| 摘要 |
PROBLEM TO BE SOLVED: To provide an extension/contraction antenna which can wait for/ receive the frequency band of a dual band and in which the length in a storage state can be shortened. SOLUTION: For a folded antenna element 10, where a linear or band-like conductor is installed in the direction of a tip side from a base end, the conductor is folded at least once on the tip sided and is installed in parallel to the direction is made into a cylindrical form. A bar-like antenna element 12 is installed in the axial direction so that it is freely movable. Capacity is connected with connection opacity C in a pull-out state and in a state, where the base end side of the bar-like antenna element 12 is inserted into the tip side of the folded antenna element 10. An effective length from the base end of the folded antenna element 10 to the tip is set to a 1/4 wavelength for a first frequency and set to a 3/4 wavelength for a second frequency f2. The effective length from the base end of the folded antenna element 10 to the tip of the bar-like antenna element 12 in the pull-out state is to be the 1/4 wavelength for the first frequency and to be the 3/4 wavelength for the second frequency. |
