JP2553137Y2 - Dielectric filter - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarized dielectric filter in which a plurality of dielectric coaxial resonators are mutually connected and input and output terminals are connected by a capacitor.

[0002]

2. Description of the Related Art A dielectric filter is composed of a plurality of dielectric coaxial resonators each formed by covering the inner and outer peripheral surfaces of a cylindrical dielectric made of ceramics or the like with a conductive member via a coupling substrate on which a coupling circuit is formed. In general, input terminals and output terminals are provided at both ends of the coupling substrate.

For example, a band-pass filter (hereinafter referred to as a BPF)
In order to increase the attenuation on both sides of the band, a capacitor is connected between the input and output terminals to form a polarized circuit configuration. In a dielectric filter having such a polarized circuit configuration, Conventionally, the capacitor is formed on the coupling substrate, or the capacitor is formed separately from the coupling substrate.

[0004]

In a conventional dielectric filter having a polarized circuit configuration, a capacitor must be formed between input and output terminals which are structurally separated from each other. When a capacitor is formed, the coupling circuit becomes complicated. Further, when the capacitor is formed separately from the coupling substrate, there is a disadvantage that the structure of the filter becomes large. Also, when finely adjusting the capacitance value of the capacitor in order to obtain a desired attenuation characteristic, it is difficult to perform the adjustment work.

[0005] The present invention has been made in view of the above problems, and has as its object to provide a dielectric filter having a simple structure and capable of easily adjusting characteristics.

[0006]

In order to solve the above-mentioned problems, the present invention provides a polarized type in which a plurality of dielectric coaxial resonators are mutually coupled and an input terminal and an output terminal are coupled by a capacitor. Wherein the capacitor is provided between a connection portion of the input terminal and a connection portion of the output terminal of a substrate on which the dielectric filter is mounted.

[0007]

When the dielectric filter of the above construction is mounted on a substrate, a capacitor provided on the substrate side is connected between the input terminal and the output terminal of the dielectric filter, and the input and output terminals are connected by a capacitor. It becomes a polarized filter circuit.

[0008]

FIG. 2 is a partially cutaway perspective view showing the structure of one embodiment of the dielectric filter according to the present invention. The dielectric filter 1 shown in the figure is a dielectric coaxial resonator θ shown in FIG.
Reference numerals 1 and θ2 denote cascade-connected two-stage BPFs via a capacitor C2. External coupling capacitors C1 and C3 are provided at input and output terminals, respectively. The input terminal and the output terminal are coupled by a capacitor C4 provided on a mounting board described later, thereby forming a polarized BPF.

The dielectric coaxial resonators .theta.1 and .theta.2 are quarter-wave coaxial resonators having a short-circuited terminal. An outer peripheral surface of the body 2 excluding one end surface and an inner peripheral surface of the hole 3 are covered with a conductive member 4 (dotted portion) such as silver or copper.

The capacitors C1 to C3 are connected to the coupling substrate 5
Are formed by electrodes d which are formed by being mutually connected to the front and back surfaces. And the dielectric coaxial resonators θ1, θ
Numerals 2 are connected to the coupling substrate 5 by connecting the center conductor (the conductive member 4 in the hole 3) to the corresponding electrode d at the coupling terminals T1 and T2, respectively, and are cascaded via the coupling substrate 5.

Terminals 6 and 7 are connected to back electrodes (not shown) at both ends of the coupling substrate 5, and a dielectric filter is formed by the dielectric coaxial resonators θ1 and θ2, the coupling substrate 5 and the terminals 6 and 7. One internal filter unit is configured. The dielectric filter 1 is configured by housing the internal filter unit in a metal box composed of a case 8 and a cover 10 on both sides of which a ground terminal 9 protrudes.

