Nonreciprocal circuit device and communication apparatus

Information

  • Patent Grant
  • 6633204
  • Patent Number
    6,633,204
  • Date Filed
    Monday, April 24, 2000
    24 years ago
  • Date Issued
    Tuesday, October 14, 2003
    21 years ago
Abstract
A nonreciprocal circuit device, which includes 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 of the matching capacitors being disposed such that the capacitor electrode face thereof and the ferrite form an angle in a range of 60 degrees to 120 degrees.
Description




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.











Other features and advantages of the present invention will become apparent from the following description of embodiments of the invention which refers to the accompanying drawings.




BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is an exploded perspective view of a nonreciprocal circuit device of a first embodiment according to the present invention.





FIG. 2

is a front view of a center electrode assembly of the nonreciprocal circuit device of FIG.


1


.





FIG. 3

is a plan view of the center electrode assembly of FIG.


2


.





FIG. 4

is a view explaining the assembly of the matching capacitors in the center electrode assembly of FIG.


2


.





FIG. 5

is a view showing the inside structure of the nonreciprocal circuit device of FIG.


1


.





FIG. 6

is an equivalent circuit diagram of the nonreciprocal circuit device of FIG.


1


.





FIG. 7

is a front view of the center electrode assembly of the nonreciprocal circuit device of a second embodiment according to the present invention.





FIG. 8

is a plan view of the center electrode assembly shown in FIG.


7


.





FIG. 9

is a block diagram showing one embodiment of a communication apparatus according to the present invention.





FIG. 10

is an exploded perspective view of a conventional nonreciprocal circuit device.











DESCRIPTION OF EMBODIMENTS OF THE INVENTION




First Embodiment, FIG.


1


-FIG.


6







FIG. 1

shows an exploded perspective view of a first embodiment of a nonreciprocal circuit device of the present invention. The nonreciprocal circuit device


41


is one which the present invention is applied to the lumped-constant type isolator


11


explained by referring to FIG.


10


. As shown in

FIG. 1

, the lumped-constant type isolator


41


comprises a lower yoke


12


, a terminal case


53


made of resin, a center electrode assembly


54


, a permanent magnet


16


and an upper yoke.




The lower yoke


12


is made of magnetic metal and comprises right and left side walls


12




a


and


12




b


. The terminal case


53


is disposed on the lower yoke


12


, the center electrode assembly


54


is accommodated in the terminal case


13


and an upper yoke


15


made of magnetic metal is placed thereon. On the lower major surface of the upper yoke


15


, the permanent magnet


16


is disposed. The permanent magnet


16


applies a DC magnetic field to the center electrode assembly


54


. A magnetic circuit is formed by the lower yoke


12


, the center electrode assembly


54


and the upper yoke


15


.




The center electrode assembly


54


comprises a microwave ferrite


20


and three center electrodes


21


-


23


disposed on the upper surface (first major surface) of the microwave ferrite


20


, as shown in FIG.


2


and FIG.


3


. The three center electrodes


21




23


cross each other at angles of 120 degrees in an electrically insulated state. Port sections P


1


-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 (second major surface) of the ferrite


20


. The common shield section


26


substantially covers the lower surface of the ferrite


20


.




A ground plate


42


is disposed on the lower surface side of the ferrite


20


and electrically connected to the common shield section of the center electrodes


21


-


23


by face-contact (by utilizing solder, electroconductive adhesive, etc. if necessary). Capacitor connecting sections


42




a


,


42




b


,


42




c


are extended from the end portion of the ground plate


42


and stand so as to be parallel to the port sections P


1


-P


3


of the center electrodes


21


-


23


. The ground plate


42


is grounded by connecting it to the bottom wall


12




b


of the lower yoke


12


through the window


53




a


of the terminal case


43


.


