δ(t) ←> 1
1 ←> 2πδ(ω)
e^{jω0t} ←> 2πδ(ω - ω0)
cos(ω0t) ←> π[δ(ω - ω0) + δ(ω + ω0)]
sin(ω0t) ←> (π/j)[δ(ω - ω0) - δ(ω + ω0)]
e^{-at}u(t), a > 0 ←> 1/(a + jω)
e^{-a|t|}, a > 0 ←> 2a/(a^2 + ω^2)
u(t) ←> πδ(ω) + 1/(jω)
矩形脉冲: x(t)=1, |t|<T1 ←> 2sin(ωT1)/ω
频域矩形: X(jω)=1, |ω|<W ←> sin(Wt)/(πt)
周期信号: x(t)=Σ ak e^{jkω0t} ←> 2πΣ ak δ(ω-kω0)
冲激串: Σ δ(t-nT) ←> (2π/T)Σ δ(ω-k2π/T)