immittance

That is, is the immittance divided by s.

It is convenient in these circumstances to use the concept of immittance which can mean either impedance or admittance.

The term immittance was invented by Bode.

The imaginary immittance of a passive, lossless one-port monotonically increases with frequency.

Immittance does not have units since it applies to both impedance and admittance, which have different units.

These circuits will have an immittance function with a phase of π/2 like a positive reactance but a frequency with a negative slope.

In electrical engineering and acoustics, immittance is a concept combining the impedance and admittance of a system or circuit.

Foster's theorem (immittance form)

A consequence of Foster's theorem is that the poles and zeroes of any passive immittance function must alternate with increasing frequency.

With the addition of a scaling factor, the poles and zeroes of an immittance function completely determine the frequency characteristics of a Foster network.

A couple of generalizations are sometimes made, with intention of characterizing the immittance functions of a wider class of passive linear electrical networks.

It is a general result that the dual of any immittance function that obeys Foster's theorem will also follow Foster's theorem.

Two Foster networks that have identical poles and zeroes will be equivalent circuits in the sense that their immittance functions will be identical.

In electronics, the "immittance" Smith chart simply has both the impedance and admittance grids on the same chart, which is useful for cascading series-connected with parallel-connected circuits.

Another consequence of Foster's theorem is that the plot of a Foster immittance function on a Smith chart must always travel around the chart in a clockwise direction with increasing frequency.

Examples of canonical forms are the realisation of a driving-point impedance by Cauer's canonical ladder network or Foster's canonical form or Brune's realisation of an immittance from his positive-real functions.