6 research outputs found
Symmetric-Reciprocal-Match Method for Vector Network Analyzer Calibration
This paper proposes a new approach, the symmetric-reciprocal-match (SRM)
method, for calibrating vector network analyzers (VNAs). The method involves
using multiple symmetric one-port loads, a two-port reciprocal device, and a
matched load. The load standards consist of two-port symmetric one-port
devices, and at least three unique loads are used. However, the specific
impedances of the loads are not specified. The reciprocal device can be any
transmissive device, although a non-reciprocal device can also be used if only
the one-port error boxes are of interest. The matched load is fully defined and
can be asymmetric. We numerically demonstrated the proposed method's accuracy
with synthetic data and with measurements of coaxial standards using a
commercial short-open-load-reciprocal (SOLR) calibration kit with verification
standards. An advantage of the proposed method is that only the match standard
is defined, whereas the remaining standards are partially defined, either
through symmetry or reciprocity.Comment: GitHub: https://github.com/ZiadHatab/srm-calibratio
Indirect Measurement of Switch Terms of a Vector Network Analyzer with Reciprocal Devices
This paper presents an indirect method for measuring the switch terms of a
vector network analyzer (VNA) using at least three reciprocal devices, which do
not need to be characterized beforehand. This method is particularly suitable
for VNAs that use a three-sampler architecture, which allows for applying
first-tier calibration methods based on the error box model. The proposed
method was experimentally verified by comparing directly and indirectly
measured switch terms and performing a multiline thru-reflect-line (TRL)
calibration.Comment: GitHub: https://github.com/ZiadHatab/vna-switch-term
Propagation of Linear Uncertainties through Multiline Thru-Reflect-Line Calibration
This study proposes a linear approach for propagating uncertainties in the
multiline thru-reflect-line (TRL) calibration method for vector network
analyzers. The multiline TRL formulation we are proposing applies the law of
uncertainty propagation as outlined in the ISO Guide to the Expression of
Uncertainty in Measurement (GUM) to both measurement and model uncertainties.
In addition, we conducted a Monte Carlo analysis using a combination of
measured and synthetic data to model various uncertainties, such as additive
noise, reflect asymmetry, line mismatch, and line length offset. The results of
our linear uncertainty formulation demonstrate agreement with the Monte Carlo
method and provide a more efficient means of assessing the uncertainty budget
of the multiline TRL calibration.Comment: GitHub:
https://github.com/ZiadHatab/uncertainty-multiline-trl-calibratio
An Impedance Transition Method to Verify the Reference Impedance of Multiline TRL Calibration
In this paper, we present a new technique for assessing the validity of the
reference impedance in multiline thru-reflect-line (mTRL) calibration. When
performing an mTRL calibration, it is assumed that all transmission line
standards exhibit the same characteristic impedance. As a result, the reference
impedance after calibration is set to the characteristic impedance of the
transmission line standards used in the calibration. However, because of
imperfections, these assumptions are prone to errors. The purpose of this paper
is to assess the validity of the reference impedance after an mTRL calibration.
The method we propose uses the reflection coefficient of an impedance
transition segment as a verification metric. The verification is achieved by
performing two mTRL calibrations. The first mTRL calibration is the one we
desire to validate, while the second mTRL calibration is based on step
impedance lines that create the impedance transition. We conclude that the mTRL
calibration is valid if the resulting reflection coefficient falls within the
expected 95% confidence interval. We demonstrate our proposed method with
printed circuit board (PCB) measurements of microstrip lines up to 150 GHz. The
advantage of our approach is that the reflection coefficient of an impedance
transition is almost constant with respect to frequency for many types of
transmission line, which makes this validation metric easy to interpret when
errors are present.Comment: Code on github:
https://github.com/ZiadHatab/verification-multiline-trl-calibratio
A Thru-free Multiline Calibration
This paper proposes a modification to the traditional multiline
thru-reflect-line (TRL) or line-reflect-line (LRL) calibration method used for
vector network analyzers (VNAs). Our proposed method eliminates the need for a
thru (or line) standard by using an arbitrary transmissive two-port device in
combination with an additional reflect standard. This combination of standards
allows us to arbitrarily set the location of the calibration plane using
physical artifacts. In contrast to the standard multiline TRL method, the
suggested approach avoids a post-processing step to shift the calibration plane
if a line standard is used. We demonstrate our proposed method with
measurements on a printed circuit board (PCB) and compare it to the multiline
TRL method with a perfectly defined thru.Comment: GitHub: https://github.com/ZiadHatab/thru-free-multiline-calibratio
Propagation Constant Measurement Based on a Single Transmission Line Standard Using a Two-Port VNA
This study presents a new method for measuring the propagation constant of transmission lines using a single line standard and without prior calibration of a two-port vector network analyzer (VNA). The method provides accurate results by emulating multiple line standards of the multiline calibration method. Each line standard was realized by sweeping an unknown network along a transmission line. The network need not be symmetric or reciprocal, but must exhibit both transmission and reflection. We performed measurements using a slab coaxial airline and repeated the measurements on three different VNAs. The measured propagation constant of the slab coaxial airline from all VNAs was nearly identical. By avoiding disconnecting or moving the cables, the proposed method eliminates errors related to the repeatability of connectors, resulting in improved broadband traceability to SI units