phased.PartitionedArray

Phased array partitioned into subarrays

Description

The PartitionedArray object represents a phased array that is partitioned into one or more subarrays.

To obtain the response of the subarrays in a partitioned array:

1. Define and set up your partitioned array. See Construction.

2. Call step to compute the response of the subarrays according to the properties of phased.PartitionedArray. The behavior of step is specific to each object in the toolbox.

You can also specify a PartitionedArray object as the value of the SensorArray or Sensor property of objects that perform beamforming, steering, and other operations.

Note

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.

Construction

H = phased.PartitionedArray creates a partitioned array System object, H. This object represents an array that is partitioned into subarrays.

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

Properties

Array	Sensor array Sensor array, specified as any array System object belonging to Phased Array System Toolbox™. Default: phased.ULA('NumElements',4)
SubarraySelection	Subarray definition matrix Specify the subarray selection as an M-by-N matrix. M is the number of subarrays and N is the number of elements in the array. Each row of the matrix corresponds to a subarray and each entry in the row indicates whether or not an element belongs to the subarray. When the entry is zero, the element does not belong to the subarray. A nonzero entry represents a complex-valued weight applied to the corresponding element. Each row must contain at least one nonzero entry. The phase center of each subarray is at the subarray geometric center. The SubarraySelection and Array properties determine the geometric center. Default: [1 1 0 0; 0 0 1 1]
SubarraySteering	Subarray steering method Specify the method of subarray steering as either 'None' | 'Phase' | 'Time' | 'Custom'. When you set this property to 'Phase', a phase shifter is used to steer the subarray. Use the STEERANG argument of the step method to define the steering direction. When you set this property to 'Time', subarrays are steered using time delays. Use the STEERANG argument of the step method to define the steering direction. When you set this property to 'Custom', subarrays are steered by setting independent weights for all elements in each subarray. Use the WS argument of the step method to define the weights for all subarrays. Default: 'None'
PhaseShifterFrequency	Subarray phase shifter frequency Specify the operating frequency of phase shifters that perform subarray steering. The property value is a positive scalar in hertz. This property applies when you set the SubarraySteering property to 'Phase'. Default: 300e6
NumPhaseShifterBits	Number of phase shifter quantization bits The number of bits used to quantize the phase shift component of beamformer or steering vector weights. Specify the number of bits as a non-negative integer. A value of zero indicates that no quantization is performed. Default: 0

Methods

Specific to phased.PartitionedArray Object
beamwidth	Compute and display beamwidth for a subarray
collectPlaneWave	Simulate received plane waves
directivity	Directivity of partitioned array
getElementPosition	Positions of array elements
getNumElements	Number of elements in array
getNumSubarrays	Number of subarrays in array
getSubarrayPosition	Positions of subarrays in array
isPolarizationCapable	Polarization capability
pattern	Plot partitioned array directivity, field, and power patterns
patternAzimuth	Plot partitioned array directivity or pattern versus azimuth
patternElevation	Plot partitioned array directivity or pattern versus elevation
plotResponse	Plot response pattern of array
step	Output responses of subarrays
viewArray	View array geometry

Common to All System Objects
release	Allow System object property value changes

Examples

Azimuth Response of Partitioned ULA

Plot the azimuth response of a 4-element ULA partitioned into two 2-element ULA's. The element spacing is one-half wavelength.

Create the ULA, and partition it into two 2-element ULA's.

sULA = phased.ULA('NumElements',4,'ElementSpacing',0.5);
sPA = phased.PartitionedArray('Array',sULA,...
    'SubarraySelection',[1 1 0 0;0 0 1 1]);

Plot the azimuth response of the array. Assume the operating frequency is 1 GHz and the propagation speed is the speed of light.

fc = 1e9;
pattern(sPA,fc,[-180:180],0,'Type','powerdb',...
    'CoordinateSystem','polar',...
    'Normalize',true)

Response of Subarrays of Partitioned ULA

Create a 4-element ULA. Then partition the ULA into two 2-element ULAs. Then, calculate the response at boresight of a 4-element ULA partitioned into two 2-element ULAs.

sULA = phased.ULA('NumElements',4,'ElementSpacing',0.5);
sPA = phased.PartitionedArray('Array',sULA,...
   'SubarraySelection',[1 1 0 0;0 0 1 1]);

Calculate the response at 1 GHz. The signal propagation speed is the speed of light.

fc = 1e9;
resp = step(sPA,fc,[0;0],physconst('LightSpeed'))

resp = 2×1

     2
     2

Subarray Element Weights for Partitioned Array

Create a partitioned URA array with three subarrays of different sizes. The subarrays have 8, 16, and 32 elements. Use different sets of subarray element weights for each subarray.

Create a 4-by-56 element URA.

antenna = phased.IsotropicAntennaElement;
fc = 300e6;
c = physconst('LightSpeed');
lambda = c/fc;
n1 = 2^3;
n2 = 2^4;
n3 = 2^5;
nrows = 4;
ncols = n1 + n2 + n3;
array = phased.URA('Element',antenna,'Size',[nrows,ncols]);

Select the three subarrays by setting the selection matrix.

sel1 = zeros(nrows,ncols);
sel2 = sel1;
sel3 = sel1;
sel = zeros(3,nrows*ncols);
for r = 1:nrows
    sel1(r,1:n1) = 1;
    sel2(r,(n1+1):(n1+n2)) = 1;
    sel3(r,((n1+n2)+1):ncols) = 1;
end
sel(1,:) = sel1(:);
sel(2,:) = sel2(:);
sel(3,:) = sel3(:);

Create the partitioned array.

partarray = phased.PartitionedArray('Array',array, ...
    'SubarraySelection',sel,'SubarraySteering','Custom');
viewArray(partarray,'ShowSubarray','All');

Set weights for each subarray and get the response of each subarray. Put the weights in a cell array.

wts1 = ones(nrows*n1,1);
wts2 = 1.5*ones(nrows*n2,1);
wts3 = 3*ones(nrows*n3,1);
resp = partarray(fc,[30;0],c,{wts1,wts2,wts3})

resp = 3×1 complex

   0.0246 + 0.0000i
   0.0738 - 0.0000i
   0.2951 - 0.0000i

References

[1] Van Trees, H.L. Optimum Array Processing. New York: Wiley-Interscience, 2002.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• pattern, patternAzimuth, patternElevation, plotResponse, and viewArray methods are not supported.

• See System Objects in MATLAB Code Generation (MATLAB Coder).