PURPOSE: To obtain high reception performance equivalent to that of a Parabolic antenna by reflecting a radio wave once in a curved recessed face formed to a window panel and converging the wave and receiving the converged radio wave with an antenna main body.

CONSTITUTION: A curved recessed face 6 is formed to a curved face equivalent to a parabolic face and acts like concentrating a radio wave D of a short wave length especially such as a microwave or a millimeter wave onto one point. Then an antenna main body 8 is projected upward from a gap between l rear window panel 5 and a trunk lid 10 only in operation and its tip 8a is positioned to a position where the radio wave D is concentrated. Thus, the radio wave D reflected in the curved recessed face 8 and concentrated onto one point is received from a tip 8a of the antenna main body 8 and the high reception perfor mance equivalent to that of a so-called parabolic antenna is obtained.