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How much power loss in the coaxial cable? I transmitted a signal with 12dBm power and I connected through the coaxial cable to the oscilloscope. Cable Assembly Coaxial is RG-316 59.1" (1.5m) and DSAV084 digital signal analyzer/ oscilloscope. But I measured 12dBm power at the 4Ghz carrier frequency in the scope. For further processing, I need to connect the oscilloscope to another PC via ethernet cable. When I analyzed the signal in the software of that PC, I measured the output -4.52dBm

I think the cable loss is huge. Do you have any idea how I can minimize the loss in the cable?

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  • \$\begingroup\$ Any serious test would calibrate out the cable, and calibrate the instrument too. A network cable carrying data elsewhere for analysis shouldn't add loss to the signal being tested, but different evaluations might yield different results. Generally speaking, an oscilloscope is not a power measurement instrument in more than a rough sense. \$\endgroup\$ – Chris Stratton Oct 16 '17 at 21:27
  • \$\begingroup\$ Thanks for replying! Do you know any formula to calculate loss in the coaxial cable? \$\endgroup\$ – Mahfuza Khatun Muni Oct 18 '17 at 3:33
  • \$\begingroup\$ There's no simple formula - beyond a per unit length for a given frequency approximation when new, as it depends not only on the design of the cable, but its condition - moisture wicking in there can make it substantially worse, for example. \$\endgroup\$ – Chris Stratton Oct 18 '17 at 3:42
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M17/113-RG316 is not sweep-tested higher than 3 GHz. It does not have guaranteed characteristics at 4 GHz. The extrapolated insertion loss is about 56 dB / 100 ft at 4 GHz (~3 dB at 1.5 m).

To reduce measurement error, check your terminations, calibration, and make sure that the cable is not bent.

Do you have access to a network analyzer with proper test cables?

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  • \$\begingroup\$ Thanks for replying! I am using DSAV084A digital signal analyzer/ oscilloscope. I think the test cables are alright with this configuration. \$\endgroup\$ – Mahfuza Khatun Muni Oct 16 '17 at 21:23

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