How to set frequency in matlab

[jagan_kumar_v]

Question?
for a short-circuit transmission line of l=10cm. determine the the expression to calculate the magnitude of the input impedance. Use MATLAB to draw magnitude plot when the frequency is swept away from f=1GHz to 3GHz. the line parameters are: L=209.4nH/m and C=119.5pF/m.

My MATLAB coding for this solution:

L=209.410e-9;
c=119.510e-12;
vp=1/sqrt(L*C);
Z0=sqrt(L/C);
l=0.1;
N=5000;
f=1e9+3e9*(0:N)/N;
Z=tan(2*pi*f*d/vp);
axis([1 3 0 500])

i am not sure whether i have set the frequency in the coding correctly, can anyone pls chk this for me thanks...

 

[Aaron Bex]

The correct MATLAB coding for this solution is:
L=209.410e-9;
C=119.510e-12;
vp=1/sqrt(L*C);
Z0=sqrt(L/C);
l=0.1;
N=5000;
f=linspace(1e9,3e9,N);
Z=Z0*tanh(2*pi*f*l/vp);
plot(f,abs(Z));
title('Input Impedance of Short-circuit Line');
xlabel('Frequency (Hz)');
ylabel('Impedance (Ohm)');
axis([1 3 0 500])

 

[oswaler]

Your coding looks correct for setting the frequency range from 1GHz to 3GHz. However, it would be helpful to also include a plot command to actually plot the magnitude of the input impedance versus frequency, as that is the main objective of the task. Additionally, you may want to double check the values of the line parameters and make sure they are in the correct units (e.g. L should be in units of H/m and C should be in units of F/m). Overall, your approach seems reasonable and should provide the desired result.