| 摘要 |
In a helical antenna operable at a plurality of frequencies, a radiation element includes a first pitch portion which is connected to a feeding point and in which the electric conductor is wound around or folded back at a first pitch, and a second pitch portion which is connected to the first pitch portion and in which the electric conductor is wound around or folded back at a second pitch different from the first pitch. A tip end stab element extended from the tip end of the radiation element is placed in close proximity of the radiation element. The radiation element and the tip end element form frequency selection means or a parallel resonant circuit at an intermediate point of the radiation element. <IMAGE> |
