Metrology and modelling of high frequency probes
Date
2008-03
Authors
Badenhorst, J.
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
This study investigates high frequency probes through good metrology and
computation software such as CST. A factor that can strongly influence the accuracy
of measurements, is common mode (CM) current. Therefore, the main focus of this
project was the CM current on the outside of an SMA, flanged, probe used for
measuring material properties.
In the course of the investigation, a clamp-on CM current probe (CP) was
calibrated using a CST model and good measurements. This calibration data
indicated that the CP was invasive on the measurement setup and could not deliver
the accuracy required for the CM current measurement.
In light of this, a second method was implemented where the material probe
was placed within a cylindrical shield. A cavity was formed between the probe and
the walls of the shield in which the electric fields could be simulated and measured.
These field measurements allowed measurements to be conducted in both the time-
(TD) and frequency-domain (FD).
For the TD measurements, a sampling oscilloscope was used. As the basic
principle of a sampling oscilloscope differs from its real-time counterpart, this
principle, as well as the systematic errors associated with these devices, was
explored.
The results of the final measurements indicated that the TD results were within
an acceptable range of both the FD results, measured on the VNA, and the results
predicted by CST. This study shows that CST can be used to simulate complex
measurement setups and deliver reliable results in cases where an accurate
measurement cannot be guaranteed.
Description
Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008.
Keywords
Metrology, Current probes, Sampling oscilloscope, CST modelling, Dissertations -- Electrical and electronic engineering, Theses -- Electrical and electronic engineering