Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Patent
1995-09-20
1997-04-15
Lee, Benny
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
3332191, H01P 1203, H01P 708
Patent
active
056213654
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a microstrip line type resonator made up of a block-shaped dielectric material in which a plurality of green sheets are laminated and sintered, an in-resonator conductor and an internal grounding conductor provided in the block-shaped dielectric material, and an external grounding conductor formed on an external surface of the dielectric material. More specifically, the present invention relates to a laminated dielectric resonator and a laminated dielectric filter in each of which an in-resonator conductor has a folded structure using a via connection part and an internal-to-external grounding conductor distance on its open-end side is shorter than an internal-to-external grounding conductor distance on its short-circuit side so as to reduce the longitudinal resonator size. Such laminated dielectric resonator or filter is used in, for example, various kinds of microwave wireless units or the like.
BACKGROUND OF THE INVENTION
There are a variety of microwave filters using dielectric material, and one type of filter includes a resonator using a microstrip line. For example, in the case of a 1/4 wavelength resonator, a rectilinear microstrip line type in-resonator conductor Is provided in a dielectric block, and one end of the in-resonator conductor is opened and the other end is short-circuited to an external grounding conductor provided on an external surface of the dielectric block. To fabricate a filter, a plurality of in-resonator conductors may be arranged in the dielectric block so as to obtain a coupling strength corresponding to the filter characteristics.
Since such in-resonator conductors are disposed in a plane, this structure has limitations in that the area required to mount the filter is difficult to reduce. As an attempt capable of solving this problem, a folded microstrip line type dielectric resonator and dielectric filter have been proposed (for example, Japanese Patent Laid-Open Nos. 5-152,815/1993 and 5-175,702/1993). The dielectric resonator and filter have a structure in which a U-shaped external grounding conductor is provided on the external peripheral face of a dielectric board which excludes both primary surfaces and each conductor is short-circuited at one end only. In this structure, the in-resonator conductor is folded back in a direction perpendicular to its pattern face.
In such structure, since the 1/4 wavelength in-resonator conductor is three-dimensionally folded back so that its entire length is made half or less, it is possible to reduce the area required to mount the dielectric resonator or filter, whereby the size of devices can be reduced. In recent years, further reductions in the sizes of wireless communication units have been demanded, so that a demand for a reduction In the size of the dielectric resonator has become stronger and stronger. However, only the above-described method may be insufficient.
One method for reducing the longitudinal size of the dielectric resonator is to dispose an external grounding conductor in close proximity to the open end of an in-resonator conductor and make use of the phenomenon in which a resonance frequency lowers owing to a load capacity occurring at that place. However, this structure causes an increase in current density at the front end of the in-resonator conductor, thereby causing an increase in loss. As another resonator short-circuit means, a step may be provided on the open-end side of the resonator. This structure, however, is disadvantageous in terms of manufacture and mounting.
SUMMARY OF INVENTION
The present invention has been made in light of the above-described background, and its first object is to provide a laminated dielectric resonator and filter which is reduced in size by means of a folded microstrip line structure as well as which is easy to manufacture and mount and is further reduced in size without impairing performance.
A second object of the present invention is to provide a dielectric filter which is prevented from being peeled or
REFERENCES:
patent: 5014024 (1991-05-01), Shimizu et al.
patent: 5344695 (1994-09-01), Hirai et al.
Endo Kazuaki
Kojima Mitsuru
Nakamura Nobuaki
Nishino Yasue
Suzuki Yasuo
Fuji Electrochemical Co. Ltd.
Lee Benny
Summons Barbara
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