Methods for measuring cable path loss in RF Testing

Question

I have been reading about various methods to perform a Cable Path Loss for RF Testing but not being a core RF person, I needed some insights on how it is done in Field or Lab. Here is my understanding so far:

Method1: Signal Generator + Power Meter Generate about 0 dBm of power from the Signal Generator and measure the same on the Power Meter e.g. assuming 10 dB pads + cable loss 5 dB = -15 dBm (this the total cable path loss).

Method2: Network Analyzer Connect the 2 ends of the paths to Port 1 & Port 2 of the Network Analyzer and measure the S21 parameter.

I kind of get the idea of Method 1 but do not understand the Method 2 much.

Answer 1

When you're using a network analyser to measure S21, it generates a signal on port 1, and receives a signal on port 2. S21 is a measurement of the ratio of those signals.

While a network analyser does much more than a signal source and power meter can (S21 is the complex ratio), for this cable loss application, if you display simply the magnitude of S21, you can regard it as a signal source and power meter in a single box.