→Neither stationary charges nor charges in uniform motion (steady currents) can create electromagnetic waves.
→Because the static electric charges produce only electro static fields, while charges in uniform motion produce magnetic fields.
→As per Maxwell's theory, accelerated charges radiate electromagnetic waves.
→An oscillating charge, which is an example of an accelerating charge, produces an oscillating electric field in space, which produces an oscillating magnetic field, which in turn, is a source of oscillating electric field and so on.
→The oscillating electric and magnetic fields thus regenerate each other, as the wave propogates through the space.
→The frequency of the EM wave is equal to the frequency of oscillation of the charge.
→An electro magnetic wave propogates in space with speed of light. In an electro magnetic wave, the Electric field, Magnetic field and direction of propogation all three are mutually perpendicular.