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I am trying to design the Powerline Communication (PLC) module JUST for the 5-socket power strip (for demo purpose). So, I only care about the powerline network for those 5-sockets only. However, I need to know the transfer characteristics of the power strip lines so that I can choose the optimum frequency band for modulation. What is the best way to conduct this experiment so I can have a transfer characteristics of the copper plates (Line to Neutral) in the power strip? What I want is the impulse response in frequency domain up to 500 MHz. How do I do that in lab? I have a frequency generator (square, pulse, sine, sawtooth) etc and 5Ghz BW agilent oscilloscope.

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  • \$\begingroup\$ That won't tell you that one of the plugs in the strip has total signal cancellation due to standing waves up and down the AC wiring due to mismatches. \$\endgroup\$
    – Andy aka
    May 11, 2015 at 9:31

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Look for something called a Line Impedance Stabilisation Network, or LISN. You'll find a circuit diagram for it in MIL-STD-461.

It's essentially a diplexer, a high pass filter for signals above a few kHz, and a low pass for the mains current at 50/60 Hz.

The Stabilisation part of it is that it isolates the circuit under test from the (presumably very low, and unknown) impedance of the mains supply.

In your case you'd turn it around and use it to isolate the load, and feed the RF into the mains.

I don't think the LISN goes as high as 500 MHz, but up there the mains impedance is irrelevant. You can just disconnect the power and test it directly with your equipment. To be thorough, try a few different power extension leads on the power strip, to get an idea of the range of values you can expect in practice.

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Here's a paper describing one approach. Essentially, they just hooked up a network analyzer to the distribution network with a highpass filter to cut out the mains. From that, they were able to generate S-parameters characterizing the distribution network. You could probably do something similar.

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