Y = step(H,X)
Y = step(H,X,MEANRCS)
Y = step(H,X,UPDATERCS)
Y = step(H,X,MEANRCS,UPDATERCS)
Y = step(H,X,ANGLE_IN,LAXES)
Y = step(H,X,ANGLE_IN,ANGLE_OUT,LAXES)
Y = step(H,X,ANGLE_IN,LAXES,SMAT)
Y = step(H,X,ANGLE_IN,LAXES,UPDATESMAT)
Y = step(H,X,ANGLE_IN,ANGLE_OUT,LAXES,SMAT,UPDATESMAT)
Y = step(H,X)
returns the reflected signal Y
due
to the incident signal X
. The argument X
is
a complex-valued N-by-1 column
vector or N-by-M matrix. The
value M is the number of signals. Each signal corresponds
to a different target. The value N is the number
of samples in each signal. Use this syntax when you set the Model
property
of H
to 'Nonfluctuating'
.
In this case, the value of the MeanRCS
property
is used as the Radar cross-section (RCS) value.
This syntax applies only when the EnablePolarization
property
is set to false
. If you specify M incident
signal, you must specify the radar cross-section as a scalar or as
a 1-by-M vector. For a scalar, the same value will
be applied to all signals.
Y = step(H,X,MEANRCS)
uses MEANRCS
as
the mean RCS value. This syntax is available when you set the MeanRCSSource
property
to 'Input port'
and Model
is
set to 'Nonfluctuating'
. The value of MEANRCS
must
be a nonnegative scalar or 1-by-M row vector for
multiple targets. This syntax applies only when the EnablePolarization
property
is set to false
.
Y = step(H,X,UPDATERCS)
uses UPDATERCS
as
the indicator of whether to update the RCS value. This syntax is available
when you set the Model
property to 'Swerling1'
, 'Swerling2'
, 'Swerling3'
,
or 'Swerling4'
. If UPDATERCS
is true
,
a new RCS value is generated. If UPDATERCS
is false
,
the previous RCS value is used. This syntax applies only when the EnablePolarization
property
is set to false
. In this case, the value of the MeanRCS
property
is used as the radar cross-section (RCS) value.
Y = step(H,X,MEANRCS,UPDATERCS)
lets you
can combine optional input arguments when their enabling properties
are set. In this syntax, MeanRCSSource
is set
to 'Input port'
and Model
is
set to one of the Swerling
models. This syntax
applies only when the EnablePolarization
property
is set to false
. For this syntax, changes in MEANRCS
will
be ignored after the first call to the step
method.
returns
the reflected signal Y
= step(H
,X
,ANGLE_IN
,LAXES
)Y
from an incident signal X
.
This syntax applies only when the EnablePolarization
property
is set to true
. The input argument, ANGLE_IN
,
specifies the direction of the incident signal with respect to the
target's local coordinate system. The input argument, LAXES
,
specifies the direction of the local coordinate axes with respect
to the global coordinate system. This syntax requires that you set
the Model
property to 'Nonfluctuating'
and
the Mode
property to 'Monostatic'
.
In this case, the value of the ScatteringMatrix
property
is used as the scattering matrix value.
X
is a 1-by-M row array
of MATLAB^{®} struct
type, each member of the
array representing a different signal. The struct
contains
three fields, X.X
, X.Y
, and X.Z
.
Each field corresponds to the x, y,
and z components of the polarized input signal.
Polarization components are measured with respect to the global coordinate
system. Each field is a column vector representing a sequence of values
for each incoming signal. The X.X
, X.Y
,
and Y.Z
fields must all have the same dimension.
The argument, ANGLE_IN
, is a 2-by-M matrix
representing the signals' incoming directions with respect
to the target's local coordinate system. Each column of ANGLE_IN
specifies
the incident direction of the corresponding signal in the form [AzimuthAngle;
ElevationAngle]
. Angle units are in degrees. The number
of columns in ANGLE_IN
must equal the number
of signals in the X
array. The argument, LAXES,
is
a 3-by-3 matrix. Each column is a unit vector specifying the local
coordinate system's orthonormal x, y,
and z axes, respectively, with respect to the global
coordinate system. Each columns is written in [x;y;z]
form.
