# Cable - Capacitance, Resistance,inductance

Discussion in 'General Electronics Chat' started by vineo763, Oct 2, 2006.

1. ### vineo763 Thread Starter Member

Aug 13, 2006
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Cables often have specifications such as resistance, inductance, and capacitance. Does anyone know how I should measure these specifications? Is it as simple as using a multimeter?

2. ### Papabravo Expert

Feb 24, 2006
10,140
1,789
Cable parameters cannot in general be measured with a multimeter. Since they are distributed paramaters capacitance, inductance and resistance are usually measured per unit of length. DC resistance of a conductor can be measured with a multimeter but that measurement is of little practical value since we are generally more interested in the cable parameters as a function of frequency.

The top of the line instrument to measure cable parameters is a network analyzer; it is a pricey bit of gear. There are also a variety of other instruments that take more work but yield similar results.

3. ### bhavesh96el Member

Apr 24, 2006
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Papabravo.. I did understand what you said that cable parameter is function of frequency.

But i didn't understand is how can we measure the capacitance and inductance of cable using network analyser ?

From frequency response impedance Z can be derived

but then how can we derive capacitance and inductance?

I guess we can say the attenuation dB/m using Network Analyser.

REgards

4. ### bhavesh96el Member

Apr 24, 2006
11
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Papabravo,

I understood that cable parameter is frequency dependant.

Frequency respone,obtained from Network Anaylser, can be used to derive impdance (Z) of the cable.

However, I can not figure out how can we obtain Capacitance and Inductance from it ?

Regards
Bhavesh

5. ### CATV Member

Apr 17, 2007
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Using a network analyzer, you can get the output presented in a Smith Chart format which will show you the capacitaive and inductive compnents of the transmission line. Call Comm/Scope in Hicory NC and they will give you more details.

6. ### Tube Tech Active Member

Jan 11, 2007
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With a tape measure. The paramaters you describe are listed in picofarads per 100 feet, et cetera. Measure and calculate.

7. ### thingmaker3 Retired Moderator

May 16, 2005
5,072
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With good cable, we don't need a tape measure. Footage should be printed on the cable every one or two feet.

Network analysers are expenisve to buy, but there are many places where such can be rented.