AbstractPulse mode sonar operation is analyzed under the assumption that the scattering object Γ lies in the far fields of both the transmitter and the receiver. It is shown that, in this approximation, the sonar signal is a plane waves(x· θ0–t) near Γ, where θ0is a unit vector directed from the transmitter toward Γ, and similarly the echo is a plane wavee(x· θ –t) near the receiver, where θ is a unit vector directed from Γ toward the receiver. Moreover, if Γ is stationary with respect to the sonar system then it is shown thatwhere š(ω) is the Fourier transform ofS(τ) andT+(ωθ,ωθ0) is the scattering amplitude in the direction θ due to the scattering by Γ of a time‐harmonic plane wave with frequence ω and propagation direction θ0. A generalization of this relation is de