how to design radiation pattern of ideal dipole antenna

how to design radiation pattern of ideal dipole antenna in matlab.

Answer 1

[Chaitanya]

Hi @Syed Manaf Ali Shah,

To design the radiation pattern of an ideal dipole antenna in MATLAB, you can use the following code:

% Constants
c = physconst('LightSpeed'); % Speed of light
f = 2.4e9; % Frequency of operation (in Hz)
lambda = c / f; % Wavelength

% Define the range of theta and phi values
theta = linspace(0, pi, 100);
phi = linspace(0, 2*pi, 200);

% Calculate the radiation pattern
E_theta = abs(sin(theta)); % E-field component in the theta direction
E_phi = zeros(size(theta)); % E-field component in the phi direction (for a dipole antenna)

% Calculate the total E-field magnitude
E_mag = sqrt(E_theta.^2 + E_phi.^2);

% Convert the E-field magnitude to dB scale
E_mag_dB = 20*log10(E_mag);

% Convert theta and phi to meshgrid for 3D plotting
[theta_mesh, phi_mesh] = meshgrid(theta, phi);

% Convert spherical coordinates to Cartesian coordinates
x = E_mag .* sin(theta_mesh) .* cos(phi_mesh);
y = E_mag .* sin(theta_mesh) .* sin(phi_mesh);
z = E_mag .* cos(theta_mesh);

% Plot the radiation pattern in dB scale
figure;
surf(x, y, z, E_mag_dB, 'EdgeColor', 'none');
axis equal;
colorbar;
title('Radiation Pattern of Ideal Dipole Antenna');
xlabel('x');
ylabel('y');
zlabel('z');

In this code, the theta variable represents the elevation angle and phi represents the azimuth angle. You can adjust the f variable to set the frequency of operation for the dipole antenna.

The code calculates the E-field components in the theta and phi directions based on the ideal dipole antenna radiation pattern. It then calculates the total E-field magnitude and converts it to dB scale.

The meshgrid function is used to create a grid of theta and phi values for 3D plotting. The spherical coordinates are then converted to Cartesian coordinates (x, y, z) for visualization.

Finally, the radiation pattern is plotted using the surf function in MATLAB, with the E-field magnitude in dB scale represented by the color of the surface. The axis equal command ensures that the plot has equal scaling in all dimensions, and the colorbar function adds a colorbar to the plot. The title, xlabel, ylabel, and zlabel functions are used to label the plot.

You can run this code in MATLAB to visualize the radiation pattern of an ideal dipole antenna in 3D, with the E-field magnitude represented in dB scale.

Hope this helps!

Answer 2

[Umar]

Hi @Syed Manaf Ali Shah,

You mentioned, “how to design radiation pattern of ideal dipole antenna in matlab”

Please see my response to your comments below.

After reviewing the following mathworks documentations regarding dipole ante and radiation pattern at the links provided below,

https://www.mathworks.com/help/antenna/dipole-antennas.html

https://www.mathworks.com/help/antenna/ug/visualize-custom-radiation- patterns.htmlsearchHighlight=Radiation%20pattern%20&s_tid=srchtitle_support_results_1_Radiation%20pattern%20

Note: dipole requires Antenna Toolbox since I don’t have access to it in Matlab mobile.

Please follow step by step instructions listed below.

Creating a Dipole Antenna: First, you need to define the dipole antenna's properties, such as its length and width.

Calculating and Plotting Radiation Patterns: then compute and visualize the radiation pattern at a specific frequency.

Visualizing in Different Formats: Finally, explore how to display this data in both polar and rectangular coordinate systems.

Here’s the complete code with detailed explanations:

% Create a Dipole Antenna
d = dipole(Length=2, Width=0.05); % Creating a dipole with 2m length and 0.05m   width

% Display the antenna structure
show(d);

% Calculate Radiation Pattern
frequency = 70e6; % Frequency set at 70 MHz
figure;
pattern(d, frequency); % Plotting the radiation pattern

% Visualize in Polar Coordinates
theta = linspace(0, 360, 361); % Azimuth angles from 0 to 360 degrees
phi = linspace(0, 180, 181); % Elevation angles from 0 to 180 degrees

% Generate Electric Field Magnitude (MagE) for the dipole
MagE = patternAzimuth(d, frequency, theta); % Get azimuth pattern data

% Convert data into appropriate matrices for visualization
[Theta, Phi] = meshgrid(theta, phi);
MagE_matrix = reshape(MagE, [length(phi), length(theta)]);

% Plotting in Polar Coordinates
figure;
patternCustom(MagE_matrix, Phi(:), Theta(:), CoordinateSystem="polar");
title('3D Radiation Pattern in Polar Coordinates');

% Visualize in Rectangular Coordinates
figure;
patternCustom(MagE_matrix, Phi(:), Theta(:), CoordinateSystem="rectangular");
title('3D Radiation Pattern in Rectangular Coordinates');

% Optional: View Slices of Radiation Pattern
sliceAngles = [30, 60]; % Slices at specified elevation angles
figure;
for i = sliceAngles
  subplot(length(sliceAngles),1,i/30);
  patternCustom(MagE_matrix(:, i), Theta(:, i), Phi(:, i), ...
                CoordinateSystem="polar", Slice="phi", SliceValue=i);
  title(['Radiation Pattern Slice at Phi = ' num2str(i) ' Degrees']);
end

So, in above code example, d = dipole(Length=2, Width=0.05); initializes a dipole antenna with specified dimensions. Then, pattern(d, frequency); computes and displays the radiation pattern of the dipole at a given frequency (70 MHz). Afterwards, MagE stores electric field magnitudes which are reshaped for plotting in different coordinate systems. Finally, patternCustom function allows for flexible visualization of the radiation pattern either in polar or rectangular formats. Following this structured approach should provide you a clear pathway for designing and visualizing an ideal dipole antenna's radiation pattern using MATLAB's Antenna Toolbox. Feel free to modify parameters like frequency or dimensions based on your specific requirements!

If you have any further questions for us, please let us know.