This paper introduces the measurements of ocean wave directional spectra from a space-borne radar.It also presents the radar spectrometer instruments.Then an End-to-End simulation method is adopted to analyze the performances of the system

taking into account data processing parameters and ocean surface conditions.The simulations show that the proposed radar can measure spectra of fully developed waves with significant wave heights (SWH) over approximately 2.0m and spectra of swell surface under low wind conditions (SWH0.8m)

in high precision.The minimum detectable wavelength in this study is about 40m.The wavelength resolution for a wavelength of 200m is better than 20m

and the directional resolution after averaging is better than 20°.Finally

it is proved that a beam configured with an incidence of 10° performs better on spectra retrieval than the one with an incidence of 6°.