# phased.ReplicatedSubarray.step

Output responses of subarrays

## Description

**Note**

The object performs an initialization the first time the object is executed. This
initialization locks nontunable properties
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.

## Examples

### Subarray Response

Calculate the response at boresight for two 2-element ULA arrays that form subarrays of a 4-element ULA array of short-dipole antenna elements.

Create a two-element ULA of short-dipole antenna elements. Then, arrange two copies to form a 4-element ULA.

antenna = phased.ShortDipoleAntennaElement; array = phased.ULA('Element',antenna,'NumElements',2,'ElementSpacing',0.5); replicatedarray = phased.ReplicatedSubarray('Subarray',array,... 'Layout','Rectangular','GridSize',[1 2],... 'GridSpacing','Auto');

Find the response of each subarray at boresight. Assume the operating frequency is 1 GHz and the wave propagation speed is the speed of light.

```
c = physconst('LightSpeed');
resp = replicatedarray(1.0e9,[0;0],c)
```

`resp = `*struct with fields:*
H: [2x1 double]
V: [2x1 double]

### Independently Steered Replicated Subarrays

Create an array consisting of three copies of a 4-element ULA having elements spaced 1/2 wavelength apart. The array operates at 300 MHz.

```
c = physconst('LightSpeed');
fc = 300e6;
lambda = c/fc;
subarray = phased.ULA(4,0.5*lambda);
```

Steer all subarrays by a common phase shift to 10 degrees azimuth.

array = phased.ReplicatedSubarray('Subarray',subarray,'GridSize',[1 3], ... 'SubarraySteering','Phase','PhaseShifterFrequency',fc); steer_ang = [10;0]; sv_array = phased.SteeringVector('SensorArray',array,... 'PropagationSpeed',c); wts_array = sv_array(fc,steer_ang); pattern(array,fc,-90:90,0,'CoordinateSystem','Rectangular',... 'Type','powerdb','PropagationSpeed',c,'Weights',wts_array,... 'SteerAngle',steer_ang); legend('phase-shifted subarrays')

Compute independent subarray weights from subarray steering vectors. The weights point to 5, 15, and 30 degrees azimuth. Set the `SubarraySteering`

property to `'Custom'`

.

steer_ang_subarrays = [5 15 30;0 0 0]; sv_subarray = phased.SteeringVector('SensorArray',subarray,... 'PropagationSpeed',c); wc = sv_subarray(fc,steer_ang_subarrays); array.SubarraySteering = 'Custom'; pattern(array,fc,-90:90,0,'CoordinateSystem','Rectangular',... 'Type','powerdb','PropagationSpeed',c,'Weights',wts_array,... 'ElementWeight',conj(wc)); legend('independent subarrays') hold off

## Input Arguments

`H`

— Replicated subarray

`phased.ReplicatedSubarray`

System
object (default)

Phased array formed by replicated subarrays.

`FREQ`

— Operating frequencies

length *L* row vector

Operating frequencies of array. `FREQ`

is a row vector
of length L. Typical values are within the range specified by a property of
`H.Subarray.Element`

. That property is named
`FrequencyRange`

or `FrequencyVector`

,
depending on the type of element in the array. The element has zero response
at frequencies outside that range. Units are in Hz.

**Example: **`[3.0e6 3.2e6]`

**Data Types: **`double`

`ANG`

— Direction angles

real-valued length-*M* row vector | real-valued 2-by-*M* matrix

Directions in degrees. `ANG`

can be either a 2-by-M
matrix or a row vector of length M.

If `ANG`

is a 2-by-M matrix, each column of the matrix
specifies the direction in the form [azimuth; elevation]. The azimuth angle
must be between –180 and 180 degrees, inclusive. The elevation angle must be
between –90 and 90 degrees, inclusive.

If `ANG`

is a row vector of length M, each element
specifies a direction’s azimuth angle. In this case, the corresponding
elevation angle is assumed to be 0.

