| 摘要 |
A disk-shaped conductor 22, a ring-shaped conductor 24 and a ring-shaped conductor 26 are arranged in that order on the same plane. One end of a linear conductor 21 is connected perpendicularly to the center of the disk-shaped conductor 22, and the outer edge of the disk-shaped conductor 22 is connected to the inner edge of the ring-shaped conductor 24 via an anti-resonance circuit 23. Moreover, the outer edge of the ring-shaped conductor 24 is connected to the inner edge of the ring-shaped conductor 26 via an anti-resonance circuit 25. Due to the anti-resonance circuits 23 and 25, electrical blocking can be attained, so that an electromagnetic wave of a first frequency f1 is excited by the system extending from the linear conductor 21 to the disk-shaped conductor 22, an electromagnetic wave of a second frequency f2 is excited by the system extending from the linear conductor 21 to the ring-shaped conductor 24, and an electromagnetic wave of a third frequency f3 is excited by the system extending from the linear conductor 21 to the ring-shaped conductor 26. Thus, a small monopole antenna can be attained that has a simple structure and can be operated at a plurality of frequencies.
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