20


Hot-side capacitor electrodes


1


of matching capacitors C


1


-C


3


are connected to the port sections P


1


-P


3


by soldering, and cold-side capacitor electrodes


2


thereof are connected to the capacitor connecting sections


42




a


,


42




b


,


42




c


of the ground plate


42


by soldering. The matching capacitors C


1


-C


3


are disposed such that the surfaces of the capacitor electrodes


1


,


2


and the upper surface of the ferrite


20


form an angle in a range from 60 degrees to 120 degrees. In the case of this first embodiment, the angle is set at 90 degrees. Each of the matching capacitors C


1


-C


3


is a single-plate type capacitor in which capacitor electrodes


1


,


2


are formed on both surfaces of a dielectric substrate


3


.




Mounting of the matching capacitors C


1


-C


3


can be performed as indicated in

FIG. 4

, for example. That is, bend portions


43


are provided at the base portion of the ground plate


42


so that the device shown in

FIG. 4

can be shaped as shown in FIG.


2


. After applying soldering paste to the capacitor connecting sections


42




a


-


42




c


of the ground plate


42


, the matching capacitors C


1


-C


3


are mounted such that the cold-side capacitor electrodes


2


are at the underside.




Further, after applying soldering paste on the hot-side capacitor electrodes


1


of the matching capacitors C


1


-C


3


, the ferrite


20


including the attached center electrodes


21


-


23


is mounted from above. The common shield section


26


of the center electrodes


21


-


23


is face-contacted to the upper surface of the ground plate


42


, and the port sections P


1


-P


3


are face-contacted to the hot-side capacitor electrodes


1


of the matching capacitors C


1


-C


3


, respectively. The solder paste is heated in this state, and the matching capacitors C


1


-C


3


are soldered. Next, the capacitor connecting sections


42




a


-


42




c


and the port sections P


1


-P


3


are bent so as to dispose the matching capacitors C


1


-C


3


with the surfaces of the capacitor electrodes


1


,


2


and the upper surface of the ferrite


20


forming an angle in a range of 60 degrees to 120 degrees. Accordingly, the center electrode assembly


54


is obtained.




Input/Output electrodes


31


,


32


and ground terminals


33


,


34


are insert molded in the terminal case


53


. First ends of the Input/Output electrodes


31


,


32


are exposed outside the side wall of the case


53


, and the other ends thereof are exposed inside the side wall of the case


53


, to form Input/Output connecting sections


18




a


,


18




b


. Similarly, a first end of the ground terminal


33


is exposed outside the side wall of the case


53


, and the other end thereof is exposed inside the side wall of the case


53


, to form ground connecting electrode section


17




b.






As shown in

FIG. 5

, the center electrode assembly


54


and the termination resistor R are accommodated in the terminal case


53


having a structure as described above. The port sections P


1


, P


2


of the center electrodes


21


,


22


are connected to the Input/Output connecting electrode sections


18




a


,


18




b


by soldering, etc. One end of the termination resistor R is connected to the ground connecting electrode section


17




b


, and the other end thereof is connected to the hot-side capacitor electrode


1


of the matching capacitor C


3


. The equivalent circuit diagram of the isolator


41


is shown in FIG.


6


.




In the isolator


41


having a structure as described above, since the matching capacitors C


1


-C


3


are mounted between the port sections P


1


-P


3


of the center electrodes


21


-


23


and the capacitor connecting sections


42




a


-


42




c


of the ground plate


42


respectively, the matching capacitors C


1


-C


3


, the center electrodes


21


-


23


and the ferrite


20


can be handled as one unit. According to this arrangement, the process in which the small-sized matching capacitors C


1


-C


3


, which are difficult to handle, are mounted in a vertical plane, is eliminated, and thereby the manufacture of the isolator


41


becomes easier.




Further, in the first embodiment, after connecting the matching capacitors C


1


-C


3


to the port sections P


1


-P


3


and the capacitor connecting sections


42




a


-


42




c


, the matching capacitors C


1


-C


3


are disposed vertically by bending the port sections P


1


P


3


and the capacitor connecting sections


42




a


-


42




c


. Accordingly, compared with the conventional isolator


11


(see

FIG. 10

) in which the port section must be bent before connecting the matching capacitor, the soldering of the port sections P


1


P


3


and the matching capacitors C


1


-C


3


can be performed with reliability, and thereby the connection reliability is improved.




