Specifications

B-2
Open measurement
When nothing is connected to the measurement terminals (open condition), I
2
is 0. Therefore,
equation (5) is derived by substituting I
2
= 0 for I
2
in the equation (2). Here, Zo means the impedance
measured with measurement terminals opened.
Zo =
AV
2
=
A
c C=
A (5)
CV
2
CZo
Short measurement
When the measurement terminals are shorted, V
2
is 0. Therefore, equation (6) is derived by substi-
tuting V
2
= 0 for V
2
in the equation (2). Here, Zs means the impedance measured with measurement
terminals shorted.
Zs =
BI
2
=
B
c B =DZs
(6)
DI
2
D
By substituting B = DZ
s
and C = A/Z
o
(of equations 6 and 5) for the parameters B and C, respectively,
of equation (4), the following equation is derived:
Zdut =
B – DZxm
=
B – DZxm
=
D(Zs – Zxm)
=
D(Zs – Zxm)
Z
(7)
CZxm – A
(
Zxm
– 1
)
A
(
Zxm
– 1
)
A
(Zxm – Zo)A
Zo Zo
Since the open/short compensation assumes that the unknown network circuit is a symmetrical net-
work, the parameters A and D are equal:
A = D (8)
Thus, equation (7) can be simplified as follows:
Zdut =
Zs – Zxm
Zo
(9)
Zxm – Zo
The definitions of the parameters used in this equation are:
Zdut Corrected impedance of the DUT
Zxm Measured impedance of the DUT
Zo Measured impedance when the measurement terminals are open
Zs Measured impedance when the measurement terminals are shorted
Note: These parameters are complex values that have real and imaginary components.