| 摘要 |
An antenna device, comprising an antenna unit including basic body comprising at least one of dielectric ceramic and magnetic ceramic, at least one conductor disposed at least one of inside and on a surface of the basic body, and a feeding electrode for applying a voltage to the conductor disposed on the surface of the basic body; a mounting board on which the antenna unit is mounted; a ground part in association with the mounting board and adapted to resonate with the antenna unit; and a length in the polarization direction of a radio wave of the ground part being about lambd/4 or more, where lambd is a wavelength of the radio wave, the basic body comprising a first generally planar sheet having a plurality of spaced, first conductors formed on one major surface thereof and a second generally planar sheet having a plurality of spaced second conductors formed on one major surface thereof; the first and second generally planar sheets being laminated together to form an elongated structure wherein respective pairs of the first and second conductors are coupled to one another to form respective spiral loops of a spiral antenna so that a central axis of the spiral antenna extends generally parallel to a longitudinal direction of the elongated structure; each of the sheets being formed of a material having a permeability of 1<mu<7 or a dielectric constant epsi of 1<epsi<130; and a feeding terminal coupled to one end of the spiral antenna so that the antenna unit forms a mono-pole antenna, the antenna unit and the ground part together functioning as a dipole antenna.
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