Dielectric filter, dielectric duplexer, and communication...

Details Dielectric filter, dielectric duplexer, and communication... Dielectric filter, dielectric duplexer, and communication...

2002-05-30

2004-07-20

Summons, Barbara (Department: 2817)

Wave transmission lines and networks

Plural channel systems

Having branched circuits

C333S206000, C333S207000

Reexamination Certificate

active

06765457

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric filter and a dielectric duplexer in which conductive through holes are provided in a dielectric block and in which an external conductor is provided on exterior surfaces of the dielectric block. The present invention also relates to a communication device using the dielectric filter and the dielectric duplexer.
2. Description of the Related Art
A typical dielectric filter is described with reference to
FIGS. 11A and 11B
.
FIG. 11A
is a perspective view of the dielectric filter and
FIG. 11B
is a front plan view of an open circuited end of the dielectric filter.
In
FIGS. 11A and 11B
, a dielectric block
1
, through holes
2
a
to
2
c
with internal conductors
3
a
to
3
c
, an external conductor
4
, conductor-free portions
5
, input-output electrodes
6
, and internal-conductor-free portions
7
a
to
7
c
are shown.
Preferably, the dielectric block
1
is in the form of a substantially rectangular solid. The holes
2
a
to
2
c
pass through the dielectric block
1
from one surface
1
a
to the opposite surface
1
b
. On the inside surface of the conductive through holes
2
a
to
2
c
, the internal conductors
3
a
to
3
c
are formed, respectively, so as to form respective conductive through holes. The external conductor
4
is preferably formed substantially on the whole outside surface of the dielectric block
1
. The internal-conductor-free portions
7
a
to
7
c
are provided on the inside surface of the conductive through holes
2
a
to
2
c
such that the internal conductors
3
a
to
3
c
are separated from the external conductor
4
and form open circuited ends. In other words, the conductor-free portions
7
a
to
7
c
of each conductive through hole capacitively couple the conductive through holes to the external conductor and form the open circuited ends thereof. The other ends of the conductive through holes are directly coupled to the external conductor
4
so as to form the short circuited ends. In this way, dielectric resonators are formed by the internal conductors
3
a
to
3
c
, the dielectric block
1
, and the external conductor
4
.
On the outside surface of the dielectric block
1
, the input-output electrodes
6
are formed so as to extend from opposite end faces of the dielectric block
1
. The input-output electrodes
6
are preferably provided at opposite sides of the arrangement of the conductive through holes and are separated from the external conductor
4
by the external-conductor-free portions
5
.
In this way, a dielectric filter is formed by the input-output electrodes
6
and the three dielectric resonators.
However, there are the following problems in such a dielectric filter which are illustrated with reference to
FIGS. 12A
to
12
C.
FIG. 12A
is an equivalent circuit diagram of a two-stage dielectric resonator,
FIG. 12B
shows the state of electric lines of force in even mode and in odd mode, and
FIG. 12C
is an equivalent circuit diagram of a two-stage dielectric resonator having a jumping coupling capacitance.
In an integral type dielectric filter composed of a plurality of resonators using a dielectric block, tip capacitance Cs is generated between an open end of the resonator and the external conductor as a grounding electrode shown in FIG.
12
A.
The electric lines of force where the tip capacitance Cs is generated in even mode and in odd mode are shown in FIG.
12
B. In even mode, the electric lines of force are generated between the resonators and the grounding electrode. In odd mode, a part of the electric lines of force is generated between the resonators. Therefore, the tip capacitance Cs generated between the resonators and the grounding electrode in odd mode becomes smaller than that in even mode, and jumping tip capacitance dCs is generated between the open ends of the resonators. Here, since Cs is set on the basis of the capacitance in even mode, the jumping coupling capacitance dCs has a minus value.
In this way, when the jumping coupling capacitance dCs generated between the open ends of the resonators is considered, the equivalent circuit diagram shown in
FIG. 12A
becomes the circuit diagram in FIG.
12
C.
A three-stage dielectric resonator is described with reference to
FIGS. 13A and 13B
.
FIG. 13A
is an equivalent circuit diagram of the three-stage dielectric resonator and
FIG. 13B
shows the attenuation characteristics of a dielectric filter provided with the three-stage dielectric resonator.
As shown in
FIG. 13A
, the tip capacitance Cs is generated between the open end and the external conductor as the grounding electrode in each resonator, and jumping coupling capacitance dCs
1
is generated between the open ends of neighboring resonators, respectively. Furthermore, jumping coupling capacitance dCs
2
, which is very small compared to the jumping coupling capacitance dCs
1
generated between the open ends of neighboring resonators, is also generated between the open ends of the non-neighboring resonators at both ends of the array of resonators.
Here, since the jumping coupling capacitance dCs
1
generated between neighboring resonators is included in the coupling capacitance between resonators, the capacitance does not have great effects on the attenuation characteristics, but, since the jumping coupling capacitance Cs
2
generated between the non-neighboring resonators is different from the coupling capacitance between resonators, the capacitance has an effect on the position of the attenuation poles as shown in FIG.
13
B. For example, in a dielectric filter composed of a three-stage resonator in which they have combined (inductive) coupling, two attenuation poles are created on the higher-frequency side of the passband If the jumping coupling capacitance dCs
2
is large, the space between the attenuation poles increases and, if the jumping coupling capacitance dCs
2
is small, the space between the attenuation poles decreases. Therefore, desired attenuation characteristics cannot be obtained outside the passband, although they are dependent on the position where the attenuation poles are generated.
In order to solve this problem, dielectric filters shown in
FIGS. 14A and 14B
have been used.
FIGS. 14A and 14
b
are perspective views of dielectric filters.
In the dielectric filter shown in
FIG. 14A
, the inner diameter of the conductive through hole
2
b
is larger than those of the other conductive through holes
2
a
and
2
c
. In the dielectric filter shown in
FIG. 14B
, the inner diameter of the conductive through hole
2
b
is smaller than those of the other conductive through holes
2
a
and
2
c.
In the dielectric filter shown in
FIG. 14A
, since the inner diameter of the conductive through hole
2
b
is large, the space between the internal conductor
3
b
and the external conductor
4
becomes smaller and the jumping coupling capacitance dCs
2
generated between the internal conductor
3
a
and the internal conductor
3
c
decreases. Since the inner diameter of the conductive through hole
2
b
is not appropriate for obtaining the optimum Q
0
, Q
0
of the resonators becomes smaller and adverse effects are added, such as insertion loss.
In the dielectric filter shown in
FIG. 14B
, since the inner diameter of the conductive through hole
2
b
is small, the space between the internal conductor
3
b
band the external conductor
4
becomes larger and the jumping coupling capacitance dCs
2
generated between the internal conductor
3
a
and the internal conductor
3
c
increases. Since the inner diameter of the conductive through hole
2
b
is not appropriate for obtaining the optimum Q
0
, Q
0
of the resonators also becomes smaller in this case and adverse effects are produced, such as insertion loss.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a dielectric filter and dielectric duplexer in which the deterioration of Q
0
of resonators is suppressed, jumping coupling capacitance generated between non-neighboring resonators is controll

Affiliated with

Also associated with

Rating

Dielectric filter, dielectric duplexer, and communication... 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, and communication..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dielectric filter, dielectric duplexer, and communication... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3224580