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Superluminal electromagnetic waves in free space

Recently it has been shown that all relativistic wave equations possess families of undistorted progressive waves (UPWs) which can travel with arbitrary speeds 0 ≤ v < ∞. In this paper we present the theory of how to generate UPW solutions of the Maxwell equation and discuss the particular case of the superluminal electromagnetic X‐wave (SEXW), clarifying its extraordinary properties. The theory of how it is possible to launch finite aperture approximations for the SEXW in free space is also discussed in detail. The theory is illustrated by computer simulations showing the birth of a finite aperture approximation for a SEXW and its superluminal propagation without appreciable distortion up to a 100 km. We discuss also the experimental evidence available and discuss if SEXWs can be used to transmit information.