JPS6239901A - Dielectric filter - Google Patents

Abstract

PURPOSE:To improve the forming performance without causing chipping by forming a large diameter part and a small diameter part connected via a taper to at least a hole adjacent to plural holes formed to a dielectric block so as to improve the density distribution of a material at press forming. CONSTITUTION:Holes 14a-14d prolonged from an open end face 12a up to an opposite end face are formed to the dielectric block 12 mutually in parallel in a line. The holes 14a-14d include large diameter parts 142a-142d and small diameter parts 143a-143d connected by tapers 141a-141d respectively. Inner conductors 16a-16d are formed respectively to each inner circumference face of the holes 14a-14d. On the other hand, an outer conductor 18 is formed to an outer circumference face of the dielectric block 12. The end face of the dielectric block 12 opposed to the open end face 12a is covered by the outer conductor 18. The impedance formed by the two parts 142a-142d and 143a-143d differs depending on the even or the odd mode because of the difference from the static capacitance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dielectric filter, and particularly to an integrated dielectric filter in which a plurality of resonant elements are formed in one dielectric block, for example.

(Prior Art) A conventional technology of this type of dielectric filter is disclosed in, for example, Patent Application Publication No. 500198 of 1982. As shown in the equivalent circuit of FIG. 2, this dielectric filter obtains coupling between each resonant element R using a gap capacitance C formed by an electrode on the open end side of each resonant element R.

In the cited prior art, since there is no need to form coupling holes or slits for coupling each resonant element to the dielectric block, the dielectric block can be easily manufactured.

However, in this conventional technique, it is necessary to form an electrode on the open end surface in order to create a gap capacitance for coupling each resonant element. To form an electrode on the open end surface,
Extra steps such as etching and patterning, which are different from the steps for forming the outer conductor and inner conductor, are required, and the manufacturing process is complicated.

Therefore, the applicant in this case first applied for patent application No. 59-17358.
No. 6, we proposed a dielectric filter that utilizes a coupling principle different from that of the prior art and can be manufactured more easily. The proposed dielectric filter utilizes the coupling principle shown in FIG. That is, the resonant element R includes two parts in its length direction, and the impedance and electrical angle of one part are represented by Zl and θ1, respectively, and the impedance and electrical angle of the other part are represented by Z2 and θ2, respectively. represented. Then, the impedances Z1 and Z2 of the two parts are made different from each other in at least one of the even mode and the odd mode, thereby establishing the following condition, ωeven≠ωodd (ω−2πf)
The combination condition is satisfied.

A specific example of realizing such a coupling principle is disclosed in FIGS. 12 and 13 of the aforementioned Japanese Patent Application No. 173586/1986. In this example, each of the inner conductors formed in the dielectric block and the inner wall thereof forms a resonant element, and a step is provided in the hole, and a step is provided between the inner conductor and the outer conductor at the upper and lower parts of each resonant element. By utilizing the fact that the thickness of the medium (dielectric material) is different, Z1≠72 is realized in both the even mode and the odd mode.

(Problems to be Solved by the Invention) As shown in FIGS. 12 and 13 of Japanese Patent Application No. 173,586/1986, the stepped portions at or near right angles are very difficult to form, and the manufacturing yield is low. Without,
It has not been easy to obtain a dielectric filter with stable characteristics.

Therefore, the main object of the present invention is to provide a dielectric filter that utilizes a new coupling principle and is easy to process.

(Means for Solving the Problems) Simply put, the present invention provides a configuration in which a large diameter portion and a small diameter portion are connected to at least one adjacent hole of a plurality of holes formed in a dielectric block by a tapered portion. a dielectric element forming a section, thereby making the impedance of a portion in the length direction of at least one adjacent resonant element different from the impedance of the other portion in at least one of an even mode and an odd mode. It is a body filter.

(Function) The large-diameter portion and the small-diameter portion have different impedances in both even mode and odd mode, thereby realizing a coupling condition, and adjacent resonant elements are coupled to each other to form a dielectric filter. Ru.

