analyzer, which has an optional built-in low-noise receiver and a flexible,
switched test set, which greatly simplifies the measurement system, as
shown by the block diagram in Figure
4. This reduces the number of cables
and connections, helping to stabilize
the setup, and offers fewer opportunities for error. A photograph of the
setup is shown in Figure 5. The Maury tuner is controlled by a USB cable
plugged into the front of the PNA-X.
Since a fixed set of tuner states is
used for the entire frequency band,
the reflection coefficient pattern may
not be as ideal at some frequencies as
with the traditional method, depend-
ing on how the states are selected. For
example, Figure 6 shows the result of
selecting uniformly spaced mechanical
tuner states. The pattern is fine at one
frequency (left chart), but very poor at
another frequency (right chart).
high end of the band. As the frequency
varies, the points rotate, but a good pattern is maintained at all frequencies.
The pattern does use about 50 percent
more points than typically used in a
traditional noise parameter measurement, but that still allows two orders of
magnitude speed improvement.
The new method may be done in
multiple frequency bands with tuners that have frequency-banded mismatch probes. For the examples in
this article, the data was taken with
a Maury tuner model MT982EU30.
The low frequency mismatch probe
covered 0.8 to 2.8 GHz; the high fre-
0.8000 GHz F1
1.7000 GHz F1
2.7000 GHz F1
s Fig. 7 Non-uniform spacing of tuner states
provides good patterns across frequency.