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Conformal Array

Support for Arrays with Custom Geometry

The phased.ConformalArray object lets you model a phased array with arbitrary geometry. For example, you can use phased.ConformalArray to design:

  • A planar array with a nonrectangular geometry, such as a circular array

  • An array with nonuniform geometry, such as a linear array with variable spacing

  • A nonplanar array

When you use phased.ConformalArray, you must specify these aspects of the array:

  • Sensor element of the array

  • Element positions

  • Direction normal to each array element

Create Default Conformal Array

To create a conformal array with default properties, use this command:

array = phased.ConformalArray
array = 

  phased.ConformalArray with properties:

            Element: [1×1 phased.IsotropicAntennaElement]
    ElementPosition: [3×1 double]
      ElementNormal: [2×1 double]
              Taper: 1

This default conformal array consists of a single phased.IsotropicAntennaElement antenna located at the origin of the local coordinate system. The direction normal to the sensor element is 0° azimuth and 0° elevation.

Uniform Circular Array Created from Conformal Array

This example shows how to construct a 60-element uniform circular array. In constructing a uniform circular array, you can use either the phased.UCA or the phased.ConformalArray System object™. The conformal array approach is more general because it allows you to point the array elements in arbitrary directions. A UCA restricts the array element directions to lie in the plane of the array. This example illustrates how you can use the phased.ConformalArray System object™ to create any other array shape. Assume an operating frequency of 400 MHz. Tune the array by specifying the arclength between the elements to be 0.5λ where λ is the wavelength corresponding to the operating frequency. Array elements lie in the x-y-plane. Element normal directions are set to $(\phi_{n},0)$ where $\phi_{n}$ is the azimuth angle of the $n^{th}$ array element.

Set the number of elements and the operating frequency of the array.

N = 60;
fc = 400e6;

Compute the element spacing in radians.

theta = 360/N;
thetarad = deg2rad(theta);

Choose the radius so that the inter-element arclength is one-half wavelength.

arclength = 0.5*(physconst('LightSpeed')/fc);
radius = arclength/thetarad;

Compute the element azimuth angles. Azimuth angles must lie in the range (-180°,180°).

ang = (0:N-1)*theta;
ang(ang >= 180.0) = ang(ang >= 180.0) - 360.0;
array = phased.ConformalArray;
array.ElementPosition = [radius*cosd(ang);...
    radius*sind(ang);...
    zeros(1,N)];
array.ElementNormal = [ang;zeros(1,N)];

Show the UCA array geometry.

viewArray(array)

Plot the array response pattern at 1 GHz.

pattern(array,1e9,[-180:180],0,'PropagationSpeed',physconst('LightSpeed'),...
    'CoordinateSystem','polar','Type','powerdb','Normalize',true)

Custom Antenna Array

This example shows how to construct and visualize a custom-geometry array containing antenna elements with a custom radiation pattern. The radiation pattern of each element is constant over each azimuth angle and has a cosine pattern for the elevation angles.

Define the custom antenna element and plot its radiation pattern.

az = -180:180;
el = -90:90;
fc = 3e8;
elresp = cosd(el);
antenna = phased.CustomAntennaElement('AzimuthAngles',az,...
    'ElevationAngles',el,...
    'RadiationPattern',repmat(elresp',1,numel(az)));
pattern(antenna,3e8,0,el,'CoordinateSystem','polar','Type','powerdb',...
    'Normalize',true);

Define the locations and normal directions of the elements. All elements lie in the z-plane. The elements are located at (1;0;0) , (0;1;0), and (0;-1;0) meters. The element normal azimuth angles are 0°, 120°, and -120°, respectively. All normal elevation angles are 0°.

xpos = [1 0 0];
ypos = [0 1 -1];
zpos = [0 0 0];
normal_az = [0 120 -120];
normal_el = [0 0 0];

Define a conformal array with those elements.

array = phased.ConformalArray('Element',antenna,...
   'ElementPosition',[xpos; ypos; zpos],...
   'ElementNormal',[normal_az; normal_el]);

Plot the positions and normal directions of the elements.

viewArray(array,'ShowNormals',true)
view(0,90)

pattern(array,fc,az,el,'CoordinateSystem','polar','Type','powerdb',...
    'Normalize',true,'PropagationSpeed',physconst('LightSpeed'))


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