Wave transmission lines and networks – Coupling networks – Nonreciprocal gyromagnetic type
Reexamination Certificate
2002-09-25
2004-05-11
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Coupling networks
Nonreciprocal gyromagnetic type
C333S001100
Reexamination Certificate
active
06734753
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a nonreciprocal circuit element, such as an isolator and a circulator, for use in, for example, a microwave band, and relates to a communication device including the same.
2. Description of the Related Art
As a concentrated constant type isolator used for a mobile communication device such as a portable telephone, an isolator disclosed in Japanese Unexamined Patent Application Publication No. 11-97908 is known. As shown in
FIG. 17
, this isolator
200
substantially includes a resin terminal case
203
, a lower metallic case
208
, and an upper metallic case
204
. These elements accommodate therein a permanent magnet
209
, a center electrode assembly
213
, matching capacitor elements C, and a resistance element R. The center electrode assembly
213
includes a center conductor
220
constituted of center electrodes
221
to
223
and a ground electrode
224
, and a ferrite
230
.
Windows
203
b
for accommodating the matching capacitor elements C formed in the resin terminal case
203
, and an insertion hole
203
a
for accommodating the center electrode assembly
213
are formed at positions adjacent to each other. The side surface of the insertion hole
203
a
and that of each of the windows
203
b
communicate with each other via grooves
203
c.
As shown in
FIG. 18
, the center conductor
220
is arranged so that the center electrodes
221
to
223
and the ground electrode
224
thereof are integral with each other. The center electrodes
221
to
223
are each constituted of two parallel lines. These lines are each connected to the ground electrode
224
in a substantially linear configuration.
As shown in
FIG. 17
, the center electrode assembly
213
is obtained by the winding center conductor
220
around the ferrite
230
. Specifically, the ferrite
230
is disposed on the ground electrode
224
, and as shown in
FIG. 19
, the center electrodes
221
to
223
are folded substantially perpendicularly to the bottom surface of the ferrite
230
. Furthermore, the center electrodes
221
to
223
are sequentially folded along the side surface and the top surface of the ferrite
230
, and are placed on the top surface of the ferrite
230
with insulating sheets therebetween, thereby obtaining the center electrode assembly
213
.
The center electrode assembly
213
, the matching capacitor elements C and others are accommodated in the resin terminal case
203
. At this time, since the insertion hole
203
a
and the windows
203
b
of the resin terminal case
203
communicate with each other via the grooves
203
c
, the center electrode
222
disposed on the side surface of the ferrite
230
is situated at a position adjacent to the hot-side electrode disposed over the entire top surface of a corresponding matching capacitor element C. Similarly, the center electrode
221
and another corresponding matching capacitor element C are also situated at positions adjacent to each other, although they are not shown in FIG.
19
.
With the demand for miniaturization of mobile communication devices, the isolator
200
used in such communication devices has also been required to be miniaturized. As a result, the distance between the center electrode assembly
213
and the capacitor electrode of each of the matching capacitor elements C has been reduced. However, the reduction in distance between the center electrode assembly
213
and each of the matching capacitor elements C may cause a problem of short-circuiting. Because, due to displacement of the center electrode assembly
213
and/or at least one of the matching capacitor elements C, e.g. the edge
222
a
of the center electrode
222
and the capacitor electrode of the corresponding matching capacitor element C may contact each other, or solder balls adhered to the capacitor electrode of the corresponding matching capacitor element C may contact the edge
222
a
of the center electrode
222
.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, preferred embodiments of the present invention provide compact and a highly reliable nonreciprocal circuit element and communication device.
According to a preferred embodiment of the present invention, a nonreciprocal circuit element includes a permanent magnet, a ferrite having a first main surface to which a DC magnetic field is applied by the permanent magnet, a second main surface opposed to the first main surface, and a side surface substantially perpendicularly intersecting the first and second main surfaces, a center conductor having a ground electrode disposed on the second main surface of the ferrite, and a plurality of center electrodes that extend from the ground electrode and that are disposed so as to intersect each other at a predetermined angle on the first main surface of the ferrite through the side surface of the ferrite, matching capacitor elements that are disposed adjacent to a center electrode assembly including the ferrite and the center conductor, and that are electrically connected to the respective center electrodes, and a metallic member that accommodates the permanent magnet and the center electrode assembly. In this nonreciprocal circuit element, the height of the top surface of each of the matching capacitor elements is lower than that of the first main surface of the ferrite. Simultaneously, on the side surface of the ferrite, one edge of at least one of the center electrodes is located closer to the electrode of the corresponding matching capacitor element than the other edge of the center electrode. Furthermore, in a direction that is substantially perpendicular to the height direction of the ferrite, the second main surface side portion of the one edge of the center electrode is located farther from the electrode of the corresponding matching capacitor element than the first main surface side portion of the one edge of the center electrode.
Another preferred embodiment of the present invention, a nonreciprocal circuit element includes a permanent magnet, a ferrite having a first main surface to which a DC magnetic field is applied by the permanent magnet, a second main surface opposed to the first main surface, and a side surface substantially perpendicularly intersecting the first and second main surfaces, a center conductor having a ground electrode disposed on the second main surface of the ferrite, and a plurality of center electrodes that extend from the ground electrode and that are disposed so as to intersect each other at a predetermined angle on the first main surface of the ferrite through the side surface of the ferrite, matching capacitor elements that are disposed adjacent to a center electrode assembly including the ferrite and the center conductor, and that are electrically connected to the respective center electrodes, and a metallic member that accommodates the permanent magnet and the center electrode assembly. In this nonreciprocal circuit element, the height of the top surface of each of the matching capacitor elements is lower than that of the first main surface of the ferrite. Simultaneously, on the side surface of the ferrite, one edge of at least one of the center electrodes is located closer to the electrode of the corresponding matching capacitor element than the other edge of the center electrode. Furthermore, in a direction that is substantially perpendicular to the height direction of the ferrite, the central portion between the first main surface side portion and the second main surface side portion of the one edge of the center electrode is located farther from the hot-side capacitor electrode of the corresponding matching capacitor element than either of the first main surface side portion and the second main surface side portion of the one edge of the center electrode. Herein, each of the center electrodes may be branched into a plurality of lines on the side surface of the ferrite, and the branched lines may be disposed on the first main surface of the ferrite.
With these arrangements, the plurality of center
Hasegawa Takashi
Kawanami Takashi
Jones Stephen E.
Keating & Bennett LLP
Lee Benny
Murata Manufacturing Co. Ltd.
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