Abstract: On a first-signal-line side, a first resonant circuit is defined by a first inductance element, a first capacitance element, a second capacitance element, a third inductance element and a fifth inductance element, a third resonant circuit is defined by the first inductance element, the first capacitance element and the second capacitance element, and a fifth resonant circuit is defined by the first inductance element, the third inductance element, the first capacitance element, the second capacitance element and the fifth capacitance element. Similarly, on a second-signal-line side, a second resonant circuit, a fourth resonant circuit and a sixth resonant circuit are provided.

Abstract: On a first-signal-line side, a first resonant circuit is defined by a first inductance element, a first capacitance element, a second capacitance element, a third inductance element and a fifth inductance element, a third resonant circuit is defined by the first inductance element, the first capacitance element and the second capacitance element, and a fifth resonant circuit is defined by the first inductance element, the third inductance element, the first capacitance element, the second capacitance element and the fifth capacitance element. Similarly, on a second-signal-line side, a second resonant circuit, a fourth resonant circuit and a sixth resonant circuit are provided.

Abstract: In a case in which a capacitor is not provided in parallel with a second inductance element, the impedance ratio between a first inductance element and the second inductance element is constant regardless of the frequency, but when a capacitor is provided, the parallel impedance of the capacitor and the second inductance element gradually increases at frequencies equal to and below the resonant frequency. Consequently, at frequencies equal to or below the resonant frequency, the higher the frequency becomes, the larger the value of the real portion of the impedance observed on a high-frequency-circuit side becomes. Therefore, by appropriately setting the values of the first inductance element, the second inductance element, and the capacitor, the frequency characteristics of the real portion of the impedance observed on the high-frequency-circuit side can be set to be similar to the frequency characteristics of the radiation resistance of the antenna.

Abstract: An antenna device includes an impedance-matching switching circuit connected to a feeding circuit, and a radiating element. The impedance-matching switching circuit matches the impedance of the radiating element as a second high frequency circuit element and the impedance of the feeding circuit as a first high frequency circuit element. The impedance-matching switching circuit includes a transformer matching circuit and a series active circuit. The transformer matching circuit matches the real parts of the impedance and matches the imaginary parts of the impedance in the series active circuit. Thus, impedance matching is performed over a wide frequency band at a point at which high frequency circuits or elements having different impedances are connected to each other.

Abstract: A front-end circuit includes a diplexer and an impedance conversion circuit. The diplexer includes a feeding side common port through which a high-frequency signal in a high band and a high-frequency signal in a low band are input and output, a first port through which a high-frequency signal in a high band is input and output, and a second port through which a high-frequency signal in a low band is input and output, and demultiplexes or multiplexes the high-frequency signal in a low band and the high-frequency signal in a high band. The impedance conversion circuit is connected between the second port of the diplexer and an antenna port. The first port of the diplexer is directly connected to the antenna port through a transmission line.

Abstract: A variable capacitance device includes a ferroelectric capacitor, a control terminal, a ground terminal, and a capacitor. The ferroelectric capacitor includes a ferroelectric film and capacitor electrodes sandwiching the ferroelectric film, and its capacitance value is changed according to a control voltage value applied between the capacitor electrodes. The control terminal is connected to a first end of the ferroelectric capacitor. The ground terminal is connected to a second end of the ferroelectric capacitor. The capacitor is connected between the control terminal and the ground terminal, and has a capacitance larger than that of the ferroelectric capacitor.

Abstract: In an impedance conversion circuit, since, in a low band, an absolute value of impedance of a primary side coil is smaller than an absolute value of impedance of a capacitor, a high-frequency signal in a low band propagates through a transformer. Thus, impedance matching of a high-frequency signal in a low band is performed by the transformer. Since, in a high band, the absolute value of the impedance of the capacitor is smaller than the absolute value of the impedance of the primary side coil, a high-frequency signal in a high band propagates through the capacitor. Thus, impedance matching of a high-frequency signal in a high band is performed in the capacitor. Accordingly, impedance matching between a high frequency circuit and an antenna element is performed in a wide frequency band.

