Manipulate Array Elements

This example shows you how to control an individual element in a linear or rectangular array. You can use this technique to change the size and tilt of the antenna, or to model dead elements etc. with individual elements in an array.

Define Dipole Array

Create a dipole antenna using the dipole object. To create a 5-by-5 dipole array, replicate the dipole antenna using a 5-by-5 matrix. Create a rectangular array using the dipole array as a single element.

d = dipole;
N = 5;
df = repmat(d,N)

df = 
  5x5 dipole array with properties:

        Length: {25x1 cell}
         Width: {25x1 cell}
    FeedOffset: {25x1 cell}
     Conductor: {25x1 cell}
          Tilt: {25x1 cell}
      TiltAxis: {25x1 cell}
          Load: {25x1 cell}

r = rectangularArray(Element=df);
show(r)

Tilt Alternate Elements

Create a vector of alternate elements in the rectangular array.

S = 1:2:N*N;

Tilt the alternate elements in the array by 90 degrees about the y-axis.

for i = 1:25
    if any(S==i)
      r.Element(i).Tilt = 90;
	  r.Element(i).TiltAxis = [0 1 0];
    end
end
show(r)

Pattern of Rectangular Array

Plot the pattern of the array at 75 MHz.

pattern(r,75e6)

Model Dead Elements

Antennas with a zero excitation voltage feed are called dead elements. By default, each element in an array is excited by an amplitude of 1 V.

Vfeed = ones(1,N*N)

Vfeed = 1×25

     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1     1

To model dead elements, set the voltage to zero for all horizontal elements. To control voltage, use the AmplitudeTaper property. This property is the excitation amplitude of the antennas in an array.

Vfeed(S) = 0

Vfeed = 1×25

     0     1     0     1     0     1     0     1     0     1     0     1     0     1     0     1     0     1     0     1     0     1     0     1     0

r.AmplitudeTaper = Vfeed

r = 
  rectangularArray with properties:

           Element: [5x5 dipole]
              Size: [5 5]
        RowSpacing: 2
     ColumnSpacing: 2
           Lattice: 'Rectangular'
    AmplitudeTaper: [0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0]
        PhaseShift: 0
              Tilt: 0
          TiltAxis: [1 0 0]

Plot the radiation pattern of the array.

figure
pattern(r,75e6)