Broadening effect of first-order ocean clutter Doppler shift of bistatic high-frequency ground wave radar

The analysis on the deviation of bistatic angle over a clutter cell indicates that the first-order bistatic ocean clutter Doppler shifts of the high-frequency ground wave radar must be broadened. This kind of broadened spectra is then defined as broadening effect. And the spatial distributions of the broadening effect is subsequently given over the whole ocean surface being interrogated by the bistatic HF ground wave radar. The effects of various factors on the spatial distributions are presented, and at the same time the generation mechanism of this broadening effect is given. The case of large bistatic scattering angle is also investigated and the analysis of energy distribution near the zero frequency is presented. All these investigations indicated that the first-order bistatic ocean clutter could be modeled as continuous spectrum signals over a clutter cell. This kind of signal character would result in a blind zone near the neighborhood of baseline and transmitter of the bastatic radar.