Y
is a row array of struct
type
having the same size as X
. Each struct
contains
the three reflected polarized fields, Y.X
, Y.Y
,
and Y.Z
. Each field corresponds to the x, y,
and z component of the signal. Polarization components
are measured with respect to the global coordinate system. Each field
is a column vector representing one reflected signal.
,
in addition, specifies the reflection angle, Y
= step(H
,X
,ANGLE_IN
,ANGLE_OUT
,LAXES
)ANGLE_OUT
,
of the reflected signal when you set the Mode
property
to 'Bistatic'
. This syntax applies only when the EnablePolarization
property
is set to true
. ANGLE_OUT
is
a 2-row matrix representing the reflected direction of each signal.
Each column of ANGLE_OUT
specifies the reflected
direction of the signal in the form [AzimuthAngle; ElevationAngle]
.
Angle units are in degrees. The number of columns in ANGLE_OUT
must
equal the number of members in the X
array. The
number of columns in ANGLE_OUT
must equal the
number of elements in the X
array.
specifies Y
= step(H
,X
,ANGLE_IN
,LAXES
,SMAT
)SMAT
as
the scattering matrix. This syntax applies only when the EnablePolarization
property
is set to true
. The input argument SMAT
is
a 2-by-2 matrix. You must set the ScatteringMatrixSource
property 'Input
port'
to use SMAT
.
specifies Y
= step(H
,X
,ANGLE_IN
,LAXES
,UPDATESMAT
)UPDATESMAT
to
indicate whether to update the scattering matrix when you set the Model
property
to 'Swerling1'
, 'Swerling2'
', 'Swerling3'
,
or 'Swerling4'
. This syntax applies only when the EnablePolarization
property
is set to true
. If UPDATESMAT
is
set to true
, a scattering matrix value is generated.
If UPDATESMAT
is false
, the
previous scattering matrix value is used.
.
You can combine optional input arguments when their enabling properties
are set. Optional inputs must be listed in the same order as the order
of their enabling properties.Y
= step(H
,X
,ANGLE_IN
,ANGLE_OUT
,LAXES
,SMAT
,UPDATESMAT
)
Note:
The object performs an initialization the first time the |
For non-polarized waves, the reflected wave is given by:
$$Y=\sqrt{G}\cdot X$$
where:
X is the incoming signal
G is the target gain factor, a dimensionless quantity given by
$$G=\frac{4\pi \sigma}{{\lambda}^{2}}$$
σ is the mean radar cross-section (RCS) of the target
λ is the wavelength of the incoming signal
The incident signal on the target is scaled by the square root of the gain factor.
For polarized waves, the scattering equation is more complicated. The single scalar signal, X, is replaced by a vector signal, (E_{H}, E_{V}), with horizontal and vertical components. A scattering matrix, S, replaces the scalar cross-section, σ. Through the scattering matrix, the incident horizontal and vertical polarized signals are converted into the reflected horizontal and vertical polarized signals
$$\left[\begin{array}{c}{E}_{H}^{(scat)}\\ {E}_{V}^{(scat)}\end{array}\right]=\sqrt{\frac{4\pi}{{\lambda}^{2}}}\left[\begin{array}{cc}{S}_{HH}& {S}_{VH}\\ {S}_{HV}& {S}_{VV}\end{array}\right]\left[\begin{array}{c}{E}_{H}^{(inc)}\\ {E}_{V}^{(inc)}\end{array}\right]=\sqrt{\frac{4\pi}{{\lambda}^{2}}}\left[S\right]\left[\begin{array}{c}{E}_{H}^{(inc)}\\ {E}_{V}^{(inc)}\end{array}\right]$$
[1] Mott, H. Antennas for Radar and Communications.John Wiley & Sons, 1992.
[2] Richards, M. A. Fundamentals of Radar Signal Processing. New York: McGraw-Hill, 2005.
[3] Skolnik, M. Introduction to Radar Systems, 3rd Ed. New York: McGraw-Hill, 2001.