I am trying to understand how to draw nyquist plot.(adsbygoogle = window.adsbygoogle || []).push({});

Lets say the transfer function is

Subbing in jω for s,

***Note: should be (jw)^4 , (jw)^3, (jw)^2

Then separating the Real and Imaginary part,

So when

w = 0, in the nyquist plot it is infinity

w = infinity, it is 0

Imaginary intercept is 1.25

For real intercept I am not sure. Since imaginary part is 0 only when w is infinity, i plug in infinity for w in real part. Would the real intercept be infinity or 0? It would be infinity/infinity but numerator is lower order than higher order so would it be 0 instead?

In any case, how am i supposed to plot the rough nyquist plot or at least be able to determine the stability using these 4 points?

In Matlab the Nyquist plot comes out like this

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Nyquist Plot by hand

**Physics Forums | Science Articles, Homework Help, Discussion**