Abstract: An information terminal device includes a casing, a wireless board, and an antenna arranged to utilize a plurality of radio systems. The antenna includes a power feeding terminal and a plurality of resonant circuits. The plurality of resonant circuits are arranged to radiate radio waves. The plurality of resonant circuits further define a matching circuit that provides impedance matching between an impedance on a power feeding side as viewed from the power feeding terminal and a radiation impedance of a free space.

Abstract: There is disclosed a method of producing a ceramic multilayer substrate by laminating a plurality of glass-ceramic green sheets made of a glass-ceramic containing an organic binder and a plasticizer to form a laminate; and firing the laminate; further comprising: applying to or overlaying on the surfaces of the glass-ceramic green sheets inorganic compositions, the sintering temperature of the inorganic compositions being higher than that of the glass-ceramic green sheets; laminating a plurality of the glass-ceramic green sheets having the inorganic compositions applied to or overlaid on the surfaces of the glass-ceramic green sheets respectively, to form a part of the laminate; and laminating a plurality of the glass-ceramic green sheets to form the other part of the laminate.

Abstract: There is disclosed a method of producing a ceramic multilayer substrate by laminating a plurality of glass-ceramic green sheets made of a glass-ceramic containing an organic binder and a plasticizer to form a laminate; and firing the laminate; further comprising: applying to or overlaying on the surfaces of the glass-ceramic green sheets inorganic compositions, the sintering temperature of the inorganic compositions being higher than that of the glass-ceramic green sheets; laminating a plurality of the glass-ceramic green sheets having the inorganic compositions applied to or overlaid on the surfaces of the glass-ceramic green sheets respectively, to form a part of the laminate; and laminating a plurality of the glass-ceramic green sheets to form the other part of the laminate.

Abstract: A compact frequency multiplier can perform high-degree frequency multiplication and can be incorporated in a wireless device. The frequency multiplier includes an input terminal for inputting an input signal, a first resonant circuit resonating with the frequency &ohgr; of the input signal, a second resonant circuit and an idler circuit, which resonate with the frequency n·&ohgr; that is, n times the frequency of the input signal, a variable reactor such as a varactor diode, coupling-adjusting capacitors, a bias resistor, and an output terminal for outputting multiplied output signals. In one embodiment, the frequency multiplier is a current-excitation type. The first resonant circuit and the second resonant circuit, each of which is constituted of an LC series resonant circuit, are connected in series between the input terminal and the output terminal.

Abstract: A band-pass filter includes a metal film provided on a dielectric body. The shape and size of the metal film and the coupling points of input-output coupling circuits are selected such that first and second resonance modes are generated. The metal film has protruding portions or concavities provided thereon such that resonance electric field strength in the first or second resonance mode is controlled to couple the first and second resonance modes to each other.

Abstract: A dual mode band pass filter is constructed to be very compact and such that the coupling strength and bandwidth can be easily and widely adjusted while maintaining sufficient freedom of design. A metal film for forming a resonator is arranged on a first main surface of a dielectric body or at a certain height in the dielectric body. At least one ground electrode is arranged such that the ground electrode is opposed to the metal film via the dielectric body. The metal film is connected to input/output coupling circuits. In the region where the metal film is opposed to the ground electrode, two portions are partially provided. Each of these two portions has a relative permittivity that is different from the relative permittivity of the remaining portion, in order to couple two resonance modes.

Abstract: A duplexer includes a branch circuit connected to an antenna and arranged to branch to a receiving side and a transmitting side, a receiving-side LC parallel resonant-type filter connected to the receiving-side of the branch circuit and arranged to cause a reception signal to be passed and a transmission signal to be attenuated, a surface acoustic wave filter connected to the receiving-side LC parallel resonant-type filter defining a subsequent stage of the receiving-side LC parallel resonant-type filter and arranged to cause the reception signal to be passed and the neighborhood of the high-frequency side of the reception signal to be attenuated, and a transmitting-side LC parallel resonant-type filter connected to the transmitting-side of the branch circuit and arranged to cause the transmission signal to be passed and the reception signal to be attenuated.

