impedance matching

[flamy78]

Does anybody have a good web resource they know of to explain what is going on in impedance matching pads?

Examples of what I'm talking about in the 3336B procedure. I was able to make sense of one of them but not the others. One is a parallel network for the most part and doing product/sums gives me the impedance i'm matching but I really don't know what is going on.

You have two outputs which are 124 ohms "balanced"
another 75 ohms "unbalanced" .

I don't need to understand this but seeing as how somebody decided you need a 62 ohm resistor here and a 352.8 ohm resistor there ( just pulling numbers out of the air) its based on some principle.