| 摘要 |
A conductor is provided from a base to a first fold point at the tip side, and sequentially folded parallel not less than once at the tip side and the base side, forming a first element; the conductor is split at the first fold point and the split conductor is, similarly, sequentially folded parallel not less than once at the tip side and the base side, forming a second element. Then, the effective length from the base to the tip of the first element is set to a quarter of the wavelength of a first frequency, and the effective length from the base to the tip of the second element is set to a quarter of the wavelength of a second frequency. Also provided is a folded antenna element, comprising a conductor in a direction from the base to the tip side, the conductor being folded at least once at the tip side and arranged parallel to the direction, is made cylindrical; a rod-like antenna element is provided so as to be freely movable in the axial direction of the folded antenna element; and, in an extended state, the base side of the rod-like antenna element becomes inserted to the tip side of the folded antenna element and is capacitance-coupled thereto by a large coupling capacitance. The effective length of the folded antenna element from the base to the tip is a quarter of the wavelength of the first frequency, and three quarters of the wavelength of the second frequency. In the extended state, the effective length from the base of the folded antenna element to the tip of the rod-like antenna element is a quarter of the wavelength of the first frequency, and three quarters of the wavelength of the second frequency.
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