How to plot s11(dB) Vs frequency of patch antenna in MATLAB Without using antenna toolbox ?

I want to plot S11(db)Vs frequecy without using antenna toolbox.

Answer 1

[AR]

Hi @sraddhanjali mohapatra,

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:

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

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

Hope this is helpful!