phased.ConformalArray System object

Package: phased

Conformal array

Description

The ConformalArray object constructs a conformal array. A conformal array can have elements in any position pointing in any direction.

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

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

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

Construction

H = phased.ConformalArray creates a conformal array System object™, H. The object models a conformal array formed with identical sensor elements.

H = phased.ConformalArray(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).

H = phased.ConformalArray(POS,NV,Name,Value) creates a conformal array object, H, with the ElementPosition property set to POS, the ElementNormal property set to NV, and other specified property Names set to the specified Values. POS and NV are value-only arguments. To specify a value-only argument, you must also specify all preceding value-only arguments. You can specify name-value arguments in any order.

Properties

Element

Element of array

Specify the element of the sensor array as a handle. The element must be an element object in the phased package.

Default: An isotropic antenna element that operates between 300 MHz and 1 GHz

ElementPosition

Element positions

ElementPosition specifies the positions of the elements in the conformal array. ElementPosition must be a 3-by-N matrix, where N indicates the number of elements in the conformal array. Each column of ElementPosition represents the position, in the form [x; y; z] (in meters), of a single element in the array's local coordinate system. The local coordinate system has its origin at an arbitrary point. The default value of this property represents a single element at the origin of the local coordinate system.

Default: [0; 0; 0]

ElementNormal

Element normal directions

ElementNormal specifies the normal directions of the elements in the conformal array. Angle units are degrees. The value assigned to ElementNormal must be either a 2-by-N matrix or a 2-by-1 column vector. The variable N indicates the number of elements in the array. If the value of ElementNormal is a matrix, each column specifies the normal direction of the corresponding element in the form [azimuth;elevation] with respect to the local coordinate system. The local coordinate system aligns the positive x-axis with the direction normal to the conformal array. If the value of ElementNormal is a 2-by-1 column vector, it specifies the same pointing direction for all elements in the array.

You can use the ElementPosition and ElementNormal properties to represent any arrangement in which pairs of elements differ by certain transformations. The transformations can combine translation, azimuth rotation, and elevation rotation. However, you cannot use transformations that require rotation about the normal.

Default: [0; 0]

Taper

Element taper or weighting

Element taper or weighting specified as a complex scalar or 1-by-N complex-valued vector. Weights are applied to each element in the sensor array. N is the number of elements along in the array as determined by the size of the ElementPosition property. If the Taper parameter is a scalar, identical weights will be applied to each element. If the value of Taper is a vector, each weight will be applied to the corresponding element.

Default: 1

Methods

cloneCreate conformal array object with same property values
collectPlaneWaveSimulate received plane waves
directivityDirectivity of conformal array
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 changes
stepOutput responses of array elements
viewArrayView array geometry

Examples

expand all

Plot Response of 8-Element Uniform Circular Array

Construct an 8-element uniform circular array (UCA) and plot its azimuth responses. Assume the operating frequency is 1 GHz and the wave propagation speed is 3e8 m/s.

N = 8;
azang = (0:N-1)*360/N-180;
ha = phased.ConformalArray(...
    'ElementPosition',[cosd(azang);sind(azang);zeros(1,N)],...
    'ElementNormal',[azang;zeros(1,N)]);
fc = 1e9;
c = 3e8;
plotResponse(ha,fc,c,'RespCut','Az','Format','Polar');

Plot Response and Directivity of 31-Element Uniform Circular Sonar Array

Construct a 31-element uniform circular sonar array (UCA), one meter in diameter. Using the ElevationAngles parameter, restrict the display to +/-40 degrees in 0.1 degree increments. Assume the operating frequency is 4 kHz. A typical value for the speed of sound in seawater is 1500.0 m/s.

N = 31;
theta = (0:N-1)*360/N-180;
Radius = 0.5;
s_mic = phased.OmnidirectionalMicrophoneElement(...
    'FrequencyRange',[0,10000],'BackBaffled',true);
s_array = phased.ConformalArray('Element',s_mic,...
    'ElementPosition',Radius*[zeros(1,N);cosd(theta);sind(theta)],...
    'ElementNormal',[ones(1,N);zeros(1,N)]);
fc = 4000;
c = 1500.0;
plotResponse(s_array,fc,c,'RespCut','El',...
    'Format','Polar','Unit','mag',...
    'ElevationAngles',[-40:0.1:40]);

Plot the directivity.

plotResponse(s_array,fc,c,'RespCut','El',...
    'Format','Polar','Unit','dbi',...
    'ElevationAngles',[-40:0.1:40]);

References

[1] Josefsson, L. and P. Persson. Conformal Array Antenna Theory and Design. Piscataway, NJ: IEEE Press, 2006.

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

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