Spiky sea clutter at low grazing angles and high range resolutions

Abstract

X-band (9.5-10.0 GHz) backscatter at near grazing incidence (0.2 deg) from the sea off the coast of Kauai, Hawaii was measured with a radar characterized by a high spatial resolution in range (0.3 m) and a high temporal resolution (2000 Hz PRF). Extensive amounts (over 1200 s per measurement) of vertically and horizontally polarized sea clutter data were taken for upwind and crosswind transmit geometries. Each type of data was analyzed over time scales varying from long (200 s), to intermediate (5 s), to short (50 ms), and over range swaths varying from full (160 m), to intermediate (30 m), to short (an individual range cell, 0.3 m). The different types of data each exhibited the spiky behavior which has come to be expected from sea backscatter observed at low grazing angles and high range resolutions, while showing, between themselves, marked transmit geometry and polarization dependent contrasts, with the horizontally polarized, upwind sea clutter being especially notable for its frequently occurring, significant high frequency spectral content.