Plotting the attenuation constant against frequency

Hello, I'm trying to plot the attenuation coefficient and phase coefficient against a frequency range. The values produced for a single freqency check out correct but my plots don't look similar to the characteristics curves that that I'm expecting from textbooks. Am I messing up the units or dimensions somewhere?

% Clear screen and variables
clc, clear all

% Define distributed parameters
R = 100;
L = 80e-9;
C = 200e-12;
G = 1.6;

% Define frequency range
low_freq = 1; % Enter low frequency here
high_freq = 1e7; % Enter high frequency here

% Calculate frequency axis
freq = low_freq:high_freq;

% Angular frequency
omega = 2*pi.*freq;

% Propagation coefficient
gamma = sqrt((R+(omega.*L*i)).*(G+(omega.*C*i)));

% Attenuation coefficient
alpha = real(gamma);

% Phase coefficient
beta = imag(gamma);

% Plot attenuation coefficient verses frequency
figure('units','pixels','position',[150 200 1000 600])%Set figure properties
plot (freq,alpha)
grid on
title('Attenuation Coefficient verses frequency')% Graph title
xlabel('Frequency (Hz)')% x axis label
ylabel('Attenuation Coefficient')% y axis label

% Plot phase coefficient verses frequency
figure('units','pixels','position',[150 200 1000 600])%Set figure properties
plot (freq,beta)
grid on
title('Phase Coefficient verses frequency')% Graph title
xlabel('Frequency (Hz)')% x axis label
ylabel('Phase Coefficient')% y axis label

[Mathieu NOE]

hello Vinci

I tested your code and double checked with equations found in

Propagation constant - Wikipedia

but seems to me your code is fine

what was the expect plot you're looking for ?

[Vinci]

Sorry about the late response. I was expecting something like this.

[Mathieu NOE]

So far I believe the input values are simply not compatible / coherent with this plot

you cannot have gamme as low as 2e-3 (max y value on this graph) with

R = 100;

L = 80e-9;

C = 200e-12;

G = 1.6;

Answer 1

[Abrham De La Torre]

12

Answer 2

[VBBV]

@Vinci Use smaller conductnce value, and semilogx for ploting graph

% Clear screen and variables
clc, clear all

% Define distributed parameters
R = 100;
L = 80e-9;
C = 200e-12;
G = 1.6e-12;  %  conductance valoue is small, 

% Define frequency range
low_freq = 1; % Enter low frequency here
high_freq = 1e7; % Enter high frequency here

% Calculate frequency axis
freq = low_freq:1:high_freq;

% Angular frequency
omega = 2*pi.*freq;

% Propagation coefficient
gamma = sqrt((R+(omega.*L*i)).*(G+(omega.*C*i)));

% Attenuation coefficient
alpha = real(gamma);

% Phase coefficient
beta = imag(gamma);

% Plot attenuation coefficient verses frequency
subplot(211)
semilogx((freq),alpha)
axis([min(freq), max(freq) min(alpha) max(alpha)])
title('Attenuation Coefficient verses frequency')% Graph title
xlabel('Frequency (Hz)')% x axis label
ylabel('Attenuation Coefficient')% y axis label

% Plot phase coefficient verses frequency
subplot(212)
semilogx(freq,beta)
axis([min(freq), max(freq) min(beta) max(beta)])
title('Phase Coefficient verses frequency')% Graph title
xlabel('Frequency (Hz)')% x axis label
ylabel('Phase Coefficient')% y axis label