JP2535893Y2 - Coaxial filter with adjustment mechanism - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial filter having an adjusting mechanism capable of adjusting various characteristics of the filter.

[0002]

2. Description of the Related Art Coaxial filters have been put to practical use as filters in microwave circuits and the like. This coaxial filter is formed by forming a plurality of enlarged portions in which the outer diameter is partially enlarged in the inner conductor with respect to the inner diameter of the outer conductor of the coaxial line. By appropriately setting the outer diameter and width of the enlarged portion of the internal conductor and the length between the enlarged portions, the values of the inductive impedance and the capacitive impedance are equivalently changed to provide desired characteristics. Configure the filter.

[0003]

In the above-mentioned conventional coaxial filter, the outer diameter and width of the enlarged portion and the enlarged portion are corrected in order to correct the deviation between the design characteristic and the actually obtained characteristic. There is a situation in which desired characteristics can be obtained only by repeatedly performing a trial production in which the length of the gap is slightly changed.

In addition, the deviation of the dimensional accuracy of each member forming the coaxial filter thus obtained has a great effect on various characteristics of the filter. Therefore, in order to maintain desired characteristics, it is necessary to manufacture each member with high dimensional accuracy. As a result, mass production is difficult and the apparatus becomes expensive. Moreover, there is a problem that it is difficult to maintain various characteristics of the filter.

The present invention has been made in order to improve such a conventional coaxial filter, in which deviations in various characteristics due to variations in dimensional accuracy can be adjusted after manufacturing so that desired characteristics can be obtained. An object of the present invention is to provide a coaxial filter having an adjustment mechanism.

[0006]

In order to achieve the above object, a coaxial filter provided with an adjusting mechanism according to the present invention is configured so that an outer diameter of an inner conductor is partially enlarged in an axial direction and a coaxial enlarged portion is formed. The inner conductor is inserted into an insulating tube, the insulating tube is inserted into an outer conductor, and the inner conductor is coaxially arranged on the outer conductor. A concave portion is provided on the surface, a screw made of a conductive material is screwed into the outer conductor by passing through the insulating cylinder facing the concave portion, and the concave portion is insulated without contacting the screw with the inner conductor. It is configured so that it can be inserted and withdrawn freely.

[0007]

The capacitive impedance between the inner conductor and the outer conductor is adjusted by inserting or pulling out a screw made of a conductive material that is screwed into the outer conductor in the recess provided in the enlarged portion of the inner conductor. The adjustment of the capacitive impedance changes the electrical characteristics formed including the capacitive impedance and the inductive impedance.

[0008]

1 and 2 show an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a longitudinal sectional view of one embodiment of a coaxial filter provided with the adjusting mechanism of the present invention, and FIG.
FIG. 2 is an equivalent circuit diagram of FIG.

In FIG. 1, the inner conductor 10 has enlarged portions 12, 12 and 12 in which the outer diameter is partially increased at intervals.
Is formed. Concave portions 14, 14, 14 each having a bottomed hole are formed in the outer peripheral surfaces of the enlarged portions 12, 12, 12. Then, the inner conductor 10 is inserted into an insulating tube 16 made of resin or the like having a small dielectric loss, and the insulating tube 16 is inserted into the outer conductor 18. Further, screw holes 2 are formed in the outer conductor 18 and the insulating cylinder 16 so as to face the recesses 14, 14, 14.
0, 20, 20 are engraved, and the screw holes 20, 20, 2
0, an impedance adjusting screw 22 made of a conductor,
22 and 22 are screwed together. These screws 22, 22, 22
It can be inserted into and pulled out of the recesses 14, 14, 14 and is electrically insulated from the internal conductor 10. Then, the screw 2 is fixed with the lock nuts 24, 24, 24.
The loosening of 2, 22, 22 is prevented.

The enlarged portions 12, 12,.
Needless to say, the outer diameter and width of 12 and the length between the enlarged portions and the outer diameter therebetween are set so as to obtain desired approximate characteristics as a coaxial filter.

In such a configuration, the screws 22, 22, 2
The value of the capacitive impedance between the enlarged portions 12, 12, 12 of the inner conductor 10 and the outer conductor 18 is adjusted by adjusting the length of insertion of the two into the recesses 14, 14, 14.

By the way, as shown in FIG. 2, the equivalent circuit in the structure of FIG. 1 has a series inductance L due to magnetic energy stored in the inner and outer conductors 10, 18.
And a series resistance R due to the resistance of the conductor caused by the current flowing through the inner and outer conductors 10, 18 and a parallel capacitance C caused by forming a capacitor between the inner and outer conductors 10, 18.
And the parallel conductance G due to the dielectric loss of the insulating cylinder 16.

Therefore, the value of the parallel capacitance C is adjusted by adjusting the screws 22, 22, and 22, so that various electric characteristics as a filter can be adjusted.

[0014]

As described above, since the coaxial filter provided with the adjusting mechanism of the present invention is constituted, the following special effects are obtained.

By adjusting the insertion length of the screw after manufacture, various electrical characteristics of the coaxial filter can be continuously adjusted, and desired characteristics can be obtained even if the dimensional accuracy of each member is not high. For this reason, it is suitable for mass-producing coaxial filters having certain characteristics, and can be manufactured at low cost, which is extremely useful in practice. In addition, the coaxial filter equipped with the adjusting mechanism of the present invention can be continuously fine-tuned even after being incorporated in the device, and the screw can be adjusted again even if the predetermined characteristics are deviated due to aging or the like. As a result, predetermined characteristics can be obtained again.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of a coaxial filter provided with an adjusting mechanism of the present invention.

FIG. 2 is an equivalent circuit diagram of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Internal conductor 12 Enlarged part 14 Recess 16 Insulation cylinder 18 External conductor 20 Screw hole 22 Screw for adjustment

Claims (1)

(57) [Scope of request for utility model registration] 1. An outer diameter of an inner conductor is partially enlarged in an axial direction to form an enlarged portion coaxially, an inner conductor is inserted into an insulating tube, and the insulating tube is inserted into an outer conductor. In a coaxial filter in which the inner conductor is disposed coaxially with the outer conductor, a concave portion is provided on the outer peripheral surface of the enlarged portion, and the insulating tube is made to penetrate the insulating cylinder facing the concave portion, and a conductive material is formed on the external conductor. A screw comprising: a screw; and a screw inserted into the recess in an insulated state without abutting the screw on the internal conductor.