You can compute and plot the 𝑆11 parameter versus frequency without using the Antenna Toolbox in MATLAB by following these steps:
1. Set up the frequency vector over which you want to compute 𝑆11.
f = linspace(1e9, 10e9, 1000); % Example: 1 GHz to 10 GHz
2. Compute S11 using the formula:
where Z is the characteristic impedance (in ohm).
% Define antenna impedance (example: varying impedance over frequency)
Z0 = 50;
Z = 75 - 10j * (f / 1e9); % Example impedance function
% Calculate Reflection Coefficient S11
S11 = (Z - Z0) ./ (Z + Z0);
3. Convert S11 to dB.
S11_dB = 20 * log10(abs(S11));
4. Plot S11 vs Frequency.
plot(f / 1e9, S11_dB, 'b', 'LineWidth', 2);
Refer the below links for more information on “linspace” and “plot” functions:
Hope this is helpful!
