Rotation of polar beam pattern using ULA.

Hi,

I would like to steer the beam pattern of a ULA so its at -25° and 25°.

My code is shown below:

c = 3e8;

fc = 2e9;

lambda = c/fc;

NoOfTxAntenna = 4;

txarray = phased.ULA('NumElements',NoOfTxAntenna,'ElementSpacing',lambda/2);

steer_ang = [25;0];

stv = phased.SteeringVector('SensorArray',txarray);

w = stv(fc,steer_ang);

figure,

pattern(txarray,fc,[-180:180],0,...

'PropagationSpeed',c,...

'CoordinateSystem','polar',...

'Type','powerdb', ...

'Weights',w)

Currently the beam pattern is as shown below.

Many thanks

Answer 1

[Suraj Kumar]

Hi Zain,

To steer the beam pattern of a Uniform Linear Array (ULA) to 25° and -25°, go through the following steps:

1. Define the required parameters and create a Uniform Linear Array using the “phased.ULA” function.

c = 3e8; 
fc = 2e9; 
lambda = c/fc; 
NoOfTxAntenna = 4; 
txarray = phased.ULA('NumElements',NoOfTxAntenna,  'ElementSpacing', lambda/2); 

2. Initialize the steering angles for both directions allowing the beam pattern to rotate accordingly.

% Initialize steering angles 
steer_ang1 = [25; 0]; 
steer_ang2 = [-25; 0]; 

3. Create a steering vector object using the “phased.SteeringVector” function and compute the weights for the ULA.

stv = phased.SteeringVector('SensorArray', txarray); 
w1 = stv(fc, steer_ang1); 
w2 = stv(fc, steer_ang2); 

4. Plot the beam pattern for both the steering angles.

figure; 
pattern(txarray, fc, [-180:180], 0, ... 
    'PropagationSpeed', c, ... 
    'CoordinateSystem', 'polar', ... 
    'Type', 'powerdb', ... 
    'Weights', w1);  
figure; 
pattern(txarray, fc, [-180:180], 0, ... 
    'PropagationSpeed', c, ... 
    'CoordinateSystem', 'polar', ... 
    'Type', 'powerdb', ... 
    'Weights', w2); 

You can look at the output below for a better understanding:

To know more about “phased.ULA” and “phased.SteeringVector” functions, please go through the documentation below:

• https://www.mathworks.com/help/phased/ref/phased.ula-system-object.html
• https://www.mathworks.com/help/phased/ref/phased.steeringvector-system-object.html

Hope this works for you!