Abstract: There is disclosed a method of producing a ceramic multilayer substrate by laminating a plurality of glass-ceramic green sheets made of a glass-ceramic containing an organic binder and a plasticizer to form a laminate; and firing the laminate; further comprising: applying to or overlaying on the surfaces of the glass-ceramic green sheets inorganic compositions, the sintering temperature of the inorganic compositions being higher than that of the glass-ceramic green sheets; laminating a plurality of the glass-ceramic green sheets having the inorganic compositions applied to or overlaid on the surfaces of the glass-ceramic green sheets respectively, to form a part of the laminate; and laminating a plurality of the glass-ceramic green sheets to form the other part of the laminate.

Abstract: A compact frequency multiplier can perform high-degree frequency multiplication and can be incorporated in a wireless device. The frequency multiplier includes an input terminal for inputting an input signal, a first resonant circuit resonating with the frequency &ohgr; of the input signal, a second resonant circuit and an idler circuit, which resonate with the frequency n·&ohgr; that is, n times the frequency of the input signal, a variable reactor such as a varactor diode, coupling-adjusting capacitors, a bias resistor, and an output terminal for outputting multiplied output signals. In one embodiment, the frequency multiplier is a current-excitation type. The first resonant circuit and the second resonant circuit, each of which is constituted of an LC series resonant circuit, are connected in series between the input terminal and the output terminal.

Abstract: A compact frequency multiplier can perform high-degree frequency multiplication and can be incorporated in a wireless device. The frequency multiplier includes an input terminal for inputting an input signal, a first resonant circuit resonating with the frequency &ohgr; of the input signal, a second resonant circuit and an idler circuit, which resonate with the frequency n·&ohgr; that is, n times the frequency of the input signal, a variable reactor such as a varactor diode, coupling-adjusting capacitors, a bias resistor, and an output terminal for outputting multiplied output signals. In one embodiment, the frequency multiplier is a current-excitation type. The first resonant circuit and the second resonant circuit, each of which is constituted of an LC series resonant circuit, are connected in series between the input terminal and the output terminal.

Abstract: A portable telephone includes a portable telephone body made from plastic having a receiver, a transmitter, and dial keys, and a chip antenna which is mounted on a circuit board secured at the inside of the portable telephone body and which is electrically connected to an RF section provided on the circuit board in the portable telephone. The chip antenna is disposed near the transmitter at a location where a transmitted electromagnetic signal is unlikely to be affected by the body of a person who is holding the portable telephone.

Abstract: There is disclosed a method of producing a ceramic multilayer substrate by laminating a plurality of glass-ceramic green sheets made of a glass-ceramic containing an organic binder and a plasticizer to form a laminate; and firing the laminate; further comprising: applying to or overlaying on the surfaces of the glass-ceramic green sheets inorganic compositions, the sintering temperature of the inorganic compositions being higher than that of the glass-ceramic green sheets; laminating a plurality of the glass-ceramic green sheets having the inorganic compositions applied to or overlaid on the surfaces of the glass-ceramic green sheets respectively, to form a part of the laminate; and laminating a plurality of the glass-ceramic green sheets to form the other part of the laminate.

Abstract: A high-frequency filter 10 serving as a bandpass filter has three transmission lines SL11 to SL13 side-coupled in three stages. The transmission lines SL11 to SL13 are respectively connected in parallel to capacitors C11 to C13. One end of the input transmission line SL11 is connected to an input terminal Pi through an input capacitor C14. One end of the output transmission line SL13 is connected to an output terminal Po through an output capacitor C15. The other ends of the transmission lines SL11 and SL13 are connected and the connection point is connected to the ground through an inductor Lg for forming a pole. One end of the transmission line SL12 is connected to the ground.

