The impedance of a cable supposing it had infinite length. It is equal to the value of the terminator resistor that should be used. The characteristic impedance is not the same as the cable's DC resistance.

A compound measurement of the resistance, inductance, conductance and capacitance of a transmission line expressed in ohms.

In a transmission cable of infinite length, the ratio of the applied voltage to the resultant current at the point the voltage is applied, or the impedance, which makes a transmission cable seem infinitely low, when connected across the cable's output terminals. For a wave-guide, it is the ratio of voltage to the current at certain points on a diameter, when the wave-guide is match-terminated.

the designed impedance of a cable.

The impedance characteristic (measured in ohms) of a device in the signal path. This device can be a cable, a connector, the input of an amplifier or its output.

The ratio of voltage to current of a conducted RF signal, at a point on the conductor.

The terminal impedance that a transmission line tends towards as its length tends to infinity.

A way of measuring a cable or wires resistance to current while assuming the wire is of infinite length.

The ratio of voltage to current at any point along a transmission line on which there are no standing waves.

A value of impedance (resistance and reactance) of a transmission line measured over a frequency range that would exist if the line were infinite in length. A transmission line of finite length will have perfect power transmission, allowing for absorptive transmission losses, if driven and terminated by an exact conjugate matching load impedance. An inexact match will cause reflections that increase transmission loss.

The impedance of a circuit that, when connected to the output terminals of a uniform transmission line of arbitrary length, causes the line to appear infinitely long. Note 1: A uniform line terminated in its characteristic impedance will have no standing waves, no reflections from the end, and a constant ratio of voltage to current at a given frequency at every point on the line. Note 2: If the line is not uniform, the iterative impedance must be used. For Maxwell's equations, the impedance of a linear, homogeneous, isotropic, dielectric propagation medium free of electric charge, given by the relation Z=(ì/.)1/2 where ì is the magnetic permeability and . is the electric permittivity of the medium.

The iterative (surge) impedance of a transmission line or an attenuator network equivalent to that which would prevail for a line of infinite length.

The impedance at which a transmission line transfers its power most efficiently, without reflection or standing wave.

The termination impedance of an electrically uniform transmission line.

Characteristic impedance of a uniform line is the ratio of an applied dynamic potential difference to the resultant current at the point where the potential difference is applied between signal conductor and its ground return conductor, when the line is of infinite length. Note that the term is applied only to a uniform line. It is an important transmission line parameter that characterizes the line's similarity to some other line, (a connector, e.g.) where a mismatch in characteristic impedance between the system transmission line and the connector implies the latter as a discontinuity creating reflection noise and signal rise time degradation, respectively. See also Zo, Connector Discontinuity, Signal Rise Time Degradation.

The ratio of an applied potential difference to the resultant current at the point where the potential difference is applied, when the line is of infinite length. The term applies only to uniform lines such as coaxial cable.

The characteristic impedance or surge impedance Z_0 of a uniform transmission line is the ratio of the amplitudes of a single pair of voltage and current waves propagating along the line in the absence of reflections. The SI unit of characteristic impedance is the ohm. A transmission line terminated at one end with its characteristic impedance will appear infinitely long to a source at the other end.