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phased.HeterogeneousULA System object

Package: phased

Heterogeneous uniform linear array

Description

The phased.HeterogeneousULA object creates a uniform linear array from a heterogeneous set of antenna elements. A heterogeneous array is an array in which the antenna or microphone elements may be of different kinds or have different properties. An example would be an array of elements each having different antenna patterns.

To compute the response for each element in the array for specified directions:

  1. Define and set up your uniform linear array. See Construction.

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

Construction

H = phased.HeterogeneousULA creates a heterogeneous uniform linear array (ULA) System object™, H. The object models a heterogeneous ULA formed with generally different sensor elements. The origin of the local coordinate system is the phase center of the array. The positive x-axis is the direction normal to the array, and the elements of the array are located along the y-axis.

H = phased.HeterogeneousULA(Name,Value) creates 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

ElementSet

Set of elements used in the array

Specify the set of different elements used in the sensor array as a row MATLAB cell array. Each member of the cell array contains an element object in the phased package. Elements specified in the ElementSet property must be either all antennas or all microphones. In addition, all specified antenna elements should have same polarization capability. Specify the element of the sensor array as a handle. The element must be an element object in the phased package.

Default: One cell containing one isotropic antenna element

ElementIndices

Elements location assignment

This property specifies the mapping of elements in the array. The property assigns elements to their locations in the array using indices into the ElementSet property. ElementIndices must be a 1-by-N row vector where N is greater than 1. N is the number of elements in the sensor array. The values in ElementIndices should be less than or equal to the number of entries in the ElementSet property.

Default: [1 1]

ElementSpacing

Element spacing

A scalar containing the spacing (in meters) between two adjacent elements in the array.

Default: 0.5

Taper

Element tapering

Element tapering specified as a complex-valued scalar or a complex-valued 1-by-N row vector. N is the number of elements in the array as determined by the size of the ElementIndices property. Tapers, also known as weights, are applied to each sensor element in the sensor array and modify both the amplitude and phase of the received data. If 'Taper' is a scalar, the same weights are applied to each element. If 'Taper' is a vector, each weight is applied to the corresponding sensor element.

Default: 1

Methods

cloneCreate new system object with identical values
collectPlaneWaveSimulate received plane waves
getElementPositionPositions of array elements
getNumElementsNumber of elements in array
getNumInputsNumber of expected inputs to step method
getNumOutputsNumber of outputs from step method
getTaperArray element tapers
isLockedLocked status for input attributes and nontunable properties
isPolarizationCapablePolarization capability
plotResponsePlot response pattern of array
releaseAllow property value and input characteristics
stepOutput responses of array elements
viewArrayView array geometry

Examples

expand all

Response of 10-Element Heterogeneous ULA Array

Create a 10-element heterogeneous ULA consisting of cosine antenna elements with different power factors. Two elements at each end have power values of 1.5 while the inside elements have power values of 1.8. Find the response of each element at boresight.

Construct the heterogeneous array and show the element responses at 1 GHz.

sElement1 = phased.CosineAntennaElement('CosinePower',1.5);
sElement2 = phased.CosineAntennaElement('CosinePower',1.8);
sArray = phased.HeterogeneousULA(...
    'ElementSet',{sElement1,sElement2},...
    'ElementIndices',[1 1 2 2 2 2 2 2 1 1 ]);
fc = 1e9;
ang = [0;0];
resp = step(sArray,fc,ang)
resp =

     1
     1
     1
     1
     1
     1
     1
     1
     1
     1

Plot an azimuth cut of the array response at 1 GHz.

c = physconst('LightSpeed');
plotResponse(sArray,fc,c,'RespCut','Az','Format','Polar');

Response of an Array of Polarized Short-Dipole Antennas

Build a heterogeneous uniform line array of 10 short-dipole sensor elements. Because short dipoles support polarization, the array should also. Verify that the array supports polarization by looking at the output of isPolarizationCapable. Then, draw the array, showing the tapering.

Build the array. Then, verify that it supports polarization by looking at the returned value of the isPolarizationCapable method.

sElement1 = phased.ShortDipoleAntennaElement(...
    'FrequencyRange',[100e6 1e9],...
    'AxisDirection','Z');
sElement2 = phased.ShortDipoleAntennaElement(...
    'FrequencyRange',[100e6 1e9],...
    'AxisDirection','Y');
sArray = phased.HeterogeneousULA(...
    'ElementSet',{sElement1,sElement2},...
    'ElementIndices',[1 1 2 2 2 2 2 2 1 1 ],...
    'Taper',taylorwin(10)');
isPolarizationCapable(sArray)
ans =

     1

View the array.

viewArray(sArray,'ShowTaper',true,'ShowIndex',...
    'All','ShowTaper',true)

Show the element horizontal polarization responses at 10 degrees azimuth angle.

fc = 150e6;
ang = [10];
resp = step(sArray,fc,ang)
resp.H
resp = 

    H: [10x1 double]
    V: [10x1 double]


ans =

         0
         0
   -1.2442
   -1.6279
   -1.8498
   -1.8498
   -1.6279
   -1.2442
         0
         0

Plot the combined polarization response.

c = physconst('LightSpeed');
plotResponse(sArray,fc,c,'RespCut','Az','Format',...
    'Polar','Polarization','C');

References

[1] Brookner, E., ed. Radar Technology. Lexington, MA: LexBook, 1996.

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

See Also

phased.CrossedDipoleAntennaElement | | | phased.ShortDipoleAntennaElement | | | |

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