Abstract: An improved waveguide circulator that eliminates the need for quarter-wave dielectric transformers or impedance steps in the interface waveguide for broadband operation is described. The circulator designs in the prior art all require impedance matching elements outside of the ferrite element in order to achieve acceptable performance. Through the use of this new invention, broadband circulator performance can be achieved without the addition of impedance matching elements in order to minimize the cost, size, mass, and loss of the circulator.

Abstract: Disclosed is one method and one apparatus which teach improved techniques in using a shaped bias magnetic field over the active region of a ferrite stripline circulator/isolator circuit. The axial component of the bias field is decreased from the center toward edge, thus it is able to accommodate the accompanying changes in magnetization. This fulfills the requirements that frequencies are scaled with distances thereby warranting broadband operation. Furthermore, the radial component of the bias field is reduced, so as to minimize the generation of non-circulation volume modes. The discontinuity in magnetization distributed over the circulator/isolator active region is reduced, so as to minimize the generation of magnetostatic surface modes. The resultant circulator/isolator performance can thus show a broad bandwidth with improved characteristics in insertion loss and in isolation.

Abstract: A two-port non-reciprocal circuit device has one end of a first central electrode electrically connected to an input port and the other end thereof electrically connected to an output port. One end of a second central electrode is electrically connected to the output port and the other end thereof is electrically connected to a ground port. A resonant capacitor and a terminating resistor are electrically connected in parallel between the input port and the output port. A resonant capacitor is electrically connected between the output port and the ground port. Matching capacitors for impedance matching are electrically connected between the input port and an input terminal and between the output port and an output terminal, respectively. A coupling capacitor element is electrically connected between the input terminal and the output terminal.

Abstract: A sheath wave barrier unit for an outer shielding of a coaxial cable that also has an inner conductor, has two sheath wave barriers that damp or suppress sheath waves that are induced in two series conductor segments of the outer shielding. Each sheath wave barrier forms a resonant oscillating circuit at a predetermined high frequency, with the high frequency being the same for both sheath wave barriers. The sheath wave barrier unit has a shielding device with at least one radial shield by means of which the sheath wave barriers are decoupled from one another. The sheath wave barriers and the shielding device are arranged on a common carrier.

Abstract: An improved waveguide isolator that eliminates the transitions to air-filled waveguides between ferrite elements and absorptive load elements is described. The waveguide isolator in accordance with the invention can be implemented in variations from a single ferrite to load transformer held in close proximity to an absorptive load element to any number of ferrite elements and absorptive load elements as required to achieve the desired isolation performance or to create a switch matrix with any combination of input and output ports. The waveguide isolator in accordance with the invention eliminates the transitions between ferrite to load transformers and absorptive load elements and thus reduces component size and mass.

Abstract: A center-electrode assembly (13) has a configuration in which center electrodes (21) to (23) are arranged, in an electrically insulated state, at the upper surface of a circular-plate microwave ferrite (20). The center electrode (21) is constituted by a first line conductor (21a) and a second line conductor (21b) which are arranged parallel to each other. The hot ends of the first line conductor (21a) and the second line conductor (21b) have connection portions (27) and (26), respectively, and the cold ends are connected to a ground electrode (25). The first and second line conductors (21a) and (21b) are arranged such that the hot end of the first line conductor (21a) and the cold end of the second line conductor (21b) oppose each other and the cold end of the first line conductor (21a) and the hot end of the second line conductor (21b) oppose each other to cause electromagnetic coupling.

Abstract: An improved multi-junction waveguide circulator that eliminates the transitions to dielectric transformers and air-filled waveguides between ferrite elements is described. The waveguide circulator in accordance with the invention can be implemented in variations from a minimum of two ferrite circulator elements joined to one another to any number of conjoined ferrite elements as required to achieve the desired isolation performance or to create a switch matrix with any combination of input and output ports. The waveguide circulator in accordance with the invention eliminates the transitions between adjacent ferrite elements and thus reduces losses, component size, and mass.