**Example: **`[10 11 12]`

**Data Types: **`double`

`V`

— Propagation speed

positive scalar

Propagation speed in meters per second. This value must be a scalar.

**Example: **`physconst('LightSpeed')`

**Data Types: **`double`

`STEERANGLE`

— Steer angles

scalar (default) | real-valued 2-element column vector

Subarray steering direction. `STEERANGLE`

can be either
a 2-element column vector or a scalar.

If this argument is a 2-element column vector, it has the form [azimuth; elevation]. The azimuth angle must be between –180° and 180°, inclusive. The elevation angle must be between –90° and 90°, inclusive.

If `STEERANGLE`

is a scalar, it specifies the
direction’s azimuth angle. In this case, the elevation angle is assumed to
be 0°.

**Example: **`[20;-30]`

#### Dependencies

To enable this argument, set the `SubarraySteering`

to `'Phase'`

or `'Time'`

.

**Data Types: **`double`

`WS`

— Subarray element weights

complex-valued
*N*_{SE}-by-*N*
matrix

_{SE}

Subarray element weights

Subarray element weights, specified as complex-valued
*N _{SE}*-by-

*N*matrix. Weights are applied to the individual elements within a subarray. All subarrays have the same dimensions and sizes.

*N*is the number of elements in each subarray and

_{SE}*N*is the number of subarrays. Each column of the matrix specifies the weights for the corresponding subarray.

#### Dependencies

To enable this argument, set the `SubarraySteering`

to `'Custom'`

.

**Data Types: **`double`

**Complex Number Support: **Yes

## Output Arguments

`RESP`

— Voltage response

complex-valued
*N*-by-*M*-by-*L*
array | `struct`

Voltage responses of the subarrays of the phased array. The output depends on whether the array supports polarization or not.

If the array is not capable of supporting polarization, the voltage response,

`RESP`

, has the dimensions*N*-by-*M*-by-*L*. The first dimension,*N*, represents the number of subarrays in the phased array, the second dimension,*M*, represents the number of angles specified in`ANG`

, while*L*represents the number of frequencies specified in`FREQ`

. Each column of`RESP`

contains the responses of the subarrays for the corresponding direction specified in`ANG`

. Each of the*L*pages of`RESP`

contains the responses of the subarrays for the corresponding frequency specified in`FREQ`

.If the array is capable of supporting polarization, the voltage response,

`RESP`

, is a MATLAB^{®}`struct`

containing two fields,`RESP.H`

and`RESP.V`

, each having dimensions*N*-by-*M*-by-*L*. The field,`RESP.H`

, represents the array’s horizontal polarization response, while`RESP.V`

represents the array’s vertical polarization response. The first dimension,*N*, represents the number of subarrays in the phased array, the second dimension,*M*, represents the number of angles specified in`ANG`

, while*L*represents the number of frequencies specified in`FREQ`

. Each of the*M*columns contains the responses of the subarrays for the corresponding direction specified in`ANG`

. Each of the*L*pages contains the responses of the subarrays for the corresponding frequency specified in`FREQ`

.

**Data Types: **`double`

**Complex Number Support: **Yes

## Version History

**Introduced in R2012a**

## See Also

## MATLAB Command

You clicked a link that corresponds to this MATLAB command:

Run the command by entering it in the MATLAB Command Window. Web browsers do not support MATLAB commands.

Select a Web Site

Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select: .

You can also select a web site from the following list:

## How to Get Best Site Performance

Select the China site (in Chinese or English) for best site performance. Other MathWorks country sites are not optimized for visits from your location.

### Americas

- América Latina (Español)
- Canada (English)
- United States (English)

### Europe

- Belgium (English)
- Denmark (English)
- Deutschland (Deutsch)
- España (Español)
- Finland (English)
- France (Français)
- Ireland (English)
- Italia (Italiano)
- Luxembourg (English)

- Netherlands (English)
- Norway (English)
- Österreich (Deutsch)
- Portugal (English)
- Sweden (English)
- Switzerland
- United Kingdom (English)