Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
1999-04-14
2001-03-20
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C333S222000, C333S134000
Reexamination Certificate
active
06204738
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric filter, a dielectric duplexer, a mounting structure having the same, and a communication device.
2. Description of the Related Art
In recent years, radio wave communication equipment, such as portable telephones and the like, of small in size, light in weight, and thin types have been spread widely and rapidly. With the spread, it has been more intensively needed to develop dielectric filters and dielectric duplexers, to be mounted on the equipment of the above-mentioned type, which are small in size, light in weight, and low in height.
Conventionally, a dielectric filter of the above-mentioned type, shown in
FIG. 11
, has been known. A dielectric filter
8
comprises a plurality of resonator holes
3
provided in a single dielectric block
2
which has an outer conductor
1
provided on the surface thereof. An inner conductor
4
is provided on the inner surface of each resonator hole
3
. The inner conductor
4
is electrically connected to the outer conductor
1
, at the side surface
2
b
of the dielectric block
2
, shown as the back-face of the dielectric filter
8
in
FIG. 11
, and is electrically left unconnected to the outer conductor
1
at the side surface
2
a
shown as the front-face in FIG.
11
.
Ordinarily, the dielectric filter
8
is so mounted onto a circuit board
6
that the axes of the resonator holes
3
are in parallel to the circuit board
6
. To reduce the height of the dielectric filter
8
having the above-described mounting form, the method may be supposed by which the diameters of the resonator holes
3
are decreased in order that the height h of the dielectric block
2
is reduced. However, it is difficult to form the dielectric block
2
by means of a metallic mould, due to the resonator holes
3
having a reduced diameter. In general, the dielectric filter
8
has a high Q
0
. To obtain the high Q
0
, it is necessary to assure the optimum height h with respect to the diameter of each resonator hole
3
. For this reason, it is problematic to reduce the height of the dielectric filter
8
. In some cases, an electromagnetic field leaking from the side surface
2
a
, which is an open-circuited surface, exerts a hazardous influence over the characteristics of other electronic components mounted onto a circuit board
6
. Similarly, in some cases, an electromagnetic field leaking from the other electronic components unfavorably affects the characteristics of the dielectric filter
8
.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a dielectric filter, a dielectric duplexer, a mounting structure having the same, and a communication device each of which is small in size, low in height, and has good characteristics.
To achieve the above object, the present invention provides a dielectric filter comprising: a dielectric block including a first surface and a second surface opposite to each other; a resonator hole extending between the first surface and second surface of the dielectric block, said resonator hole including a large-sectional area portion, a small-sectional area portion and a step portion between the large-sectional area portion and the small-sectional area portion; an inner conductor provided on the inner surface of the resonator hole; an outer conductor provided on the outer surface of the dielectric block; the inner conductor being electrically left unconnected to the outer conductor at the first surface of the dielectric block and being electrically connected to the outer conductor at the second surface of the dielectric block; and a seat portion provided on the first surface of the dielectric block to allow the first surface to serve as a mounting surface of the dielectric filter.
The present invention also provides a dielectric duplexer comprising the above described dielectric filter, wherein a plurality of said resonator holes are provided, at least one of which constituting a transmitting filter and at least the other one of which constituting a receiving filter.
According to the above described structure and arrangement, the dielectric filter or the dielectric duplexer is so mounted to a circuit board or the like that the axes of the resonator holes are substantially perpendicular to the circuit board or the like. In each resonator hole, the step portion is formed between the large-sectional area portion and the small-sectional area portion. The conductor path of the inner conductor is extended to lie on the surface of the step. Thus, the conductor path is longer by an amount corresponding to the step portion. Accordingly, the size of the dielectric filter or the dielectric duplexer can be reduced in the axial direction of the resonator hole, compared with the filter or duplexer which does not have such a step portion. Thus, the mounting height of the dielectric filter or the dielectric duplexer can be reduced. Further, a gap is formed between the first surface of the dielectric block which serves as the mounting surface, and the circuit board or the like, due to the seat portion provided on the first surface of the dielectric block. With the gap, a stray capacitance, produced between the first surface of the dielectric block and the circuit board, is reduced. In addition, since the first surface, which is the open-circuited surface, is opposed to the circuit board, an electromagnetic field leaking from the first surface can be inhibited from exerting an unfavorable influence over other electronic components mounted on the circuit board. Similarly, an electromagnetic field leaking from the other electronic components can be inhibited from affecting the dielectric filter or the dielectric duplexer.
A depression may be provided on the step portion between the large-sectional area portion and the small-sectional area portion of each resonator hole, and the conductor path of the inner conductor is extended to lie on the surface of the depression on the step. Thus, the conductor path is longer by an amount corresponding to the depression. Accordingly, the size of the dielectric filter or the dielectric duplexer can be further reduced in the axial direction of the resonator hole.
Furthermore, a slot may be provided on the first surface of the dielectric block. Depending on the size and shape of the slot, it is possible to change the resonator length of each dielectric resonator composed of one of the resonator holes, the outer conductor, and the dielectric block, and moreover, the coupling coefficients of the capacitive coupling and the inductive coupling between adjacent resonators.
Further, the mounting structure and the communication device of the present invention, equipped with at least one of the dielectric filters and the dielectric duplexer, can meet flexibly the requirement that the device should be reduced in height.
REFERENCES:
patent: 4342972 (1982-08-01), Nishikawa et al.
patent: 5764118 (1998-06-01), Saito et al.
patent: 6060967 (2000-05-01), Asada
Patent Abstracts of Japan, vol. 15, No. 355 (E-1109), Sep. 9, 1991 & JP 03 136502 A (Murata Mfg Co Ltd), Jun. 11, 1991, abstract.
Patent Abstracts of Japan, vol. 13, No. 333 (E-794), Jul. 26, 1989 & JP 01 097002 A (Fuji Electrochem Co Ltd), Apr. 14, 1989, abstract.
Patent Abstracts of Japan, vol. 17, No. 676 (E-1475), Dec. 13, 1993 & JP 05 226909 A (Sony Chem Corp), Sep. 3, 1993, abstract; figure 6, 7.
Ishihara Jinsei
Kato Hideyuki
Maruyama Takashi
Toda Jun
Murata Manufacturing Co. Ltd.
Nguyen Patricia T.
Ostrolenk Faber Gerb & Soffen, LLP
Pascal Robert
LandOfFree
Dielectric filter, dielectric duplexer, mounting structure... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dielectric filter, dielectric duplexer, mounting structure..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dielectric filter, dielectric duplexer, mounting structure... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2540143