HF Radar Ocean Surface Cross Section for the Case of Floating Platform Incorporating a Six-DOF Oscillation Motion Model

To interpret the characteristics of ocean surface echo signals, the general first- and second-order high-frequency surface wave radar (HFSWR) ocean surface scattering cross sections are mathematically derived for an omnidirectional receiving antenna being deployed on a floating ocean platform incorporating a six-degree-of-freedom (DOF) oscillation motion model. The six-DOF oscillation motion includes sway, surge, yaw, heave, pitch, and roll. The derived radar cross sections can be degenerated to existing results involving some simple oscillation motion models or an onshore case. Simulation results show that six-DOF oscillation motion can induce additional peaks in radar spectra and these motion-induced peaks appear symmetrically in frequency. Furthermore, the positions and intensities of these motion-induced peaks depend on the angular frequency and amplitude of each 1-D oscillation motion. In particular, the intensities of the Bragg peaks may be lower than those of the motion-induced peaks in some conditions, which is an extremely important phenomenon for ocean remote sensing using floating-based platform HFSWR. In addition, yaw appears to have the largest effect on the radar spectra and the antenna should be placed near the center of rotation. Measured radar spectra also preliminarily confirmed the reliability of the derived scattering model. This article provides a significant theoretical foundation in future investigation and practical application of ocean remote sensing and moving target detection using floating-based platform HFSWR.