Abstract: The invention provides a complex electronic component, comprising; a multilayer substrate formed by laminating a plurality of dielectric layers; a first concave part being provided at least at the bottom surface of said multilayer substrate; a filter comprising at least one first passive element disposed within said multilayer substrate; an external terminal provided on at least one of the flat portion of the bottom surface and the side face of said multilayer substrate; either one of an active element or a second passive element mounted on the top surface of said multilayer substrate, a surface acoustic wave element mounted inside of said first concave portion of said multilayer substrate; and a flat cap provided at the opening of said first concave portion of said multilayer substrate so as to cover said opening said first concave portion. The size of the above complex electronic component is compact.

Abstract: The invention provides a complex electronic component, comprising; a multilayer substrate formed by laminating a plurality of dielectric layers; a first concave part being provided at least at the bottom surface of said multilayer substrate; a filter comprising at least one first passive element disposed within said multilayer substrate; an external terminal provided on at least one of the flat portion of the bottom surface and the side face of said multilayer substrate; either one of an active element or a second passive element mounted on the top surface of said multilayer substrate, a surface acoustic wave element mounted inside of said first concave portion of said multilayer substrate; and a flat cap provided at the opening of said first concave portion of said multilayer substrate so as to cover said opening said first concave portion. The size of the above complex electronic component is compact.

Abstract: A band-pass filter includes a metal film provided on a dielectric body. The shape and size of the metal film and the coupling points of input-output coupling circuits are selected such that first and second resonance modes are generated. The metal film has protruding portions or concavities provided thereon such that resonance electric field strength in the first or second resonance mode is controlled to couple the first and second resonance modes to each other.

Abstract: A duplexer includes a branch circuit connected to an antenna and arranged to branch to a receiving side and a transmitting side, a receiving-side LC parallel resonant-type filter connected to the receiving-side of the branch circuit and arranged to cause a reception signal to be passed and a transmission signal to be attenuated, a surface acoustic wave filter connected to the receiving-side LC parallel resonant-type filter defining a subsequent stage of the receiving-side LC parallel resonant-type filter and arranged to cause the reception signal to be passed and the neighborhood of the high-frequency side of the reception signal to be attenuated, and a transmitting-side LC parallel resonant-type filter connected to the transmitting-side of the branch circuit and arranged to cause the transmission signal to be passed and the reception signal to be attenuated.

Abstract: A portable terminal device including a main body including a data entry keyboard; a cover openably and closably attached to the main body and establishing a connecting portion between the main body and the cover; a display disposed on the inner side of the cover; a chip antenna disposed on the cover at a place other than the display and opposed to the connecting portion; the chip antenna including a ceramic base body, a conductor disposed at least either inside the base body or on a surface thereof, and a feeding terminal disposed on a surface of the base body and connected to one end of the conductor. The above portable terminal device has the directivity of an antenna in a desired direction without increasing the size and weight of the portable terminal device and without having a bulky and/or separate and/or protruding antenna device.

Abstract: An antenna includes a spirally wound conductor composed of a copper wire or a covered copper wire, and a covering material consisting essentially of a resin or a resin mixture with 1<&egr;≦10. At least part of the conductor is covered with the covering material. One end of the conductor leads to the outside of the covering material to form an external terminal. Another end of the conductor forms a free end in the covering material. In addition, a method for adjusting the resonant frequency of the antenna includes at least the step of changing a winding interval of a part of the conductor which is not covered with the covering material or the step of covering with the covering material a part of the conductor which is not covered with the covering material, or both. Furthermore, the antenna preferably satisfies the following numerical expression: 1.

Abstract: An antenna apparatus 10 includes a chip antenna 14 provided with a conductor 11, a power-supply electrode 12 to which one end of the conductor 11 is connected, and a terminal electrode 13 to which the other end of the conductor is connected; and a mounting substrate 18 provided with a line-shaped radiative conductor 15 formed by printing an electrically conductive material on a surface, a line-shaped conductive pattern 16, and a substantially rectangular ground electrode 17. The chip antenna 14 is mounted on the mounting substrate 18. The power-supply electrode 12 of the chip antenna 14 is connected through the conductive pattern 16 on the mounting substrate 18 to a power-supply source V. The terminal electrode 13 of the chip antenna 14 is connected to one end of the radiative conductor 15 on the mounting substrate 18.