Generate approximate antenna field pattern usign Beamwidth and FBR

The inputs to the process are

* the antenna beam width in the horizontal and vertical planes

* the front-back ratio

Resulting in two Matlab programs:

* a program to estimate the ADF file from the simpler data

* a program to plot the horizontal and vertical fields from an ADF file.

Answer 1

[AR]

Hi @Syed Muhammad Umar,

Here is my attempt to plot the horizontal and vertical fields from an ADF file:

• The function “estimateADF” takes the horizontal and vertical beam widths along with the front-back ratio as inputs. It creates a structure with these parameters and generates field patterns using a Gaussian model. The data is then saved as an ADF file.

function estimateADF(horizontalBeamWidth, verticalBeamWidth, frontBackRatio, outputFileName)
    % Create a simple ADF structure
    adfData = struct();
    adfData.horizontalBeamWidth = horizontalBeamWidth;
    adfData.verticalBeamWidth = verticalBeamWidth;
    adfData.frontBackRatio = frontBackRatio;
    % Estimate pattern data (simple Gaussian model)
    adfData.pattern = createPattern(horizontalBeamWidth, verticalBeamWidth, frontBackRatio);
    % Save the ADF data to a file
    save(outputFileName, '-struct', 'adfData');
    fprintf('ADF file estimated and saved as %s\n', outputFileName);
end
function pattern = createPattern(horizontalBW, verticalBW, fbr)
    % Generate pattern data using a Gaussian model
    theta = linspace(0, 360, 360); % 0 to 360 degrees
    phi = linspace(0, 180, 180);  % 0 to 180 degrees

    % Gaussian pattern for horizontal and vertical planes
    pattern.horizontal = exp(-((theta - 180).^2) / (2 * (horizontalBW / 2)^2));
    pattern.vertical = exp(-((phi - 90).^2) / (2 * (verticalBW / 2)^2));

    % Apply front-back ratio as a simple scaling factor
    pattern.horizontal = pattern.horizontal * (1 / (1 + fbr));
    pattern.vertical = pattern.vertical * (1 / (1 + fbr));
end

• The function plotADF reads the ADF file and visualizes the horizontal and vertical field patterns.

function plotADF(adfFileName)
    % Load the ADF data
    adfData = load(adfFileName);
    % Plot horizontal pattern
    figure;
    subplot(2, 1, 1);
    plot(1:360, adfData.pattern.horizontal);
    title('Horizontal Field Pattern');
    xlabel('Degrees');
    ylabel('Magnitude');
    grid on;
    % Plot vertical pattern
    subplot(2, 1, 2);
    plot(1:180, adfData.pattern.vertical);
    title('Vertical Field Pattern');
    xlabel('Degrees');
    ylabel('Magnitude');
    grid on;
end

• Type the below command in the MATLAB Command Window to run the program:

estimateADF(60, 30, 20, 'antenna_adf.mat');%60: Horizontal beam width in degrees. %30: Vertical beam width in degrees. %20: Front-back ratio 

ADF file estimated and saved as antenna_adf.mat

plotADF('antenna_adf.mat'); 

Output above shows the Gaussian-based antenna field patterns, with the horizontal field centered at 180° (0°–360°) and the vertical field at 90° (0°–180°). The symmetry and scaling reflect the beam widths and front-back ratio.

For reference, below are the links for few of the functions used in the program:

https://www.mathworks.com/help/matlab/ref/struct.html

https://www.mathworks.com/help/matlab/ref/double.linspace.html

https://www.mathworks.com/help/matlab/ref/double.exp.html

Hope it helps!