Agilent Technologies N4413A User Manual page 82

Using the Multiport Test System
How to Measure Simultaneous Conjugate Match of a Differential 2-Port Device
Pull down Data > User-Defined Display > View Equations... to open the Defined
Equations dialog box. Notice the listed formula for the differential stability factor display:
DSF=(1-ABS(SDD11)^2-ABS(SDD22)^2+ABS(D)^2)/(2*ABS(SDD12)*ABS(SDD21))
This translates to:
1
K = ------------------------------------------------------------------------
where:
D = S
72
2 2
– S – S + D
D D11 DD 22
⋅ ⋅
2 S S
DD 12 D D21
⋅ ( ⋅
S – S S
DD 11 DD22 DD 12
2
)
DD 21
Chapter 3