Post subject: Regarding Cable Loss
Thu Jun 16, 2005 11:38 pm
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!
Post subject: Cable
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)
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.
that cable loss is a function of frequency, so measure at the frequency
or frequencies that you're interested in.
Post subject: Regarding Cable
Unread postPosted: Fri Jun 17, 2005 1:45 pm
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.