Inherent Limitations in High-Frequency Radar Remote Sensing Based on Bragg Scattering From the Ocean Surface

In this paper, the existence and statistical properties of the first-order (Bragg) fluctuations in high-frequency (HF) radar Doppler spectra due to ocean wave random phase are investigated. Here, a pulsed radar waveform is used and the ocean surface is assumed to first order to be a time-varying random rough surface representable as a zero-mean, Gaussian process. Theoretical analysis for the source of the Bragg fluctuations begins with the radar backscattered electric fields in the time domain. The statistical properties of the Bragg fluctuations are investigated through simulation for various radar operating frequencies and pulse widths. The magnitude and significance of the Bragg fluctuations are discussed in terms of the operating parameters. The results can be used in setting minimum error bounds for HF radar ocean surface current measurement.