Abstract: A three-phase current detection device is configured to be used with first to third conductors allowing respective three-phase currents to flow therethrough in a flow direction, and is configured to detect the three-phase currents. The three-phase current detection device includes a substrate, a grounding wiring provided on the substrate, first to third loop magnetic cores, first to third magnetoelectric conversion elements, and first to third grounding electrodes. The first to third loop magnetic cores are extended along first to third loop lines surrounding the first to third conductors, the first to third loop lines are on a plane perpendicular to the flow direction, the first to third loop magnetic cores have first to third magnetic gaps, respectively. The first to third magnetoelectric conversion elements are disposed in the first to third magnetic gaps, respectively.

Abstract: A high-frequency receiver has both interference characteristic and reception characteristic. The high-frequency receiver includes an electronic switch that is connected in parallel to input and output terminals of antenna amplifying circuit, and an antenna control unit that controls the electronic switch and an antenna amplifying circuit. When an antenna control signal output from a high-frequency receiving unit is input to the antenna control unit, the electronic switch is opened and simultaneously power supply to the antenna amplifying circuit starts in a weak electric field area, and the electronic switch is closed and simultaneously power supply to the antenna amplifying circuit stops in a strong electric field area.

Abstract: A portable receiver includes an antenna to which at least FM broadcast wave is inputted, a matching circuit to which the signal input to the antenna is supplied via minute resistance component, an FM receiver unit with the output of the matching circuit connected thereto, and an earphone connected to the output of the FM receiver unit. The antenna is formed from rigid metal, and its length is shorter than the quarter wavelength of the FM broadcast wave. The matching circuit is formed by reactance element having fine DC resistance. The impedance value of the resistance component as viewed via the resistance component from the matching circuit is nearly equal to the impedance of the matching circuit.

Abstract: A matching unit includes a switching means for switching an inductance of a first inductor. This switching means sets an inductance such that a first inductor shows an inductance property to both of the VHF low-band and high-band, and shows a capacitance property to the UHF band. This structure allows the matching unit to achieve the matching for both the VHF low-band and high-band by just switching the two circuits of the VHF low-band and high-band, also allows the matching unit to show a capacitance property to the UHF band. Thus the loss produced in transmitting signals can be reduced, and the circuit can be simplified. As a result, the matching unit can be downsized, and the cost can be reduced.

Abstract: A matching device causes an antenna to match a receiving section arranged to receive a signal in a first frequency band and a signal in a second frequency band lower than the first frequency band. The matching device includes a first terminal arranged to be connected to the antenna, a first inductor connected between the first terminal and a first node, a second inductor connected between the first node and a ground, a first capacitor connected between the first node and a second node, a second terminal arranged to be connected to the receiving section, the second terminal being connected to the second node, and a third inductor connected between the second node and the ground. The second inductor has a capacitive impedance in the first frequency band, and has an inductive impedance in the second frequency band. This matching device can supply a signal in the second frequency band received by the antenna to the receiving section with a small loss.

Abstract: A matching device causes an antenna to match a receiving section arranged to receive a signal in a first frequency band and a signal in a second frequency band lower than the first frequency band. The matching device includes a first terminal arranged to be connected to the antenna, a first inductor connected between the first terminal and a first node, a second inductor connected between the first node and a ground, a first capacitor connected between the first node and a second node, a second terminal arranged to be connected to the receiving section, the second terminal being connected to the second node, and a third inductor connected between the second node and the ground. The second inductor has a capacitive impedance in the first frequency band, and has an inductive impedance in the second frequency band. This matching device can supply a signal in the second frequency band received by the antenna to the receiving section with a small loss.

Abstract: An antenna device comprises an antenna element formed in a sufficiently shorter length as compared with the wavelength of transmission or reception wave, a resistor, a matching circuit including at least a reactance element, and an output terminal connected to outside, which are connected in series in this sequence. As a result, an antenna device of smaller size and small loss is obtained.

Abstract: A portable receiver includes an antenna to which at least FM broadcast wave is inputted, a matching circuit to which the signal input to the antenna is supplied via minute resistance component, an FM receiver unit with the output of the matching circuit connected thereto, and an earphone connected to the output of the FM receiver unit. The antenna is formed from rigid metal, and its length is shorter than the quarter wavelength of the FM broadcast wave. The matching circuit is formed by reactance element having fine DC resistance. The impedance value of the resistance component as viewed via the resistance component from the matching circuit is nearly equal to the impedance of the matching circuit.

Abstract: A matching unit includes a switching means for switching an inductance of a first inductor. This switching means sets an inductance such that a first inductor shows an inductance property to both of the VHF low-band and high-band, and shows a capacitance property to the UHF band. This structure allows the matching unit to achieve the matching for both the VHF low-band and high-band by just switching the two circuits of the VHF low-band and high-band, also allows the matching unit to show a capacitance property to the UHF band. Thus the loss produced in transmitting signals can be reduced, and the circuit can be simplified. As a result, the matching unit can be downsized, and the cost can be reduced.

Abstract: An antenna device comprises an antenna element formed in a sufficiently shorter length as compared with the wavelength of transmission or reception wave, a resistor, a matching circuit including at least a reactance element, and an output terminal connected to outside, which are connected in series in this sequence. As a result, an antenna device of smaller size and small loss is obtained.

Abstract: The present invention provides a low cost microstrip line with low loss and a microwave device using the microstrip line. The microstrip line comprises (a) a dielectric substrate for general purpose use with relatively high loss in a microwave frequency, (b) a strip conductor foil disposed on the front surface of the substrate, (c) a metal plate for grounding disposed in contact with the back of the dielectric substrate, and (d) an air layer formed on a portion of the metal plate for grounding, the portion facing to the strip conductor foil.