Abstract: The present invention relates to a base station antenna comprising: a reflective plate; at least one first band radiation element positioned on the upper surface of the reflective plate, including a first power feed unit, and having a first wavelength (?H); and at least one second band radiation element positioned on the upper surface of the reflective plate, including a second power feed unit, and having a second wavelength (?L), wherein the first power feed unit is connected to a power feed line on the lower surface of the reflective plate, and the power feed line is shorted with the reflective plate at a short point spaced apart at a preset interval from the first band radiation element.

Abstract: The present invention relates to a base station antenna comprising: a reflective plate; at least one first band radiation element positioned on the upper surface of the reflective plate, including a first power feed unit, and having a first wavelength (?H); and at least one second band radiation element positioned on the upper surface of the reflective plate, including a second power feed unit, and having a second wavelength (?L), wherein the first power feed unit is connected to a power feed line on the lower surface of the reflective plate, and the power feed line is shorted with the reflective plate at a short point spaced apart at a preset interval from the first band radiation element.

Abstract: The present invention relates to a process for manufacturing polyolefin polymerization catalysts and provides a process for manufacturing polyolefin polymerization catalysts, wherein after manufacturing a homogeneous solution of magnesium compounds using magnesium compounds and alcohols along with hydrocarbon solvents and contacting with titanium compounds by adding organic aluminum, the mixture is treated again with organic aluminum or alcohols having 5 or less carbon atoms, then contacted with titanium compounds. Polyolefin polymerization catalysts prepared by the preparation process of the present invention have superior polyolefin polymerization activities, they prepare polymers having high Melt Flow Ratios, and produce a lesser amount of fine particle polymers.