Code:

%% Parameters

R = 10; % Resistance

L = 0.1; % Inductance

C = 0.01; % Capacitance

%% Frequency range

f = linspace(1, 100, 1000); % Frequency range

%% Impedance calculation of the circuit

Z = R + 1i*(2*pi*f*L - 1./(2*pi*f*C));

%% Plot impedance magnitude

figure;

semilogx(f, abs(Z));

xlabel('Frequency (Hz)');

ylabel('Impedance Magnitude (\Omega)');

title('Circuit Model for Cavity Impedance');

grid on;

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% Define parameters

L = 1e-6; % Inductance of the cavity (in Henry)

C = 1e-9; % Capacitance of the cavity (in Farads)

R = 0.01; % Resistance in the cavity (in Ohms)

L_feed = 5e-8; % Inductance of the feed structure (in Henry)

C_feed = 2e-12; % Capacitance of the feed structure (in Farads)

R_load = 5; % Load resistance (in Ohms)

f0 = 1 / (2 * pi * sqrt(L * C)); % Resonant frequency of the cavity (in Hertz)

% Frequency range

f = linspace(0.1 * f0, 2 * f0, 1000);

% Impedance of the equivalent circuit

Z_cavity = R + 1j * (2 * pi * f * L - 1./(2 * pi * f * C));

Z_feed = R + 1j * (2 * pi * f * L_feed - 1./(2 * pi * f * C_feed));

Z_total = Z_cavity + (R_load * Z_feed) ./ (R_load + Z_feed);

% Plot impedance magnitude

figure;

semilogx(f, abs(Z_total));

xlabel('Frequency (Hz)');

ylabel('Impedance Magnitude (\Omega)');

title('Equivalent Circuit Impedance Magnitude of Resonant Cavity with Feed Structure');

grid on;