**3. Simulation Results**

In this study, using the product of a Pierson–Moskowiz ocean spectral model [38] and a cardioid directional factor [39] as directional ocean wave spectrum, simulations are conducted to analyze the effect of the antenna motion on radar Doppler spectra. The radar operating frequency, range resolution, bistatic angle, and the angle of ellipse normal are set to 5 MHz, 3 km, 45◦ , and 90◦ , respectively. The platform parameters are obtained from a deep-water floating platform [40], where the length and width of the platform are, respectively, 240 and 46 m. A single-frequency six DOF oscillation motion for wave frequency (WF) is first considered and the oscillation motion parameters are listed in Table 1. The wind speed and direction are, respectively, 41.12 m/s and 180◦ with respect to the direction of ellipse normal. A Hamming window is added to smooth the derived RCS curves.

**Table 1.** Single-frequency six DOF oscillation motion parameters for wave frequency (WF).

