Antenna apparatus for base station

An antenna apparatus for a base station, comprising:

• a printed circuit board having a power divider pattern including power divider terminals disposed on one side of said printed circuit board in one line, each of said power divider terminals having a length being a quarter of a wavelength .lambda.;
• a conducting ground plate having therein circular apertures disposed in one line as radiation elements respectively and electromagnetically coupled with each of said power divider terminals of the printed circuit board, wherein said apertures are separated from each other by a distance "d" defined by d=.lambda..sub.min /(1+sin.epsilon..sub.max), where .lambda..sub.min is a minimal wavelength and sin.epsilon..sub.max is an edge angle of a cosecant zone, and said power divider terminals of the printed circuit board are disposed to terminate above respective ones of said apertures and all;
• a foamed dielectric sheet, with a predetermined thickness, disposed between said one side of the printed circuit board and the conducting ground plate;
• and
• a cavity having a rectangular box with one side open and connected by its open side and by its edges to said ground plate so that all the apertures are disposed above said cavity.