Abstract: A ferrite circulator having integrated alignment members and a method for aligning a ferrite element within a ferrite circulator are provided. The ferrite circulator includes a ferrite circulator housing having a body for receiving at least one ferrite element therein. The ferrite circulator housing further includes a plurality of alignment members positioned and configured to maintain the alignment of the at least one ferrite element in an alignment region defined by the plurality of alignment members.

Abstract: A radio frequency (RF) filter includes a substrate, first and second dielectric layers formed on first and second portions of the substrate, a ground plane formed on a third portion of said substrate, a carbon nanotube array, and first and second electrodes. The third portion of the substrate includes, at least in part, the area between the first and second portions thereof. The carbon nanotube array is formed on a portion of said ground plane between the first and second dielectric layers. The first and second electrodes are formed on the first and second dielectric layers, such that an RF signal may be input to and output from the carbon nanotube array via the first and second signal guides. A third electrode is disposed over the carbon nanotube array and is used to voltage bias the array.

Abstract: In a non-reciprocal circuit element, capacitors are disposed on a bottom surface of a dielectric facing a ferrite member in a state in which first electrodes are connected to port portions serving as one end of central conductors, and second electrodes of the capacitors and ground portions serving as the other ends of the central conductors are connected to a ground plate composed of one sheet of metal plate and the ground plate is connected to a lower plate of a second yoke. Therefore, by means of the ground plate made of one sheet of metal plate, the second electrodes of the capacitors and the ground portions of the central conductors can be connected to ground.

Abstract: A structure according to the present invention relates to the non-reciprocal microwave device such as circulator/isolator and includes the circuit, a ferrite member and a dielectric film. The circuit has three arms, each composed of two branches incorporating multiple strips. The branches are folded over a ferrite and isolated from each other by dielectric films to compose a multi-layer structure coupled with ferrite. The branches and strips are shaped to minimize the overall thickness of layer structure and to avoid triple crossover at intersections. The described assembly method allows maintaining symmetry between the ports of circulator/isolator. The broadband and high power operation of resonant structure is achieved by minimizing the asymmetry and improving the power distribution over the entire ferrite area.

Abstract: A circulator comprises first and second couplers. The first and second couplers are coupled by first and second transmission lines. First and second magnetic fields are provided crossing the first and second transmission lines, respectively. In an exemplary embodiment, the magnetic fields are substantially parallel with and within a plane defined by the first and second transmission lines.

Abstract: The present invention is directed to a non-reciprocal device whose use makes it possible to reduce the insertion loss, and the size and thickness of its body, and broaden the frequency band treated by it. The DC magnetic field is adjusted such that, in a Smith chart where the center O1 represents the normalized impedance, the impedance of the gyromagnetic component 2 is positioned at a value which is on a constant conductance circle smaller than the reference constant conductance circle EC0 passing the center O1 and which is on a constant reactance line above the reference constant reactance line EX0 passing the center O1. Inductor L11 or L12 has one end connected to a terminal of the center conductor such that in the Smith chart, the impedance of the gyromagnetic component 2 seen from the other end of the inductor L11 or L12 is positioned at a value which is on the reference constant conductance circle EC0 passing the center O1.

Abstract: An improved multi-junction waveguide circulator that eliminates the transitions to dielectric transformers and air-filled waveguides between ferrite elements is described. The elimination of the additional transformer sections between the ferrite elements allows for closer spacing of the ferrite elements. With the ferrite elements spaced in close proximity, it is feasible to run a single magnetizing winding through multiple ferrite elements without first exiting the conductive waveguide structure. This decreases the total number of magnetizing windings required for the assembly, resulting in a more efficient and lower cost manufacturing and assembly process.

Abstract: In an isolator, a common electrode is disposed on a first surface of a magnetic plate. On a second surface of the magnetic plate, first, second, and third center conductors are disposed crossing each other. The center conductors have their respective first ends connected to the common electrode, and their respective second ends connected to matching capacitors. Furthermore, the second end of the third center conductor is connected to a terminating resistor. The matching capacitor connected to the third center conductor has a Q factor of 200 or smaller and a capacitance of 18 pF or larger. The matching capacitors connected to the first and second center conductors respectively have Q factors of 400 or larger.