Further, since each of the cold-side electrodes


2


of the matching capacitors C


1


-C


3


is grounded via the ground plate


42


, the ground connecting electrode sections


17




a


,


17




b


,


17




c


formed in the conventional terminal case


13


(see

FIG. 10

) can be omitted. Accordingly, the structure of the terminal case


53


becomes simple and cost-reduction can be realized.




Second Embodiment, FIG.


7


and FIG.


8






A center electrode assembly


64


according to another embodiment of the nonreciprocal circuit device of the present invention is shown in FIG.


7


and FIG.


8


. In the center electrode assembly


64


, insulators


65


,


66


(indicated by hatching in FIG.


7


and

FIG. 8

) are provided for preventing solder bridges.




The insulator


65


is provided on the ground plate


42


in the vicinity of where the matching capacitors C


1


-C


3


are connected. The insulator


66


is provided in the vicinity of the port sections P


1


-P


3


of the center electrodes


21


-


23


. The insulators


65


,


66


prevent a solder bridge and thereby prevent a short-circuit between the hot-side electrodes


1


of the matching capacitors C


1


-C


3


and the ground electrode


42


or a short-circuit between the hot-side electrodes


1


and the cold-side electrodes


2


. Further, since a solder bridge is eliminated by the insulators


65


,


66


, the positioning accuracy of the matching capacitors is improved.




Moreover, in the second embodiment, to eliminate a short-circuit between the hot-side electrodes


1


when the matching capacitors C


1


, C


2


are held in a vertical orientation and the center electrodes


21


,


22


, an insulator


67


is provided where the center electrodes


21


,


22


and the hot-side electrodes


1


oppose each other. By this, an isolator having higher reliability can be obtained.




Third Embodiment, FIG.


9






A third embodiment of the invention will be explained, taking a mobile phone as an example of a communication apparatus of the present invention.





FIG. 9

is a block diagram of an RF part of a circuit in a mobile phone


120


. In

FIG. 9

,


122


denotes an antenna element,


123


denotes a duplexer,


131


denotes a transmission-side isolator,


132


denotes a transmission-side amplifier,


133


denotes a transmission-side band-pass filter,


134


denotes a transmission-side mixer,


135


denotes a reception-side amplifier,


136


denotes a reception-side inter-stage band-pass filter,


137


denotes a reception-side mixer,


138


denotes a voltage control oscillator (VCO), and


139


denotes a local band-pass filter.




Here, the lumped-constant type isolator of the first and second embodiments can be used as the transmission-side isolator


131


. By attaching this isolator, a mobile phone with low-cost and high-reliability cane be realized.




Other Embodiment




The present invention is not restricted to the above described embodiments. It is possible to have various arrangements within the scope of the subject matter of the present invention.




For example, in the above first and second embodiments, the mounting of all of the matching capacitors C


1


-C


3


is longitudinal, i.e., the capacitor electrode surfaces thereof are perpendicular to the horizontal surface. However, it is not necessary to mount all of the matching capacitors C


1


-C


3


longitudinally. Two of the matching capacitors C


1


-C


2


may be mounted longitudinally and the other one of the matching capacitors C


3


may be mounted horizontally, in which the capacitor electrode surface thereof is parallel to the horizontal surface. That is, the advantages of the invention, such as saving space, reducing costs, and facilitating assembly, are obtained as long as at least one of the matching capacitors is disposed with the capacitor electrode face thereof forming an angle with the ferrite in a range of 60 degrees to 120 degrees.




Further, the mounting of the matching capacitors C


1


-C


3


can be performed by electroconductive adhesive instead of by soldering. The matching capacitors C


1


-C


3


may be monolithic-type capacitors. Further, the present invention is also applicable to a nonreciprocal circuit device other than an isolator for use in other high-frequency components such as a circulator.




