An antenna having an emission unit emits first and second polarized waves which intersect each other and a supply unit that supplies the first and second polarized waves to the emission unit is provided. The supply unit includes a plurality of cross-shaped coupling apertures that allow first and second slots that the first and second polarized waves are transmitted to intersect and supply the first and second polarized waves to the emission unit. The first and second polarized wave guide directs the first and second polarized waves to the plurality of cross-shaped coupling apertures. The distances from first polarized wave supply slots to the first polarized waves to the first polarized wave guide to the plurality of cross-shaped coupling apertures and from second polarized wave supply slots to the second polarized waves to the second polarized wave guide to the plurality of cross-shaped coupling apertures are respectively about the same.