Abstract: The present invention relates to a collinear antenna structure. The structure comprises a dipole antenna, a coil, and a set of stacked radiator, wherein the length of the dipole antenna is ½&lgr;, the ground end and the signal end of the dipole antenna are connected to a coaxial cable, the length of the cable line is less than ¼&lgr;, one end of the cable line is connected in series to the top of the signal end, wherein the stacked radiator comprising at least two parallel radiators in series, the length of each radiator is ½&lgr;, the distance between the two radiators is about 1.0 to 4.0 mm, one of the stacked radiator is axially connected in series to the other end of the coil, thus forming the structure of the antenna.