Wave transmission lines and networks – Plural channel systems – Nonreciprocal gyromagnetic type
Reexamination Certificate
2000-04-24
2003-10-14
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Nonreciprocal gyromagnetic type
C333S024200
Reexamination Certificate
active
06633204
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a nonreciprocal circuit device. More particularly, the present invention relates to a nonreciprocal circuit device such as an isolator or a circulator for use in a microwave communication apparatus, and to a communication apparatus using the isolator or circulator.
2. Description of the Related Art
Generally, the function of a lumped-constant type isolator is to pass a signal only in a transmitting direction and to eliminate the transmission of the signal in the reverse direction.
Recently, in mobile communication apparatus, cost-reduction has been strongly demanded as well as miniaturization and weight-reduction. In such a circumstance, miniaturization, weight-reduction and cost-reduction have also been demanded in an isolator.
A lumped-constant type isolator shown in
FIG. 10
has been proposed to meet the above demand. The lumped-constant type isolator
11
comprises a terminal case
13
which is made of resin and disposed on a lower yoke
12
. The lower yoke
12
is made of magnetic metal and comprises right and left side walls
12
a
and a bottom wall
12
b
. A center electrode assembly
14
is accommodated in the terminal case
13
and an upper yoke
15
made of magnetic metal is placed thereon. Inside the upper yoke
15
, a permanent magnet
16
is disposed. The permanent magnet
16
applies a DC magnetic field to the center electrode assembly
14
.
The center electrode assembly
14
comprises a microwave ferrite
20
and three center electrodes
21
,
22
and
23
disposed on the microwave ferrite
20
. The three center electrodes
21
-
23
cross each other at angles of 120 degrees in an electrically insulated state. Port sections P
1
, P
2
and P
3
at first ends of the three center electrodes
21
-
23
are bent vertically and a shield section
26
which is common to the other ends of the three center electrodes
21
-
23
is contacted to the lower surface of the ferrite
20
. The common shield section
26
substantially covers the lower surface of the ferrite
20
, and is connected to the bottom wall
12
b
of the lower yoke
12
through a window
13
a
of the terminal case
13
.
Input/Output electrodes
31
,
32
and ground terminals
33
,
34
are insert molded in the terminal case
13
. First ends of the Input/Output electrodes
31
,
32
are exposed outside the side wall of the case
13
, and the other ends thereof are exposed inside the side wall of the case
13
, to thereby form Input/Output connecting sections
18
a
,
18
b
inside the case
13
. Similarly, first ends of the ground terminals
33
,
34
are exposed outside the side wall of the case
13
, and the other ends thereof are exposed inside the side wall of the case
13
, to thereby form ground connecting electrode sections
17
a
,
17
b
and
17
c
,
17
d
, respectively.
Each of the port sections P
1
-P
3
of the center electrodes
21
-
23
is connected to a hot-side capacitor electrode
1
of one of matching capacitors C
1
, C
2
and C
3
. A cold-side capacitor electrode
2
of each of the matching capacitors C
1
-C
3
is connected to the ground connecting electrode sections
17
a
,
17
b
,
17
c
,
17
d
. One end of a termination resistor R is connected to the hot-side capacitor electrode
1
of the matching capacitor C
3
, and the other end thereof is connected to the ground connecting electrode section
17
b
. That is, the matching capacitor C
3
and the termination resistor R are electrically connected in parallel between the port section P
3
of the center electrode
23
and ground. Further, the port sections P
1
and P
2
are connected to the Input/Output connecting electrode sections
18
a
and
18
b
, respectively.
In the above conventional isolator
11
, each of the matching capacitors C
1
-C
3
must be inserted between one of the port sections P
1
-P
3
and one of the ground connecting electrode sections
17
a
,
17
c
,
17
d
, respectively, while holding the capacitor in a vertical orientation. Further, it is necessary to connect the capacitor electrodes
1
,
2
of the matching capacitors C
1
-C
3
to the port sections P
1
-P
3
and the ground connecting electrode sections
17
a
,
17
c
,
17
d
by soldering.
However, the isolator
11
has the problem that the process of inserting the matching capacitors C
1
-C
3
between the port sections P
1
-P
3
and the ground connecting electrode sections
17
a
,
17
c
,
17
d
requires much time and effort, because the matching capacitors C
1
-C
3
are small in size and difficult to handle. Further, since the port sections P
1
-P
3
of the center electrodes
21
-
23
must be bent vertically in one of the initial steps in the assembly process, it is possible for the solder connection between the port sections P
1
-P
3
and the matching capacitors C
1
-C
3
to become unstable because of variations in the bend angle of the port sections P
1
-P
3
. Moreover, it is possible for the solder to spill and cause a short-circuit between the hot-side capacitor electrodes
1
and the cold-side capacitor electrodes
2
of the matching capacitors C
1
-C
3
, resulting in a defective product.
SUMMARY OF THE INVENTION
To overcome the above described problems, preferred embodiments of the present invention provide a nonreciprocal circuit device and a communication apparatus having high reliability, including a matching capacitor which is easy to assemble.
One embodiment of the present invention provides a nonreciprocal circuit device, comprising: a permanent magnet; a ferrite to which a DC magnetic field is applied by the permanent magnet; a plurality of center electrodes extending from a first major surface of the ferrite to a second major surface of the ferrite via side surfaces of the ferrite; a ground plate disposed on the second major surface side of the ferrite and electrically connected to the plurality of center electrodes; a plurality of matching capacitors electrically connected between the ground plate and port sections of the plurality of center electrodes respectively; and at least one matching capacitor being disposed such that a major surface thereof forms an angle in a range of 60 degrees to 120 degrees with a major surface of the ferrite.
According to the above arrangement, the matching capacitors can be connected between the center electrodes and the ground plate assembled with the ferrite in an initial assembly step. Thus, it becomes possible to handle the matching capacitors integrally with the center electrodes, the ground plate and the ferrite, as one unit. Therefore, mounting the matching capacitors becomes easier.
Further, an insulator for preventing a short circuit may be provided in the vicinity of the portion of the ground plate at which the matching capacitor is connected and in the vicinity of the port section of the center electrode. This insulator prevents an undesirable solder bridge from being formed by spilled solder when the matching capacitor is soldered. By this, for example, a short-circuit between the hot-side capacitor electrode and the cold-side capacitor electrode of the matching capacitor can be prevented.
Further, a communication apparatus according to the present invention has a lower manufacturing cost and higher reliability because the apparatus is provided with a nonreciprocal circuit device having the above described arrangement.
Also disclosed is a method of assembling the nonreciprocal circuit device.
REFERENCES:
patent: 4101850 (1978-07-01), Dworsky et al.
patent: 0903801 (1999-03-01), None
patent: 10303605 (1998-11-01), None
patent: 11-55009 (1999-02-01), None
patent: 11-068411 (1999-03-01), None
patent: 11-097910 (1999-04-01), None
European Search Report dated Feb. 14, 2002 for EP 00 10 8475.
Dejima Hiroki
Hasegawa Takashi
Jodo Takahiro
Makino Toshihiro
Mori Masakatsu
Jones Stephen E.
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
Pascal Robert
LandOfFree
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