The Zreal and -Zimaginary values plotted on a Nyquist plot are orthogonal. Bode is a plot of the vector quantities of impedance (phase and magnitude).

Hello Mohadeseh Rastgooy Deylami ,

I hope that you are doing well. Do you mean orthonormal rather than orthogonal?

Like Jacob Ketter stated earlier a Nyquist diagram represents the imaginary part of the impedance of your system -Im(Z) plotted against the real part of the impedance of your system Re(Z). For this diagram to be orthonormal you would need to work in a basis of equal unit vectors (1,1). I attached two figures to illustrate the difference.

The bode diagram represents the module of the impedance of your system (Z/ Ohm) or the phase (phase/°) plotted against the frequency (f/Hz) range of your system. It is then another way to describe the impedance of your system.

I hope my response was helpful.

Best regards,

Marie.

Thank you so much for your helpful comment Jacob Ketter and Marie Berthuel .

Dear Marie, are you talking about equalness of the scale for X,Y axes when you say orthonormal?