| 摘要 |
PROBLEM TO BE SOLVED: To provide a helical antenna, the resonance frequency of which can easily be adjusted with high accuracy without the need for mechanical processing. SOLUTION: The helical antenna is provided, which is characterized in including: a dielectric support wherein a hollow part is penetratingly formed along the length direction and a prescribed spiral groove is formed on an inner wall face of the hollow part; a helical element made of a metallic member wound on an outer circumference face of the dielectric support and fixed; and a tuning element freely movably fitted in the hollow part of the dielectric support while being in press contact with the inner wall face, and that the resonance frequency is adjusted at feeding to the helical element by changing the position of the tuning element in the hollow part of the dielectric support in response to an external operation. COPYRIGHT: (C)2007,JPO&INPIT
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