Measured forward‐scatter sea clutter at near‐zero grazing angle: analysis of spectral and statistical properties

Abstract

To develop forward-scatter radar (FSR) systems for use in maritime applications, a fundamental understanding of the operating environment is required. Currently, there is a lack of published experimental FSR sea clutter data at very low (near-zero) grazing angle over the sea. This data is necessary for the development of FSR systems for maritime applications. Therefore to facilitate further investigation, clutter data for such a system has been recorded at frequencies of 7.5 and 24 GHz with static, medium gain antennas for low sea states 1-3 on the Douglas scale. Analysis of forward scatter propagation phenomena is presented, and spectral and statistical analysis of forward-scatter clutter is performed.

Radar parameters influence on the clutter in maritime forward scatter radar

“…It can be easily seen, the spectral shape is reasonably invariant to the antenna beamwidth and major part of clutter is within 1 Hz bamdwidth. This also confirms that the slope is approximately 20-35 dB per decade as it was discussed in [8][9][10]. Probability density function (PDF) and cumulative distribution function (CDF) for the same clutter data are plotted on Fig.…”

“…In the maritime conditions, this FS approach allows detection of low targets in the presence of significant sea clutter. This paper is continuation of previous published work [5][6][7][8][9][10] and it presents the results of clutter studies of an FSR. Essentially this type of radar does not have range/angular resolution [3,5], clutter is picked up from the large surface area illuminated by Tx/Rx antennas.…”

“…Some explanation on the fundamentally different physics behind of the backscatter and forward scatter clutters can be found in our paper [10].…”

“…Received clutter signals are recorded at the output of the received signal strength indicator (RSSI) channel, which represents a composition of direct path and the Doppler shifted scattered components. More information about the FSR receiver can be found in [3,5,10]. The radar hardware parameters varied throughout the measurements by changing antenna azimuth beamwidth (12°, 20° and >60°), polarization (HH and VV) and radar operating frequencies (7.5GHz and 24GHz).…”

“…Spectral and statistical analysis of the sea clutter data have been made and will be presented in the paper. Sea clutter has been discussed previously in [8][9][10] where it was shown that the clutter statistics obey mainly Rayleigh distribution while the spectra been demonstrated to be limited from above by 1Hz and the slopes were of 20 -35 dB per decade. These results are in good agreement with numerical simulation of near-zero grazing angle FS performed in [13] where spectral and statistical properties of clutter were discussed.…”