Transfer function G(s)= 2/(0.0625*s^2+0.1*s+1) phase calculation problem for ω>ωn

Question

I am trying to create a table of values and the bode plot for the tranfer function G(s)= 2/(0.0625*s^2 + 0.1*s + 1). However when i use values above ω{n} the the values of phase does not agree with the bode plot result of matlab or wolfram alpha. For example if ω=0.5, bode plot of wolfram gives arround Φ = -142deg but the calculation gives 41.633deg. The phase equation is: Φ(ω)= -arctan[0.1*ω/(1-ω^2/16)] []1 []2

Answer 1

You need to use a 4 quadrant arctan. In Excel, it is ATAN2(real, imag). For omega = 5, I get -138.37 deg.