One-way radar propagation factor
calculates the one-way propagation factor assuming a surface target and a sea state of
F = radarpropfactor(
0. The calculation estimates the complex relative permittivity
(dielectric constant) of the reflecting surface using a sea water model described in 
that is valid from
100 MHz to
10 GHz. The target
height is assumed to be the height of significant clutter sources above the average surface
height. Specifically, the target height is calculated as
3 times the
standard deviation of the surface height. Assuming the paths are the same, the two-way
propagation factor is 2
radarpropfactor(___) plots the one-way propagation
factor in dB versus range in km. Default range units are km.
Plot the propagation factor for a
3 GHz S-band radar assuming an antenna height of 10 m and a target height of
1 km. Assume that the surface has a height standard deviation of
1 m, and the surface slope is
R = (30:0.5:180)*1e3; % Range (m) freq = 3e9; % Frequency (Hz) anht = 10; % Radar height (m) tgtht = 1e3; % Target height (m) hgtsd = 1; % Height standard deviation (m) beta0 = 0.05; % Surface slope (deg) radarpropfactor(R,freq,anht,tgtht,... 'SurfaceHeightStandardDeviation',hgtsd,... 'SurfaceSlope',beta0)
R— Free space range
Free space range, specified as a scalar or an M-length vector. Units are in meters.
freq— Radar frequency
Radar frequency in hertz, specified as a positive real scalar or a vector.
ANHT— Antenna height
Antenna height as referenced from ground level, specified as a positive scalar. Units are in meters.
TGTHT— Target height
Target height as referenced from ground level, specified as a positive scalar. Units are in meters.
comma-separated pairs of
the argument name and
Value is the corresponding value.
Name must appear inside quotes. You can specify several name and value
pair arguments in any order as
'Polarization'— Polarization of transmitted wave
Polarization of the transmitted wave, specified as
'H' indicates horizontal polarization and
'V' indicates vertical polarization.
'SurfaceRelativePermittivity'— Complex relative permittivity
Complex relative permittivity (dielectric constant) of the reflecting surface,
specified as a complex scalar. The default value of dielectric constant depends on the
value of the
freq argument. The function uses a sea water model
in  that is valid up to
Complex Number Support: Yes
'SurfaceHeightStandardDeviation'— Standard deviation of surface height
0.01(default) | positive scalar
Standard deviation of the surface height in meters, specified as positive scalar.
The default value of
0.01 m indicates a sea state of
0. Units are in meters.
'SurfaceSlope'— Surface slope
Surface slope, specified as a nonnegative scalar. This value is expected to be 1.4 times the RMS surface slope. Given the condition that 2*GRAZ/BETA0 < 1, where GRAZ is the grazing angle of the geometry specified in degrees, the effective surface height standard deviation in meters is calculated as
Effective HGTSD = HGTSD*(2*GRAZ/BETA0)^(0.2)
This calculation better accounts for shadowing. Otherwise, the effective height
standard deviation is equal to HGTSD. BETA0 defaults to the surface slope value output
searoughness function for a sea state of
0. Units are
'VegetationType'— Vegetation type
Surface vegetation type, specified as
'Brush' are assumed to be dense
'Grass' is assumed to be thin grass. Use this argument
when using the function on surfaces different from the sea.
'ElevationBeamwidth'— Half-power elevation beamwidth
10(default) | scalar between 0° and 90°
Half-power elevation beamwidth, specified as a scalar between 0° and 90°. The
elevation beamwidth is used in the calculation of a
pattern. The default antenna pattern is symmetrical with respect to the beam maximum
and is of the form sin(u)/u. The parameter u is given by u = k*sin(theta), where theta
is the elevation angle in radians and k is given by k = 1.39157/sin(ELBW/2). Units are
'AntennaPattern'— Antenna elevation pattern
Antenna elevation pattern, specified as an M-length vector.
This is an alternative to specifying the elevation beamwidth. Both
must be vectors of the same size. If both an antenna pattern and elevation beamwidth
are provided, the function uses the antenna pattern and ignores the elevation
beamwidth value. Defaults to a
sinc antenna pattern.
'PatternAngle'— Antenna pattern angle
Antenna pattern angle, specified as an M-length vector
corresponding to the
'AntennaPattern' argument. In general, to
properly compute the coverage, the pattern should be specified from
90°. Units are in degrees.
'TiltAngle'— Tilt angle
0(default) | scalar between
Tilt angle of the antenna with respect to the surface, specified as a scalar
90°. Units are in
'EffectiveEarthRadius'— Effective Earth radius
Effective Earth radius, specified as a positive scalar. The default value
calculates the effective Earth radius using a refraction gradient of
-39e-9, which results in approximately
the real earth radius. Units are in meters.
'RefractiveIndex'— Refractive index at surface
1.000318(default) | scalar greater than
Refractive index at the surface, specified as a nonnegative scalar. Defaults to
1.000318, which is the output of the
refractiveidx function at an altitude of
F— One-way propagation factor
The one-way propagation factor, returned as a scalar or M-length column vector. Units are in decibels.
 Blake, L.V. "Machine Plotting of Radar Vertical-Plane Coverage Diagrams." Naval Research Laboratory, 1970 (NRL Report 7098).