Abstract: A dielectric body includes a first radiating element on a first side and a second radiating element on a second side. The first radiating element and the second radiating element are linear conductors that each extend from a first end to a second end (an open end), and are parallel or substantially parallel to each other in a direction from the first end to the second end. The first end of the first radiating element is connected to a first port of a coupling degree adjustment circuit, and the first end of the second radiating element is connected to a second port of the coupling degree adjustment circuit. The first radiating element and the second radiating element are mainly coupled to each other in the coupling degree adjustment circuit.

Abstract: In a case in which a capacitor is not provided in parallel with a second inductance element, the impedance ratio between a first inductance element and the second inductance element is constant regardless of the frequency, but when a capacitor is provided, the parallel impedance of the capacitor and the second inductance element gradually increases at frequencies equal to and below the resonant frequency. Consequently, at frequencies equal to or below the resonant frequency, the higher the frequency becomes, the larger the value of the real portion of the impedance observed on a high-frequency-circuit side becomes. Therefore, by appropriately setting the values of the first inductance element, the second inductance element, and the capacitor, the frequency characteristics of the real portion of the impedance observed on the high-frequency-circuit side can be set to be similar to the frequency characteristics of the radiation resistance of the antenna.

Abstract: An antenna device includes a first antenna element that resonates with a first resonant frequency, a second antenna element that resonates with a second resonant frequency, a first frequency stabilizing circuit connected to a feeding end of the first antenna element, and a second frequency stabilizing circuit connected to a feeding end of the second antenna element. The first antenna element and the second antenna element can be arranged along two sides of a case of a communication terminal apparatus, for example.

Abstract: An antenna device includes an impedance-matching switching circuit connected to a feeding circuit, and a radiating element. The impedance-matching switching circuit matches the impedance of the radiating element as a second high frequency circuit element and the impedance of the feeding circuit as a first high frequency circuit element. The impedance-matching switching circuit includes a transformer matching circuit and a series active circuit. The transformer matching circuit matches the real parts of the impedance and matches the imaginary parts of the impedance in the series active circuit. Thus, impedance matching is performed over a wide frequency band at a point at which high frequency circuits or elements having different impedances are connected to each other.

Abstract: In an impedance conversion circuit, since, in a low band, an absolute value of impedance of a primary side coil is smaller than an absolute value of impedance of a capacitor, a high-frequency signal in a low band propagates through a transformer. Thus, impedance matching of a high-frequency signal in a low band is performed by the transformer. Since, in a high band, the absolute value of the impedance of the capacitor is smaller than the absolute value of the impedance of the primary side coil, a high-frequency signal in a high band propagates through the capacitor. Thus, impedance matching of a high-frequency signal in a high band is performed in the capacitor. Accordingly, impedance matching between a high frequency circuit and an antenna element is performed in a wide frequency band.

Abstract: A front-end circuit includes a diplexer and an impedance conversion circuit. The diplexer includes a feeding side common port through which a high-frequency signal in a high band and a high-frequency signal in a low band are input and output, a first port through which a high-frequency signal in a high band is input and output, and a second port through which a high-frequency signal in a low band is input and output, and demultiplexes or multiplexes the high-frequency signal in a low band and the high-frequency signal in a high band. The impedance conversion circuit is connected between the second port of the diplexer and an antenna port. The first port of the diplexer is directly connected to the antenna port through a transmission line.

Abstract: A dielectric body includes a first radiating element on a first side and a second radiating element on a second side. The first radiating element and the second radiating element are linear conductors that each extend from a first end to a second end (an open end), and are parallel or substantially parallel to each other in a direction from the first end to the second end. The first end of the first radiating element is connected to a first port of a coupling degree adjustment circuit, and the first end of the second radiating element is connected to a second port of the coupling degree adjustment circuit. The first radiating element and the second radiating element are mainly coupled to each other in the coupling degree adjustment circuit.

