Superluminal electromagnetic waves in free space

Recently it has been shown that all relativistic wave equations possess fam ilies of undistorted progressive waves (UPWs) which can travel with arbitra ry speeds 0 less than or equal to v < infinity. In this paper we present th e theory of how to generate UPW solutions of the Maxwell equation and discu ss the particular case of the superluminal electromagnetic X-wave (SEXW), c larifying its extraordinary properties. The theory of how it is possible to launch finite aperture approximations for the SEXW in free space is also d iscussed in detail. The theory is illustrated by computer simulations showi ng the birth of a finite aperture approximation for a SEXW and its superlum inal propagation without appreciable distortion up to a 100 km. We discuss also the experimental evidence available and discuss if SEXWs can be used t o transmit information.