JPS6119201A - Distributed constant type filter - Google Patents

Abstract

PURPOSE:To obtain steep attenuation characteristics with less number of stages of resonance elements by arranging plural resonance elements to plural rows and columns and using a coupling hole formed to a dielectric block to couple the resonance elements of each row and the resonance elements of each column. CONSTITUTION:The distributed constant type filter 10 has the dielectric block 12, and holes 14a-14d prolonged to an opposite face on a face 12a of the block 12 are formed in parallel mutually in the arrangement of 2 rows and 2 columns. Inner conductors 16a-16d are formed on the inner peripheral face of the holes 14a-14d and coupling holes 18a-18d are formed among the inner conductors 16a-16d. An outer conductor 20 is formed on the outer peripheral face of the block 12. Holes 24a, 24b are formed near the holes 14a, 14d and connecting electrodes 26a, 26b are formed on the inner peripheral face of the holes 24a, 24b to fix input terminals 30a, 30b. Moreover, coupling holes 28a, 28b are formed between the holes 24a and 24b and between the holes 14a and 14d. Through the constitution above, the resonance elements of the input terminal 30a, the inner conductor 16a and the terminal 30b, the conductor 16b are coupled inductively (magnetic field) and the steep attenuation characteristic is formed with less number of stages of the resonance elements.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a distributed parameter filter, and more particularly to an integral distributed parameter filter in which a plurality of resonant elements are coupled together through coupling holes.

(Prior Art) FIG. 8 is a plan view showing a conventional example of this type of distributed constant type filter. FIG. 9 is a sectional view taken along line IX-IX in FIG. 8. The distributed constant type filter 10 includes one rectangular parallelepiped dielectric block 12, and one surface 12a of the rectangular parallelepiped dielectric block 12 has a plurality of holes 14a, 14b,
14c and 14d are formed extending to opposing end surfaces. On the inner peripheral surface of each of these holes 14a to 14d, an inner conductor 16a, each forming a part of a resonant element,
16b, 16c and 16d are formed. In addition, these inner conductors are formed on the outer peripheral surface of the dielectric block 12.
16d and 17/l ('$11) Outer conductor 20 is formed.Therefore, multiple holes, i.e. inner conductors 16a to 16d, are formed.
and a common outer conductor, a plurality of T E
An M dielectric coaxial resonator element is formed.

Square holes 18a, 18b, and 18c for coupling are formed between the respective resonant elements.

Furthermore, inner conductor 1 constituting the first stage and final stage resonant elements
6a and 16d, that is, near the holes 14a and 14d, from the outer surface of the dielectric block 12, respectively.
Further holes 24a and 24b are formed for external coupling.

Connection electrodes 26a and 26b are formed on the inner peripheral surfaces of the holes 24a and 24b, respectively.

Input terminals 30a and 30b are inserted into the connection electrodes 26a and 26b, respectively, and are electrically connected and mechanically fixed. Hole 14 that constitutes first-stage and final-stage resonant elements with other holes 24a and 24b
Between a and 14d, coupling cavities or sulins 28a and 28b are formed, respectively. These slits 28a and 28b are formed by the square holes 18a to 18d.
It has a similar structure and function.

It is already well known that such an integrated distributed constant filter has a four-stage combline structure and Chebyshev type attenuation characteristics, and the explanation thereof will be omitted here.

(Problem to be solved by the invention) However, in conventional distributed constant filters, in order to steepen the attenuation characteristics of the filter, it is necessary to increase the number of stages of resonant elements, which requires additional space. However, there are some difficulties in miniaturizing it.

Therefore, the main object of the present invention is to provide a distributed constant filter having a steep damping characteristic with a smaller number of resonant element stages.

(Means for resolving the problem) The second invention arranges a plurality of resonant elements in a plurality of rows and columns, and couples the resonant elements in each row with each other through coupling holes.
It is also a distributed constant type filter in which the resonant elements in each row are coupled together.

(Function) Holes are formed in a dielectric material having an outer conductor on its outer circumferential surface in multiple rows and columns, and inner conductors are formed on the inner circumferential surface of the dielectric material. arranged in
On the other hand, coupling holes formed in the dielectric block couple the resonant elements in each row and the resonant elements in each column.

(Effects of the Invention) According to the present invention, in the distributed constant type filter, the resonant elements in each row are not coupled to each other, but the resonant elements in each column are coupled to each other, so that the filter characteristic becomes elibutic type, which is different from the conventional one. Compared to the Chebyshev type filter, it is possible to construct a filter with steeper attenuation characteristics using the same number of resonant element stages. Therefore, the number of stages of resonant elements can be reduced compared to the conventional method, and the size of the distributed constant filter can be reduced.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Embodiment) FIG. 1 is a plan view showing an embodiment of the present invention. The distributed constant filter 1o includes one dielectric block 12. One surface 12a of the dielectric block 12 has a hole 14a extending to the opposite end surface.

14b, 14c and 14d are formed parallel to each other in an array of 2 rows and 2 columns. And these holes 14
Inner conductors 16a, 16b, 16c are provided on the inner peripheral surfaces of a to 14d.
and 16d are formed, respectively, and the dielectric block 12
An outer conductor 20 is formed on the outer peripheral surface of. In this embodiment, the portion facing the open end surface 12a is covered with an outer conductor, so that a plurality of TEM dielectric coaxial resonant elements are arranged in two rows and two columns as λ/4 elements. and,
Coupling holes 13a to 18d are formed between each of the resonant elements, that is, the inner conductors 16a to L6d, and the resonant elements formed in a plurality of rows and columns are coupled with each other between the resonant elements in each row. The resonant elements in each column are coupled together.

