conformalArray

Create conformal antenna array

Description

The conformalArray class creates an antenna array using any element from the antenna or array library. You can also specify an array of any arbitrary geometry, such as a circular array, a nonplanar array, an array with nonuniform geometry, or a conformal array of arrays.

Conformal arrays are used in:

• Direction-finding systems that use circular arrays or stacked circular arrays

• Aircraft systems due to surface irregularities or mechanical stress

Creation

Syntax

array = conformalArray

array = conformalArray(Name=Value)

Description

array = conformalArray creates a conformal antenna array using the default antenna element, shape, and antenna positions.

array = conformalArray(Name=Value) creates a conformal antenna array with additional properties specified by one or more name-value arguments. Name is the property name and Value is the corresponding value. You can specify several name-value arguments in any order as Name1=Value1, ..., NameN=ValueN. Properties not specified retain default values.

Properties

ElementPosition — Position of feed or origin

[0 0 0; 0 0 0.1500] (default) | M-by-3 real matrix

Position of the feed or origin for each antenna element, specified as an M-by-3 real matrix. M is the number of element positions. By default, M is 2. To specify additional antenna elements, add additional element positions in the conformal array.

Example: [0.1 0.1 0.1; -0.1 -0.1 -0.1; 0.2 0.2]

Data Types: double

Element — Individual antenna or array elements, or backing structure without exciter

1-by-M cell array of antenna, array objects, or backing structures

Individual antenna or array elements or backing structure without exciter (cavity or reflector), specified as a 1-by-M cell array, where M is the number of positions defined by the ElementPosition property. By default, a conformal array has two elements, a dipole and a bowtie antenna. To specify additional elements, add more element positions to the conformal array. You can add balanced and unbalanced antennas to the same conformal array. You can also add cavity and reflector backing structures without an exciter as elements of the conformal array.

A conformal array cannot have only backing structure as the element. Specify at least one antenna or array element in addition to the backing structure.

Example: conformalArray(Element={monopole monopole}) creates a conformal array consisting of two monopole antenna elements.

Example: conformalArray(Element={linearArray rectangularArray}) creates a conformal array consisting of a linear array and a rectangular array.

Example: ca =conformalArray;ca.Element={cavity(Exciter=[]) ca.Element{2}}; creates a conformal array of a cavity backing structure and a bowtie antenna element.

Data Types: cell

Reference — Position reference for antenna element

"feed" (default) | "origin"

Position reference for the antenna element, specified as either "origin" or "feed". For more information, see Position Reference.

Example: "origin"

Data Types: string

AmplitudeTaper — Excitation amplitude of antenna elements

1 (default) | scalar | nonnegative vector

Excitation amplitude of the antenna elements, specified as a scalar or a nonnegative vector. To model dead elements, set the property value to 0.

Example: 3

Example: [3 0]. Creates a two-element conformal array with the excitation amplitudes of the two elements equal to 3 and 0 respectively.

Data Types: double

PhaseShift — Phase shift for antenna elements

0 (default) | scalar | real vector

Phase shift for antenna elements, specified as a scalar or a real vector in degrees.

Example: [-45 -45 45 45]

Data Types: double

Tilt — Tilt angle of array

0 (default) | scalar | vector

Tilt angle of the array specified as a scalar or vector with each element unit in degrees. For more information, see Rotate Antennas and Arrays.

Example: Tilt=90,

Example: Tilt=[90 90],TiltAxis=[0 1 0;0 1 1] tilts the array at 90 degrees about the two axes, defined by vectors.

Data Types: double

TiltAxis — Tilt axis of array

[1 0 0] (default) | three-element vector of Cartesian coordinates | two three-element vectors of Cartesian coordinates | 'X' | 'Y' | 'Z'

Tilt axis of the array, specified as:

• Three-element vectors of Cartesian coordinates in meters. In this case, each vector starts at the origin and lies along the specified points on the X-, Y-, and Z-axes.

• Two points in space, each specified as three-element vectors of Cartesian coordinates. In this case, the array rotates around the line joining the two points in space.

• A string input describing simple rotations around one of the principal axes, 'X', 'Y', or 'Z'.

For more information, see Rotate Antennas and Arrays.

