marker in Fig.
) and the end reflection from the longer Microstrip
line (see right marker) are included.
•
The software automatically calculates and displays the dielectric con-
stant of the material in the result field of the
Main Window
.
Remark 1:
Result visualization is not available for this measurement
mode.
Remark 2:
The TTC is not mandatory but recommended for the mea-
surement mode.
6.6 Measurement Mode
ε
plus
(optional, not for DTDR-800)
This measurement mode is an optional software module for measuring the
frequency dependent dielectric properties
ε
r
(
f
)
of cores and prepregs as
well as the frequency dependent wave impedance
Z
0
(
f
)
. This mode is also
called
Advanced Line Parameter
mode.
The measurements are carried out according to the
ε
base
mode described in
the previous section
. The main difference between the two measure-
ment modes is buried in the greater complexity of the applied data process-
ing algorithms. It is essential to activate the
TTC
before measuring, because
the calculations of the resulting frequency domain data demand very accu-
rate measurements.
Furthermore, it is recommended to contact the Microstrip line via a coaxial
connector (e.g. Rosenberger 02K80A-40ML5). Thus accurate values can be
measured up to frequencies higher than 5 GHz. When using a single-ended
probe the frequency range is limited to less than 2.5 GHz, depending on the
used probe.
Please be aware, that at lower frequencies (below 500 MHz), which are in-
herently not in scope of the
ε
plus
mode, side effects due to the skin effect in
62