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# Documentation

Package: phased

## Description

To compute the signal reflected from a radar target:

2. Call step to compute the reflected signal according to the properties of phased.RadarTarget. The behavior of step is specific to each object in the toolbox.

## Construction

H = phased.RadarTarget creates a radar target System object™, H, that computes the reflected signal from a target.

H = phased.RadarTarget(Name,Value) creates a radar target object, H, with each specified property set to the specified value. You can specify additional name-value pair arguments in any order as (Name1,Value1,...,NameN,ValueN).

## Properties

EnablePolarization

Allow polarized signals

Set this property to true to allow the target to simulate the reflection of polarized radiation. Set this property to false to ignore polarization.

Default: false

Mode

Target scattering mode

Target scattering mode specified as one of 'Monostatic' or 'Bistatic'. If you set this property to 'Monostatic', the signal's reflection direction is the opposite to its incoming direction. If you set this property to 'Bistatic', the signal's reflection direction differs from its incoming direction. This property applies when you set the EnablePolarization property to true.

Default: 'Monostatic'

ScatteringMatrixSource

Source of target mean scattering matrix

Source of target mean scattering matrix specified as one of 'Property' or 'Input port'. If you set the ScatteringMatrixSource property to 'Property', the target's mean scattering matrix is determined by the value of the ScatteringMatrix property. If you set this property to 'Input port', the mean scattering matrix is determined by an input argument of the step method. This property applies only when you set the EnablePolarization property to true. When the EnablePolarization property is set to false, use the MeanRCSSource property instead, together with the MeanRCS property, if needed.

Default: 'Property'

ScatteringMatrix

Mean radar scattering matrix specified as a 2-by-2 matrix. This matrix represents the mean value of the target's radar cross-section (in square meters). The matrix has the form [s_hh s_hv;s_vh s_vv]. In this matrix, the component s_hv specifies the complex scattering response when the input signal is vertically polarized and the reflected signal is horizontally polarized. The other components are defined similarly. This property applies when you set the ScatteringMatrixSource property to 'Property' and the EnablePolarization property to true. When the EnablePolarization property is set to false, use the MeanRCS property instead, together with the MeanRCSSource property. This property is tunable.

Default: [1 0;0 1]

MeanRCSSource

Source of mean radar cross section

Specify whether the target's mean RCS value comes from the MeanRCS property of this object or from an input argument in step. Values of this property are:

 'Property' The MeanRCS property of this object specifies the mean RCS value. 'Input port' An input argument in each invocation of step specifies the mean RCS value.

When EnablePolarization property is set to true, use the ScatteringMatrixSource property together with the ScatteringMatrix property if needed.

Default: 'Property'

MeanRCS

Specify the mean value of the target's radar cross section (in square meters) as a nonnegative scalar. This property applies when the MeanRCSSource property is 'Property'. This property is tunable.

When EnablePolarization property is set to true, use the ScatteringMatrix property together with the ScatteringMatrixSource.

Default: 1

Model

Target statistical model

Specify the statistical model of the target as one of 'Nonfluctuating', 'Swerling1', 'Swerling2', 'Swerling3', or 'Swerling4'. If you set this property to a value other than 'Nonfluctuating', you must use the UPDATERCS input argument when invoking step.

Default: 'Nonfluctuating'

PropagationSpeed

Signal propagation speed

Specify the propagation speed of the signal, in meters per second, as a positive scalar.

Default: Speed of light

OperatingFrequency

Signal carrier frequency

Specify the carrier frequency of the signal you are reflecting from the target, as a scalar in hertz. The default value of this property corresponds to 300 MHz.

Default: 3e8

SeedSource

Source of seed for random number generator

Specify how the object generates random numbers. Values of this property are:

 'Auto' The default MATLAB® random number generator produces the random numbers. Use 'Auto' if you are using this object with Parallel Computing Toolbox™ software. 'Property' The object uses its own private random number generator to produce random numbers. The Seed property of this object specifies the seed of the random number generator. Use 'Property' if you want repeatable results and are not using this object with Parallel Computing Toolbox software.

The random numbers are used to model random RCS values. This property applies when the Model property is 'Swerling1', 'Swerling2','Swerling3', or 'Swerling4'.

Default: 'Auto'

Seed

Seed for random number generator

Specify the seed for the random number generator as a scalar integer between 0 and 232–1. This property applies when you set the SeedSource property to 'Property'.

Default: 0

## Methods

 clone Create radar target object with same property values getNumInputs Number of expected inputs to step method getNumOutputs Number of outputs from step method isLocked Locked status for input attributes and nontunable properties release Allow property value and input characteristics changes reset Reset states of radar target object step Reflect incoming signal

## Examples

Calculate the reflected signal from a nonfluctuating point target.

```x = ones(10,1);
y = step(hr,x);```

## Algorithms

The reflected signal 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 RCS of the target

• λ is the wavelength of the incoming signal

Each element of the signal incident on the target is scaled by the gain factor.

For polarized waves, the scattering equation is more complicated. The single scalar signal, X, is replaced by a vector signal, (EH, EV), 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

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

For further details, see Mott, [1] or Richards, [2] .

## References

[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.