Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
2003-03-27
2004-10-05
Nguyen, Long (Department: 2816)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C333S202000
Reexamination Certificate
active
06801106
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric electronic component such as a dielectric filter or a dielectric duplexer including a plurality of resonators arranged in parallel and adapted to use in a mobile communication device such as a cellular telephone.
2. Description of the Related Art
Conventional dielectric electronic components include a dielectric filter having a configuration as described below.
Referring to
FIG. 1
of the accompanying drawings, the dielectric filter F comprises a substantially rectangularly parallelepipedic dielectric ceramic block B, resonators r
1
and r
2
arranged in parallel in a given direction and excitation holes t
1
and t
2
arranged at the opposite outer lateral sides of the resonators r
1
and r
2
. Each of the resonators r
1
and r
2
includes a through hole provided in the dielectric ceramic block B, each through hole having an inner peripheral surface coated with an internal conductor. Each of the excitation holes t
1
and t
2
has an inner peripheral surface coated with an internal conductor.
The top surface e of the dielectric ceramic block B defines the open-circuiting ends a
1
and a
2
of the resonators r
1
and r
2
and the short-circuiting ends b
1
and b
2
of the excitation holes t
1
and t
2
. The bottom surface f of the dielectric ceramic block B defines the short-circuiting ends of the resonators r
1
and r
2
and the open-circuiting ends of the excitation holes t
1
and t
2
. Then, the outer surfaces of the dielectric block B are coated with an external conductor g by means of a known technique such as screen printing except regions surrounding the open-circuiting ends a
1
and a
2
of the resonators r
1
and r
2
and those surrounding the open-circuiting ends of the excitation holes t
1
and t
2
. Therefore, the resonators r
1
and r
2
and the excitation holes t
1
and t
2
are connected to the external conductor g at the short-circuiting ends thereof and isolated from the external conductor g by respective insulating sections at the open-circuiting ends thereof.
The length of the resonators r
1
and r
2
, or the resonance length, is made substantially equal to ¼ of the resonance wavelength &lgr;. The resonator r
1
and the excitation hole t
1
are electromagnetically coupled. So are the resonator r
2
and the excitation hole t
2
. An input/output pad P
1
is formed at a position close to the open-circuiting end of the excitation hole t
1
on a lateral surface of the dielectric ceramic block B as extension of the internal conductor of the excitation hole t
1
. Similarly, another input/output pad P
2
is formed at a position close to the open-circuiting end of the excitation hole t
2
on the same lateral surface of the dielectric ceramic block B as extension of the internal conductor of the excitation hole t
2
. The input/output pads P
1
and P
2
are formed isolated from the external conductor g.
Meanwhile, dielectric filters having the above described configuration are always required to show a desired reflection characteristic. It is necessary to adjust the extent of input/output coupling in order to acquire a desired reflection characteristic. Known means for adjusting the extent of input/output coupling include those that are adapted to do so by regulating the diameter and the positions of the excitation holes.
In the dielectric filter F having the above described configuration, the internal conductors of the excitation holes t
1
and t
2
are formed normally by drawing an electrically conductive material from an end of each of the excitation holes by vacuum and applying the conductive material to the inner peripheral surfaces of the excitation holes. On the other hand, the external conductor g is laid on the short-circuiting end facets of the top surface e of the dielectric ceramic block B where the short-circuiting ends b
1
and b
2
of the excitation holes t
1
and t
2
are formed. This external conductor g is normally produced by a known printing technique such as screen printing.
However, to meet the demand for down-sized devices that has remarkably increased in recent years, dielectric filters are required to show reduced dimensions. Under these circumstances, it is often difficult to modify the diameter of the excitation holes to a desired value and hence it is no longer possible to adjust the extent of input/output coupling over a wide range in a dielectric filter. Then, such a dielectric filter can find only a limited scope of application. Dielectric duplexers face similar problems.
Additionally, known dielectric filters having the above described configuration are accompanied by a problem of a large number of manufacturing steps and high manufacturing cost because they are manufactured by forming internal conductors on the excitation holes and external conductors on the short-circuiting end facets of the excitation holes independently in separate respective printing steps. Furthermore, there are occasions where each of the internal conductors of the excitation holes desirably has a given thickness in a given region thereof. There are also occasions where they desirably have a given surface area. Again, dielectric duplexers face similar problems.
SUMMARY OF THE INVENTION
In view of the above identified problems, it is therefore the object of the present invention to provide a dielectric electronic component such as a dielectric filter or a dielectric duplexer that can dissolve those problems.
In an aspect of the invention, the above object is achieved by providing a dielectric electronic component for a communication device comprising:
a plurality of resonators provided in a dielectric ceramic block, each of which includes a through hole bored through the dielectric ceramic block and having an inner peripheral surface coated with an internal conductor;
a plurality of excitation holes formed in the dielectric ceramic block and electromagnetically coupled with the resonators, each of which has an inner peripheral surface coated with an internal conductor, said resonators and said excitation holes being arranged in parallel;
the dielectric ceramic block having a top surface on which open-circuiting ends of the resonators and short-circuiting ends of the excitation holes are defined;
the dielectric ceramic block having a bottom surface on which short-circuiting ends of the resonators and the open-circuiting ends of the excitation holes are defined;
the dielectric ceramic block having an outer peripheral surface coated with an external conductor except regions surrounding the open-circuiting ends of the resonators and those of the excitation holes; and
the short-circuiting ends of the excitation holes being provided with respective coupling-adjusting countersinks showing an increased diameter.
With the above defined arrangement, the input/output coupling of the dielectric electronic component can be weakened without raising the outer dimensions of the dielectric electronic component.
In another aspect of the present invention, there is provided a dielectric electronic component for a communication device comprising:
a plurality of resonators provided in a dielectric ceramic block, each of which includes a through hole bored through the dielectric ceramic block and having an inner peripheral surface coated with an internal conductor;
a plurality of excitation holes formed in the dielectric ceramic block and electromagnetically coupled with the resonators, each of which has an inner peripheral surface coated with an internal conductor, said resonators and said excitation holes being arranged in parallel with each other;
the dielectric ceramic block having a top surface on which open-circuiting ends of the resonators and short-circuiting ends of the excitation holes are defined;
the dielectric ceramic block having a bottom surface on which short-circuiting ends of the resonators and the open-circuiting ends of the excitation holes are defined;
the dielectric ceramic block having an outer peripheral surface coated with an external conductor except regio
Hamaguchi Yukihiro
Ono Shoji
Suzuki Hidefumi
Hunt, Jr. Ross F.
NGK Spark Plug Co. Ltd.
Nguyen Long
Stites & Harbison PLLC
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