How can I generate a simple azimuth polar plot using antenna weights for beam steering?

Hi there,

I am trying to generate a simple polar plot of beam steering in the azimuth direction. Using the phased array toolbox I have generated an 8 element array, and calculated the weights to steer the beam to a direction of 30 degrees. I am only trying to direct the angle. However, when I pass the weights into the pattern Azimuth function, the beam is not correctly steered. Could I please have some advice on this?

Thank you :)

M = 8;
w = zeros(M, 1);
fc = 500000000;
d = (1/fc)/2;
deltad = 0.5;
c = physconst('LightSpeed');
element = phased.ShortDipoleAntennaElement();
array = phased.ULA('NumElements',M,'ElementSpacing',d,'Element',element);

for m=0:M-1
    w(m+1) = exp(-j*2*pi*m*deltad*cos(pi/6));
end

patternAzimuth(array,fc,'Weights', w)

Answer 1

[Zuber Khan]

Hi,

I understand that you want to steer a beam in a specific direction using a uniform linear array (ULA) in MATLAB. It is crucial to ensure that the weights applied to the array elements are correctly computed to achieve the desired steering angle.

Kindly note that the wavelength should be computed using speed of light. Further, you can specify the frequency range in "phased.ShortDipoleAntennaElement" function.

I have attached the modified code as follows:

M = 8; % Number of elements
fc = 500e6; % Carrier frequency (500 MHz)
c = physconst('LightSpeed'); % Speed of light
lambda = c / fc; % Wavelength
d = lambda / 2; % Element spacing (half wavelength)
steering_angle_deg = 30; % Desired steering angle in degrees

% Create the array
element = phased.ShortDipoleAntennaElement('FrequencyRange',[fc-1e6 fc+1e6]);
array = phased.ULA('NumElements', M, 'ElementSpacing', d, 'Element', element);

% Calculate the steering vector for 30 degrees
steering_angle_rad = deg2rad(steering_angle_deg); % Convert to radians
w = exp(-1i * 2 * pi * d * (0:M-1).' * cos(steering_angle_rad)/lambda);

% Plot the beam pattern
patternAzimuth(array, fc, 'Weights', w);

You can rotate the plot by changing the values of 'steering_angle_deg' in above code.

I hope it addresses your concerns.

Regards,

Zuber