Abstract: A method of manufacturing a circulator comprising the steps of providing a central substrate layer with at least one cut-out section and circuit lines. Next, providing a magnet placed within said cut-out section and a ferrite placed on each side of said substrate layer. A steel plate is placed on each side of the substrate layer. Spacer layers are provided on each side of the substrate layer. Another shim layer is placed on each side of the central substrate layer. Laminate sheets are placed between the substrate layer, the spacer layers, and the outer shim layers. Holes are drilled through each of the substrate, the spacer layers, the outer shims, and the laminate sheets. Heat and pressure are provided to cause the laminate sheets to flow in order to join the substrate, magnets, ferrites, steel plates, spacer layers and outer shim layers into a unitary structure. Finally the structure is plated.

Abstract: An above resonance circulator/isolator and method for manufacturing the same is described. In one implementation, the above resonance circulator/isolator includes a magnet, a spacer, a single ferrite element, a center conductor and a pole piece. The center conductor is sandwiched between the magnet and the single ferrite element with the spacer interposed between the magnet and the center conductor. The pole piece is coupled to the single ferrite element, such that the single ferrite element is sandwiched between the center conductor and the pole piece. Magnetic shielding is not necessary in particular implementations.

Abstract: A high frequency composite switch module for a mobile communication device, wherein high frequency circuits such as a power amplifier, a circuit functioning as a transmitter/receiver switching circuit, a surface acoustic wave (SAW) filter for reception, and the like are modularized into one unit. A transmitter circuit includes a transmitter side impedance converter comprising an impedance matching circuit and an impedance converter circuit, a power amplifier and a power supply unit. A receiver circuit includes a receiver-side impedance converter comprising a phase shifting circuit and a SAW filter. The power amplifier and the impedance converter circuit are integrated into one IC chip. At least one of the matching circuit, the power supply unit and the phase shifting circuit is formed inside a multilayer board comprised of a conductor layer and a dielectric layer. The IC chip and the SAW filter are also mounted on the multilayer board.

Abstract: A frequency selective limiter operative in a magnetostatic surface mode with a pair of parallel microstrip transducers formed on a substrate and having a length at least equal to the width of an overlaying YIG film ranging in thickness from about 0.1 ?m and about 5.0 ?m and having a width equal to or less than about 20. mm and which is biased by a permanent magnetic field applied in the plane of the film parallel to the transducers so that magnetostatic surface waves propagate therebetween in the YIG film so as to provide a limiter threshold level in the range of ?75 dBm to ?35 dBm. The transducers have specific spacings and dimensions.

Abstract: A two-port isolator includes a microwave ferrite member, first and second center electrodes that intersect with each other on the ferrite member with isolation therebetween, a permanent magnet that applies a DC magnetic field to the ferrite member, and a multilayer substrate having center-electrode-connecting electrodes and first and second matching capacitors. The ferrite member, the first and second center electrodes, the permanent magnet, and the multilayer substrate are accommodated in a housing that includes a magnetic cap and a case having a magnetic metal plate molded thereonto. The second matching capacitor has a higher Q factor than the first matching capacitor.

Abstract: A non-reciprocal circuit element includes a magnetic plate, a common electrode, a first main segment, a second main segment, a third main segment, and a magnet opposing to the magnetic plate and the magnet applying a bias magnetic field. The temperature coefficient of the saturation magnetization of the magnetic plate is from ?0.2%/° C. to ?0.1%/° C. in the temperature range from ?35° C. to 85° C. The temperature coefficient of the residual magnetization of the magnet is from ?0.20%/° C. to ?0.15%/° C. in a temperature range from ?35° C. to 85° C.