As is apparent from the above description, according to the present invention, since matching capacitors are mounted between center electrodes attached to a ferrite and a ground plate, the matching capacitors can be treated as one unit with the center electrodes, the ground plate and the ferrite. Accordingly, mounting of the small-sized matching capacitors, which are difficult to handle, becomes easier. The matching efficiency of the nonreciprocal circuit device is drastically improved, and thereby costs can be reduced. As a result, cost-reduction of a communication apparatus can be realized.




Further, by providing an insulator for preventing a solder bridge at the portion of the ground plate where the matching capacitor is connected and in the vicinity of the port section of the center electrode, unnecessary short-circuits are eliminated, and thereby a nonreciprocal circuit device and a communication apparatus with higher reliability can be obtained.




While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit of the invention.



Claims
  • 1. A nonreciprocal circuit device, comprising:a yoke comprising a magnetic material, said yoke enclosing: a permanent magnet; a ferrite to which a DC magnetic field is applied by the permanent magnet; a plurality of center electrodes extending via side surfaces of the ferrite, from a first major surface of the ferrite to a shield section of said center electrodes which is disposed at a second major surface of the ferrite, said center electrodes having respective port sections at ends thereof; a ground plate disposed on the second major surface of the ferrite and electrically connected to the shield section of the center electrodes, said ground plate having a plurality of connecting sections which correspond respectively to said port sections of said center electrodes; a plurality of matching capacitors each being sandwiched between and directly connected to a respective connecting section of the ground plate and a corresponding one of the port sections of the plurality of center electrodes, each of the matching capacitors having a pair of electrodes on major surfaces of said matching capacitor connected respectively to the corresponding connecting section and port section; and at least one of the matching capacitors being disposed such that the respective major surfaces thereof and the ferrite form an angle in a range of 60 degrees to 120 degrees; wherein said ground plate is disposed under the ferrite, said plurality of center electrodes are disposed on said ground plate and said ground plate is directly connected to the shield section on the second major surface of the ferrite.
  • 2. The nonreciprocal circuit device according to claim 1, further comprising an insulator disposed in the vicinity of the ground plate and said at least one matching capacitor so as to prevent a solder bridge between the ground plate and said at least one matching capacitor due to spilled solder.
  • 3. The nonreciprocal circuit device according to claim 2, further comprising an insulator disposed in the vicinity of the port section of the center electrode corresponding to said at least one matching capacitor, for preventing a solder bridge between said portion section and said at least one matching capacitor due to spilled solder.
  • 4. The nonreciprocal circuit device according to claim 1, further comprising an insulator disposed in the vicinity of the port section of the center electrode corresponding to said at least one matching capacitor, for preventing a solder bridge between said port section and said at least one matching capacitor due to spilled solder.
  • 5. A communication device comprising:a high-frequency comprising at lest one of a transmission circuit and a reception circuit, and connected to said high-frequency circuit, a nonreciprocal circuit device comprising: a yoke comprising a magnetic material, said yoke enclosing: a permanent magnet; a ferrite to which a DC magnetic field is applied by the permanent magnet; a plurality of center electrodes extending via side surfaces of the ferrite, from a first major surface of the ferrite to a shield section of said center electrodes which is disposed at a second major surface of the ferrite, said center electrodes having respective port sections at ends thereof; a ground plate disposed on the second major surface of the ferrite and electrically connected to the shield section of the center electrodes, said ground plate having a plurality of connecting sections which correspond respectively to said port sections of said center electrodes; a plurality of matching capacitors each being sandwiched between and directly connected to a respective connecting section of the ground plate and a corresponding one of the port sections of the plurality of center electrodes, each of the matching capacitors having a pair of electrodes on major surfaces of said matching capacitor connected respectively to the corresponding connecting section and port section; and at least one of the matching capacitors being disposed such that the respective major surfaces thereof and the ferrite form an angle in a range of 60 degrees to 120 degrees; wherein said ground plate is disposed under the ferrite, said plurality of center electrodes are disposed on said ground plate, and said ground plate is directly connected to the shield section on the second major surface of the ferrite.
