N port parameters

1. Aug 30, 2007

seang

In my previous classes we did just a bit of 2 port stuff. Where you shorted one port and then you just divided port 1's current by port 1's voltage and bam. Now we're starting to learn about n port microwave networks, and I really want to know what's going on. This post will probably be filled with questions so thanks in advance for any help.

Alright, so back to basics, lets just say I have a basic (low freq) 2 port network and I'm about to find the y parameters. Let's say I'm finding in particular y11. I divide port 1's current by port 1's voltage. What exactly have I found? You know? this is what's troubling me. I'm thinking since port 2 is shorted during measurement, y11 is the admittance of the network? That's all I can think of, and I am even more clueless for y12, y21, y22. I have no idea what these quantities mean or what they say about the network.

Now the other half of the puzzle...the equations:

I1 = (y11*V1) + (y12*v2)
I2 = (y21*V1) + (y22*v2)

I don't really understand these equations. I think I might have a better handle on them if i could get my head around the meanings of y11...y22. But if anyone can put these equations into words that would probably help alot.

Oh yeah, can anyone recommend a text on this kind of thing? my microwave texts assume i already know all this stuff really well, and my previous texts don't really cover the basics. i need something to cover the gap i guess.

2. Aug 31, 2007

Corneo

Ok I assume you know whats Z parameters.

y11 = I1/V1 (with V2 = 0, short port 2)

This represents the input admittance seen looking into port 1. Much like Z11 would be the input impedance seen looking into port 1.

y21 would be the transfer admittance seen looking from port 1 to port 2.

transfer admittance and transfer impedances makes more sense when you learn S - parameters.