# How do I find the w-axis intercepts of a Bode Plot?

I'm looking at this example here, and am using the additive method to plot my bode plots.

To help me draw more accurate plots, I was wondering whether there is an easy way to find all $0 dB$ points?

Doing this question for example:

$H(s) = -10\frac{s}{(s+1)^2 (\frac{s}{10} + 1)}$

I'd need to find all points where $|H(s)| = 1$

so I compute $|H(s)| = |10| \frac{w^2}{(w^2 + 1)\sqrt{0.01w^2+1}} = 1$ which is not easy to solve at all.

How do I go about doing this?

• Why would finding the points with magnitude 1 help with creating a more accurate bode plot? These points depend on the overall scaling factor (20 in your case), which doesn't influence the shape of the plot at all, just its position relative to the 0dB line... – fgp Feb 18 '14 at 13:46
• Since 20 log mag 1 = 0? And the w at which this occurs would be your intercept, correct? – Louis93 Feb 18 '14 at 14:52