Comments on "Propagation of EM pulses excited by electric dipole in a conducting medium"

The authors of the above cited paper dismiss previous work as being "either incomplete or approximate". They deal with the "exact" solution of the electromagnetic fields of a Hertzian electric dipole or current element excited by an impulsive current. It should be pointed out that their solution, for the magnetic field waveform, is identical to that given by Wait and Spies(1970), who give the waveform of the derivative of the magnetic field for the excitation of the dipole by a step-function of current. Also, in another paper by Wait and Spies, the electric field waveforms, for step-function excitation, were given along with a discussion of the diffusion approximation, which seems to parallel that of Song and Chen. It is moot whether Song and Chen\´s solution is "complete". Their solution and similar ones published in the past are valid only for an assumed frequency independent conductivity and permittivity. Such is really an approximation for any material media. I suggest that such adjectives as "exact" and "complete", in describing formal solutions of unrealistically posed problems, should be discouraged.<>