PE Power Question - Bode Plots

[firstoption]

Hey everyone.
I'd like some tips on bode plots. Here is an issue i have,


I haven't seen an example of a scenario like this:
H(s) = [1+(s/0.5)] / [1+(s/0.3)]
or
H(s) = [1-(s/5)] / [1-(s/3)]
or
H(s) = [1-(s/0.5)] / [1-(s/0.3)]

the issue here is the denominators have decimals and the terms have negative signs
Again, none of the examples i've seen or worked out had a situation like these and i'd like to know how they would be plotted
thanks

 

[xnuke]

There's no problem with a decimal, it's just a decimal value where the pole or zero is located.

The negative sign in the numerator or denominator indicates the zero or pole is in the right half of the complex plane. There is no effect on the magnitude plot, i.e., the pole or zero has the same magnitude effect, but the phase angle plots go the opposite direction from left-half plane poles or zeros. While a left-half plane pole has a -45°/decade slope for the two decades surrounding it and contributes a total of 90° of phase lag, a right-half plane pole has a +45°/decade slope for the two decades surrounding it and contributes a total of 90° of phase lead. While a left-half plane zero has a +45°/decade slope for the two decades surrounding it and contributes a total of 90° of phase lead, a right-half plane zero has a -45°/decade slope for the two decades surrounding it and contributes a total of 90° of phase lag.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[firstoption]

There's no problem with a decimal, it's just a decimal value where the pole or zero is located.

The negative sign in the numerator or denominator indicates the zero or pole is in the right half of the complex plane. There is no effect on the magnitude plot, i.e., the pole or zero has the same magnitude effect, but the phase angle plots go the opposite direction from left-half plane poles or zeros. While a left-half plane pole has a -45°/decade slope for the two decades surrounding it and contributes a total of 90° of phase lag, a right-half plane pole has a +45°/decade slope for the two decades surrounding it and contributes a total of 90° of phase lead. While a left-half plane zero has a +45°/decade slope for the two decades surrounding it and contributes a total of 90° of phase lead, a right-half plane zero has a -45°/decade slope for the two decades surrounding it and contributes a total of 90° of phase lag.

shoot, i'm gonna have to read this a few times with a plot in front of me. it's kinda hard to follow for me.
thanks for the reply

 

[xnuke]

I'll try to make it simpler:

Positive signs in the binomial terms, i.e., negative real parts, mean they lie in the Left-Half Plane (LHP):
LHP pole: magnitude slopes down at 20 dB/decade above pole frequency, phase slopes down at -45°/decade for the decade above and the decade below the pole frequency.
LHP zero: magnitude slopes up at 20 dB/decade above zero frequency, phase slopes up at +45°/decade for the decade above and the decade below the zero frequency.

Negative signs in the binomial terms, i.e., positive real parts, mean they lie in the Right-Half Plane (RHP):
RHP pole: magnitude slopes down at 20 dB/decade above pole frequency, phase slopes up at +45°/decade for the decade above and the decade below the pole frequency.
RHP zero: magnitude slopes up at 20 dB/decade above zero frequency, phase slopes down at -45°/decade for the decade above and the decade below the zero frequency.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.