Broadband Reflectometry: Theoretical Background - Broadband Reflectometry for Enhanced Diagnostics and Monitoring Applications - page 41

Fig. 3.13 Serpentine-
shaped probe [40]

Fig. 3.14 Schematic of
the longitudinal section
of a three-rod probe. The
section where the reference
standard impedances should
be connected is indicated

Indeed, the calibration procedure plays a major role in terms of minimization of
systematic errors, thus leading to a significant enhancement of the final measure-
ment accuracy. A viable alternative is to specifically design and realize the probe
that would suit the specific needs [39] and to realize the corresponding calibration
structure (as described for the application discussed in Sect. 4.3).

3.6 Strategies for Enhancing Accuracy in BMR Measurements

As well known, measurements are typically affected by both systematic and random
errors. The effects of systematic errors can be compensated for through appropriate
calibration procedures [28]. On the other hand, the residual random measurement
fluctuations (essentially due the environmental and operating conditions, noise, etc.)
are taken into account through a statistical analysis performed on a series of repeated
measurements.

3.6.1 Calibration Procedure in Time Domain

In TD measurements, since the information on the SUT is retrieved from direct mea-
surement of the apparent length of the probe immersed in the SUT, it is necessary to