Reflectivity of sea clutter
returns the normalized radar cross section (
nrcs = seareflectivity(
nrcs) in meters squared for
the specified sea scale
scale, at the grazing angle
graz, with the transmitted frequency
hgtsd — Standard deviation of the surface height for the
specified sea state number as a scalar in meters
beta0 — slope of the sea type in degrees.
beta0 is 1.4 times the root mean square (RMS) surface slope.
The surface σ0 value for sea clutter reflectivity is
computed based on the NRL Sea Clutter Model by Gregers-Hansen and Mittal
windvelocity — wind velocity in meters per second.
Calculate the NRCS of a sea clutter patch. Assume that the patch is the sea with sea state number equal to
2 and the radar system operates at a frequency of
30 GHz. Also assume the grazing angle is
scale = 2; graz = 10; freq = 30e9;
Calculate the normalized NRCS for the sea clutter patch.
nrcs = seareflectivity(scale,graz,freq)
nrcs = 2.1555e-04
Use the normalized RCS to calculate the clutter patch RCS.
scale— Sea state or wind scale
If you set
scale is the sea state,
specified as a nonnegative scalar between [0,8].
If you set
is the wind scale, specified as a positive scalar between [1,9].
seastate = 3
Acceptable input values depend on the value of
graz— Grazing angle
Grazing angle, specified as a scalar or an N-length row vector of nonnegative grazing angles in degrees. Specifies the grazing angles of the clutter patch relative to the radar.
graz_angle = 10
freq— Transmitted frequencies
10e9(default) | scalar | positive M-length vector
Transmitted frequencies, specified as a scalar or positive M-length vector.
freq = 7*10e9
pol— Polarization of transmitted wave
Polarization of transmitted wave, specified as
'H' for horizontal
'V' for vertical polarization.
pol = 'V'
scaletype— Scale type
Scale type, specified as either:
'SeaState' — The function uses the Sea State model.
When you specify this option, the
scale input scale
must be a nonnegative scalar between [0,8].
'WindScale' — The function uses the Beaufort Wind Scale
model. When you specify this option, the
scale must be a positive scalars between [1,9].
scaleType = 'WindScale'
nrcs— Normalized radar cross section of surface reflectivity
hgtsd— Standard deviation of surface height
Standard deviation of the surface height, returned as a scalar in meters.
beta0— Slope of the sea type
Slope of the sea type β0, in degrees, returned as a scalar.
windvelocity— Wind velocity
Wind velocity, returned as a scalar in meters per second.
The sea reflectivity model is valid given the following conditions:
Frequencies from 0.5 - 35 GHz
Sea States from 0 - 6 (Wind Scale from 1 - 7)
Grazing angles from 0.1 - 60 degrees
The model does not include variation with azimuth or wind direction. The NRL empirical model matches experimental results with an absolute deviation of about 2.2 to 2.3 dB for grazing angles from 0.1 to 10 degrees. A deviation of 2.6 dB can be seen for grazing angles above 10 degrees and below 60 degrees. The model for the height deviation, surface slope, and wind velocity is based on a model by Barton.