Abstract: A low cost base station antenna for preventing insertion loss. In the antenna, a printed circuit board (PCB) has a power divider pattern including power divider terminals disposed on one side of the PCB. A conducting ground plate has therein rectangular apertures disposed in line as radiation elements respectively and electromagnetically coupled with each of the power divider terminals of the PCB and disposed to be separated from the PCB by a foamed dielectric sheet with a predetermined thickness so as to be insulated with respect to the power divider pattern. The power divider terminals of the PCB are disposed to terminate within the contour of the apertures and all the power divider terminals are disposed in one line and have a length being a quarter of wavelength. A cavity has a rectangular box with one side open and connected by its open side and by its edges to the ground plate so that all the apertures are disposed within contour of the capacity.