R&S
®
ZVL
System Overview
Basic Concepts
Quick Start Guide 1303.6538.62-01
81
3.1.7.2 Conversion of Complex into Real Quantities
The results to be selected in the
Trace –
Meas menu can be divided into two groups:
E
S-Parameters, Impedances, and Admittances are complex.
E
Stability Factors are real.
The following table shows how the response values in the different Cartesian diagrams
are calculated from the complex measurement values z = x + jy (where x, y, z are
functions of the sweep variable). The formulas also hold for real results, which are
treated as complex values with zero imaginary part (y = 0).
Trace Format
Description
Formula
dB Mag
Magnitude of z in dB
|z| = sqrt ( x
2
+ y
2
)
dB Mag(z) = 20 * log|z| dB
Lin Mag
Magnitude of z, unconverted
|z| = sqrt ( x
2
+ y
2
)
Phase
Phase of z
(z) = arctan (y/x)
Real
Real part of z
Re(z) = x
Imag
Imaginary part of z
Im(z) = y
SWR
(Voltage) Standing Wave Ratio
SWR = (1 + |z|) / (1 – |z|)
Group Delay
Group delay, neg. derivative of
the phase response
– d (z) / d ( = 2 * f)
