Plotting the Nyquist Diagram - Stuck

thomas49th

1. The problem statement, all variables and given/known data
http://gyazo.com/8187e80897fe361d555dbb9e5399366d

Okay, quite stuck here. Spent a few hours with the notes and tried some websites, but I'm still not confident in plotting Nyquist Diagrams
2. Relevant equations
N = Z-P


3. The attempt at a solution
Well, at w=0, gain is -2 and at w= ∞ gain = 0.

We also have a pole at s=0.5 in the right half plane... so P=1, correct? As we have an unstable pole?

As for the phase it goes from 0 to -90°. WHY is calculating the phase important, where is this show on the Nyquist plot!?


Do I now have enough information to draw it?
How would you go about drawing it?

How do I know what values to the j-axis should take? How do I know if it's meant to loop around under the real axis and back up to (0,0)

Many Thanks
Thomas


Answers:
http://gyazo.com/da99d7751508263c497af7270010228f