Patent attributes
An antenna device capable of being applied to a portable radio terminal and showing a good antenna characteristic regardless of the direction, and a portable radio terminal provided with the antenna device. The antenna device applied to a portable radio terminal whose housing length is equal to or more than λ/4 with respect to the wavelength λ of transmission-reception signals comprises an antenna element disposed on one end of the housing in the longitudinal direction in which at least one point of one end is connected to a signal wiring pattern on a substrate and the other end is an open end, and a parasitic element disposed on the same side of the housing as the antenna element in which one point of one end is connected to a ground wiring on the substrate and the other end is an open end, wherein the open end of the antenna element and the open end of the parasitic element are approximated to each other and capacity coupled.