Abstract: An antenna apparatus and a radio communication apparatus are capable of separately controlling a resonance frequency in a basic mode and a resonance frequency in a higher mode and have a wide bandwidth in which the resonance frequency in the basic mode is variable. The antenna apparatus includes a feeding electrode 2, a loop-shaped radiation electrode 3, a capacitance portion 4, and inductors 5 and 6. The capacitance portion 4 is formed by a gap between an open end 3a of the loop-shaped radiation electrode 3 and the feeding electrode 2. The inductor 5 is disposed at a position where a large current is obtained in the basic mode and a small current is obtained in the higher mode. The inductor 6 is disposed at a position where a large current is obtained in the higher mode and a small current is obtained in the basic mode.

Abstract: An antenna device and a wireless communication apparatus that are capable of obtaining a plurality of resonant frequencies and varying the plurality of resonant frequencies over a wide range are provided. A first antenna unit of an antenna device includes a feed electrode, a first radiation electrode, and a first frequency-variable circuit. The first frequency-variable circuit includes first and second reactance circuits each including a variable-capacitance diode. A control voltage is applied to the first frequency-variable circuit, and the resonant frequency of the first antenna unit can thus be varied. A second antenna unit includes the feed electrode, a second radiation electrode, and a second frequency-variable circuit. The second frequency-variable circuit includes first and third reactance circuits each including a variable-capacitance diode. A control voltage is applied to the second frequency-variable circuit, and the resonant frequency of the second antenna unit can thus be varied.

Abstract: A compact and low-cost antenna device in which no interference occurs even when many antenna units corresponding to various systems are mounted close together in a small area, and a wireless communication apparatus including the antenna device. An antenna device includes plural antenna units mounted on a single dielectric base. A first antenna unit having a lowest fundamental frequency is disposed at a left end of a non-ground region, a second antenna unit having a highest fundamental frequency of the plurality of the antenna units is disposed at a right end of the non-ground region, and a third antenna unit having a fundamental frequency between those of the first antenna unit and the second antenna unit is disposed between the first and second antenna units. A current-density control coil is connected between a first radiation electrode and a power feeder of the first antenna unit, while a reactance circuit is disposed in the middle of the first radiation electrode.

Abstract: An antenna apparatus and a radio communication apparatus are capable of separately controlling a resonance frequency in a basic mode and a resonance frequency in a higher mode and have a wide bandwidth in which the resonance frequency in the basic mode is variable. The antenna apparatus includes a feeding electrode 2, a loop-shaped radiation electrode 3, a capacitance portion 4, and inductors 5 and 6. The capacitance portion 4 is formed by a gap between an open end 3a of the loop-shaped radiation electrode 3 and the feeding electrode 2. The inductor 5 is disposed at a position where a large current is obtained in the basic mode and a small current is obtained in the higher mode. The inductor 6 is disposed at a position where a large current is obtained in the higher mode and a small current is obtained in the basic mode.

Abstract: A compact and low-cost antenna device in which no interference occurs even when many antenna units corresponding to various systems are mounted close together in a small area, and a wireless communication apparatus including the antenna device. An antenna device includes plural antenna units mounted on a single dielectric base. A first antenna unit having a lowest fundamental frequency is disposed at a left end of a non-ground region, a second antenna unit having a highest fundamental frequency of the plurality of the antenna units is disposed at a right end of the non-ground region, and a third antenna unit having a fundamental frequency between those of the first antenna unit and the second antenna unit is disposed between the first and second antenna units. A current-density control coil is connected between a first radiation electrode and a power feeder of the first antenna unit, while a reactance circuit is disposed in the middle of the first radiation electrode.

Abstract: An antenna device and a wireless communication apparatus that are capable of obtaining a plurality of resonant frequencies and varying the plurality of resonant frequencies over a wide range are provided. A first antenna unit of an antenna device includes a feed electrode, a first radiation electrode, and a first frequency-variable circuit. The first frequency-variable circuit includes first and second reactance circuits each including a variable-capacitance diode. A control voltage is applied to the first frequency-variable circuit, and the resonant frequency of the first antenna unit can thus be varied. A second antenna unit includes the feed electrode, a second radiation electrode, and a second frequency-variable circuit. The second frequency-variable circuit includes first and third reactance circuits each including a variable-capacitance diode. A control voltage is applied to the second frequency-variable circuit, and the resonant frequency of the second antenna unit can thus be varied.