Simulation of FMCW radar in frequency domain
The function of the FMCW radar is equal to the scanning of the environment with a si-pulse. Thats why the following approach can be made:


Formulate reflection transfer function, with bandwidth $\Delta\omega$, center frequency $\omega_c$, reflection coefficient $r$, distance to target $l$, phase constant $\beta=\frac{\omega}{c_0}n_0=kn_0$ i.e.


$$R(\omega)=re^{-j2\frac{\omega}{c_0}n_0 l}= re^{-j\omega \tau n_0 }$$


Calculate the $R(\omega)$ for a wished center frequency and bandwidth in MatLab
Calculate the inverse fourier transformation of $R(\omega)$ to get $R(t)$, zero padding is recommended 


You finally get the time domain response for a single target, which is a si pulse at the time $\tau=\frac{2l}{c_0}$ which can be transformed into range by the previous in line equation

Hope I could help some of those who are looking for a start.