Abstract: A nonreciprocal circuit element includes a magnetic plate, a common electrode on a first surface of the magnetic plate, and first, second, and third central conductors each including a pair of divisions. The three central conductors extend from the common electrode, are bent along the magnetic plate towards a second surface of the magnetic plate, and cross one another on the second surface of the magnetic plate at a predetermined angle relative to one another. The first and second central conductors are connected to input and output terminals. The nonreciprocal circuit element satisfies the relationship ?1>?2, where ?1 is the angle between the divisions of the first central conductor and ?2 is the angle between the divisions of the second central conductor, when the first central conductor is farther away from the magnetic plate than the second central conductor.

Abstract: An isolator suitable for miniaturization due to a reduction in the size of a capacitor is provided. The isolator includes a flat plate-shaped ferrite member 4, and first, second, and third central conductors 5, 6, and 7 arranged on different planes in a vertical direction with dielectric bodies sandwiched therebetween so that parts thereof cross each other in the vertical direction. The ferrite member 4 is of a rectangle with long sides 4a and short sides 4b. One of the central conductors is located on the long side 4a and is arranged so as to transverse the short surface of the ferrite member 4 at an oblique angle to the short sides 4b. Therefore, the length of the central conductor increases, thereby increasing the inductance component. As a result, it is possible to reduce the size of the capacitor for performing resonance and to thus miniaturize the isolator.

Abstract: Provided is a nonreciprocal circuit element which has increased lengths of central conductors to be compatible with miniaturization while exhibiting superior performance. In the nonreciprocal circuit element, a first yoke has a rectangular upper plate, a pair of side plates bent downward from sides of the upper plate facing each other, and notch parts formed at the central portion of the pair of side plates. Ends of a magnet are placed within the notch parts. Thus, the magnet can be enlarged and a ferrite member provided corresponding thereto can also be enlarged. Accordingly, the lengths of conductors of central conductors mounted on the ferrite member are increased, thereby achieving high performance while not adversely affecting miniaturization.

Abstract: A nonreciprocal circuit device, in which metal members which form a metal case can be resistance-welded stably and reliably, having high reliability and satisfactory characteristics, a communication device using the nonreciprocal circuit device, and a method of manufacturing the nonreciprocal circuit device. Protruding portions are formed at two places on each side wall of an upper metal case. The upper metal case and a lower metal case are bonded together by resistance welding the two side walls of the lower metal case to the two side walls of the upper metal case at the protruding portions.

Abstract: A method detects relaying of a contactless data communication by a radio amplifier for intercepting and manipulating the communication to achieve an unauthorized authentication. The method involves transmitting an electromagnetic field successively from at least two spatially separated antennas of a transmitting unit, receiving the transmitted fields in a receiving unit, determining field strength vectors of the received fields allocated to each antenna, and comparing actual values of the vectors with prescribed nominal values stored in a nominal value field that maps the true field strength distribution in multi-dimensional space around the transmitting unit. The actual field strength magnitude and the reception angle between the transmitting antennas can be determined from the vectors and compared with stored nominal values in this manner. When the determined actual values match prescribed nominal values of the nominal value field, the occurrence of a relaying of the signal can be reliably excluded.

Abstract: In a two-port non-reciprocal circuit device, connecting portions of a first central electrode are electrically connected to first and second balanced input terminals, respectively. Likewise, connecting portions of a second central electrode are electrically connected to first and second balanced output terminals, respectively. First and second resistors are electrically connected between the first balanced input terminal and the first balanced output terminal and between the second balanced input terminal and the second balanced output terminal, respectively. First to fourth matching capacitors are electrically connected between the connecting portions of the first and second central electrodes and ground, respectively.

Abstract: A two-port isolator capable of suppressing propagation of the second harmonic wave (2f) or the third harmonic wave (3f) of the used frequency f includes a parallel RC circuit, which includes a first matching capacitor and a resistor, and the parallel RC circuit is electrically connected between an input port P1 and an output port P2. A series resonant circuit including a second matching capacitor and an inductor is electrically connected between the output port P2 and ground. The resonant frequency of the series resonant circuit is set between the frequencies of the second and third harmonic waves.

