ABCD transformation to S matrix (RF Engineering)

Discussion in 'Homework Help' started by Ledwardz, Apr 27, 2014.

Oct 31, 2010
37
2
Hey guys,

the question is on the attachement. I am a little stuck on part b

my answers to part a for the ABCD is

A = 1
B = 0
C = 1/Z
D = 1

and for the S parameters i have

S11 = S22 = -Y/ 2 + Y
where Y, the admittance is normalised - i.e. it is Y = yZ0 = Z0/Z
S12 = S21 = 2/2+Y

anyways, moving on to part b.

I think the question wants me to show the derivation from ABCD to S parameters. i have done this for S11 and S22 which is also shown in the attachements. My question is how do i do this for S12 and S21??

I also dont know what the question is getting at when it asks for the impedance and power loss advantages and disadvantages seperately, mayb i am reading the question wrong? it isn't very well worded? I assume this refers to transduer and insertion losses which can both be calculated in terms of ABCD and S parameters??? soooo yeh no idea what this wants?

anyways, any help appreciated.

Thanks,

Lee.

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2. t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
This may provide some insights

http://www.home.agilent.com/agilent/editorial.jspx?ckey=1000002126:epsg:faq&id=1000002126:epsg:faq&nid=-11143.0.00&lc=eng&cc=AU

Also one could consider what 's' parameters mean in each case.

For example s21 is the forward transmission coefficient and is useful in relation to comparative power transmission ....

$\text{{|s_{\small{21}}|}^{\ \small{2}}=\frac{Power \ delivered \ to \ port2}{Power \ delivered \ by \ V_{gen}}}$

What might one say about s12 in a similar context?

Last edited: Apr 27, 2014