Comparison Identities for Wave Propagation in a Time-Varying Plasma Medium

An unbounded space-invariant but time-varying medium conserves the wave number
k
of the wave but alters the frequency of the wave. Thus a switched medium acts like a frequency transformer, the frequencies of the newly created waves (output waves) are easily computed. The amplitudes of the output waves depend on the rise time
Tr
of the profiles of the parameters of the switched medium.