| 摘要 |
PROBLEM TO BE SOLVED: To provide a horizontally polarized omnidirectional antenna system having a simple structure and a small diameter and capable of being downsized. SOLUTION: Second and third antennas 3, 6 are respectively placed above and below a first antenna 1 at substantially an interval ofλ/4. Each of the antennas 1, 3, 6 comprises a couple of semicircular antenna elements each having a length ofλ/4 faced to each other, and a current is supplied from feeding points 2a, 2b of the antenna elements 1a, 1b configuring the first antenna 1. In this case, the feeding phase is selected such that currents i flowing through the antenna elements 1a, 1b are opposite to each other in the phase. The second and third antennas 3, 6 are provided with an arm with a length ofλ/8 at the tip of them. Interconnecting the first antenna 1 and the second and third antennas 3, 6 with feeders 5, 8 causes the current with the same phase as that of the first antenna 1 to flow through the second and third antennas 3, 6.
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