Pulse distortion in resonant and nonresonant gases

The effect of resonant and nonresonant gases on the propagation of an arbitrarily modulated pulse is investigated. A general expression is derived for the transient response of the signal; the result is valid even for carrier frequencies near the resonant frequency. For propagation through a nonresonant medium, the expression is exact. The application to tropospheric pulse propagation is briefly discussed, and the effects on a rectangular pulse are shown.