| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an antenna device which can be made to be operated as a magnetic field type antenna where receiving sensitivity is satisfactory from a low region to a high region, and in which a variation in an antenna characteristic is small and the mounting is also easy. <P>SOLUTION: There are provided: a first belt-like conductor 11 where a radiation conductor part 1 of an antenna device which is built in a portable device and can receives a broadcast signal wave is extended in a three-dimensional loop shape, and one end is made as a feeding point P1, and the other end is made as a grounding terminal Q1; and a second belt-like conductor 12 which extends branching off from the middle of this first belt-like conductor 11, and in which the tip end is made as a feeding point P2. The first belt-like conductor 11 is excited as a first loop antenna element A1 by the feeding to the feeding point P1, and a part of the first belt-like conductors 11 and the second belt-like conductor 12 are excited as a second loop antenna element A2 in cooperation with each other by the feeding to the feeding point P2. Each of feeding points P1 and P2 is connected to variable tuning means 3, and a tuning frequency of each of loop antenna elements A1 and A2 is can be made to be changed by controlling a capacitance value of a variable capacitance diode 4. <P>COPYRIGHT: (C)2012,JPO&INPIT |
