Wave transmission lines and networks – Resonators – Dielectric type
Reexamination Certificate
1999-11-30
2001-11-20
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Resonators
Dielectric type
C333S202000, C333S222000
Reexamination Certificate
active
06320484
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a high frequency (micro-wave) dielectric filter which uses a dielectric resonator.
The basic structure of a dielectric filter for use a TM (Transverse Magnetic) mode which is comprised of a metal case and a dielectric resonator is disclosed in a scholarly paper (Kobayashi et al.: IEEE MTT-S Digest, p 233-235 (1978)). In such a basic structure, however, the relative positional relationship between the dielectric resonator and the case is changed due to vibration and impact and hence, the characteristics of the dielectric filter is changed. Accordingly, such a dielectric filter is not practical.
Furthermore, in case the case and the dielectric resonator are fixed to each other by some methods, there is a chance that the quality factor is remarkably deteriorated and accordingly the dielectric filter is not usable in such a case.
In view of the above, conventionally, a method in which the case and the dielectric resonator are fixed to each other by means of a conductive paste or adhesive agent has been adopted.
The frequency band ranging from a few hundreds MHz to a few GHz has been widely used in various fields, chiefly in a mobile radio communication system. Here, the dielectric filter which works as a passive element is required to sustain little loss in quality and to be stable against the external environment.
The dielectric filter using the TM mode resonance is constructed such that a pillar-like dielectric has both ends thereof securely fixed to a metal case. It is indispensable that the dielectric filter has a relative positional relationship which does not change between the dielectric resonator and the case, and has highly stable against vibration and impact. From this point of view, there has been a practical problem that the conventional conductive paste or adhesive agent is less than optimal in terms of the stability, deterioration of the quality factor being likely to occur.
As described above, the fixing method which uses conductive paste or the adhering agent easily gives rise to dispersion by irregularities of the amount of coating of the dielectric filter. Therefore, the successful application of the fixing method largely depends on the experience of the workman and it is difficult to manufacture products of uniform characteristics. Furthermore, because of the poor reproducibility, it is not necessarily suitable the mass production.
SUMMARY OF THE INVENTION
To solve such a problem, a method which mechanically fixes the metal case and the dielectric resonator without using paste or the adhesive agent becomes necessary. The present invention has been made in view of the above background and it is an object of the present invention to provide a high frequency dielectric filter which exhibits high stability and suffers from the least loss against the vibration and the impact, by mechanically fixing the metal case and the dielectric resonator to each other.
It is another object of the present invention to provide a uniform and stable high frequency dielectric filter which can fix the metal case and the dielectric to each other easily and in a manner such that they can be separated later contrary to the conventional method which fixes the metal case and the dielectric resonator with the conductive paste or the adhering agent.
It is still another object of the present invention to provide a high frequency filter with the high reliability.
It is a further object of the present invention to provide a high frequency dielectric filter which has stable electric characteristics and which can be manufactured with the uniform electric characteristics.
It is a still further object of the present invention to provide a high frequency dielectric filter which can be manufactured on a mass production basis at a low cost.
The high frequency dielectric filter of the present invention is comprised of a dielectric resonator, a case provided with a plurality of first through holes, and a hollow resonator fixing plate.
The resonator fixing plate includes a second through hole at the center thereof, a plurality of third through holes around the second through hole, and at least two fourth through holes extending from the outer side surface thereof to the inner side surface thereof.
In the condition that the end portion of the dielectric resonator passes through the second thorough hole, resonator fixing screws are screwed into the fourth through holes from the outer peripheral surface to the inner peripheral surface and hence, the dielectric resonator is fixed to the metal case.
The resonator fixing plate is fixed to the case by screwing fixing plate fixing screws through the third through holes into the case.
REFERENCES:
patent: 4291287 (1981-09-01), Young et al.
patent: 4613838 (1986-09-01), Wada et al.
patent: 4639699 (1987-01-01), Nishikawa et al.
patent: 4642591 (1987-02-01), Kobayashi
patent: 4839773 (1989-06-01), Ishikawa et al.
patent: 6175286 (2001-01-01), Ueno
patent: 63-250201 (1988-10-01), None
patent: 63-266902 (1988-11-01), None
patent: 6-34307 (1994-05-01), None
patent: 11-68426 (1999-03-01), None
Bandpass Filters Using™010Dielectric Rod Resonators, Yoshio Kobayashi and Shinichiro Yoshida, Department of Electrical Engineering, Saitama University, Urawa, Saitmam 338 Japan, IEEE 1978, p. 233 through 235.
Furuya Mitsuru
Yokoyama Yoshiyasu
Hutchins, Wheeler & Dittmar
NEC Corporation
Nguyen Patricia T.
Pascal Robert
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