phased.URA System object

Package: phased

Uniform rectangular array

Description

The URA object constructs a uniform rectangular array (URA).

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

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

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

Construction

H = phased.URA creates a uniform rectangular array System object™, H. The object models a URA formed with identical sensor elements. Array elements are distributed in the yz-plane in a rectangular lattice. The array look direction (boresight) is along the positive x-axis.

H = phased.URA(Name,Value) creates the 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.URA(SZ,D,Name,Value) creates a URA object, H, with the Size property set to SZ, the ElementSpacing property set to D and other specified property Names set to the specified Values. SZ and D are value-only arguments. To specify a value-only argument, you must also specify all preceding value-only arguments. You can specify name-value pair arguments in any order.

Properties

Element

Phased array toolbox system object

Element specified as a Phased Array System Toolbox object. This object can be an antenna or microphone element.

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

Size

Size of array

A 1-by-2 integer vector or a single integer containing the size of the array. If Size is a 1-by-2 vector, the vector has the form [NumberOfRows, NumberOfColumns]. If Size is a scalar, the array has the same number of elements in each row and column. For a URA, array elements are indexed from top to bottom along a column and continuing to the next columns from left to right. In this illustration, a 'Size' value of [3,2] array has three rows and two columns.

Default: [2 2]

ElementSpacing

Element spacing

A 1-by-2 vector or a scalar containing the element spacing of the array, expressed in meters. If ElementSpacing is a 1-by-2 vector, it is in the form of [SpacingBetweenRows,SpacingBetweenColumns]. See Spacing Between Columns and Spacing Between Rows. If ElementSpacing is a scalar, both spacings are the same.

Default: [0.5 0.5]

Lattice

Element lattice

Specify the element lattice as one of 'Rectangular' | 'Triangular'. When you set the Lattice property to 'Rectangular', all elements in the URA are aligned in both row and column directions. When you set the Lattice property to 'Triangular', the elements in even rows are shifted toward the positive row axis direction by a distance of half the element spacing along the row.

Default: 'Rectangular'

Taper

Element taper

Element taper specified as a scalar or M-by-N complex-valued matrix. Tapers are applied to each element in the sensor array. Tapers are often referred to as element weights. M is the number of elements along the z-axis, and N is the number of elements along y-axis. M and N correspond to the values of [NumberofRows, NumberOfColumns] in the Size property. If Taper is a scalar, identical weights are applied to each element. If the value of Taper is a matrix, a taper value is applied to the corresponding element.

Default: 1

Methods

cloneCreate URA object with same property values
collectPlaneWaveSimulate received plane waves
directivityDirectivity of uniform rectangular 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
plotGratingLobeDiagramPlot grating lobe diagram of array
plotResponsePlot response pattern of array
releaseAllow property value and input characteristics
stepOutput responses of array elements
viewArrayView array geometry

Definitions

Spacing Between Columns

The spacing between columns is the distance between adjacent elements in the same row.

Spacing Between Rows

The spacing between rows is the distance along the column axis direction between adjacent rows.

Examples

expand all

Azimuth Response of a 3-by-2 URA at Boresight

This example shows how to construct a 3-by-2 rectangular lattice URA. Find the response of each element at boresight. Assume the operating frequency is 1 GHz.

ha = phased.URA('Size',[3 2]);
fc = 1e9; ang = [0;0];
resp = step(ha,fc,ang);
disp(resp)
     1
     1
     1
     1
     1
     1

Plot the azimuth response of the array.

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

Compare Triangular and Rectangular Lattice URA's

This example shows how to find and plot the positions of the elements of a 5-row-by-6-column URA with a triangular lattice and a URA with a rectangular lattice. The element spacing is 0.5 meters for both lattices.

Create the arrays.

h_tri = phased.URA('Size',[5 6],'Lattice','Triangular');
h_rec = phased.URA('Size',[5 6],'Lattice','Rectangular');

Get the element y,z positions for each array. All the x coordinates are zero.

pos_tri = getElementPosition(h_tri);
pos_rec = getElementPosition(h_rec);
pos_yz_tri = pos_tri(2:3,:);
pos_yz_rec = pos_rec(2:3,:);

Plot the element positions in the yz-plane.

figure;
gcf.Position = [100 100 300 400];
subplot(2,1,1);
plot(pos_yz_tri(1,:), pos_yz_tri(2,:), '.')
axis([-1.5 1.5 -2 2])
xlabel('y'); ylabel('z')
title('Triangular Lattice')
subplot(2,1,2);
plot(pos_yz_rec(1,:), pos_yz_rec(2,:), '.')
axis([-1.5 1.5 -2 2])
xlabel('y'); ylabel('z')
title('Rectangular Lattice')

Adding Tapers to an Array

Construct a 5-by-2 element URA with a Taylor window taper along each column. The tapers form a 5-by-2 matrix.

taper = taylorwin(5);
ha = phased.URA([5,2],'Taper',[taper,taper]);
w = getTaper(ha)
w =

    0.5181
    1.2029
    1.5581
    1.2029
    0.5181
    0.5181
    1.2029
    1.5581
    1.2029
    0.5181

References

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

[2] Brookner, E., ed. Practical Phased Array Antenna Systems. Boston: Artech House, 1991.

[3] Mailloux, R. J. "Phased Array Theory and Technology," Proceedings of the IEEE, Vol., 70, Number 3s, pp. 246–291.

[4] Mott, H. Antennas for Radar and Communications, A Polarimetric Approach. New York: John Wiley & Sons, 1992.

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

Was this topic helpful?