FIG. 1 shows that the dielectric filter 1 is mounted on a substrate 11.
FIG. 4 is a plan view showing a state in which the device is mounted on the device. Electrodes D1, D2, and D3 are formed at positions on the substrate 11 where the terminals 6, 7 and the ground terminal 9 of the dielectric filter 1 are mounted. Further, between the electrode D1 corresponding to the terminal 6 and the electrode D2 corresponding to the terminal 7, the electrodes are opposed in a comb shape to form the capacitor C4.
Is formed. Note that the capacitor 12 can be set to any capacitance value depending on the shape of the counter electrode.

The dielectric filter 1 is mounted on the substrate 11 by connecting the terminals 6, 7 and the ground terminal 9 to the corresponding electrodes D1 to D3 by soldering or the like. Then, by mounting the dielectric filter 1 on the substrate 11, the capacitor 12 (C4) is connected between the input / output terminals 6 and 7, and the polarized BPF circuit shown in FIG. 3 is completed.

FIG. 6 is a schematic diagram showing the pass characteristics of the dielectric filter 1, wherein a capacitor 12 (C4) is connected between the input and output terminals.
To form a pair of attenuation poles P on both sides of the pass band. The amount of attenuation of the attenuation pole P changes depending on the capacitance value of the capacitor C4, and can be set to a desired attenuation amount by adjusting the capacitance value of the capacitor 12 formed on the substrate 11.

In the above embodiment, the capacitor corresponding to the capacitor C4 formed on the substrate 11 is formed by an electrode pattern. However, as shown in FIG. 4, a single capacitor 13 is connected between the electrodes D1 and D2. You may make it. Note that the capacitors 12 and 13 may be formed on the back side of the substrate 11.

As shown in FIG. 5, the substrate 11 may be constituted by a multilayer substrate, and a capacitor corresponding to the capacitor C4 may be formed by layered electrodes D4 and D5 formed inside the multilayer substrate.

Although the above embodiment has been described with reference to a two-stage dielectric filter, the present invention can be applied to an arbitrary number of dielectric filters having three or more stages. Also, the present invention is not limited to the BPF, but may be applied to other types of polarized dielectric filters provided that the input and output terminals are coupled by a capacitor.

[0018]

[Effects of the Invention] As described above, according to the present invention,
Since the input / output terminal is a dielectric filter coupled by a capacitor, and the capacitor is provided between the connection part of the input terminal and the connection part of the output terminal of the substrate on which the dielectric filter is mounted, The structure of the filter is simplified, which contributes to cost reduction. Further, fine adjustment of the filter characteristics of the dielectric filter can be easily performed by adjusting the capacitance value of the capacitor on the substrate side.

[Brief description of the drawings]

FIG. 1 is a plan view showing a state in which a dielectric filter according to the present invention is mounted on a substrate.

FIG. 2 is a partially cutaway perspective view showing the structure of one embodiment of the dielectric filter according to the present invention.

FIG. 3 is a diagram showing a circuit configuration of the dielectric filter according to the present invention.

FIG. 4 is a main part plan view showing a state in which the dielectric filter according to the present invention is mounted on a substrate provided with a single capacitor between a connection part of an input terminal and a connection part of an output terminal.

FIG. 5 is a cross-sectional view of a main part showing a state in which the dielectric filter according to the present invention is mounted on a multilayer substrate in which a capacitor is formed by a layered electrode between a connection part of an input terminal and a connection part of an output terminal.

FIG. 6 is a schematic diagram showing an example of a pass characteristic of the dielectric filter according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 dielectric filter 2 dielectric 3 hole 4 conductive member 5 coupling substrate 6, 7 terminal 8 case 9 ground terminal 10 cover 11 substrate C1 to C4, 12, 13 capacitor D1 to D5 electrode θ1, θ2 dielectric coaxial resonator

Claims (1)

(57) [Scope of request for utility model registration] 1. A polarized dielectric filter in which a plurality of dielectric coaxial resonators are mutually coupled and an input terminal and an output terminal are coupled with a capacitor, wherein the capacitor is a dielectric filter. A dielectric filter, which is provided between a connection portion of the input terminal and a connection portion of the output terminal of a board to be mounted.