Fourier Transform Catalog

#Math

Time DomainFrequency DomainNote
$\displaystyle \text{rect}(t /T)$$\displaystyle T \text{ sinc}(\omega T /2\pi)$
$\displaystyle e^{-at}u(t)$$\displaystyle \frac{1}{a+j\omega}$
$\displaystyle e^{a\lvert t\rvert}$$\displaystyle \frac{2a}{a^{2}+\omega ^{2}}$
$\displaystyle \text{sinc}(t /2\pi)$$\displaystyle 2\pi ,\text{rect}(\omega)$
$\displaystyle \Delta(t)$$\displaystyle T^{2}\text{ sinc}^{2}(\omega T /2\pi)$
$\displaystyle \text{sinc}^{2}(t)$$\displaystyle \Delta(\omega /2\pi)$
$\displaystyle \delta(t)$$\displaystyle 1$
$\displaystyle \delta(t-\tau)$$\displaystyle e^{-j\omega \tau}$
$\displaystyle 1$$\displaystyle 2\pi \delta(\omega)$
$\displaystyle u(t)$$\displaystyle \pi \delta(\omega)+\frac{1}{j\omega}$
$\displaystyle e^{j{\omega}_{0}t}$$\displaystyle 2\pi \delta(\omega-{\omega}_{0})$
$\displaystyle \cos({\omega}_{0}t)$$\displaystyle \pi(\delta(\omega-{\omega}{0})+\delta(\omega+{\omega}{0}))$
$\displaystyle \sin({\omega}_{0}t)$$\displaystyle j\pi(\delta(\omega+{\omega}{0})-\delta(\omega-{\omega}{0}))$
$\displaystyle \delta_{T}(t)$$\displaystyle {\omega}_{0}\delta {\omega{0}}(\omega)$$\displaystyle \delta_{T}(t)$ is the impulse train
$\displaystyle \text{square wave}$$\displaystyle T\text{ sinc}(\omega T /2\pi) \delta_{T}(t)$