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Regarding Cable Loss - RF Cafe Forums
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Dreamer
Post subject: Regarding Cable Loss
Unread postPosted:
Thu Jun 16, 2005 11:38 pm
Hi all,
I had a question regarding
measuring cable loss, How to connect the equipments to calculate the
cable loss from one end of the cable to another if you have a Signal
Generator, Spectrum Analyser and Power meter. How should I connect the
cable to and what are the parameters Should I change to know the cable
loss.
Thanks in Advance!
Dreamer
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Guest
Post subject: Cable Loss Measurement
Unread postPosted:
Fri Jun 17, 2005 1:26 pm
Assuming you've got cable and equipment
with the same impedances (usually 50 Ohms):
1. Measure output
of signal generator with power meter
2. Insert significant length
of cable between signal generator and power meter.
3. Measure output
from cable
4. a. Cable loss (dB) = dBm(gen) - dBm(cable output)
b. Cable loss (fraction) = Pout(cable)/Pout(gen) powers in W, mw, etc.
Note that some power meters require external termination - you will,
of course, have to provide that.
An important point is that the
terminating impedance must be equal to the characteristic impedance
of the line for this simple method to work.
Remember that cable
loss is a function of frequency, so measure at the frequency or frequencies
that you're interested in.
Good luck.
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Dreamer
Post subject: Regarding Cable Loss
Unread postPosted:
Fri Jun 17, 2005 1:45 pm
Thank you very much,
Both impedances
are at 50 ohms also you have told to measure signal generator with power
meter, so mean just input some power from gen into meter and check the
reading on the power meter? for that frequency.
Thanks,
Dreamer.
Posted 11/12/2012
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