Why A radio wave is an electromagnetic wave, meaning it consists of an oscillating electric field and an oscillating magnetic field that regenerate each other as the wave travels. The two fields are perpendicular to each other and to the direction of travel, which is why antenna polarization is defined by the orientation of the electric field. Voltage and current exist in the feed line and antenna conductor, but once the energy radiates into space it propagates as these two fields.
Watch out Voltage and current is tempting because that is what you measure in the circuit driving the antenna, but a wave traveling through free space has no conductor to carry current.
Electro-Magnetic wave: the name itself lists the two fields, electric and magnetic.