Abstract: An isolator with resistive termination and carbon steel housing wherein required magnetic performance is combined with improved efficiency of transmission of heat from termination to the heat sink. The improvement is achieved due to the copper/aluminum plug that mechanically and electrically connects the soldering base of termination to the base of isolator, which in operation is installed on the heat sink. The plug is pressed into the housing from the base side to provide tight coplanarity tolerance to exposed end of the plug and the base without any secondary machining. The termination is soldered to the opposite end of the plug, which is flush to or slightly above the top surface of the housing. Thus, magnetic flux required for operation of isolator is looped through a material having good magnetic susceptibility, and heat from the termination is transmitted to the heat sink through a material having high coefficient of heat transmission.

Abstract: A nonreciprocal circuit element includes a magnetic plate having through holes; center conductors crossing each other at a predetermined angle on a side associated with a first surface of the magnetic plate; and a common electrode disposed on a side associated with a second surface of the magnetic plate and connected to the center conductors via the through holes.

Abstract: A non-reciprocal circuit element includes first, second, and third central conductors, which are formed of thin films or thick films. Each of the first, second, and third central conductors includes a first extended portion which extends from one end of the corresponding central conductor and which is disposed on a side surface of the ferrite part and a second extended portion which extends from the other end of the corresponding central conductor and which is disposed on the side surface of the ferrite part. The adjacent first and second extended portions face each other with a second dielectric part formed of a thin film or a thick film disposed therebetween, and hence a capacitor is formed between the adjacent first and second extended portions. Without using known chip capacitors, the capacitors are thinly formed, leading to reduction in cost and size of the non-reciprocal circuit element.

Abstract: A two-port isolator comprising a thin ferrite plate, a permanent magnet for applying a static magnetic field to the thin ferrite plate, first and second central conductors disposed substantially in a center portion of the thin ferrite plate and crossing each other with electric insulation, first and second input-output terminals each connected to an end of each of the first and second central conductors, a common terminal connected to the other ends of the first and second central conductors, a first matching capacitor connected between the first input-output terminal and the common terminal, a second matching capacitor connected between the second input-output terminal and the common terminal, and a resistor connected between the first input-output terminal and the second input-output terminal, wherein the DC resistance of the resistor is set, such that with loss in a high-frequency signal entering into the first input-output terminal and exiting from the second input-output terminal defined as insertion los

Abstract: A method of manufacturing a nonreciprocal circuit device is performed such that matching capacitors are formed of single-board-type capacitors including capacitor electrodes formed so as to be opposed to each other on both main surfaces of a dielectric substrate with the substrate in between. An outer peripheral edge of a ground electrode (or another connected electrode), to which a capacitor electrode of the single-board-type capacitor is connected, is positioned inwardly from an outer peripheral edge of the capacitor electrode.

Abstract: A non-reciprocal device includes at least one ferrimagnetic member (21 or 22). By controlling the FMR linewidth ?H of the ferrimagnetic members (21 and 22), intermodulation distortion is controlled.

Abstract: A nonreciprocal circuit element of the present invention comprises a first yoke and a second yoke that form a magnetic closed circuit. A plurality of chip capacitors with a first electrode and a second electrode are installed in the box-shaped second yoke. Subsequently, a circuit substrate used for the nonreciprocal circuit element can be smaller than conventional circuit substrates, and the assembly of the nonreciprocal circuit element is excellent. Further, since the capacitances of the chip capacitors can be adjusted through windows of the second yoke, the electrical performance of the nonreciprocal circuit element is excellent.

Abstract: A radio frequency (RF) circulator includes a low temperature co-fired ceramic (LTCC) substrate and a ferrite structure disposed in the LTCC substrate. The circulator also includes first, second and third transmission lines disposed in the LTCC substrate and coupled between the ferrite disk and first, second and third ports of the circulator. The ferrite structure embedded in the LTCC substrate is exposed to an appropriate direct current (DC) magnetic field, to provide the circulator as an integrated LTCC substrate circulator.

