TDR, Cable, Wire, & Power Test, ECAD, - CM Technologies- Distributed Measurements

Distributed Measurements

Distributed element data are measured using time domain reflectometry (TDR). Analysis of the TDR data is enhanced by understanding that the distributed elements represent an r-f transmission line that has special properties at special frequencies. This allows circuit components to be separated in time and analyzed individually while measurements are made from a remote location.

By definition, an r-f transmission line is a system of material boundaries forming a continuous path and capable of directing energy along the path. In addition, an r-f line exhibits the following characteristics:

	Uniformity.
	Delay from input to output.
	Directs AC energy.
	All energy contained in dielectric.

Examples of typical transmission lines include parallel conductors, conductor over a ground plane and concentric coaxial conductors.

Incremental Segment
of Transmission Line

	R is the series ohmic resistance of the line. It includes both conductors and is defined in terms of ohms/unit length.
	L is the series inductance of the line. It also includes both conductors and is defined in terms of henries/unit length.
	C is the shunt capacitance due to the physical proximity of 2 or more conductors separated by a dielectric. Defined in terms of farads/unit length.
	G is the shunt conductance caused by less than infinite insulation resistance. Defined by the reciprocal of insulation resistance/unit length equal to siemens/unit length.

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