, making it easy to increase the accuracy of the coupling coefficient. It is.

[Brief explanation of the drawing]

1 to 5 are perspective views respectively showing a dielectric filter according to an embodiment of the present invention with its short-circuited end facing upward. FIG. 6 is a perspective view showing an example of a conventional dielectric filter with its open end surface facing upward. 2... Dielectric block, 4... Resonator hole, 6...
Inner conductor, 8... Outer conductor, 10... Short circuit conductor, 12.
...Coupling hole, C...area without short-circuit conductor.

Claims (1)

[Claims] (1) A plurality of resonator holes are arranged in parallel in a dielectric block, an inner conductor is provided on the inner peripheral surface of each resonator hole, an outer conductor is provided on the outer peripheral surface of the dielectric block, and one end surface of the dielectric block A dielectric filter comprising a shorting conductor for shorting the outer conductor and the inner conductor, characterized in that an area without the shorting conductor is provided between the resonator holes on the one end surface of the dielectric block. dielectric filter.