Wave transmission lines and networks – Plural channel systems – Nonreciprocal gyromagnetic type
Reexamination Certificate
2002-02-12
2003-11-11
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Nonreciprocal gyromagnetic type
C333S024200
Reexamination Certificate
active
06646515
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an isolator/circulator used for the components' protection and impedance matching of systems and terminals in mobile communication, personal communication, cordless telephones, and satellite communication, and more particularly, to a microstripline/stripline isolator/circulator having a propeller resonator.
2. Description of the Related Art
An isolator/circulator can operate in a predetermined direction, taking advantage of irreversibility of a permanent magnet and ferrite, and its frequency can be easily adjusted. A compact-sized isolator/circulator for terminals uses a microstripline, and a large-sized isolator/circulator uses a stripline. In recent years, the size of systems used for mobile communication, satellite communication, and millimeter waves has been reduced, and accordingly, it has been required to decrease the size, weight, and manufacturing costs of an isolator/circulator. In addition, the isolator/circulator has been required to have a low insertion loss, a high isolation, and a wide bandwidth.
FIG. 1
is a cross-sectional view of a conventional isolator/circulator including a stripline, and
FIG. 2
is a cross-sectional view of a conventional isolator/circulator including a microstripline
Referring to
FIG. 1
, a conventional isolator/circulator includes a stripline
104
interpolated between an upper ferrite substrate
102
a
and a lower ferrite substrate
102
b
. A ground electrode
107
is formed at the top surface of the upper ferrite substrate
102
a
and at the bottom surface of the lower ferrite substrate
102
b
. An upper permanent magnet
103
a
is formed on the upper ferrite substrate
102
a
, and a lower permanent magnet
103
b
is formed under the lower ferrite substrate
102
b
. A thin iron plate
108
is interpolated between the upper permanent magnet
103
a
and the ground electrode
107
and between the lower permanent magnet
103
b
and the ground electrode
107
.
Referring to
FIG. 2
, a conventional isolator/circulator includes a microstripline
104
formed on a ferrite substrate
102
. A ground electrode
107
is formed at the bottom surface of the ferrite substrate
102
. An upper permanent magnet
103
a
is formed on the microstripline
104
, and a lower permanent magnet
103
b
is formed under the ferrite substrate
102
. A thin Teflon® film
109
is interpolated between the upper permanent magnet
103
a
and the microstripline
104
, and a thin iron plate
108
is interpolated between the lower permanent magnet
103
b
and the ground electrode
107
.
The microstripline/stripline
104
that may be included in the conventional isolator/circulators shown in
FIGS. 1 and 2
will be described in greater detail with reference to FIG.
3
. As shown in
FIG. 3
, a circular resonator
100
, which resonates at a predetermined frequency, is formed at the center of the microstripline/stripline
104
. A first electrode
105
a
, a second electrode
105
b
, and a third electrode
105
c
are symmetrically formed along the circumference of the circular resonator
100
to connect the circular resonator
100
to an external circuit via their respective transfer tracks
106
a
,
106
b
, and
106
c
. In the case of an isolator, a load resistance of 50 &OHgr; (a load resistor having resistance of 50 &OHgr; is connected to the third electrode
105
c
. Here, reference numerals
102
and
103
represent a ferrite substrate and an upper or lower permanent magnet, respectively.
In a circulator having the microstripline/stripline
104
, a signal of the external circuit is transmitted counterclockwise from the first electrode
105
a
to the second electrode
105
b
, from the second electrode
105
b
to the third electrode
105
c
, and from the third electrode
105
c
to the first electrode
105
a
. Here, the signal of the external circuit may be set to be transmitted clockwise. Accordingly, signals are circularly input into/output from a plurality of ports of the circulator.
In an isolator having the microstripline/stripline
104
, a signal of the external circuit is transmitted counterclockwise from the first electrode
105
a
to the second electrode
105
b
and from the second electrode
105
b
to the third electrode
105
c
and then is extinguished passing through the load resistor connected to the third electrode
105
c
. In other words, while the signal of the external circuit is transmitted from the first electrode
105
a
to the second electrode
105
b
, the signal of the external circuit is not transmitted from the second electrode
105
b
to the first electrode
105
a
. Thus, the signal input into the isolator can be transmitted in a forward direction without being diminished but cannot be transmitted in a reverse direction. The signal of the external circuit may be set to be transmitted in a clockwise direction, like in the circulator.
In the microstripline/stripline
104
, the resonant frequency of the circular resonator
100
is inversely proportional to the size of the circular resonator
100
. Thus, in order to obtain a higher resonant frequency from the circular resonator
100
, the circular resonator
100
is designed to have a smaller size. However, there is a limit in reducing the size of the circular resonator
100
to be capable of being used for ultrahigh frequency (UHF) for mobile communication or personal communication, and thus it is difficult to manufacture a compact-sized isolator/circulator.
FIG. 4
is a pattern view of a conventional microstripline/stripline. Referring to
FIG. 4
, a circular resonator
200
is formed at the center of a microstripline/stripline
204
, and three slots
207
are formed along the circumference of the circular resonator
200
toward the center of the circular resonator
200
. Three ports including a first electrode
205
a
, a second electrode
205
b
, and a third electrode
205
c
are symmetrically formed along the circumference of the circular resonator
200
to connect the circular resonator
200
to an external circuit via their respective transfer tracks
206
a
,
206
b
, and
206
c
. Here, reference numerals
202
and
203
represent a ferrite substrate and an upper or lower permanent magnet, respectively.
In the microstripline/stripline
204
, a magnetic wall is formed at the slots
207
so that magnetic coupling quantity can be controlled. Accordingly, it is possible to manufacture an isolator/circulator having the same resonant frequency as an isolator/circulator having the microstripline/stripline
104
shown in
FIG. 3
but having a smaller size by appropriately adjusting the length of the slots
207
. However, in this case, in order to expand bandwidth, a bandwidth expansion circuit must be connected to the isolator/circulator, and thus there is a limit in manufacturing the isolator/circulator to be compact-sized at lower manufacturing costs. In addition, since the magnetic wall formed at the circular resonator
200
is used, the size of the upper or lower permanent magnet
203
is greater than the size of the circular resonator
200
. Accordingly, ferromagnetic resonance line width (AH), which corresponds to loss of a magnetic body and amounts to at least the size of the circular resonator
200
, exists. Thus, there is a limit in decreasing insertion loss.
FIG. 5
is a pattern view of a conventional microstripline/stripline. Referring to
FIG. 5
, a triangular resonator
300
is formed at the center of a microstripline/stripline
304
, and three slots
307
is formed at the central portion of each side of the triangular resonator
300
toward the center of the triangular resonator
300
in order to control magnetic coupling quantity. Open-ring-shaped transfer tracks
306
a
,
306
b
, and
306
c
are formed extending from the vertexes of the triangular resonator
300
toward the outside of the triangular resonator
300
. Three ports including a first electrode
305
a
, a second electrode
305
b
, and a third electrode
305
c
are symmetrically formed to connect the transfer tracks
306
a
,
306
b
, and
30
Choy Tae-goo
Jun Dong-suk
Lee Sang-seok
Blakely & Sokoloff, Taylor & Zafman
Electronics and Telecommunications Research Institute
Jones Stephen E.
Pascal Robert
LandOfFree
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