What are the different characteristic impedance cables commercially available?

[A.Anand Srinivasan]

i just want to know what are the different characteristic impedance cables commercially available.... i.e. like the 50Ω coax wire used with the CRO in the lab...

 

[sonal]

cable

The increasing use of electrical pulses in the transmission of data by cable has resulted in a need for a better understanding of the electrical characteristics of a cable.

Many system specifications state that the cables used shall have a certain characteristic impedance, specified in ohms. Any cable-maker's catalogue will list the characteristic impedance values of most coaxial cables, which usually range from 50 to 95 ohms. But impedance information on the more common types of shielded pairs is not readily available to the cable user. Why? Because there are too many variations of applications involved with these cables.

IMPEDANCE DEFINED

Let us examine characteristic impedance - what it is and what it is not - so that a better understanding of what the numbers mean and how they apply to our application can be derived.

Magnitude of Impedance

Ohm's Law states that if a voltage (E) is applied to a pair of terminals and a current (I) is measured in this circuit, the following equation can be used to determine the magnitude of the impedance (Z).