Example: TiltAxis=[0 1 0]

Example: TiltAxis=[0 0 0;0 1 0]

Example: TiltAxis='Z'

Data Types: double

Object Functions

show	Display antenna, array structures or shapes
info	Display information about antenna or array
beamwidth	Beamwidth of antenna
charge	Charge distribution on antenna or array surface
correlation	Correlation coefficient between two antennas in array
current	Current distribution on antenna or array surface
design	Design prototype antenna or arrays for resonance around specified frequency
doa	Direction of arrival of signal
efficiency	Radiation efficiency of antenna
EHfields	Electric and magnetic fields of antennas; Embedded electric and magnetic fields of antenna element in arrays
impedance	Input impedance of antenna; scan impedance of array
layout	Display array or PCB stack layout
mesh	Mesh properties of metal, dielectric antenna, or array structure
optimize	Optimize antenna or array using SADEA optimizer
pattern	Radiation pattern and phase of antenna or array; Embedded pattern of antenna element in array
patternAzimuth	Azimuth pattern of antenna or array
patternElevation	Elevation pattern of antenna or array
rcs	Calculate and plot radar cross section (RCS) of platform, antenna, or array
returnLoss	Return loss of antenna; scan return loss of array
sparameters	Calculate S-parameter for antenna and antenna array objects

Examples

Default Conformal Array

Create a default conformal array.

c = conformalArray

c = 
  conformalArray with properties:

            Element: {[1x1 dipole]  [1x1 bowtieTriangular]}
    ElementPosition: [2x3 double]
          Reference: 'feed'
     AmplitudeTaper: 1
         PhaseShift: 0
               Tilt: 0
           TiltAxis: [1 0 0]

show(c)

Circular Array of Dipoles

Define the radius and the number of elements for the array.

r = 2;
N = 12;

Create an array of 12 dipoles.

elem = repmat(dipole(Length=1.5),1,N);

Define the x,y,z values for the element positions in the array.

del_th = 360/N;
th = del_th:del_th:360;
x = r.*cosd(th);
y = r.*sind(th);
z = ones(1,N);
pos = [x;y;z];

Create a circular array using the defined dipoles and then visualize it. Display the layout of the array.

c = conformalArray(Element=elem,ElementPosition=pos');
show(c)

figure
layout(c)

Change the width of the fourth and the twelfth element of the circular array. Visualize the new arrangement.

c.Element(4).Width = 0.05;
c.Element(12).Width = 0.2;
figure
show(c)

Calculate and plot the impedance of the circular array at 100 MHz. The plot shows the impedance of the first element in the array.

figure
impedance(c,100e6)

To view the impedance of all the elements in the array change the value from 1 to 1:12 as shown in the figure.

Radiation Pattern of Concentric Array of Circular Loop Antennas

Define three circular loop antennas of radii 0.6366 m (default), 0.85 m, and 1 m, respectively.

l1 = loopCircular;
l2 = loopCircular(Radius=0.85);
l3 = loopCircular(Radius=1);

Create a concentric array that uses the origin of circular loop antennas as its position reference.

c = conformalArray(Element={l1 l2 l3},ElementPosition=[0 0 0; 0 0 0;...
     0 0 0],Reference="origin");
show(c)

Visualize the radiation pattern of the array at 80 MHz.

pattern(c,80e6)

Conformal Array Using Infinite Ground Plane Antenna

Create a dipole antenna to use in the reflector and the conformal array.

d = dipole(Length=0.13,Width=5e-3,Tilt=90,TiltAxis='Y');

Create an infinite groundplane reflector antenna using the dipole as exciter.

rf = reflector(Exciter=d,Spacing=0.15/2,GroundPlaneLength=inf);

Create a conformal array using 36 dipole antennas and one infinite groundplane reflector antenna. View the array.

x = linspace(-0.4,0.4,6);
y = linspace(-0.4,0.4,6);
[X,Y] = meshgrid(x,y);
pos = [X(:) Y(:) 0.15*ones(numel(X),1)];
for i = 1:36
    element{i} = d;
end
element{37} = rf;
lwa = conformalArray(Element=element,ElementPosition=[pos; 0 0 0.15/2]);
show(lwa)

Drive only the reflector antenna with an amplitude of 1.

