Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
2000-04-07
2001-10-16
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C333S219000, C333S132000, C501S137000, C501S138000
Reexamination Certificate
active
06304157
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high-frequency dielectric ceramic composition, and to a dielectric resonator, a dielectric filter, a dielectric duplexer, and a communication apparatus using the same.
2. Description of the Related Art
Dielectric ceramic components are widely used as dielectric resonators and dielectric filters which are mounted in electronic devices, such as portable phones, personal radio equipment and satellite broadcasting receivers, used in high-frequency bands including microwave bands and millimeter-wave bands. These high-frequency dielectric ceramic components require high dielectric constants and high Q values, and adjusting of the temperature coefficient of the resonant frequency to appropriate values near zero.
Examples of disclosed dielectric ceramic compositions include a BaO—Nd
2
O
3
—TiO
2
—PbO composition (disclosed in Japanese Examined Patent Publication No. 56-26321), a BaO—Nd
2
O
3
—TiO
2
—Bi
2
O
3
composition (disclosed in Japanese Examined Patent Publication No. 59-51091), a BaO—Nd
2
O
3
—Ce
2
O
4
—Sm
2
O
3
—TiO
2
—Bi
2
O
3
—Fe
2
O
3
composition (disclosed in Japanese Laid-open No. 63-237304), and a BaO—Nd
2
O
3
—Sm
2
O
3
—TiO
2
—Bi
2
O
3
composition (disclosed in Japanese Laid-open No. 4-104946).
These conventional BaO—Nd
2
O
3
—TiO
2
—PbO and BaO—Nd
2
O
3
—TiO
2
—Bi
2
O
3
compositions have low Q values with respect to relative dielectric constants ∈
r
, which are of insufficient levels for dielectric resonators. In the BaO—Nd
2
O
3
—Ce
2
O
4
—Sm
2
O
3
—TiO
2
—Bi
2
O
3
—Fe
2
O
3
composition, the Q value is improved but relative dielectric constant is decreased to an insufficient level in practical use by the addition of Fe
2
O
3
. Although the BaO—Nd
2
O
3
—Sm
2
O
3
—TiO
2
—Bi
2
O
3
composition has a high Q value, the Q value is unstable due to oxygen defects which are formed by reduction during the sintering process.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a high-frequency dielectric ceramic composition which does not cause the formation of oxygen defects, that is, exhibits high reduction resistance during sintering, which has a high relative dielectric constant ∈
r
and a stable Q value in the microwave band, and which can control the temperature coefficient &tgr;f of the resonant frequency to an appropriate value in the vicinity of zero ppm/° C.
It is another object of the present invention to provide a dielectric resonator, a dielectric filter, a dielectric duplexer and communication apparatus using this high-frequency dielectric ceramic composition.
According to an aspect of the present invention, a high-frequency dielectric ceramic composition comprises Ba, Ti, Nd, Sm and Pr as primary components represented by the formula xBaO-yTiO
2
-z{(1−m−n)Nd
2
O
3
-mSm
2
O
3
inPr
2
O
11/3
} wherein coefficients x, y, z, m, and n represent molar ratios, x+y+z=1, 0<m≦0.40, 0<n≦0.25, and the coefficients x, y, and z are in an area bounded by points A, B, C and D in a ternary diagram, wherein point A is at (x=0.16, y=0.70, z=0.14), point B is at (x=0.16, y=0.68, z=0.16), point C is at (x=0.13, y=0.68, z=0.19), and point D is at (x=0.13, y=0.70, z=0.17); wherein the composition further comprises a Bi compound in an amount of more than 0 parts by weight to about 9 parts by weight in terms of Bi
2
O
3
and an Fe compound in an amount of more than 0 parts by weight to about 0.3 parts by weight in terms of Fe
2
O
3
as additional components with respect to 100 parts by weight of the primary components.
According to another aspect of the present invention, a dielectric resonator comprises a dielectric ceramic component and input/output terminals, the dielectric resonator operating by electromagnetically coupling the dielectric ceramic component to the input/output terminals, wherein the dielectric ceramic component comprises the above high-frequency dielectric ceramic composition.
According to another aspect of the present invention, a dielectric filter comprises the above dielectric resonator and external coupling means.
According to another aspect of the present invention, a dielectric duplexer comprises at least two dielectric filters, input/output connecting means, each connected to each of the dielectric filters, and an antenna connecting means commonly connected to the dielectric filters, wherein at least one of the dielectric filters is the above dielectric filter.
REFERENCES:
patent: 5077247 (1991-12-01), Sato et al.
patent: 5130281 (1992-07-01), Sano et al.
patent: 5256639 (1993-10-01), Fujimaru et al.
patent: 5493262 (1996-02-01), Abe et al.
patent: 63-237304 (1988-10-01), None
Patent Abstracts of Japan, vol. 017, No. 630 (E-1463), Nov. 22, 1993 and JP 05 205520 A (Nippon Steel Corp.) Aug. 13, 1993, Abstract.
Patent Abstracts of Japan, vol. 018, No. 210 (E-1537), Apr. 14, 1994 and JP 06 012915 A (Denki Nagaku Kogyo KK) Jan. 21 1994, Abstract.
Patent Abstracts of Japan, vol. 018, No. 210 (E-1537), Apr. 14, 1994 and JP 06 012913 A (Denki Nagaku Kogyo KK) Jan. 21, 1994, Abstract.
Patent Abstracts of Japan, vol. 018, No. 434 (E-1592), Aug. 12, 1994 and JP 06 139820 A (Ube Ind. Ltd.) May 20, 1994, Abstract.
Tamura Hiroshi
Wada Takaya
Murata Manufacturing Co. Ltd.
Nguyen Patricia T.
Ostrolenk Faber Gerb & Soffen, LLP
Pascal Robert
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