Allice Messtechnik R&S ZND, User Manual, Page: 112 / 1252

Concepts and features
R&S
®
ZND
112 User Manual 1173.9557.02 ─ 61













 
 
 






i
i
i i i i
i i i i
i i
i
i
b
a
Z Z Z Z
Z Z Z Z
Z Z
b
a
0
0
1 0 1 0
1 0 1 0
1 0
1
1
) Re( ) Re( 2
1
The renormalized S-matrix S1 is calculated as:
 
 
A S E S A S
1
0 0
1
1

     
with the unit matrix E and two additional matrices with the elements
i i
i i
ii
Z Z
Z Z
0 1
0 1


 
ii ii
ii
ii
ii
A
  
 
 

1
1
1
4.3.3 Impedance parameters
An impedance is the complex ratio between a voltage and a current. The analyzer pro-
vides two independent sets of impedance parameters:
●
Converted impedances (each impedance parameter is obtained from a single S-
parameter)
●
Z-parameters (complete description of an n-port DUT)
4.3.3.1 Converted impedances
The converted impedance parameters Z
ij
(1 ≤i,j ≤n) describe the input impedances of
an n-port DUT with fully matched outputs. The analyzer converts a single measured S-
parameter S
ij
to determine the corresponding converted impedance, under the
assumption that each of the other ports is terminated with its respective reference
impedance Z
0k
(matched-circuit parameters). As a result, converted impedances can-
not completely describe general n-port DUTs.
With a unidirectional R&S ZND (see Chapter 4.1.4.3, "R&S ZND: unidirectional vs.
bidirectional operation" , on page 80) "reverse direction" converted impedances Z
i2
can-
not be measured.
The Converted admittances are defined as the inverse of the converted impedances.
Reflection impedance
The converted impedance Z
ii
(1 ≤ i ≤n) describes the input impedance at port i of the
DUT.
Measurement results
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