Ultrawideband sea clutter: system and measurements at X-band

Abstract

This paper presents a system description, along with data examples, for an ultrawideband instrumentation radar which has been used by the Radar Division of the Naval Research Laboratory to measure low grazing angle sea clutter at X-band frequencies (3 cm wavelength). The radar system employs a video impulse excited traveling wave tube (TWT), dual wideband horns and multiple head, digital sampling oscilloscope circuitry. In its highest resolution mode, the system utilizes sub-nanosecond transmit pulses (0.15 ns, 3 dB pulsewidth) at a 9 GHz center frequency to achieve resolutions as fine as 2 cm in the range dimension. Multiple resolution waveforms, combined with dual polarization, provide insights into the varied and dynamic character of the radar sea clutter. Upwind data examples, measured at a 4 degree grazing angle in 20 knot winds, are examined.