Abstract: A structure for a passive microwave device capable of low IMD and high power operation, and adapted for automated assembling and placement is disclosed. The device exhibits a high degree of coplanarity on its mounting surface, as well as a high degree of flatness and alignment between its respective components. The inherent self-aligning qualities of the design are used in conjunction with an assembly fixture that has three or more alignment pins to provide a highly manufacturable and reliable device. Related manufacturing methods and fixturing are also disclosed.

Abstract: There are provided a center-electrode assembly and a manufacturing method therefor, in which electrical characteristics are stable and handling is easy, and which is suitable for mass-production, and a nonreciprocal circuit device and a communication apparatus using the center-electrode assembly. A center-electrode assembly for an isolator includes a ferrite, center-electrode patterns and insulating films deposited on the top surface of the ferrite, a ground pattern formed on the back surface of the ferrite, and connecting electrodes formed on side-faces of the ferrite. Each connecting electrode electrically connects between the center-electrode patterns formed on the top surface and the ground pattern formed on the back surface.

Abstract: A resin casing for use in a non-reciprocal circuit device comprising an assembly of a ferrimagnetic body and a plurality of central conductors enclosing it, and a plurality of elongated flat capacitors connected to ends of the central conductors; the resin casing being constituted by a thin conductor plate having a substantially flat bottom portion and a resin frame injection-molded integrally with the thin conductor plate; the resin frame comprising sidewalls, and partition walls provided inside the sidewalls for defining a plurality of recesses for receiving the flat capacitors, a pair of opposing sidewalls being provided with external terminals constituted by the thin conductor plate; any bottoms of a plurality of the recesses being integrally constituted by a substantially flat bottom portion of the thin conductor plate; the recesses being formed such that all flat capacitors received in the recesses are aligned substantially in parallel with sidewalls having external terminals; and the assembly being dis

Abstract: A two-port isolator includes a metal case including an upper metal case and a lower metal case, a permanent magnet, a central electrode assembly made of a ferrite and central electrodes, and a laminated substrate. In the central electrode assembly, the first and second central electrodes are disposed on the top surface of the disk-shaped microwave ferrite such that the first and second central electrodes intersect each other at right angles with an insulating layer therebetween. The electrode width of the first central electrode is different from the electrode width of the second central electrode. Thus, the inductance of the first central electrode and the inductance of the second central electrode are different from each other.

Abstract: The present invention is an electronic isolator that provides low input to output insertion loss, high output to input insertion loss, and substantial asymmetric isolation between a source circuit and a load circuit. The invention actively reduces noise and reflected power appearing on the isolator output. In numerous embodiments, the invention operates in circuit applications from dc through millimeter wave. Multistage electronic isolator embodiments provide increased isolation and greater noise reduction. In other embodiments, the electronic isolator also removes noise appearing on its input. In another embodiment, the invention is configured for high power applications. This embodiment includes circuitry for redirecting power away from the load into resistors or other dissipative elements. In another embodiment, the electronic isolator is configured to remove signal distortion produced by one or more power amplifiers in the system.

Abstract: An irreversible circuit module includes a permanent magnet for providing a DC magnetic field for a magnetic member; an assembly having a magnetic member provided with a plurality of conductors being common on one end and serving as input and output terminals for high-frequency signals on the other end; a plurality of load capacitors connected to the conductors, the load capacitors being formed in a laminate having a conductor layer: a first transmission line connected to any of the conductors; and a second transmission line coupled magnetically to the first transmission line. The first transmission line and the second transmission line are included in the laminate. The assembly is received in a hole in the middle of the laminate.

Abstract: A circulator (100) is comprised of a transmission line three port Y junction (104). At least one cylindrical cavity structure (113, 115) is disposed adjacent to the Y junction and contains a ferromagnetic fluid (114). One or more magnets (112) are provided for applying a magnetic field (118) to the ferromagnetic fluid and the Y junction in a direction normal to a plane defined by said Y junction. A composition processor (301) is provided for dynamically changing a composition of the ferromagnetic fluid in response to a control signal to vary the permittivity and permeability of the ferromagnetic fluid.