(Effects of the Invention) According to the present invention, since the large-diameter portion and the small-diameter portion are continuous by the tapered portion, compared to the prior art in which the space between them is formed as a right-angled step portion, , the density distribution of the material during press molding is improved, no chipping occurs, and therefore the moldability is improved. In addition, in the conventional filter having a right-angled step, the TEM wave is greatly disturbed at the step, resulting in fringing capacitance, which greatly affects filter characteristics. On the other hand, according to the present invention, since the large-diameter portion and the small-diameter portion are continuous by the tapered portion, disturbances in the electromagnetic field distribution in the continuous portion are reduced.
Therefore, since the fringing capacitance is reduced, a dielectric filter with stable characteristics can be obtained.

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. 1A is a perspective view showing an embodiment of the present invention, and FIG. 1B is a sectional view taken along the line IB-IB.

The dielectric filter 10 includes one cubic dielectric block 12. The dielectric block 12 has holes 14a, 14b extending from the open end surface 12a to the opposite end surface.
14c and 14d are arranged parallel to each other in one row. And these holes 14a, 14b,
14c and 14d are the tapered portions 141. +
, 142b, 141c, and 141d are continuous large diameter portions 142a, 142b, 142c, and 142d.
and small diameter portions 143 a, 143 b, 143
c and 143d. These holes 14a, 14b
, 14c and 14d each has an inner conductor 1 on its inner peripheral surface.
6a, ], 6b, 16c and 16d are formed. On the other hand, an outer conductor 18 is formed on the outer peripheral surface of the dielectric block 12. An end surface of the dielectric block 12 opposite to the open end surface 12 a is covered with an outer conductor 18 . In this manner, in this embodiment, a plurality of λ/4 TEM dielectric coaxial resonant elements are formed in one dielectric block 12.

Large diameter portions 14.2a to 142d of inner conductors 16a to 16d
The thickness of the dielectric between the part and the outer conductor 18 and the small diameter part 1
The thickness of the dielectric material between the portions 43a to 143d and the outer conductor 18 is different, and therefore the large diameter portions 142a to 142
d and the small diameter portions 143a to 143d have different capacitances. Due to this difference in capacitance,
Two parts 142a-142d and 143a-1
The impedances Z1 and Z2 (FIG. 3) formed by 4.3 d will be different in both even and odd modes. Therefore, as described above and detailed in Japanese Patent Application No. 59-173586, the coupling condition ωeven≠ωodd is satisfied. That is, each inner conductor 16a to l6 (
] and the outer conductor 18 are coupled together to form a dielectric filter as a whole.

[Brief explanation of the drawing]

FIG. 1A is a perspective view showing one embodiment of the present invention, and FIG. 1B is a sectional view taken along the line IB-IB of FIG. 1A. FIG. 2 is an equivalent circuit diagram for explaining the coupling principle of the prior art. FIG. 3 is an equivalent circuit diagram for explaining the coupling principle of the present invention. In the figure, 12 is a dielectric block, 14a to 14d are holes, 141a to 141d are tapered portions, and 142a to 141d are tapered portions.
142 d is a large diameter portion, 143 a to 143 d are small diameter portions, 16 a to 16 d are inner conductors, and 18 is an outer conductor. Patent applicant Murata Manufacturing Co., Ltd. Agent Patent attorney Yama 1) Yoshito (and 1 other person) Figure 1A Figure 18

Claims (1)

[Scope of Claims] A dielectric block, an outer conductor formed on the outer peripheral surface of the dielectric block, a plurality of holes formed in the dielectric block, and an inner peripheral surface of each of the plurality of holes. and a plurality of inner conductors each forming a resonant element in cooperation with the outer conductor, wherein at least one of the adjacent holes has a large diameter portion and a diameter portion connected by a tapered portion. a small portion, thereby making the impedance of a portion of the at least one resonant element in the length direction different from the impedance of the other portion in at least one of an even mode and an odd mode. A dielectric filter.