JPH0631767Y2 - Dielectric filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a waveguide mode dielectric filter in which a dielectric resonant element is arranged in a metal case.

[Problems to be Solved by the Related Art] Conventionally, a waveguide mode dielectric filter in which a dielectric resonant element is disposed in a metal case is configured as shown in FIG. In FIG. 1, reference numeral 1 denotes a metal case that forms an outer conductor, and a cylindrical dielectric resonance element 2 is arranged in the metal case 1. Input / output connectors 3, 4 are mounted on the metal case 1 so as to face each other with the dielectric resonance element 2 in between, and the dielectric connectors are attached to the inner ends of the input / output connectors 3, 4. Loops 5 and 6 that are coupled to the body resonance element 2 are provided.

Therefore, the dimensions of the metal case 1 and the dielectric resonant element 2 in the dielectric filter are set to optimal values such that the close-up high-order mode is separated from the fundamental frequency as much as possible. But,
In the case of the optimum size, the distance between the dielectric resonant element 2 and the inner wall surface of the metal case 1 becomes considerably large as shown in FIG. Therefore, if the coupling between the dielectric resonance element 2 and the coupling loops 5 and 6 is set so as to obtain the characteristics required as a filter, the coupling loops 5 and 6 will be large in size and will be in the several GHz band. In the high frequency band of, the attenuation characteristic is deteriorated due to generation of unnecessary resonance.

Further, as shown in FIG. 4, the distance between the dielectric resonance element 2 and the inner wall surface of the metal case 1 is narrowed to reduce the coupling loops 5, 6
If one tries to obtain the required coupling without increasing the, the higher-order mode will occur near the fundamental frequency and the attenuation characteristics will deteriorate.

The present invention has been made in view of the above circumstances, and it is possible to set the dimensions of each part so that the proximity higher-order mode is as far as possible from the fundamental frequency, and to obtain the required characteristics without causing unnecessary resonance. The purpose is to provide a body filter.

[Means and Actions for Solving the Problems] The present invention is directed to a dielectric filter having a dielectric resonance element arranged in a metal case forming an outer conductor, in which a center conductor and an outer conductor of an input / output connector are fixed. Is extended in the axial direction while maintaining the impedance of No. 3, the extension is projected into the metal case and attached, and the coupling loop is incorporated at the tip.

With the above configuration, the coupling loop is arranged near the dielectric resonance element, and as a result, the required degree of coupling can be obtained without increasing the size of the coupling loop. As a result, it is possible to reduce the occurrence of unnecessary resonance and prevent deterioration of the damping characteristic.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a top view of the dielectric filter with the upper lid removed, and FIG. 2 is a sectional view taken along the line XX ′ of FIG. In FIGS. 1 and 2, reference numeral 11 denotes a bottomed cylindrical metal case forming an outer conductor, and a cylindrical dielectric resonance element 12 is arranged in the center of the metal case 11. In this case, the dielectric resonance element 12 is, for example, an insulator support member 10
Thus, it is fixed to the bottom of the metal case 11 with an adhesive or the like. The metal case 11 and the dielectric resonant element 12 are set to have optimum dimensions such that the close-up high-order mode is separated from the fundamental frequency as much as possible. Then, the metal case 11 has an input / output connector 13, which is opposed to the metal case 11 with a dielectric resonance element 12 interposed therebetween.
14 is mounted, and coupling loops 15 and 16 for coupling to the dielectric resonant element 12 are provided at the inner ends of the input / output connectors 13 and 14.

The input / output connectors 13 and 14 are center conductors 13a and 14a and outer conductors.
13b and 14b each have a specific impedance, eg 50Ω
Is extended in the axial direction while holding
c and 14c are mounted so as to project into the metal case 11. At this time, the outer conductors 13b and 14b of the input / output connectors 13 and 14 are metal cases.
It is fixed by conducting to 11. I / O connector 13, as described above
By mounting the extended portions 13c and 14c of 14 so as to project into the metal case 11, the tip end portion thereof is arranged close to the dielectric resonant element 12. Then, at the tips of the input / output connectors 13 and 14 protruding into the metal case 11, the center conductor 13
Coupling loop 1 between a and 14a and outer conductors 13b and 14b, respectively
5, 16 are fixed by soldering or the like, and the dielectric resonance element 12
Are arranged so that the required coupling degree can be obtained. An upper lid 17 is attached to the upper end opening of the metal case 11 as shown by a chain line.

The input / output connectors 13 and 14 are connected to the center conductors 13a and 14a.
Also, since the outer conductors 13b and 14b are extended while maintaining a specific impedance, the standing wave ratio characteristic is not deteriorated. Further, since the tips of the extended portions 13c, 14c of the input / output plugs 13, 14 are arranged near the dielectric resonant element 12, it is necessary even if the input / output coupling loops 15, 16 are made small. The coupling degree of is obtained. Therefore, unnecessary resonance and unnecessary coupling due to the size of the coupling loops 15 and 16 can be reduced, and deterioration of the attenuation characteristics can be prevented.

[Effects of the Invention] As described in detail above, according to the present invention, in the dielectric filter in which the dielectric resonance element is arranged in the metal case forming the outer conductor, the center conductor and the outer conductor of the input / output connector are provided. Is extended in the axial direction while maintaining a constant impedance, the extended part is projected and installed in the metal case, and the coupling loop is incorporated into the tip part, so that the coupling loop is placed close to the dielectric resonant element. , The required coupling degree can be obtained without increasing the coupling loop. Therefore, it is possible to prevent the close-up higher-order modes from occurring near the fundamental frequency and to reduce the size of the coupling loop, thereby reducing the occurrence of unnecessary resonance and preventing the deterioration of the attenuation characteristics. can do. Also, the number of parts is the same as the conventional method,
It can be easily realized without incurring a significant cost increase.

[Brief description of drawings]

FIGS. 1 and 2 show an embodiment of the present invention. FIG. 1 is a top view with a top lid removed, and FIG. 2 is a sectional view taken along the line XX 'in FIG. 3 and 4 are sectional views showing a conventional dielectric filter. 11 …… Metal case, 12 …… Dielectric resonance element, 13,14 ……
Input / output connector, 13a, 14a ...... central conductor, 13b, 14b …… outer conductor, 15, 16 …… coupling loop, 17 …… top lid.

Claims (1)

[Scope of utility model registration request] 1. A dielectric filter comprising a dielectric resonance element arranged in a metal case forming an outer conductor, and an input / output connector mounted on the metal case and the input / output connector. And a means for axially extending the central conductor and the outer conductor, projecting the extended portion into the metal case, and disposing the tip of the extended portion in the vicinity of the dielectric resonant element. A dielectric filter provided with a coupling loop which is attached to the tip of the input / output connector and obtains a predetermined degree of coupling with the dielectric resonant element.