Abstract: A transmitting apparatus, receiving apparatus and communication system are disclosed, and great improvement in an S/N ratio, preventing an actual throughput from decreasing, and preventing the number of circuits for synchronizing spread spectrum signals from increasing can be expected at the receiving apparatus side. The transmitting apparatus includes a pulse generating circuit, pulse repetition cycle determining circuit, peak power determining circuit, and modulator. The pulse generating circuit generates pulse strings, pulse repetition cycle determining circuit determines, based on a clock signal, a pulse repetition cycle of the pulse string generated by the pulse generating circuit. The peak power determining circuit determines a pulse peak power of the pulse string. The modulator modulates the pulse string with transmission data, and then generates a transmission signal.

Abstract: A transmitting apparatus, receiving apparatus and communication system are disclosed, and great improvement in an S/N ratio, preventing an actual throughput from decreasing, and preventing the number of circuits for synchronizing spread spectrum signals from increasing can be expected at the receiving apparatus side. The transmitting apparatus includes a pulse generating circuit, pulse repetition cycle determining circuit, peak power determining circuit, and modulator. The pulse generating circuit generates pulse strings, pulse repetition cycle determining circuit determines, based on a clock signal, a pulse repetition cycle of the pulse string generated by the pulse generating circuit. The peak power determining circuit determines a pulse peak power of the pulse string. The modulator modulates the pulse string with transmission data, and then generates a transmission signal.

Abstract: This disclosure provides an antenna apparatus in which stable antenna characteristics are maintained by detecting surrounding conditions that affect the antenna characteristics and appropriately compensating the antenna characteristics. More specifically, when surrounding condition such as a human body (e.g., a palm or fingers) approaches and enters an electric field of a pseudo dipole formed by an antenna element electrode, a stray capacitance is sensed and stable antenna characteristics are maintained by appropriately controlling an antenna matching circuit to compensate for a change in the antenna characteristics due to the approach of the surrounding condition.

Abstract: An antenna device includes a first antenna element that resonates with a first resonant frequency, a second antenna element that resonates with a second resonant frequency, a first frequency stabilizing circuit connected to a feeding end of the first antenna element, and a second frequency stabilizing circuit connected to a feeding end of the second antenna element. The first antenna element and the second antenna element can be arranged along two sides of a case of a communication terminal apparatus, for example.

Abstract: A switching function and multiband compatibility and a function handling deviation of matching caused by the influence of the human body are configured in a single matching circuit. An antenna matching circuit is formed by a reactance changing section and a matching section. The matching section is formed by a parallel circuit of an inductor and a capacitor, and the LC parallel circuit is shunt-connected between a feed section and the ground. The reactance changing section changes the resonant frequency to be compatible with a plurality of bands, and performs fine adjustment of the resonant frequency changed by the influence of the human body. The parallel inductor causes the locus of input impedance of the antenna matching circuit to draw a small circle locus in the first quadrant of a Smith chart. The parallel capacitor is adjustable to move the small circle locus to the center on the Smith chart.

Abstract: A plate-like radiation element is arranged above a ground plane with a space from the ground plane. The radiation element 2 resonates at a predetermined low-frequency wavelength ?1 and a predetermined high-frequency wavelength ?2. A feeding portion for being connected to a feed circuit and a pair of short-circuit portions are provided on peripheral edge portions of the radiation element. The feeding portion is provided on one end of the radiation element. The pair of short-circuit portions for being connected to a ground plane are arranged in areas positioned at opposite sides, on both sides of the feeding portion along peripheral edge directions of the radiation element, where the voltages of high-frequency resonance supplied from the feeding portion to the individual short-circuit portions are zero. The short-circuit portions extend toward the ground plane for being connected to the ground plane. At the other end opposite to the feeding portion of the radiation element is an open end.