V = zeros(1,37);
V(end) = 1;
lwa.AmplitudeTaper = V;

Compute the radiation pattern of the conformal array.

figure
pattern(lwa,1e9,Type='efield')

Conformal Array of Dielectric Antennas

Create two patch microstrip antennas using dielectric substrate FR4. Tilt the second patch microstrip antenna by 180 degrees.

p1 = patchMicrostrip(Substrate=dielectric('FR4'));
p2 = patchMicrostrip(Substrate=dielectric('FR4'),Tilt=180);

Create and view a conformal array using the two patch microstrip antennas placed 11 cm apart.

c = conformalArray(ElementPosition=[0 0 0; 0 0 0.1100],Element={p1 p2});
show(c)

Conformal Array Using Balanced and Unbalanced Antennas

Create a conformal array using dipole and monopole antennas and display it.

c = conformalArray(Element={dipole monopole},...
    ElementPosition=[0 0 0; 1.5 0 0]);
show(c)

Plot the radiation pattern of the array at 70 MHz.

pattern(c,70e6)

Subarrays of Linear Arrays

Create a subarray of linear arrays at different locations.

la = linearArray(ElementSpacing=1)

la = 
  linearArray with properties:

           Element: [1x1 dipole]
       NumElements: 2
    ElementSpacing: 1
    AmplitudeTaper: 1
        PhaseShift: 0
              Tilt: 0
          TiltAxis: [1 0 0]

subArr = conformalArray(Element=[la la],ElementPosition=[1 0 0; -1 1 0])

subArr = 
  conformalArray with properties:

            Element: [1x2 linearArray]
    ElementPosition: [2x3 double]
          Reference: 'feed'
     AmplitudeTaper: 1
         PhaseShift: 0
               Tilt: 0
           TiltAxis: [1 0 0]

show(subArr)

Conformal Array of Subarrays and Antennas

Create a linear array of dipoles with and element spacing of 1m.

la = linearArray(ElementSpacing=1);

Create a rectangular array of microstrip patch antennas.

ra = rectangularArray(Element=patchMicrostrip,RowSpacing=0.1,ColumnSpacing=0.1);

Create a subarray containing the above linear and rectangular arrays with changes in amplitude taper and phase shift values.

subArr = conformalArray(Element={la ra dipole},ElementPosition=[0 0 1.5; 0 0 0; 1 1 1],...
    AmplitudeTaper=[3 0.3 0.03],PhaseShift=[90 180 120]);
show(subArr)

Analyze Circular Cavity Structure in Conformal Array

This example shows how to create a circular cavity structure as an element in a conformalArray and plot its surface current distribution.

Create Circular Cavity Antenna

Create a circular cavity antenna operating at 1 GHz using the design function and the cavityCircular element from the antenna catalog. Display the antenna.

f = 1e9;
lambda = 3e8/f;
ant = design(cavityCircular,f);
figure
show(ant)

Derive Backing Structure

Derive the circular cavity backing structure from the cavity antenna by specifying the 'Exciter' property as an empty array. Display the backing structure.

ant.Exciter = [];
figure
show(ant)

Create Conformal Array

Create and display a conformal array with circular cavity as one of its elements.

ca = conformalArray;
ca.Reference = "origin";
ca.ElementPosition = [0 0 0; 0 0 0.25; 0 0 0.5];
ca.Element = {ca.Element{1} ant ca.Element{2}};
figure
show(ca)

Plot Surface Current Distribution

Calculate the current at the feed location and plot the surface current distribution of the conformal array at 1 GHz.

If = feedCurrent(ca,f)

If = 1×2 complex

   0.0024 - 0.0005i   0.0029 + 0.0007i

figure
current(ca,f,Scale="log10")

More About

Position Reference

Reference property of conformalArray object defines the position reference of an antenna element in 3–D space. You can position the antenna by specifying the Reference property as "feed" or "origin".

Choose the position reference as "feed" to move the antenna element with respect to the feed point so that the new feed location is at the specified coordinates. Following diagram shows a rectangular loop antenna and reflector-backed antenna before and after relocation with respect to the feed point:

Choose the position reference as "origin" to move the antenna element so that new antenna origin is at the specified coordinates. Following diagram shows a rectangular loop antenna and a reflector-backed antenna before and after the relocation with respect to origin:

References

[1] Balanis, Constantine A. Antenna Theory: Analysis and Design. 3rd Ed. New York: John Wiley and Sons, 2005.

Version History

Introduced in R2016a