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**System object: **phased.RadarTarget

**Package: **phased

Reflect incoming signal

`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)`

Starting in R2016b, instead of using the `step`

method
to perform the operation defined by the System
object™, you can
call the object with arguments, as if it were a function. For example, ```
y
= step(obj,x)
```

and `y = obj(x)`

perform
equivalent operations.

`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
signals, you can 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.

The size of the first dimension of this input matrix can vary to simulate a changing signal length, such as a pulse waveform with variable pulse repetition frequency.

`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 set `Model`

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. The columns are unit vectors specifying the local
coordinate system's orthonormal *x*, *y*,
and *z* axes, respectively, with respect to the global
coordinate system. Each column 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.

The size of the first dimension of the matrix fields within
the `struct`

can vary to simulate a changing signal
length such as a pulse waveform with variable pulse repetition frequency.

,
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`

)

The object performs an initialization the first time the `step`

method
is executed. This initialization locks nontunable
properties (MATLAB) and input specifications, such as dimensions, complexity,
and data type of the input data. If you change a nontunable property
or an input specification, the System
object issues an error.
To change nontunable properties or inputs, you must first call the `release`

method
to unlock the object.

For a narrowband nonpolarized signal, the reflected signal, *Y*,
is

$$Y=\sqrt{G}\cdot X,$$

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 narrowband polarized waves, the single scalar signal, *X*,
is replaced by a vector signal, *(E _{H},
E_{V})*, with horizontal and vertical
components. The scattering matrix,

$$\left[\begin{array}{c}{E}_{H}^{(scat)}\\ {E}_{V}^{(scat)}\end{array}\right]=\sqrt{\frac{4\pi}{{\lambda}^{2}}}\left[\begin{array}{cc}{S}_{HH}& {S}_{VH}\\ {S}_{HV}& {S}_{VV}\end{array}\right]\left[\begin{array}{c}{E}_{H}^{(inc)}\\ {E}_{V}^{(inc)}\end{array}\right]=\sqrt{\frac{4\pi}{{\lambda}^{2}}}\left[S\right]\left[\begin{array}{c}{E}_{H}^{(inc)}\\ {E}_{V}^{(inc)}\end{array}\right]$$

[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.

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