JPS61230403A - Dielectric filter - Google Patents

Abstract

PURPOSE:To attain miniaturization and low cost and also to improve the attenuation by giving a static capacitance between input and output terminals in a band-pass dielectric filter constituted by combining plural dielectric coaxial resonators. CONSTITUTION:Two through-holes are provided in parallel with a dielectric block 1 and a conductor film being a center conductor is formed to the inner circumferential face. A conductor film 2 is formed to four circumferential faces of the block 1 and an upper end face to form an outer conductor and an electrode. Thus, the filter has two 1/4 wavelength dielectric coaxial resonators. That is, an alumina base 10 functions as a dielectric substance in a capacitor. Capacitor electrodes 11, 12 are provided to one face of the base 10. Through holes 13, 14 are provided to the electrodes 11, 12 and lead terminals 3, 4 are projected. In soldering the lead terminal 3 and the electrode 11, and the lead terminal 4 and the electrode 12, the input/output terminals are coupled by a static capacitance and the characteristic having the attenuation pole is obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a band-pass dielectric filter constructed by combining a plurality of dielectric coaxial resonators in which a solid dielectric exists between a center conductor and an outer conductor. Regarding.

(Prior Art) A filter as disclosed in Japanese Utility Model Application Publication No. 58-54102 is conventionally known. In this filter, the degree of coupling is determined by the size and shape of the coupling holes provided between the resonators, but there is a limit to the improvement of the damping characteristics (see FIG. 5).

The objective is to improve the damping characteristics of the

(Structure of the Invention) In the present invention, in a band-pass dielectric filter configured by combining a plurality of dielectric coaxial resonators in which a solid dielectric exists between a center conductor and an outer conductor, static electricity is generated between input and output terminals. It is characterized by having a capacitance.

(Function) Then, a pole occurs in the attenuation characteristic and the amount of attenuation increases.

(Example) In FIG. 1, reference numeral 1 denotes a rectangular dielectric block made of a titanium oxide ceramic dielectric. block
1 has two through holes (not shown) provided in parallel, and a conductive film serving as a center conductor is formed on the inner circumferential surface of the through holes. Continuous conductor films 2 are formed on the four circumferential surfaces of the block 1 and on the upper end surface in the figure, and serve as an outer conductor and an electrode that short-circuits the outer conductor and the center conductor, respectively. Therefore, the illustrated filter has two 1/4 wavelength dielectric coaxial co-carriers. A through hole (not shown) parallel to the through hole is provided between the common camera devices, and no electrode is provided on the inner peripheral surface of this hole.

This hole is necessary to combine both resonators with a desired degree of coupling to form a bandpass filter. Dielectric bushings 5, 6 in which lead terminals 3.4 are embedded are inserted into the through holes in which the center conductors are provided. Note that 7 is a shield case. Such a configuration is based on the aforementioned Utility Model Application No.
-54102@publication.

The embodiment of the present invention has a capacitor as shown in FIG. 3 as a first example. That is, in Figure 3, 1
0 is an alumina substrate that functions as a dielectric in a capacitor. Two capacitor electrodes 11 are provided on one side of the substrate 10.
．． 12 are provided. The board 10 is a shield case 1
The capacitor electrode 11.12 is preferably sized to be accommodated in the opening of the capacitor electrode 11.12, and the capacitor electrode 11.12 is provided with a through hole 13.14 through which the lead terminal 3.4 protrudes, as shown in FIG. Then, when the lead terminal 3 and the capacitor electrode 11 are soldered, and the lead terminal 4 and the capacitor electrode 12 are soldered, the input and output terminals are coupled by capacitance. Then, a characteristic having an attenuation pole as shown in FIG. 2 is obtained. FIGS. 4(a) and 4(b) show the front and back sides of the second example of the capacitor. In this example, board 1
0 has a capacitor electrode 15 on the front side and a capacitor WA16 on the back side. When the lead terminal 3 and the capacitor electrode 1B are soldered, and the lead terminal 4 and the capacitor electrode 15 are soldered, the input/output terminals are connected. This means that they are coupled by capacitance.

In addition to the above-mentioned method, providing capacitance between the input and output terminals can also be achieved, for example, by forming a capacitor electrode film continuous with the center conductor on the open end surface of the bronze wire 1.

(Effects) As is clear from the above embodiments, according to the present invention, by providing capacitance between the input and output terminals, a characteristic having an attenuation pole can be obtained, while being small, inexpensive, and simple. Such excellent results can be obtained.

[Brief explanation of drawings]

FIG. 1 is an internal front view of an embodiment of the present invention, FIG. 2 is a characteristic diagram, FIG. 3 is a front view of a capacitor used in one embodiment of the invention, and FIG. 4 is another embodiment. The capacitor used is shown, (a) is a front view, (b) is a back view,
FIG. 5 is a characteristic diagram of a conventional example. 1 is a dielectric block, 2 is a conductor film, 3 and 4 are lead terminals, 10 is a capacitor board, 11, 12, 15 and 16
is a capacitor electrode. Patent applicant Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] (1) In a bandpass dielectric filter constructed by combining multiple dielectric coaxial resonators with a solid dielectric between the center conductor and the outer conductor, capacitance is provided between the input and output terminals. A dielectric filter characterized by: