| 摘要 |
PROBLEM TO BE SOLVED: To provide the dual band antenna of a short physical length capable of receiving the signals of two bands that are first frequency signals f1 and second frequency signals f2. SOLUTION: This dual band antenna 10 is formed by turning the base end side of a conductive linear body to a linear part 12 and turning the tip side to a helical coil-like part 14. An effective length from the base end of the linear part 12 to the tip is set to the 1/4 wavelength of the first frequency signals f1, the helical coil-like part 14 is set so as to act as a choke coil to the first frequency signals f1 and further, the effective length from the base end of the linear part 12 to the tip of the helical coil-like part 14 is set to the 1/4 wavelength of the second frequency signals f2 of a frequency lower than the first frequency signals f1. |
