ANTENNA WITH PARASITIC ELEMENT

摘要

An antenna having the parasitic radial part is provided to increase the transmission-reception power by providing the antenna having the transforming function of monopole antenna/dipole antenna. The length of emitting part(122) and parasitic radial part(124) is 1/4 of the wavelength about the resonance electro magnetic wave. The emitting part is connected to a wireless communications unit(110). The parasitic radial part is selectively connected to the wireless communications unit. In the separation state of the wireless communications unit and the parasitic radial part, the parasitic radial part does not perform the role as the antenna element. In the separation state of the wireless communications unit and the parasitic radial part, only the emitting part performs the role as the antenna element. Therefore, the antenna of the wireless communications unit becomes the monopole antenna. In the connected state of the wireless communications unit and the parasitic radial part, the parasitic radial part and the emitting part perform the role as the antenna element. Therefore, the antenna of the wireless communications unit becomes the dipole antenna.