Furthermore, inner conductor 1 constituting the first stage and final stage resonant elements
6a and 16d, that is, near the holes 14a and 14d, from the outer surface of the dielectric block 12, respectively.
Further holes 24a and 24b are formed for external coupling.

Connection electrodes 26a and 26b are formed on the inner peripheral surfaces of the holes 24a and 24b, respectively. And each of the connection electrodes 26a and 26b has
Input terminals 30a and 30b are inserted, electrically connected, and mechanically fixed. Furthermore, another hole 24
a and 24b, and the holes 14 that constitute the first and final stage resonant elements. Coupling holes 28a and 28b are formed between a and 14d, respectively. these holes 2
8a and 28b have the same structure and function as the previous holes 18a-18d. If you shift to such a bonding structure,
The input terminal 30a and the resonant element formed by the inner conductor 16a are inductively coupled, that is, magnetically coupled. Similarly, the resonant element formed by the input terminal 30b and the inner conductor 16b is also inductively coupled, that is, magnetically coupled.

Note that capacitive coupling, that is, electric field coupling may be performed between the input terminals 30a and 30b and the respective resonance elements formed by the inner conductors 16a and 16b.

The integrated distributed constant filter 10 thus completed is formed in a plurality of rows and columns, and the resonant elements in each row are coupled together, and the resonant elements in each column are coupled together. The filter characteristics suddenly become sharper, as shown by the solid line in FIG. On the other hand, the characteristics of a conventional Chebyshev type filter are shown by the dotted line in FIG. That is,
Even with a distributed constant type filter composed of the same number of stages (four stages) of resonant elements as the conventional filter, according to the embodiment shown in FIG. 1, it is possible to obtain a steeper attenuation characteristic of an elybution type filter.

FIGS. 3 and 4 are plan views showing other embodiments of the invention, respectively. These distributed constant type filters 1
0 differs from the embodiment shown in FIG. 1 in that only coupling holes 18b and 18d or coupling holes 18a and 18c are formed. As shown in FIG. 3, only coupling holes 18b and 18d may be formed, or as shown in FIG. 4, coupling holes 18a and 18C may be formed.
In either case, the resonant elements in each row and the resonant elements in each column are coupled. Therefore, the filter characteristics of these distributed constant type filters 10 are also of the elibutic type. In this way, the coupling holes may be formed only between the rows or columns of the array of resonant elements to couple the resonant elements. In this way, the number of coupling holes can be reduced.

FIG. 5 and FIG. 6 are plan views showing still other embodiments of the present invention. These distributed constant type filters 10 differ from the above-mentioned embodiments in particular in that only one coupling hole is provided. Distributed constant type filter 10 shown in FIG.
Here, the coupling slit 18e is formed as one approximately cross-shaped hole so that the end face leaking electromagnetic energy is located between the arrays of each resonant element. Further, in the distributed constant filter lO shown in FIG. 6, one coupling hole 18f is formed at the center of each resonant element so as to be surrounded by them.

It is clear that the resonant elements can also be coupled to each other using these coupling slits 18e or holes 18f.

The filter characteristics of these distributed constant type filters are also of the elibutic type. In this way, the number of coupling holes may be one.

FIG. 7 is a sectional view showing a modification of the coupling hole. In this FIG. 7, the hole 18a is shown as a representative of the others, but the other hole 1
8b to 18d, 28a and 28b. For example, an electrode 22 electrically connected to the outer conductor 20 is formed on the inner wall of the coupling hole 18a around the short-circuited end of the dielectric block 12.

This electrode 22 is formed below the hole 18a, and by changing its length, thickness, etc., the degree of coupling due to the hole 18a can be adjusted.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention. FIG. 2 is a diagram showing the attenuation characteristics of the filter, where the dotted line shows the characteristics of the conventional example and the solid line shows the characteristics of the embodiment of the present invention. FIGS. 3 and 4 are plan views showing other embodiments of the invention, respectively. FIG. 5 and FIG. 6 are plan views showing still other embodiments of the present invention. FIG. 7 is a sectional view showing a modification of the hole for connection. FIG. 8 is a plan view showing a conventional example of a distributed constant type filter. FIG. 9 is a sectional view taken along line IX-IX in FIG. 8. In the figure, 10 is a distributed constant filter, 12 is a dielectric block, 14a to 14d are holes, 162 to L6d are inner conductors, 188 to 18 are coupling holes, and 20 is an outer conductor. Patent applicant: Murata Risakusho Co., Ltd. Agent: Patent attorney: Oka 1) Zen Kei (and 1 other person) Figure 2, Ward 7 iu zz

Claims (1)

[Scope of Claims] An integrated distributed constant filter in which a plurality of resonant elements are formed in one dielectric block, comprising: an outer conductor formed on an outer peripheral surface of the dielectric block; a plurality of holes formed in an array of a plurality of rows and a plurality of columns; a resonant element formed on the inner circumferential surface of each of the plurality of holes, each of which cooperates with the outer conductor to form a resonant element in an arrangement of a plurality of rows and a plurality of columns; a plurality of inner conductors formed in the dielectric block, and coupling holes formed in the dielectric block for coupling the resonance elements in each row and coupling the resonance elements in each column.