One-Port Driving-Point Impedances

One-Port ``Black Box''

• Port state $s(t)$ determined by force $f(t)$ and velocity $v(t)$ $s(t) = \{f(t),v(t)\}$
• Exactly analogous to network theory for RLC circuits
• Velocity always positive flowing into device
• ``Network'' characterized by port impedance (admittance)
• $R(s) \isdef \frac{F(s)}{V(s)} = \hbox{impedance \lq\lq seen'' at port}$
• $R(s)$ also called the driving-point impedance
• $\Gamma(s) \isdef \frac{V(s)}{F(s)} = \hbox{\emph{driving-point admittance}}$