  • 6. The nonreciprocal circuit device according to claim 5, further comprising an insulator disposed in the vicinity of the ground plate and said at least one matching capacitor so as to prevent a solder bridge between the ground plate and said at least one matching capacitor due to spilled solder.
  • 7. The nonreciprocal circuit device according to claim 6, further comprising an insulator disposed in the vicinity of the port section of the center electrode corresponding to said at least one matching capacitor, for preventing a solder bridge between said portion section and said at least one matching capacitor due to spilled solder.
  • 8. The nonreciprocal circuit device according to claim 5, further comprising an insulator disposed in the vicinity of the port section of the center electrode corresponding to said at least one matching capacitor, for preventing a solder bridge between said port section and said at least one matching capacitor due to spilled solder.
  • 9. A nonreciprocal circuit device, comprising:a yoke comprising a magnetic material; a permanent magnet; and a unitary center electrode assembly comprising: a ferrite; a plurality of center electrodes extending via side surfaces of the ferrite, from a first major surface to a shield section of said center electrodes which is disposed at a second major surface of the ferrite, said center electrodes having respective port sections at ends thereof; a ground plate attached to the second major surface of the ferrite and electrically connected to the shield section of the center electrodes, said ground plate having a plurality of connecting sections which correspond respectively to said port sections of said center electrodes; and a plurality of matching capacitors each being sandwiched between and directly connected to respective connecting portions of the ground plate and a corresponding one of the port sections of the plurality of center electrodes, each of the matching capacitors having a pair of electrodes on major surfaces of said matching capacitor connected respectively to the corresponding connecting section and port section; said permanent magnet and said unitary center electrode assembly being disposed in said yoke; wherein said ground plate is disposed under the ferrite, said plurality of center electrodes are disposed on said ground plate, and said ground plate is directly connected to the shield section on the second major surface of the ferrite.
  • 10. A method of assembling a nonreciprocal circuit device, comprising the steps of:assembling a center electrode assembly by the steps of: providing a ferrite; attaching to the ferrite a plurality of center electrodes extending via side surfaces of the ferrite, from a first major surface to a shield section of said center electrodes which is disposed at a second major surface of the ferrite, said center electrodes having respective port sections at ends thereof; attaching a ground plate to the second major surface of the ferrite and electrically connecting said ground plate to the shield section of the center electrodes, said ground plate having a plurality of connecting sections which correspond respectively to said port section of said center electrodes; bending at least one of said connecting sections of said ground plate to define an angle of 60 degrees to 120 degrees with respect to said second major surface of said ferrite; electrically connecting and sandwiching each one of a plurality of matching capacitors between a respective connecting section of said ground plate and a corresponding one of the port sections of the plurality of center electrodes, each of the matching capacitors having a pair of electrodes on major surfaces of said matching capacitor connected respectively to the corresponding connecting section and port section; whereby at least one of the matching capacitors is disposed such that the respective major surfaces thereof and the ferrite form an angle in a range of 60 degrees to 120 degrees; and disposing said central electrode assembly inside a yoke which comprises a magnetic material; wherein said bending step is performed after said step of electrically connecting and sandwiching said matching capacitors between the respective connecting section and the corresponding port section.
  • 11. The method according to claim 10, further comprising the step of disposing a permanent magnet inside said yoke.
Priority Claims (2)
Number Date Country Kind
11-117254 Apr 1999 JP
2000-038459 Feb 2000 JP
US Referenced Citations (1)
Number Name Date Kind
4101850 Dworsky et al. Jul 1978 A
Foreign Referenced Citations (5)
Number Date Country
0903801 Mar 1999 EP
10303605 Nov 1998 JP
11-55009 Feb 1999 JP
11-068411 Mar 1999 JP
11-097910 Apr 1999 JP
Non-Patent Literature Citations (1)
Entry
European Search Report dated Feb. 14, 2002 for EP 00 10 8475.