Abstract: An improved multi-junction waveguide circulator that eliminates the transitions to dielectric transformers and air-filled waveguides between ferrite elements is described. The waveguide circulator in accordance with the invention can be implemented in variations from a minimum of two ferrite circulator elements held in close proximity to one another to any number of ferrite elements as required to achieve the desired isolation performance or to create a switch matrix with any combination of input and output ports. The waveguide circulator in accordance with the invention eliminates the transitions between adjacent ferrite elements and thus reduces losses, component size, and mass.

Abstract: A highly reliable nonreciprocal circuit device can be easily manufactured at low cost. In the nonreciprocal circuit device, a resin layer is formed on the surface of a metal case. On a ferrite member, the terminals of central conductors are arranged with a predetermined angle therebetween. Inside a resin case including input/output terminals and ground terminals, there are arranged the ferrite member, the central conductors, a permanent magnet for applying a static magnetic field to the ferrite member and the central conductors, a resistor, and capacitors. The resin case is sandwiched by an upper yoke and a lower yoke. A resin layer formed of a thermosetting resin is arranged on each of the yokes. When the permanent magnet is thermally demagnetized, the thermosetting resin layer is hardened at the same time.

Abstract: A nonreciprocal circuit element includes a magnetic assembly including a ferrite magnetic body, a common electrode, and three central conductors; capacitors connecting to the respective central conductors; a permanent magnet which applies a DC bias magnetic field to the magnetic body; and a metal case which accommodates the magnetic assembly, the capacitors, and the permanent magnet, the metal case functioning as a magnetic yoke. The saturation magnetic flux density of at least a portion of the metal case and the residual magnetic flux density of the permanent magnet have negative temperature coefficients. Moreover, the portion of the metal case is composed of a magnetic material having a larger absolute value of the temperature coefficient of the saturation magnetic flux density than the absolute value of the temperature coefficient of the residual magnetic flux density of the permanent magnet in the range of ?35° C. to +85° C.

Abstract: In a nonreciprocal circuit device, receiving surfaces for bending first and second line conductors are formed at the respective ends of the confronting two sides of a magnetic substrate, the first and second line conductors are bent to the other surface of the magnetic substrate through the receiving surfaces thereof as well as disposed on the other surface of the magnetic substrate along the diagonal lines.

Abstract: A high-frequency amplifier in a power amplifier module includes, on a substrate on which the amplifier is formed, first- and second-stage amplifiers for receiving and amplifying an input signal, a harmonic processing circuit for matching of harmonics included in an output signal from the second-stage amplifier, and a low-pass filter receiving an output from the harmonic processing circuit to selectively pass a signal to be supplied to a non-reciprocal circuit element using a predetermined frequency as a cutoff frequency.

Abstract: Three mutually intersecting central conductors are positioned on ferrite to which a direct current magnetic field is applied, the port portions of two of the central conductors are branched and one branched portion of each is extended and bent so as to form an inductor. These inductors and capacitors with one end connected to a ground terminal make up series resonant circuits. The resonance frequencies of the series resonant circuits are set to approximately two times and approximately three times that of the center frequency of the pass band of the device which is the fundamental frequency, thereby causing attenuation of the second harmonic frequency and third harmonic frequency of the fundamental frequency, thus acting as matching capacitance of the fundamental frequency. Accordingly, a small nonreciprocal circuit device having a great amount of attenuation of a particular frequency is obtained without increasing costs, a nonreciprocal circuit device, and a communication device using the same, are provided.

Abstract: An irreversible circuit device with small insertion loss and excellent isolation is to be provided. An irreversible circuit device according to the invention has a flat plate shaped ferrite member and first, second and third central conductors placed on the ferrite member. In the central conductors, second conductor parts are placed on the ferrite member as input or output first conductor parts are placed on notch parts of the ferrite member. Therefore, when a magnetic flux passes through V-shaped extension parts as a magnetic path, the current generation is reduced and the energy transmission is increased in the first conductor part placed therebetween. Consequently, the insertion loss is reduced, and the isolation becomes excellent.