Wave transmission lines and networks – Plural channel systems – Nonreciprocal gyromagnetic type
Reexamination Certificate
2003-05-19
2004-12-07
Tokar, Michael (Department: 2819)
Wave transmission lines and networks
Plural channel systems
Nonreciprocal gyromagnetic type
C333S024200, C361S311000, C361S312000
Reexamination Certificate
active
06828872
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an irreversible circuit device typified by an isolator or a circulator that is used in a high frequency band such as a microwave band.
2. Description of the Related Art
FIG. 13
of the accompanying drawings is an exploded perspective view of an ordinary isolator (irreversible circuit device) according to the prior art. The isolator
60
shown in the drawing includes a lower yoke
61
and an upper yoke
62
, and sandwiches a magnetic member
63
, a spacer member
64
, a magnetic assembly
65
, capacitor substrates
66
,
67
and
68
, a terminating resistor
69
and a substrate
70
between the upper and lower yokes
62
and
61
.
The magnetic assembly
65
in this prior art example includes a magnetic substrate
72
formed of a ferrite sheet, etc, center conductors
73
,
74
and
75
arranged on a top surface side of the magnetic substrate
72
and a common electrode connected to these conductors on the back side of the magnetic substrate
72
. A slit splits each center conductor
73
,
74
,
75
into two parts.
Thin sheet-like capacitor substrates
66
,
67
and
68
are arranged on the substrate
70
. The magnetic assembly
65
is arranged inside these capacitor substrates
66
,
67
and
68
. A distal end
73
a
,
74
a
,
75
a
of each center conductor
73
,
74
,
75
of the magnetic assembly
65
is soldered to the capacitor substrate
66
,
67
,
68
arranged beneath it. A sheet-like spacer member
64
having protuberances
64
a
and
64
a
is arranged above the magnetic assembly
65
and a sheet-like magnetic member
63
is arranged on the spacer member
64
.
In the isolator of the prior art example shown in
FIG. 13
, the magnetic member
63
is disposed to apply a bias magnetic field to the magnetic substrate
72
. To form a magnetic path of the bias magnetic field from the magnetic member
63
, the side end portions of the lower and upper yokes
61
and
62
are bent vertically to form bent portions. The lower and upper yokes
61
and
62
are so shaped as to constitute a box shape as a whole when they are put together.
However, as the device size of the isolator has been reduced year by year in the unit of millimeters (mm), however, positional influences of the yoke side surface portions invite deterioration of uniformity of the bias magnetic field applied to the magnetic substrate
72
because the side surface portions of the yokes and the magnetic substrate
72
are arranged close to one another or because the yoke side surface portions and the magnetic member
63
are arranged close to one another. In consequence, there is problem that performance drops such as the increase of the insertion loss as the isolator.
To allow a uniform bias magnetic field to act on the magnetic substrate
72
in the isolator
60
shown in
FIG. 13
, it has been customary to shape the magnetic substrate
72
into a size smaller than that of the magnetic member
63
and to let the uniform bias magnetic field act on the magnetic substrate
72
as a whole. Therefore, the size of the magnetic substrate
72
has been set to about 50% of the full width of the isolator
60
in the prior art. To improve performance as the isolator
60
, however, there is a problem that the magnetic substrate
72
is preferably as large as possible.
SUMMARY OF THE INVENTION
In view of the problems of the prior art described above, it is an object of the invention to provide an irreversible circuit device that can suppress disturbance of a bias magnetic field acting on a peripheral portion of a magnetic substrate by forming a gap portion at sidewall portions of yokes formed of a ferromagnetic materials, can prevent the drop of an insertion loss as an irreversible circuit device, and can reduce an overall size of the device without inviting the drop of the insertion loss.
In view of the problems of the prior art described above, it is another object of the invention to provide an irreversible circuit device that can suppress disturbance of a bias magnetic field acting on a peripheral portion of a magnetic substrate by forming a gap portion at sidewall portions of yokes formed of a ferromagnetic materials, can prevent the drop of an insertion loss as an irreversible circuit device, can reduce an overall size of the device without inviting the drop of the insertion loss and can improve performance by increasing as much as possible the size of the magnetic substrate.
To accomplish the objects described above, one aspect of the invention provides an irreversible circuit device comprising a yoke main body having sidewall portions defined by an upper yoke and a lower yoke, and accommodating therein a magnetic substrate, a plurality of line conductors arranged on a main plane of the magnetic substrate while being individually insulated from one another, a plurality of capacitor substrates arranged around the magnetic substrate and a magnetic member for applying a DC bias magnetic field in substantially a vertical direction to the main plane of the magnetic substrate, wherein the line conductors are put one upon another on the main surface side of the magnetic substrate and are connected to one another on the other surface side of the magnetic substrate, each end of the line conductors put one upon another on the main surface side of the magnetic substrate is connected to the capacitor substrate, and a gap portion for magnetically insulating the upper yoke and the lower yoke is formed on the sidewall portion of the yoke main body.
When the gap portion for magnetically isolating the upper yoke and the lower yoke is interposed between them, magnetic interference between the magnetic member and the sidewall portions of the upper and lower yokes and between the magnetic substrate and the sidewall portions of the upper and lower yokes does not easily occur, and disturbance of the bias magnetic field acting on from the magnetic member to the magnetic substrate can be reduced even when the irreversible circuit device is rendered compact in size. Eventually, the insertion loss can be suppressed. Because disturbance of the bias magnetic field can be thus suppressed, the sidewall portions of the yoke main body can be brought closer to the magnetic member or to the magnetic substrate than in the prior art construction, and the size of the irreversible circuit device can be reduced.
To accomplish the objects described above, another aspect of the invention provides an irreversible circuit device comprising a yoke main body having sidewall portions defined by an upper yoke and a lower yoke, and accommodating therein a magnetic substrate, a plurality of line conductors arranged on a main plane of the magnetic substrate while being individually insulated from one another, a plurality of capacitor substrates arranged around the magnetic substrate and a magnetic member for applying a DC bias magnetic field in substantially a vertical direction to the main plane of the magnetic substrate, wherein the line conductors are put one upon another on the main surface side of the magnetic substrate and are connected to one another on one of surface sides of the magnetic substrate, each end of the line conductors put one upon another on the main surface side of the magnetic substrate is connected to the capacitor substrate, the magnetic substrate is formed into a rectangular shape as viewed in a plan view, the length of a major side of the rectangular magnetic substrate is set to a length within the range of 65 to 100% of an inner diameter of the yoke main body, and a gap portion for magnetically insulating the upper yoke and the lower yoke is formed on the sidewall portion of the yoke main body.
When the gap portion for magnetically isolating the upper yoke and the lower yoke is interposed between them, magnetic interference between the magnetic member and the sidewall portions of the upper and lower yokes and between the magnetic substrate and the sidewall portions of the upper and lower yokes does not easily occur, and disturbance of the bias magnetic field acting
Komai Eiichi
Onishi Hitoshi
Takahashi Toshio
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Mai Lam T.
Tokar Michael
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