| 摘要 |
PROBLEM TO BE SOLVED: To easily adjust a radiation beam direction and an operation frequency by increasing/decreasing the amount of an external dielectric present around the external conductor of a coaxial line and adjusting a resonance frequency. SOLUTION: For a helical antenna 11, a conductor 13 and the coaxial line (the center conductor of the coaxial line) 12 to be a radiation element are helically wound on a dielectric cylinder surface. The center conductor 12a of the coaxial line and the conductor 13 are electrically connected at a power feeding point 14 at a tip. The two conductor lines are wound downwards from the power feeding point 14. Then, the conductor 13 and the external conductor 12c of the coaxial line 12 are electrically connected at a winding end terminal 15. A frequency for operating the antenna as a circularly polarized wave antenna and the radiation beam direction depend on parameters. Then, the beam direction is turned to an almost desired elevation angle and the frequency is relatively coarsely adjusted first. Then, so as to match with the desired frequency, the dielectric 12d is increased/decreased near the external conductor 12c of the coaxial line 12 and the resonance frequency is precisely adjusted. |
